/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenkernel/intern/text.c
 *  \ingroup bke
 */

#include <stdlib.h> /* abort */
#include <string.h> /* strstr */
#include <sys/types.h>
#include <sys/stat.h>
#include <wchar.h>
#include <wctype.h>

#include "MEM_guardedalloc.h"

#include "BLI_utildefines.h"
#include "BLI_path_util.h"
#include "BLI_string.h"
#include "BLI_string_cursor_utf8.h"
#include "BLI_string_utf8.h"
#include "BLI_listbase.h"
#include "BLI_fileops.h"

#include "DNA_constraint_types.h"
#include "DNA_controller_types.h"
#include "DNA_actuator_types.h"
#include "DNA_scene_types.h"
#include "DNA_screen_types.h"
#include "DNA_space_types.h"
#include "DNA_text_types.h"
#include "DNA_userdef_types.h"
#include "DNA_object_types.h"
#include "DNA_node_types.h"
#include "DNA_material_types.h"

#include "BKE_depsgraph.h"
#include "BKE_global.h"
#include "BKE_library.h"
#include "BKE_main.h"
#include "BKE_text.h"
#include "BKE_node.h"


#ifdef WITH_PYTHON
#include "BPY_extern.h"
#endif

/*
 * How Texts should work
 * --
 * A text should relate to a file as follows -
 * (Text *)->name should be the place where the
 *     file will or has been saved.
 *
 * (Text *)->flags has the following bits
 *     TXT_ISDIRTY - should always be set if the file in mem. differs from
 *                     the file on disk, or if there is no file on disk.
 *     TXT_ISMEM - should always be set if the Text has not been mapped to
 *                     a file, in which case (Text *)->name may be NULL or garbage.
 *     TXT_ISEXT - should always be set if the Text is not to be written into
 *                     the .blend
 *     TXT_ISSCRIPT - should be set if the user has designated the text
 *                     as a script. (NEW: this was unused, but now it is needed by
 *                     space handler script links (see header_view3d.c, for example)
 *
 * ->>> see also: /makesdna/DNA_text_types.h
 *
 * Display
 * --
 * The st->top determines at what line the top of the text is displayed.
 * If the user moves the cursor the st containing that cursor should
 * be popped ... other st's retain their own top location.
 *
 * Undo
 * --
 * Undo/Redo works by storing
 * events in a queue, and a pointer
 * to the current position in the
 * queue...
 *
 * Events are stored using an
 * arbitrary op-code system
 * to keep track of
 * a) the two cursors (normal and selected)
 * b) input (visible and control (ie backspace))
 *
 * input data is stored as its
 * ASCII value, the opcodes are
 * then selected to not conflict.
 *
 * opcodes with data in between are
 * written at the beginning and end
 * of the data to allow undo and redo
 * to simply check the code at the current
 * undo position
 *
 */

/***/

static void txt_pop_first(Text *text);
static void txt_pop_last(Text *text);
static void txt_undo_add_blockop(Text *text, int op, const char *buf);
static void txt_delete_line(Text *text, TextLine *line);
static void txt_delete_sel(Text *text);
static void txt_make_dirty(Text *text);

/***/

static unsigned char undoing;

/* allow to switch off undoing externally */
void txt_set_undostate(int u)
{
	undoing = u;
}

int txt_get_undostate(void)
{
	return undoing;
}

static void init_undo_text(Text *text)
{
	text->undo_pos = -1;
	text->undo_len = TXT_INIT_UNDO;
	text->undo_buf = MEM_mallocN(text->undo_len, "undo buf");
}

void BKE_text_free(Text *text)
{
	TextLine *tmp;

	for (tmp = text->lines.first; tmp; tmp = tmp->next) {
		MEM_freeN(tmp->line);
		if (tmp->format)
			MEM_freeN(tmp->format);
	}
	
	BLI_freelistN(&text->lines);

	if (text->name) MEM_freeN(text->name);
	MEM_freeN(text->undo_buf);
#ifdef WITH_PYTHON
	if (text->compiled) BPY_text_free_code(text);
#endif
}

Text *BKE_text_add(Main *bmain, const char *name) 
{
	Text *ta;
	TextLine *tmp;
	
	ta = BKE_libblock_alloc(bmain, ID_TXT, name);
	ta->id.us = 1;
	
	ta->name = NULL;

	init_undo_text(ta);

	ta->nlines = 1;
	ta->flags = TXT_ISDIRTY | TXT_ISMEM;
	if ((U.flag & USER_TXT_TABSTOSPACES_DISABLE) == 0)
		ta->flags |= TXT_TABSTOSPACES;

	BLI_listbase_clear(&ta->lines);

	tmp = (TextLine *) MEM_mallocN(sizeof(TextLine), "textline");
	tmp->line = (char *) MEM_mallocN(1, "textline_string");
	tmp->format = NULL;
	
	tmp->line[0] = 0;
	tmp->len = 0;
				
	tmp->next = NULL;
	tmp->prev = NULL;
				
	BLI_addhead(&ta->lines, tmp);
	
	ta->curl = ta->lines.first;
	ta->curc = 0;
	ta->sell = ta->lines.first;
	ta->selc = 0;

	return ta;
}

/* this function replaces extended ascii characters */
/* to a valid utf-8 sequences */
int txt_extended_ascii_as_utf8(char **str)
{
	int bad_char, added = 0, i = 0;
	int length = strlen(*str);

	while ((*str)[i]) {
		if ((bad_char = BLI_utf8_invalid_byte(*str + i, length - i)) == -1)
			break;

		added++;
		i += bad_char + 1;
	}
	
	if (added != 0) {
		char *newstr = MEM_mallocN(length + added + 1, "text_line");
		int mi = 0;
		i = 0;
		
		while ((*str)[i]) {
			if ((bad_char = BLI_utf8_invalid_byte((*str) + i, length - i)) == -1) {
				memcpy(newstr + mi, (*str) + i, length - i + 1);
				break;
			}
			
			memcpy(newstr + mi, (*str) + i, bad_char);

			BLI_str_utf8_from_unicode((*str)[i + bad_char], newstr + mi + bad_char);
			i += bad_char + 1;
			mi += bad_char + 2;
		}
		newstr[length + added] = '\0';
		MEM_freeN(*str);
		*str = newstr;
	}
	
	return added;
}

// this function removes any control characters from
// a textline and fixes invalid utf-8 sequences

static void cleanup_textline(TextLine *tl)
{
	int i;

	for (i = 0; i < tl->len; i++) {
		if (tl->line[i] < ' ' && tl->line[i] != '\t') {
			memmove(tl->line + i, tl->line + i + 1, tl->len - i);
			tl->len--;
			i--;
		}
	}
	tl->len += txt_extended_ascii_as_utf8(&tl->line);
}

/**
 * used for load and reload (unlike txt_insert_buf)
 * assumes all fields are empty
 */
static void text_from_buf(Text *text, const unsigned char *buffer, const int len)
{
	int i, llen;

	BLI_assert(BLI_listbase_is_empty(&text->lines));

	text->nlines = 0;
	llen = 0;
	for (i = 0; i < len; i++) {
		if (buffer[i] == '\n') {
			TextLine *tmp;

			tmp = (TextLine *) MEM_mallocN(sizeof(TextLine), "textline");
			tmp->line = (char *) MEM_mallocN(llen + 1, "textline_string");
			tmp->format = NULL;

			if (llen) memcpy(tmp->line, &buffer[i - llen], llen);
			tmp->line[llen] = 0;
			tmp->len = llen;

			cleanup_textline(tmp);

			BLI_addtail(&text->lines, tmp);
			text->nlines++;

			llen = 0;
			continue;
		}
		llen++;
	}

	/* create new line in cases:
	 * - rest of line (if last line in file hasn't got \n terminator).
	 *   in this case content of such line would be used to fill text line buffer
	 * - file is empty. in this case new line is needed to start editing from.
	 * - last characted in buffer is \n. in this case new line is needed to
	 *   deal with newline at end of file. (see [#28087]) (sergey) */
	if (llen != 0 || text->nlines == 0 || buffer[len - 1] == '\n') {
		TextLine *tmp;

		tmp = (TextLine *) MEM_mallocN(sizeof(TextLine), "textline");
		tmp->line = (char *) MEM_mallocN(llen + 1, "textline_string");
		tmp->format = NULL;

		if (llen) memcpy(tmp->line, &buffer[i - llen], llen);

		tmp->line[llen] = 0;
		tmp->len = llen;

		cleanup_textline(tmp);

		BLI_addtail(&text->lines, tmp);
		text->nlines++;
	}

	text->curl = text->sell = text->lines.first;
	text->curc = text->selc = 0;
}

bool BKE_text_reload(Text *text)
{
	FILE *fp;
	int len;
	unsigned char *buffer;
	TextLine *tmp;
	char str[FILE_MAX];
	BLI_stat_t st;

	if (!text->name) {
		return false;
	}

	BLI_strncpy(str, text->name, FILE_MAX);
	BLI_path_abs(str, G.main->name);
	
	fp = BLI_fopen(str, "r");
	if (fp == NULL) {
		return false;
	}
	fseek(fp, 0L, SEEK_END);
	len = ftell(fp);
	fseek(fp, 0L, SEEK_SET);
	if (UNLIKELY(len == -1)) {
		fclose(fp);
		return false;
	}

	/* free memory: */

	for (tmp = text->lines.first; tmp; tmp = tmp->next) {
		MEM_freeN(tmp->line);
		if (tmp->format) MEM_freeN(tmp->format);
	}
	
	BLI_freelistN(&text->lines);

	BLI_listbase_clear(&text->lines);
	text->curl = text->sell = NULL;

	/* clear undo buffer */
	MEM_freeN(text->undo_buf);
	init_undo_text(text);

	buffer = MEM_mallocN(len, "text_buffer");
	/* under windows fread can return less than len bytes because
	 * of CR stripping */
	len = fread(buffer, 1, len, fp);

	fclose(fp);

	if (BLI_stat(str, &st) != -1) {
		text->mtime = st.st_mtime;
	}
	else {
		text->mtime = 0;
	}

	text_from_buf(text, buffer, len);

	MEM_freeN(buffer);
	return true;
}

Text *BKE_text_load_ex(Main *bmain, const char *file, const char *relpath, const bool is_internal)
{
	FILE *fp;
	int len;
	unsigned char *buffer;
	Text *ta;
	char str[FILE_MAX];
	BLI_stat_t st;

	BLI_strncpy(str, file, FILE_MAX);
	if (relpath) /* can be NULL (bg mode) */
		BLI_path_abs(str, relpath);
	
	fp = BLI_fopen(str, "r");
	if (fp == NULL) {
		return NULL;
	}

	fseek(fp, 0L, SEEK_END);
	len = ftell(fp);
	fseek(fp, 0L, SEEK_SET);
	if (UNLIKELY(len == -1)) {
		fclose(fp);
		return NULL;
	}

	ta = BKE_libblock_alloc(bmain, ID_TXT, BLI_path_basename(str));
	ta->id.us = 1;

	BLI_listbase_clear(&ta->lines);
	ta->curl = ta->sell = NULL;

	if ((U.flag & USER_TXT_TABSTOSPACES_DISABLE) == 0)
		ta->flags = TXT_TABSTOSPACES;

	if (is_internal == false) {
		ta->name = MEM_mallocN(strlen(file) + 1, "text_name");
		strcpy(ta->name, file);
	}
	else {
		ta->flags |= TXT_ISMEM | TXT_ISDIRTY;
	}

	/* clear undo buffer */
	init_undo_text(ta);
	
	buffer = MEM_mallocN(len, "text_buffer");
	/* under windows fread can return less than len bytes because
	 * of CR stripping */
	len = fread(buffer, 1, len, fp);

	fclose(fp);

	if (BLI_stat(str, &st) != -1) {
		ta->mtime = st.st_mtime;
	}
	else {
		ta->mtime = 0;
	}
	
	text_from_buf(ta, buffer, len);
	
	MEM_freeN(buffer);

	return ta;
}

Text *BKE_text_load(Main *bmain, const char *file, const char *relpath)
{
	return BKE_text_load_ex(bmain, file, relpath, false);
}

Text *BKE_text_copy(Main *bmain, Text *ta)
{
	Text *tan;
	TextLine *line, *tmp;
	
	tan = BKE_libblock_copy(&ta->id);
	
	/* file name can be NULL */
	if (ta->name) {
		tan->name = BLI_strdup(ta->name);
	}
	else {
		tan->name = NULL;
	}

	tan->flags = ta->flags | TXT_ISDIRTY;
	
	BLI_listbase_clear(&tan->lines);
	tan->curl = tan->sell = NULL;
	tan->compiled = NULL;
	
	tan->nlines = ta->nlines;

	line = ta->lines.first;
	/* Walk down, reconstructing */
	while (line) {
		tmp = (TextLine *) MEM_mallocN(sizeof(TextLine), "textline");
		tmp->line = MEM_mallocN(line->len + 1, "textline_string");
		tmp->format = NULL;
		
		strcpy(tmp->line, line->line);

		tmp->len = line->len;
		
		BLI_addtail(&tan->lines, tmp);
		
		line = line->next;
	}

	tan->curl = tan->sell = tan->lines.first;
	tan->curc = tan->selc = 0;

	init_undo_text(tan);

	if (ta->id.lib) {
		BKE_id_lib_local_paths(bmain, ta->id.lib, &tan->id);
	}

	return tan;
}

void BKE_text_unlink(Main *bmain, Text *text)
{
	bScreen *scr;
	ScrArea *area;
	SpaceLink *sl;
	Object *ob;
	bController *cont;
	bActuator *act;
	bConstraint *con;
	bNodeTree *ntree;
	bNode *node;
	Material *mat;
	Lamp *la;
	Tex *te;
	World *wo;
	FreestyleLineStyle *linestyle;
	Scene *sce;
	SceneRenderLayer *srl;
	FreestyleModuleConfig *module;
	bool update;

	for (ob = bmain->object.first; ob; ob = ob->id.next) {
		/* game controllers */
		for (cont = ob->controllers.first; cont; cont = cont->next) {
			if (cont->type == CONT_PYTHON) {
				bPythonCont *pc;
				
				pc = cont->data;
				if (pc->text == text) pc->text = NULL;
			}
		}
		/* game actuators */
		for (act = ob->actuators.first; act; act = act->next) {
			if (act->type == ACT_2DFILTER) {
				bTwoDFilterActuator *tfa;
				
				tfa = act->data;
				if (tfa->text == text) tfa->text = NULL;
			}
		}

		/* pyconstraints */
		update = 0;

		if (ob->type == OB_ARMATURE && ob->pose) {
			bPoseChannel *pchan;
			for (pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
				for (con = pchan->constraints.first; con; con = con->next) {
					if (con->type == CONSTRAINT_TYPE_PYTHON) {
						bPythonConstraint *data = con->data;
						if (data->text == text) data->text = NULL;
						update = 1;
						
					}
				}
			}
		}

		for (con = ob->constraints.first; con; con = con->next) {
			if (con->type == CONSTRAINT_TYPE_PYTHON) {
				bPythonConstraint *data = con->data;
				if (data->text == text) data->text = NULL;
				update = 1;
			}
		}
		
		if (update)
			DAG_id_tag_update(&ob->id, OB_RECALC_DATA);
	}
	
	/* nodes */
	for (la = bmain->lamp.first; la; la = la->id.next) {
		ntree = la->nodetree;
		if (!ntree)
			continue;
		for (node = ntree->nodes.first; node; node = node->next) {
			if (node->type == NODE_FRAME) {
				if ((Text *)node->id == text) {
					node->id = NULL;
				}
			}
		}
	}

	for (linestyle = bmain->linestyle.first; linestyle; linestyle = linestyle->id.next) {
		ntree = linestyle->nodetree;
		if (!ntree)
			continue;
		for (node = ntree->nodes.first; node; node = node->next) {
			if (node->type == NODE_FRAME) {
				if ((Text *)node->id == text) {
					node->id = NULL;
				}
			}
		}
	}

	for (mat = bmain->mat.first; mat; mat = mat->id.next) {
		ntree = mat->nodetree;
		if (!ntree)
			continue;
		for (node = ntree->nodes.first; node; node = node->next) {
			if (ELEM(node->type, SH_NODE_SCRIPT, NODE_FRAME)) {
				if ((Text *)node->id == text) {
					node->id = NULL;
				}
			}
		}
	}

	for (te = bmain->tex.first; te; te = te->id.next) {
		ntree = te->nodetree;
		if (!ntree)
			continue;
		for (node = ntree->nodes.first; node; node = node->next) {
			if (node->type == NODE_FRAME) {
				if ((Text *)node->id == text) {
					node->id = NULL;
				}
			}
		}
	}

	for (wo = bmain->world.first; wo; wo = wo->id.next) {
		ntree = wo->nodetree;
		if (!ntree)
			continue;
		for (node = ntree->nodes.first; node; node = node->next) {
			if (node->type == NODE_FRAME) {
				if ((Text *)node->id == text) {
					node->id = NULL;
				}
			}
		}
	}

	for (sce = bmain->scene.first; sce; sce = sce->id.next) {
		ntree = sce->nodetree;
		if (!ntree)
			continue;
		for (node = ntree->nodes.first; node; node = node->next) {
			if (node->type == NODE_FRAME) {
				Text *ntext = (Text *)node->id;
				if (ntext == text) node->id = NULL;
			}
		}

		/* Freestyle (while looping over the scene) */
		for (srl = sce->r.layers.first; srl; srl = srl->next) {
			for (module = srl->freestyleConfig.modules.first; module; module = module->next) {
				if (module->script == text)
					module->script = NULL;
			}
		}
	}

	for (ntree = bmain->nodetree.first; ntree; ntree = ntree->id.next) {
		for (node = ntree->nodes.first; node; node = node->next) {
			if (ELEM(node->type, SH_NODE_SCRIPT, NODE_FRAME)) {
				if ((Text *)node->id == text) {
					node->id = NULL;
				}
			}
		}
	}
	
	/* text space */
	for (scr = bmain->screen.first; scr; scr = scr->id.next) {
		for (area = scr->areabase.first; area; area = area->next) {
			for (sl = area->spacedata.first; sl; sl = sl->next) {
				if (sl->spacetype == SPACE_TEXT) {
					SpaceText *st = (SpaceText *) sl;

					if (st->text == text) {
						st->text = NULL;
						st->top = 0;
					}
				}
			}
		}
	}

	text->id.us = 0;
}

void BKE_text_clear(Text *text) /* called directly from rna */
{
	int oldstate;

	oldstate = txt_get_undostate();
	txt_set_undostate(1);
	txt_sel_all(text);
	txt_delete_sel(text);
	txt_set_undostate(oldstate);

	txt_make_dirty(text);
}

void BKE_text_write(Text *text, const char *str) /* called directly from rna */
{
	int oldstate;

	oldstate = txt_get_undostate();
	txt_insert_buf(text, str);
	txt_move_eof(text, 0);
	txt_set_undostate(oldstate);

	txt_make_dirty(text);
}


/* returns 0 if file on disk is the same or Text is in memory only
 * returns 1 if file has been modified on disk since last local edit
 * returns 2 if file on disk has been deleted
 * -1 is returned if an error occurs */

int BKE_text_file_modified_check(Text *text)
{
	BLI_stat_t st;
	int result;
	char file[FILE_MAX];

	if (!text->name)
		return 0;

	BLI_strncpy(file, text->name, FILE_MAX);
	BLI_path_abs(file, G.main->name);

	if (!BLI_exists(file))
		return 2;

	result = BLI_stat(file, &st);

	if (result == -1)
		return -1;

	if ((st.st_mode & S_IFMT) != S_IFREG)
		return -1;

	if (st.st_mtime > text->mtime)
		return 1;

	return 0;
}

void BKE_text_file_modified_ignore(Text *text)
{
	BLI_stat_t st;
	int result;
	char file[FILE_MAX];

	if (!text->name) return;

	BLI_strncpy(file, text->name, FILE_MAX);
	BLI_path_abs(file, G.main->name);

	if (!BLI_exists(file)) return;

	result = BLI_stat(file, &st);

	if (result == -1 || (st.st_mode & S_IFMT) != S_IFREG)
		return;

	text->mtime = st.st_mtime;
}

/*****************************/
/* Editing utility functions */
/*****************************/

static void make_new_line(TextLine *line, char *newline)
{
	if (line->line) MEM_freeN(line->line);
	if (line->format) MEM_freeN(line->format);
	
	line->line = newline;
	line->len = strlen(newline);
	line->format = NULL;
}

static TextLine *txt_new_line(const char *str)
{
	TextLine *tmp;

	if (!str) str = "";
	
	tmp = (TextLine *) MEM_mallocN(sizeof(TextLine), "textline");
	tmp->line = MEM_mallocN(strlen(str) + 1, "textline_string");
	tmp->format = NULL;
	
	strcpy(tmp->line, str);
	
	tmp->len = strlen(str);
	tmp->next = tmp->prev = NULL;
	
	return tmp;
}

static TextLine *txt_new_linen(const char *str, int n)
{
	TextLine *tmp;

	tmp = (TextLine *) MEM_mallocN(sizeof(TextLine), "textline");
	tmp->line = MEM_mallocN(n + 1, "textline_string");
	tmp->format = NULL;
	
	BLI_strncpy(tmp->line, (str) ? str : "", n + 1);
	
	tmp->len = strlen(tmp->line);
	tmp->next = tmp->prev = NULL;
	
	return tmp;
}

void txt_clean_text(Text *text)
{	
	TextLine **top, **bot;

	if (!text->lines.first) {
		if (text->lines.last) text->lines.first = text->lines.last;
		else text->lines.first = text->lines.last = txt_new_line(NULL);
	}
	
	if (!text->lines.last) text->lines.last = text->lines.first;

	top = (TextLine **) &text->lines.first;
	bot = (TextLine **) &text->lines.last;
	
	while ((*top)->prev) *top = (*top)->prev;
	while ((*bot)->next) *bot = (*bot)->next;

	if (!text->curl) {
		if (text->sell) text->curl = text->sell;
		else text->curl = text->lines.first;
		text->curc = 0;
	}

	if (!text->sell) {
		text->sell = text->curl;
		text->selc = 0;
	}
}

int txt_get_span(TextLine *from, TextLine *to)
{
	int ret = 0;
	TextLine *tmp = from;

	if (!to || !from) return 0;
	if (from == to) return 0;

	/* Look forwards */
	while (tmp) {
		if (tmp == to) return ret;
		ret++;
		tmp = tmp->next;
	}

	/* Look backwards */
	if (!tmp) {
		tmp = from;
		ret = 0;
		while (tmp) {
			if (tmp == to) break;
			ret--;
			tmp = tmp->prev;
		}
		if (!tmp) ret = 0;
	}

	return ret;
}

static void txt_make_dirty(Text *text)
{
	text->flags |= TXT_ISDIRTY;
#ifdef WITH_PYTHON
	if (text->compiled) BPY_text_free_code(text);
#endif
}

/****************************/
/* Cursor utility functions */
/****************************/

static void txt_curs_cur(Text *text, TextLine ***linep, int **charp)
{
	*linep = &text->curl; *charp = &text->curc;
}

static void txt_curs_sel(Text *text, TextLine ***linep, int **charp)
{
	*linep = &text->sell; *charp = &text->selc;
}

bool txt_cursor_is_line_start(Text *text)
{
	return (text->selc == 0);
}

bool txt_cursor_is_line_end(Text *text)
{
	return (text->selc == text->sell->len);
}

/*****************************/
/* Cursor movement functions */
/*****************************/

int txt_utf8_offset_to_index(const char *str, int offset)
{
	int index = 0, pos = 0;
	while (pos != offset) {
		pos += BLI_str_utf8_size(str + pos);
		index++;
	}
	return index;
}

int txt_utf8_index_to_offset(const char *str, int index)
{
	int offset = 0, pos = 0;
	while (pos != index) {
		offset += BLI_str_utf8_size(str + offset);
		pos++;
	}
	return offset;
}

int txt_utf8_offset_to_column(const char *str, int offset)
{
	int column = 0, pos = 0;
	while (pos < offset) {
		column += BLI_str_utf8_char_width_safe(str + pos);
		pos += BLI_str_utf8_size_safe(str + pos);
	}
	return column;
}

int txt_utf8_column_to_offset(const char *str, int column)
{
	int offset = 0, pos = 0, col;
	while (*(str + offset) && pos < column) {
		col = BLI_str_utf8_char_width_safe(str + offset);
		if (pos + col > column)
			break;
		offset += BLI_str_utf8_size_safe(str + offset);
		pos += col;
	}
	return offset;
}

void txt_move_up(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else { txt_pop_first(text); txt_curs_cur(text, &linep, &charp); }
	if (!*linep) return;

	if ((*linep)->prev) {
		int column = txt_utf8_offset_to_column((*linep)->line, *charp);
		*linep = (*linep)->prev;
		*charp = txt_utf8_column_to_offset((*linep)->line, column);
		
	}
	else {
		txt_move_bol(text, sel);
	}

	if (!sel) txt_pop_sel(text);
}

void txt_move_down(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else { txt_pop_last(text); txt_curs_cur(text, &linep, &charp); }
	if (!*linep) return;

	if ((*linep)->next) {
		int column = txt_utf8_offset_to_column((*linep)->line, *charp);
		*linep = (*linep)->next;
		*charp = txt_utf8_column_to_offset((*linep)->line, column);
	}
	else {
		txt_move_eol(text, sel);
	}

	if (!sel) txt_pop_sel(text);
}

void txt_move_left(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp;
	int tabsize = 0, i = 0;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else { txt_pop_first(text); txt_curs_cur(text, &linep, &charp); }
	if (!*linep) return;

	if (*charp == 0) {
		if ((*linep)->prev) {
			txt_move_up(text, sel);
			*charp = (*linep)->len;
		}
	}
	else {
		// do nice left only if there are only spaces
		// TXT_TABSIZE hardcoded in DNA_text_types.h
		if (text->flags & TXT_TABSTOSPACES) {
			tabsize = (*charp < TXT_TABSIZE) ? *charp : TXT_TABSIZE;
			
			for (i = 0; i < (*charp); i++)
				if ((*linep)->line[i] != ' ') {
					tabsize = 0;
					break;
				}
			
			// if in the middle of the space-tab
			if (tabsize && (*charp) % TXT_TABSIZE != 0)
				tabsize = ((*charp) % TXT_TABSIZE);
		}
		
		if (tabsize)
			(*charp) -= tabsize;
		else {
			const char *prev = BLI_str_prev_char_utf8((*linep)->line + *charp);
			*charp = prev - (*linep)->line;
		}
	}

	if (!sel) txt_pop_sel(text);
}

void txt_move_right(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp, i;
	bool do_tab = false;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else { txt_pop_last(text); txt_curs_cur(text, &linep, &charp); }
	if (!*linep) return;

	if (*charp == (*linep)->len) {
		if ((*linep)->next) {
			txt_move_down(text, sel);
			*charp = 0;
		}
	}
	else {
		// do nice right only if there are only spaces
		// spaces hardcoded in DNA_text_types.h
		if (text->flags & TXT_TABSTOSPACES && (*linep)->line[*charp] == ' ') {
			do_tab = true;
			for (i = 0; i < *charp; i++)
				if ((*linep)->line[i] != ' ') {
					do_tab = false;
					break;
				}
		}
		
		if (do_tab) {
			int tabsize = (*charp) % TXT_TABSIZE + 1;
			for (i = *charp + 1; (*linep)->line[i] == ' ' && tabsize < TXT_TABSIZE; i++)
				tabsize++;
			(*charp) = i;
		}
		else {
			(*charp) += BLI_str_utf8_size((*linep)->line + *charp);
		}
	}
	
	if (!sel) txt_pop_sel(text);
}

void txt_jump_left(Text *text, const bool sel, const bool use_init_step)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else { txt_pop_first(text); txt_curs_cur(text, &linep, &charp); }
	if (!*linep) return;

	BLI_str_cursor_step_utf8((*linep)->line, (*linep)->len,
	                         charp, STRCUR_DIR_PREV,
	                         STRCUR_JUMP_DELIM, use_init_step);
	
	if (!sel) txt_pop_sel(text);
}

void txt_jump_right(Text *text, const bool sel, const bool use_init_step)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else { txt_pop_last(text); txt_curs_cur(text, &linep, &charp); }
	if (!*linep) return;
	
	BLI_str_cursor_step_utf8((*linep)->line, (*linep)->len,
	                         charp, STRCUR_DIR_NEXT,
	                         STRCUR_JUMP_DELIM, use_init_step);
	
	if (!sel) txt_pop_sel(text);
}

void txt_move_bol(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else txt_curs_cur(text, &linep, &charp);
	if (!*linep) return;
	
	*charp = 0;

	if (!sel) txt_pop_sel(text);
}

void txt_move_eol(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else txt_curs_cur(text, &linep, &charp);
	if (!*linep) return;

	*charp = (*linep)->len;

	if (!sel) txt_pop_sel(text);
}

void txt_move_bof(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else txt_curs_cur(text, &linep, &charp);
	if (!*linep) return;

	*linep = text->lines.first;
	*charp = 0;

	if (!sel) txt_pop_sel(text);
}

void txt_move_eof(Text *text, const bool sel)
{
	TextLine **linep;
	int *charp;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else txt_curs_cur(text, &linep, &charp);
	if (!*linep) return;

	*linep = text->lines.last;
	*charp = (*linep)->len;

	if (!sel) txt_pop_sel(text);
}

void txt_move_toline(Text *text, unsigned int line, const bool sel)
{
	txt_move_to(text, line, 0, sel);
}

/* Moves to a certain byte in a line, not a certain utf8-character! */
void txt_move_to(Text *text, unsigned int line, unsigned int ch, const bool sel)
{
	TextLine **linep;
	int *charp;
	unsigned int i;

	if (sel) txt_curs_sel(text, &linep, &charp);
	else txt_curs_cur(text, &linep, &charp);
	if (!*linep) return;
	
	*linep = text->lines.first;
	for (i = 0; i < line; i++) {
		if ((*linep)->next) *linep = (*linep)->next;
		else break;
	}
	if (ch > (unsigned int)((*linep)->len))
		ch = (unsigned int)((*linep)->len);
	*charp = ch;
	
	if (!sel) txt_pop_sel(text);
}

/****************************/
/* Text selection functions */
/****************************/

static void txt_curs_swap(Text *text)
{
	TextLine *tmpl;
	int tmpc;
		
	tmpl = text->curl;
	text->curl = text->sell;
	text->sell = tmpl;

	tmpc = text->curc;
	text->curc = text->selc;
	text->selc = tmpc;
}

static void txt_pop_first(Text *text)
{
	if (txt_get_span(text->curl, text->sell) < 0 ||
	    (text->curl == text->sell && text->curc > text->selc))
	{
		txt_curs_swap(text);
	}
	
	txt_pop_sel(text);
}

static void txt_pop_last(Text *text)
{
	if (txt_get_span(text->curl, text->sell) > 0 ||
	    (text->curl == text->sell && text->curc < text->selc))
	{
		txt_curs_swap(text);
	}
	
	txt_pop_sel(text);
}

void txt_pop_sel(Text *text)
{
	text->sell = text->curl;
	text->selc = text->curc;
}

void txt_order_cursors(Text *text, const bool reverse)
{
	if (!text->curl) return;
	if (!text->sell) return;
	
	/* Flip so text->curl is before/after text->sell */
	if (reverse == false) {
		if ((txt_get_span(text->curl, text->sell) < 0) ||
		    (text->curl == text->sell && text->curc > text->selc))
		{
			txt_curs_swap(text);
		}
	}
	else {
		if ((txt_get_span(text->curl, text->sell) > 0) ||
		    (text->curl == text->sell && text->curc < text->selc))
		{
			txt_curs_swap(text);
		}
	}
}

bool txt_has_sel(Text *text)
{
	return ((text->curl != text->sell) || (text->curc != text->selc));
}

static void txt_delete_sel(Text *text)
{
	TextLine *tmpl;
	char *buf;

	if (!text->curl) return;
	if (!text->sell) return;

	if (!txt_has_sel(text)) return;
	
	txt_order_cursors(text, false);

	if (!undoing) {
		buf = txt_sel_to_buf(text);
		txt_undo_add_blockop(text, UNDO_DBLOCK, buf);
		MEM_freeN(buf);
	}

	buf = MEM_mallocN(text->curc + (text->sell->len - text->selc) + 1, "textline_string");

	strncpy(buf, text->curl->line, text->curc);
	strcpy(buf + text->curc, text->sell->line + text->selc);
	buf[text->curc + (text->sell->len - text->selc)] = 0;

	make_new_line(text->curl, buf);
	
	tmpl = text->sell;
	while (tmpl != text->curl) {
		tmpl = tmpl->prev;
		if (!tmpl) break;
		
		txt_delete_line(text, tmpl->next);
	}
	
	text->sell = text->curl;
	text->selc = text->curc;
}

void txt_sel_all(Text *text)
{
	text->curl = text->lines.first;
	text->curc = 0;
	
	text->sell = text->lines.last;
	text->selc = text->sell->len;
}

/**
 * Reverse of #txt_pop_sel
 * Clears the selection and ensures the cursor is located
 * at the selection (where the cursor is visually while editing).
 */
void txt_sel_clear(Text *text)
{
	if (text->sell) {
		text->curl = text->sell;
		text->curc = text->selc;
	}
}

void txt_sel_line(Text *text)
{
	if (!text->curl) return;
	
	text->curc = 0;
	text->sell = text->curl;
	text->selc = text->sell->len;
}

/***************************/
/* Cut and paste functions */
/***************************/

char *txt_to_buf(Text *text)
{
	int length;
	TextLine *tmp, *linef, *linel;
	int charf, charl;
	char *buf;

	if (!text->curl) return NULL;
	if (!text->sell) return NULL;
	if (!text->lines.first) return NULL;

	linef = text->lines.first;
	charf = 0;
		
	linel = text->lines.last;
	charl = linel->len;

	if (linef == text->lines.last) {
		length = charl - charf;

		buf = MEM_mallocN(length + 2, "text buffer");
		
		BLI_strncpy(buf, linef->line + charf, length + 1);
		buf[length] = 0;
	}
	else {
		length = linef->len - charf;
		length += charl;
		length += 2; /* For the 2 '\n' */
		
		tmp = linef->next;
		while (tmp && tmp != linel) {
			length += tmp->len + 1;
			tmp = tmp->next;
		}
		
		buf = MEM_mallocN(length + 1, "cut buffer");

		strncpy(buf, linef->line + charf, linef->len - charf);
		length = linef->len - charf;
		
		buf[length++] = '\n';
		
		tmp = linef->next;
		while (tmp && tmp != linel) {
			strncpy(buf + length, tmp->line, tmp->len);
			length += tmp->len;
			
			buf[length++] = '\n';
			
			tmp = tmp->next;
		}
		strncpy(buf + length, linel->line, charl);
		length += charl;
		
		/* python compiler wants an empty end line */
		buf[length++] = '\n';
		buf[length] = 0;
	}
	
	return buf;
}

int txt_find_string(Text *text, const char *findstr, int wrap, int match_case)
{
	TextLine *tl, *startl;
	const char *s = NULL;

	if (!text->curl || !text->sell) return 0;
	
	txt_order_cursors(text, false);

	tl = startl = text->sell;
	
	if (match_case) s = strstr(&tl->line[text->selc], findstr);
	else s = BLI_strcasestr(&tl->line[text->selc], findstr);
	while (!s) {
		tl = tl->next;
		if (!tl) {
			if (wrap)
				tl = text->lines.first;
			else
				break;
		}

		if (match_case) s = strstr(tl->line, findstr);
		else s = BLI_strcasestr(tl->line, findstr);
		if (tl == startl)
			break;
	}
	
	if (s) {
		int newl = txt_get_span(text->lines.first, tl);
		int newc = (int)(s - tl->line);
		txt_move_to(text, newl, newc, 0);
		txt_move_to(text, newl, newc + strlen(findstr), 1);
		return 1;
	}
	else
		return 0;
}

char *txt_sel_to_buf(Text *text)
{
	char *buf;
	int length = 0;
	TextLine *tmp, *linef, *linel;
	int charf, charl;

	if (!text->curl) return NULL;
	if (!text->sell) return NULL;
	
	if (text->curl == text->sell) {
		linef = linel = text->curl;
		
		if (text->curc < text->selc) {
			charf = text->curc;
			charl = text->selc;
		}
		else {
			charf = text->selc;
			charl = text->curc;
		}
	}
	else if (txt_get_span(text->curl, text->sell) < 0) {
		linef = text->sell;
		linel = text->curl;

		charf = text->selc;
		charl = text->curc;
	}
	else {
		linef = text->curl;
		linel = text->sell;
		
		charf = text->curc;
		charl = text->selc;
	}

	if (linef == linel) {
		length = charl - charf;

		buf = MEM_mallocN(length + 1, "sel buffer");
		
		BLI_strncpy(buf, linef->line + charf, length + 1);
	}
	else {
		length += linef->len - charf;
		length += charl;
		length++; /* For the '\n' */
		
		tmp = linef->next;
		while (tmp && tmp != linel) {
			length += tmp->len + 1;
			tmp = tmp->next;
		}
		
		buf = MEM_mallocN(length + 1, "sel buffer");
		
		strncpy(buf, linef->line + charf, linef->len - charf);
		length = linef->len - charf;
		
		buf[length++] = '\n';
		
		tmp = linef->next;
		while (tmp && tmp != linel) {
			strncpy(buf + length, tmp->line, tmp->len);
			length += tmp->len;
			
			buf[length++] = '\n';
			
			tmp = tmp->next;
		}
		strncpy(buf + length, linel->line, charl);
		length += charl;
		
		buf[length] = 0;
	}

	return buf;
}

void txt_insert_buf(Text *text, const char *in_buffer)
{
	int l = 0, u, len;
	size_t i = 0, j;
	TextLine *add;
	char *buffer;

	if (!in_buffer) return;

	txt_delete_sel(text);
	
	len = strlen(in_buffer);
	buffer = BLI_strdupn(in_buffer, len);
	len += txt_extended_ascii_as_utf8(&buffer);
	
	if (!undoing) txt_undo_add_blockop(text, UNDO_IBLOCK, buffer);

	u = undoing;
	undoing = 1;

	/* Read the first line (or as close as possible */
	while (buffer[i] && buffer[i] != '\n')
		txt_add_raw_char(text, BLI_str_utf8_as_unicode_step(buffer, &i));
	
	if (buffer[i] == '\n') txt_split_curline(text);
	else { undoing = u; MEM_freeN(buffer); return; }
	i++;

	while (i < len) {
		l = 0;

		while (buffer[i] && buffer[i] != '\n') {
			i++; l++;
		}
	
		if (buffer[i] == '\n') {
			add = txt_new_linen(buffer + (i - l), l);
			BLI_insertlinkbefore(&text->lines, text->curl, add);
			i++;
		}
		else {
			for (j = i - l; j < i && j < len; )
				txt_add_raw_char(text, BLI_str_utf8_as_unicode_step(buffer, &j));
			break;
		}
	}
	
	MEM_freeN(buffer);

	undoing = u;
}

/******************/
/* Undo functions */
/******************/

static bool max_undo_test(Text *text, int x)
{
	while (text->undo_pos + x >= text->undo_len) {
		if (text->undo_len * 2 > TXT_MAX_UNDO) {
			/* XXX error("Undo limit reached, buffer cleared\n"); */
			MEM_freeN(text->undo_buf);
			init_undo_text(text);
			return false;
		}
		else {
			void *tmp = text->undo_buf;
			text->undo_buf = MEM_callocN(text->undo_len * 2, "undo buf");
			memcpy(text->undo_buf, tmp, text->undo_len);
			text->undo_len *= 2;
			MEM_freeN(tmp);
		}
	}

	return true;
}

#if 0  /* UNUSED */
static void dump_buffer(Text *text) 
{
	int i = 0;
	
	while (i++ < text->undo_pos) printf("%d: %d %c\n", i, text->undo_buf[i], text->undo_buf[i]);
}

/* Note: this function is outdated and must be updated if needed for future use */
void txt_print_undo(Text *text)
{
	int i = 0;
	int op;
	const char *ops;
	int linep, charp;
	
	dump_buffer(text);
	
	printf("---< Undo Buffer >---\n");
	
	printf("UndoPosition is %d\n", text->undo_pos);
	
	while (i <= text->undo_pos) {
		op = text->undo_buf[i];
		
		if (op == UNDO_INSERT_1) {
			ops = "Insert ascii ";
		}
		else if (op == UNDO_INSERT_2) {
			ops = "Insert 2 bytes ";
		}
		else if (op == UNDO_INSERT_3) {
			ops = "Insert 3 bytes ";
		}
		else if (op == UNDO_INSERT_4) {
			ops = "Insert unicode ";
		}
		else if (op == UNDO_BS_1) {
			ops = "Backspace for ascii ";
		}
		else if (op == UNDO_BS_2) {
			ops = "Backspace for 2 bytes ";
		}
		else if (op == UNDO_BS_3) {
			ops = "Backspace for 3 bytes ";
		}
		else if (op == UNDO_BS_4) {
			ops = "Backspace for unicode ";
		}
		else if (op == UNDO_DEL_1) {
			ops = "Delete ascii ";
		}
		else if (op == UNDO_DEL_2) {
			ops = "Delete 2 bytes ";
		}
		else if (op == UNDO_DEL_3) {
			ops = "Delete 3 bytes ";
		}
		else if (op == UNDO_DEL_4) {
			ops = "Delete unicode ";
		}
		else if (op == UNDO_DBLOCK) {
			ops = "Delete text block";
		}
		else if (op == UNDO_IBLOCK) {
			ops = "Insert text block";
		}
		else if (op == UNDO_INDENT) {
			ops = "Indent ";
		}
		else if (op == UNDO_UNINDENT) {
			ops = "Unindent ";
		}
		else if (op == UNDO_COMMENT) {
			ops = "Comment ";
		}
		else if (op == UNDO_UNCOMMENT) {
			ops = "Uncomment ";
		}
		else {
			ops = "Unknown";
		}
		
		printf("Op (%o) at %d = %s", op, i, ops);
		if (op >= UNDO_INSERT_1 && op <= UNDO_DEL_4) {
			i++;
			printf(" - Char is ");
			switch (op) {
				case UNDO_INSERT_1: case UNDO_BS_1: case UNDO_DEL_1:
					printf("%c", text->undo_buf[i]);
					i++;
					break;
				case UNDO_INSERT_2: case UNDO_BS_2: case UNDO_DEL_2:
					printf("%c%c", text->undo_buf[i], text->undo_buf[i + 1]);
					i += 2;
					break;
				case UNDO_INSERT_3: case UNDO_BS_3: case UNDO_DEL_3:
					printf("%c%c%c", text->undo_buf[i], text->undo_buf[i + 1], text->undo_buf[i + 2]);
					i += 3;
					break;
				case UNDO_INSERT_4: case UNDO_BS_4: case UNDO_DEL_4:
				{
					unsigned int uc;
					char c[BLI_UTF8_MAX + 1];
					size_t c_len;
					uc = text->undo_buf[i]; i++;
					uc = uc + (text->undo_buf[i] << 8); i++;
					uc = uc + (text->undo_buf[i] << 16); i++;
					uc = uc + (text->undo_buf[i] << 24); i++;
					c_len = BLI_str_utf8_from_unicode(uc, c);
					c[c_len] = '\0';
					puts(c);
					break;
				}
			}
		}
		else if (op == UNDO_DBLOCK || op == UNDO_IBLOCK) {
			i++;

			linep = text->undo_buf[i]; i++;
			linep = linep + (text->undo_buf[i] << 8); i++;
			linep = linep + (text->undo_buf[i] << 16); i++;
			linep = linep + (text->undo_buf[i] << 24); i++;
			
			printf(" (length %d) <", linep);
			
			while (linep > 0) {
				putchar(text->undo_buf[i]);
				linep--; i++;
			}
			
			linep = text->undo_buf[i]; i++;
			linep = linep + (text->undo_buf[i] << 8); i++;
			linep = linep + (text->undo_buf[i] << 16); i++;
			linep = linep + (text->undo_buf[i] << 24); i++;
			printf("> (%d)", linep);
		}
		else if (op == UNDO_INDENT || op == UNDO_UNINDENT) {
			i++;

			charp = text->undo_buf[i]; i++;
			charp = charp + (text->undo_buf[i] << 8); i++;

			linep = text->undo_buf[i]; i++;
			linep = linep + (text->undo_buf[i] << 8); i++;
			linep = linep + (text->undo_buf[i] << 16); i++;
			linep = linep + (text->undo_buf[i] << 24); i++;
			
			printf("to <%d, %d> ", linep, charp);

			charp = text->undo_buf[i]; i++;
			charp = charp + (text->undo_buf[i] << 8); i++;

			linep = text->undo_buf[i]; i++;
			linep = linep + (text->undo_buf[i] << 8); i++;
			linep = linep + (text->undo_buf[i] << 16); i++;
			linep = linep + (text->undo_buf[i] << 24); i++;
			
			printf("from <%d, %d>", linep, charp);
		}
		
		printf(" %d\n",  i);
		i++;
	}
}
#endif

static void txt_undo_store_uint16(char *undo_buf, int *undo_pos, unsigned short value) 
{
	undo_buf[*undo_pos] = (value) & 0xff;
	(*undo_pos)++;
	undo_buf[*undo_pos] = (value >> 8) & 0xff;
	(*undo_pos)++;
}

static void txt_undo_store_uint32(char *undo_buf, int *undo_pos, unsigned int value) 
{
	undo_buf[*undo_pos] = (value) & 0xff;
	(*undo_pos)++;
	undo_buf[*undo_pos] = (value >> 8) & 0xff;
	(*undo_pos)++;
	undo_buf[*undo_pos] = (value >> 16) & 0xff;
	(*undo_pos)++;
	undo_buf[*undo_pos] = (value >> 24) & 0xff;
	(*undo_pos)++;
}

/* store the cur cursor to the undo buffer */
static void txt_undo_store_cur(Text *text)
{
	txt_undo_store_uint16(text->undo_buf, &text->undo_pos, text->curc);
	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, txt_get_span(text->lines.first, text->curl));
}

/* store the sel cursor to the undo buffer */
static void txt_undo_store_sel(Text *text)
{
	txt_undo_store_uint16(text->undo_buf, &text->undo_pos, text->selc);
	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, txt_get_span(text->lines.first, text->sell));
}

/* store both cursors to the undo buffer */
static void txt_undo_store_cursors(Text *text)
{
	txt_undo_store_cur(text);
	txt_undo_store_sel(text);
}

/* store an operator along with a block of data */
static void txt_undo_add_blockop(Text *text, int op, const char *buf)
{
	unsigned int length = strlen(buf);
	
	if (!max_undo_test(text, length + 11 + 12))
		return;

	text->undo_pos++;
	text->undo_buf[text->undo_pos] = op;
	text->undo_pos++;
	
	txt_undo_store_cursors(text);

	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, length);
	
	strncpy(text->undo_buf + text->undo_pos, buf, length);
	text->undo_pos += length;

	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, length);
	text->undo_buf[text->undo_pos] = op;
	
	text->undo_buf[text->undo_pos + 1] = 0;
}

/* store a regular operator */
void txt_undo_add_op(Text *text, int op)
{
	if (!max_undo_test(text, 15))
		return;

	text->undo_pos++;
	text->undo_buf[text->undo_pos] = op;

	text->undo_pos++;
	
	txt_undo_store_cursors(text);
		
	text->undo_buf[text->undo_pos] = op;
	text->undo_buf[text->undo_pos + 1] = 0;
}

/* store an operator for a single character */
static void txt_undo_add_charop(Text *text, int op_start, unsigned int c)
{
	char utf8[BLI_UTF8_MAX];
	size_t i, utf8_size = BLI_str_utf8_from_unicode(c, utf8);
	
	if (!max_undo_test(text, 3 + utf8_size + 12))
		return;
	
	text->undo_pos++;
	
	if (utf8_size < 4) {
		text->undo_buf[text->undo_pos] = op_start + utf8_size - 1;
		text->undo_pos++;
		
		txt_undo_store_cur(text);

		for (i = 0; i < utf8_size; i++) {
			text->undo_buf[text->undo_pos] = utf8[i];
			text->undo_pos++;
		}
		
		text->undo_buf[text->undo_pos] = op_start + utf8_size - 1;
	}
	else {
		text->undo_buf[text->undo_pos] = op_start + 3;
		text->undo_pos++;

		txt_undo_store_cursors(text);

		txt_undo_store_uint32(text->undo_buf, &text->undo_pos, c);
		text->undo_buf[text->undo_pos] = op_start + 3;
	}
	
	text->undo_buf[text->undo_pos + 1] = 0;
}

/* extends Link */
struct LinkInt {
	struct LinkInt *next, *prev;
	int value;
};

/* unindentLines points to a ListBase composed of LinkInt elements, listing the numbers
 * of the lines that should not be indented back. */
static void txt_undo_add_unindent_op(Text *text, const ListBase *line_index_mask, const int line_index_mask_len)
{
	struct LinkInt *idata;

	BLI_assert(BLI_listbase_count(line_index_mask) == line_index_mask_len);

	/* OP byte + UInt32 count + counted UInt32 line numbers + UInt32 count + 12-bytes selection + OP byte */
	if (!max_undo_test(text, 1 + 4 + (line_index_mask_len * 4) + 4 + 12 + 1)) {
		return;
	}

	/* Opening buffer sequence with OP */
	text->undo_pos++;
	text->undo_buf[text->undo_pos] = UNDO_UNINDENT;
	text->undo_pos++;
	/* Adding number of line numbers to read */
	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, line_index_mask_len);

	/* Adding linenumbers of lines that shall not be indented if undoing */
	for (idata = line_index_mask->first; idata; idata = idata->next) {
		txt_undo_store_uint32(text->undo_buf, &text->undo_pos, idata->value);
	}

	/* Adding number of line numbers to read again */
	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, line_index_mask_len);
	/* Adding current selection */
	txt_undo_store_cursors(text);
	/* Closing with OP (same as above) */
	text->undo_buf[text->undo_pos] = UNDO_UNINDENT;
	/* Marking as last undo operation */
	text->undo_buf[text->undo_pos + 1] = 0;
}

static unsigned short txt_undo_read_uint16(const char *undo_buf, int *undo_pos)
{
	unsigned short val;
	val = undo_buf[*undo_pos]; (*undo_pos)--;
	val = (val << 8) + undo_buf[*undo_pos]; (*undo_pos)--;
	return val;
}

static unsigned int txt_undo_read_uint32(const char *undo_buf, int *undo_pos)
{
	unsigned int val;
	val = undo_buf[*undo_pos]; (*undo_pos)--;
	val = (val << 8) + undo_buf[*undo_pos]; (*undo_pos)--;
	val = (val << 8) + undo_buf[*undo_pos]; (*undo_pos)--;
	val = (val << 8) + undo_buf[*undo_pos]; (*undo_pos)--;
	return val;
}

/* read the cur cursor from the undo buffer */
static void txt_undo_read_cur(const char *undo_buf, int *undo_pos, unsigned int *curln, unsigned short *curc)
{
	*curln = txt_undo_read_uint32(undo_buf, undo_pos);
	*curc  = txt_undo_read_uint16(undo_buf, undo_pos);
}

/* read the sel cursor from the undo buffer */
static void txt_undo_read_sel(const char *undo_buf, int *undo_pos, unsigned int *selln, unsigned short *selc)
{
	*selln = txt_undo_read_uint32(undo_buf, undo_pos);
	*selc  = txt_undo_read_uint16(undo_buf, undo_pos);
}

/* read both cursors from the undo buffer */
static void txt_undo_read_cursors(const char *undo_buf, int *undo_pos,
                                  unsigned int *curln, unsigned short *curc,
                                  unsigned int *selln, unsigned short *selc)
{
	txt_undo_read_sel(undo_buf, undo_pos, selln, selc);
	txt_undo_read_cur(undo_buf, undo_pos, curln, curc);
}

static unsigned int txt_undo_read_unicode(const char *undo_buf, int *undo_pos, short bytes)
{
	unsigned int unicode;
	char utf8[BLI_UTF8_MAX + 1];
	
	switch (bytes) {
		case 1: /* ascii */
			unicode = undo_buf[*undo_pos]; (*undo_pos)--; 
			break;
		case 2: /* 2-byte symbol */
			utf8[2] = '\0';
			utf8[1] = undo_buf[*undo_pos]; (*undo_pos)--;
			utf8[0] = undo_buf[*undo_pos]; (*undo_pos)--;
			unicode = BLI_str_utf8_as_unicode(utf8);
			break;
		case 3: /* 3-byte symbol */
			utf8[3] = '\0';
			utf8[2] = undo_buf[*undo_pos]; (*undo_pos)--;
			utf8[1] = undo_buf[*undo_pos]; (*undo_pos)--;
			utf8[0] = undo_buf[*undo_pos]; (*undo_pos)--;
			unicode = BLI_str_utf8_as_unicode(utf8);
			break;
		case 4: /* 32-bit unicode symbol */
			unicode = txt_undo_read_uint32(undo_buf, undo_pos);
			break;
		default:
			/* should never happen */
			BLI_assert(0);
			unicode = 0;
			break;
	}
	
	return unicode;
}

static unsigned short txt_redo_read_uint16(const char *undo_buf, int *undo_pos)
{
	unsigned short val;
	val = undo_buf[*undo_pos]; (*undo_pos)++;
	val = val + (undo_buf[*undo_pos] << 8); (*undo_pos)++;
	return val;
}

static unsigned int txt_redo_read_uint32(const char *undo_buf, int *undo_pos)
{
	unsigned int val;
	val = undo_buf[*undo_pos]; (*undo_pos)++;
	val = val + (undo_buf[*undo_pos] << 8); (*undo_pos)++;
	val = val + (undo_buf[*undo_pos] << 16); (*undo_pos)++;
	val = val + (undo_buf[*undo_pos] << 24); (*undo_pos)++;
	return val;
}

/* redo read cur cursor from the undo buffer */
static void txt_redo_read_cur(const char *undo_buf, int *undo_pos, unsigned int *curln, unsigned short *curc)
{
	*curc  = txt_redo_read_uint16(undo_buf, undo_pos);
	*curln = txt_redo_read_uint32(undo_buf, undo_pos);
}

/* redo read sel cursor from the undo buffer */
static void txt_redo_read_sel(const char *undo_buf, int *undo_pos, unsigned int *selln, unsigned short *selc)
{
	*selc  = txt_redo_read_uint16(undo_buf, undo_pos);
	*selln = txt_redo_read_uint32(undo_buf, undo_pos);
}

/* redo read both cursors from the undo buffer */
static void txt_redo_read_cursors(const char *undo_buf, int *undo_pos,
                                  unsigned int *curln, unsigned short *curc,
                                  unsigned int *selln, unsigned short *selc)
{
	txt_redo_read_cur(undo_buf, undo_pos, curln, curc);
	txt_redo_read_sel(undo_buf, undo_pos, selln, selc);
}

static unsigned int txt_redo_read_unicode(const char *undo_buf, int *undo_pos, short bytes)
{
	unsigned int unicode;
	char utf8[BLI_UTF8_MAX + 1];
	
	switch (bytes) {
		case 1: /* ascii */
			unicode = undo_buf[*undo_pos]; (*undo_pos)++; 
			break;
		case 2: /* 2-byte symbol */
			utf8[0] = undo_buf[*undo_pos]; (*undo_pos)++;
			utf8[1] = undo_buf[*undo_pos]; (*undo_pos)++;
			utf8[2] = '\0';
			unicode = BLI_str_utf8_as_unicode(utf8);
			break;
		case 3: /* 3-byte symbol */
			utf8[0] = undo_buf[*undo_pos]; (*undo_pos)++;
			utf8[1] = undo_buf[*undo_pos]; (*undo_pos)++;
			utf8[2] = undo_buf[*undo_pos]; (*undo_pos)++;
			utf8[3] = '\0';
			unicode = BLI_str_utf8_as_unicode(utf8);
			break;
		case 4: /* 32-bit unicode symbol */
			unicode = txt_undo_read_uint32(undo_buf, undo_pos);
			break;
		default:
			/* should never happen */
			BLI_assert(0);
			unicode = 0;
			break;
	}
	
	return unicode;
}

void txt_do_undo(Text *text)
{
	int op = text->undo_buf[text->undo_pos];
	int prev_flags;
	unsigned int linep, i;
	unsigned int uchar;
	unsigned int curln, selln;
	unsigned short curc, selc;
	unsigned short charp;
	char *buf;
	
	if (text->undo_pos < 0) {
		return;
	}

	text->undo_pos--;

	undoing = 1;
	
	switch (op) {
		case UNDO_INSERT_1:
		case UNDO_INSERT_2:
		case UNDO_INSERT_3:
		case UNDO_INSERT_4:
			text->undo_pos -= op - UNDO_INSERT_1 + 1;
			
			/* get and restore the cursors */
			txt_undo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, curln, curc, 1);
			
			txt_delete_char(text);
			
			text->undo_pos--;
			break;

		case UNDO_BS_1:
		case UNDO_BS_2:
		case UNDO_BS_3:
		case UNDO_BS_4:
			charp = op - UNDO_BS_1 + 1;
			uchar = txt_undo_read_unicode(text->undo_buf, &text->undo_pos, charp);
			
			/* get and restore the cursors */
			txt_undo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, curln, curc, 1);
			
			txt_add_char(text, uchar);

			text->undo_pos--;
			break;

		case UNDO_DEL_1:
		case UNDO_DEL_2:
		case UNDO_DEL_3:
		case UNDO_DEL_4:
			charp = op - UNDO_DEL_1 + 1;
			uchar = txt_undo_read_unicode(text->undo_buf, &text->undo_pos, charp);

			/* get and restore the cursors */
			txt_undo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, curln, curc, 1);

			txt_add_char(text, uchar);

			txt_move_left(text, 0);

			text->undo_pos--;
			break;

		case UNDO_DBLOCK:
			/* length of the string in the buffer */
			linep = txt_undo_read_uint32(text->undo_buf, &text->undo_pos);

			buf = MEM_mallocN(linep + 1, "dblock buffer");
			for (i = 0; i < linep; i++) {
				buf[(linep - 1) - i] = text->undo_buf[text->undo_pos];
				text->undo_pos--;
			}
			buf[i] = 0;

			/* skip over the length that was stored again */
			text->undo_pos -= 4;

			/* Get the cursor positions */
			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);

			/* move cur to location that needs buff inserted */
			txt_move_to(text, curln, curc, 0);
			
			txt_insert_buf(text, buf);
			MEM_freeN(buf);

			/* restore the cursors */
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);

			text->undo_pos--;
			
			break;

		case UNDO_IBLOCK:
			/* length of the string in the buffer */
			linep = txt_undo_read_uint32(text->undo_buf, &text->undo_pos);
			
			/* txt_backspace_char removes utf8-characters, not bytes */
			buf = MEM_mallocN(linep + 1, "iblock buffer");
			for (i = 0; i < linep; i++) {
				buf[(linep - 1) - i] = text->undo_buf[text->undo_pos];
				text->undo_pos--;
			}
			buf[i] = 0;
			linep = BLI_strlen_utf8(buf);
			MEM_freeN(buf);
			
			/* skip over the length that was stored again */
			text->undo_pos -= 4;

			/* get and restore the cursors */
			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
			
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);
			
			if ((curln == selln) && (curc == selc)) {
				/* disable tabs to spaces since moving right may involve skipping multiple spaces */
				prev_flags = text->flags;
				text->flags &= ~TXT_TABSTOSPACES;
				
				for (i = 0; i < linep; i++)
					txt_move_right(text, 1);
				
				text->flags = prev_flags;
			}
			
			txt_delete_selected(text);
			
			text->undo_pos--;
			break;
		case UNDO_INDENT:
		case UNDO_COMMENT:
		case UNDO_UNCOMMENT:
		case UNDO_DUPLICATE:
		case UNDO_MOVE_LINES_UP:
		case UNDO_MOVE_LINES_DOWN:
			/* get and restore the cursors */
			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);
			
			if (op == UNDO_INDENT) {
				txt_unindent(text);
			}
			else if (op == UNDO_COMMENT) {
				txt_uncomment(text);
			}
			else if (op == UNDO_UNCOMMENT) {
				txt_comment(text);
			}
			else if (op == UNDO_DUPLICATE) {
				txt_delete_line(text, text->curl->next);
			}
			else if (op == UNDO_MOVE_LINES_UP) {
				txt_move_lines(text, TXT_MOVE_LINE_DOWN);
			}
			else if (op == UNDO_MOVE_LINES_DOWN) {
				txt_move_lines(text, TXT_MOVE_LINE_UP);
			}
			
			text->undo_pos--;
			break;
		case UNDO_UNINDENT:
		{
			int count;
			int i;
			/* Get and restore the cursors */
			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);

			/* Un-unindent */
			txt_indent(text);

			/* Get the count */
			count = txt_undo_read_uint32(text->undo_buf, &text->undo_pos);
			/* Iterate! */
			txt_pop_sel(text);

			for (i = 0; i < count; i++) {
				txt_move_to(text, txt_undo_read_uint32(text->undo_buf, &text->undo_pos), 0, 0);
				/* Un-un-unindent */
				txt_unindent(text);
			}
			/* Restore selection */
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);
			/* Jumo over count */
			txt_undo_read_uint32(text->undo_buf, &text->undo_pos);
			/* Jump over closing OP byte */
			text->undo_pos--;
			break;
		}
		default:
			//XXX error("Undo buffer error - resetting");
			text->undo_pos = -1;
			
			break;
	}
	
	undoing = 0;
}

void txt_do_redo(Text *text)
{
	char op;
	char *buf;
	unsigned int linep;
	unsigned short charp;
	unsigned int uchar;
	unsigned int curln, selln;
	unsigned short curc, selc;
	
	text->undo_pos++;
	op = text->undo_buf[text->undo_pos];
	
	if (!op) {
		text->undo_pos--;
		return;
	}
	
	undoing = 1;

	switch (op) {
		case UNDO_INSERT_1:
		case UNDO_INSERT_2:
		case UNDO_INSERT_3:
		case UNDO_INSERT_4:
			text->undo_pos++;
			
			/* get and restore the cursors */
			txt_redo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, curln, curc, 1);
			
			charp = op - UNDO_INSERT_1 + 1;
			uchar = txt_redo_read_unicode(text->undo_buf, &text->undo_pos, charp);

			txt_add_char(text, uchar);
			break;

		case UNDO_BS_1:
		case UNDO_BS_2:
		case UNDO_BS_3:
		case UNDO_BS_4:
			text->undo_pos++;

			/* get and restore the cursors */
			txt_redo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, curln, curc, 1);

			text->undo_pos += op - UNDO_BS_1 + 1;
			
			/* move right so we backspace the correct char */
			txt_move_right(text, 0);
			txt_backspace_char(text);

			break;

		case UNDO_DEL_1:
		case UNDO_DEL_2:
		case UNDO_DEL_3:
		case UNDO_DEL_4:
			text->undo_pos++;

			/* get and restore the cursors */
			txt_redo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, curln, curc, 1);
			
			text->undo_pos += op - UNDO_DEL_1 + 1;

			txt_delete_char(text);

			break;

		case UNDO_DBLOCK:
			text->undo_pos++;

			/* get and restore the cursors */
			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);

			/* length of the block */
			linep = txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
			
			text->undo_pos += linep;

			/* skip over the length that was stored again */
			text->undo_pos += 4;
			
			txt_delete_sel(text);

			break;

		case UNDO_IBLOCK:
			text->undo_pos++;

			/* get and restore the cursors */
			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, curln, curc, 1);

			/* length of the block */
			linep = txt_redo_read_uint32(text->undo_buf, &text->undo_pos);

			buf = MEM_mallocN(linep + 1, "iblock buffer");
			memcpy(buf, &text->undo_buf[text->undo_pos], linep);
			text->undo_pos += linep;
			buf[linep] = 0;
			
			txt_insert_buf(text, buf);
			MEM_freeN(buf);

			/* skip over the length that was stored again */
			text->undo_pos += 4;

			break;
			
		case UNDO_INDENT:
		case UNDO_COMMENT:
		case UNDO_UNCOMMENT:
		case UNDO_DUPLICATE:
		case UNDO_MOVE_LINES_UP:
		case UNDO_MOVE_LINES_DOWN:
			text->undo_pos++;

			/* get and restore the cursors */
			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);

			if (op == UNDO_INDENT) {
				txt_indent(text);
			}
			else if (op == UNDO_COMMENT) {
				txt_comment(text);
			}
			else if (op == UNDO_UNCOMMENT) {
				txt_uncomment(text);
			}
			else if (op == UNDO_DUPLICATE) {
				txt_duplicate_line(text);
			}
			else if (op == UNDO_MOVE_LINES_UP) {
				/* offset the cursor by + 1 */
				txt_move_to(text, curln + 1, curc, 0);
				txt_move_to(text, selln + 1, selc, 1);

				txt_move_lines(text, TXT_MOVE_LINE_UP);
			}
			else if (op == UNDO_MOVE_LINES_DOWN) {
				/* offset the cursor by - 1 */
				txt_move_to(text, curln - 1, curc, 0);
				txt_move_to(text, selln - 1, selc, 1);

				txt_move_lines(text, TXT_MOVE_LINE_DOWN);
			}

			/* re-restore the cursors since they got moved when redoing */
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);

			break;
		case UNDO_UNINDENT:
		{
			int count;
			int i;

			text->undo_pos++;
			/* Scan all the stuff described in txt_undo_add_unindent_op */
			count = txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
			for (i = 0; i < count; i++) {
				txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
			}
			/* Count again */
			txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
			/* Get the selection and re-unindent */
			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
			txt_move_to(text, curln, curc, 0);
			txt_move_to(text, selln, selc, 1);
			txt_unindent(text);
			break;
		}
		default:
			//XXX error("Undo buffer error - resetting");
			text->undo_pos = -1;
			
			break;
	}
	
	undoing = 0;
}

/**************************/
/* Line editing functions */ 
/**************************/

void txt_split_curline(Text *text)
{
	TextLine *ins;
	char *left, *right;

	if (!text->curl) return;

	txt_delete_sel(text);

	if (!undoing) txt_undo_add_charop(text, UNDO_INSERT_1, '\n');
	
	/* Make the two half strings */

	left = MEM_mallocN(text->curc + 1, "textline_string");
	if (text->curc) memcpy(left, text->curl->line, text->curc);
	left[text->curc] = 0;
	
	right = MEM_mallocN(text->curl->len - text->curc + 1, "textline_string");
	memcpy(right, text->curl->line + text->curc, text->curl->len - text->curc + 1);

	MEM_freeN(text->curl->line);
	if (text->curl->format) MEM_freeN(text->curl->format);

	/* Make the new TextLine */
	
	ins = MEM_mallocN(sizeof(TextLine), "textline");
	ins->line = left;
	ins->format = NULL;
	ins->len = text->curc;

	text->curl->line = right;
	text->curl->format = NULL;
	text->curl->len = text->curl->len - text->curc;
	
	BLI_insertlinkbefore(&text->lines, text->curl, ins);
	
	text->curc = 0;
	
	txt_make_dirty(text);
	txt_clean_text(text);
	
	txt_pop_sel(text);
}

static void txt_delete_line(Text *text, TextLine *line)
{
	if (!text->curl) return;

	BLI_remlink(&text->lines, line);
	
	if (line->line) MEM_freeN(line->line);
	if (line->format) MEM_freeN(line->format);

	MEM_freeN(line);

	txt_make_dirty(text);
	txt_clean_text(text);
}

static void txt_combine_lines(Text *text, TextLine *linea, TextLine *lineb)
{
	char *tmp, *s;
	
	if (!linea || !lineb) return;


	tmp = MEM_mallocN(linea->len + lineb->len + 1, "textline_string");
	
	s = tmp;
	s += BLI_strcpy_rlen(s, linea->line);
	s += BLI_strcpy_rlen(s, lineb->line);
	(void)s;

	make_new_line(linea, tmp);
	
	txt_delete_line(text, lineb);
	
	txt_make_dirty(text);
	txt_clean_text(text);
}

void txt_duplicate_line(Text *text)
{
	TextLine *textline;
	
	if (!text->curl) return;
	
	if (text->curl == text->sell) {
		textline = txt_new_line(text->curl->line);
		BLI_insertlinkafter(&text->lines, text->curl, textline);
		
		txt_make_dirty(text);
		txt_clean_text(text);
		
		if (!undoing) txt_undo_add_op(text, UNDO_DUPLICATE);
	}
}

void txt_delete_char(Text *text) 
{
	unsigned int c = '\n';

	if (!text->curl) return;

	if (txt_has_sel(text)) { /* deleting a selection */
		txt_delete_sel(text);
		txt_make_dirty(text);
		return;
	}
	else if (text->curc == text->curl->len) { /* Appending two lines */
		if (text->curl->next) {
			txt_combine_lines(text, text->curl, text->curl->next);
			txt_pop_sel(text);
		}
		else
			return;
	}
	else { /* Just deleting a char */
		size_t c_len = 0;
		c = BLI_str_utf8_as_unicode_and_size(text->curl->line + text->curc, &c_len);
		
		memmove(text->curl->line + text->curc, text->curl->line + text->curc + c_len, text->curl->len - text->curc - c_len + 1);

		text->curl->len -= c_len;

		txt_pop_sel(text);
	}

	txt_make_dirty(text);
	txt_clean_text(text);
	
	if (!undoing) txt_undo_add_charop(text, UNDO_DEL_1, c);
}

void txt_delete_word(Text *text)
{
	txt_jump_right(text, true, true);
	txt_delete_sel(text);
	txt_make_dirty(text);
}

void txt_backspace_char(Text *text)
{
	unsigned int c = '\n';
	
	if (!text->curl) return;
	
	if (txt_has_sel(text)) { /* deleting a selection */
		txt_delete_sel(text);
		txt_make_dirty(text);
		return;
	}
	else if (text->curc == 0) { /* Appending two lines */
		if (!text->curl->prev) return;
		
		text->curl = text->curl->prev;
		text->curc = text->curl->len;
		
		txt_combine_lines(text, text->curl, text->curl->next);
		txt_pop_sel(text);
	}
	else { /* Just backspacing a char */
		size_t c_len = 0;
		const char *prev = BLI_str_prev_char_utf8(text->curl->line + text->curc);
		c = BLI_str_utf8_as_unicode_and_size(prev, &c_len);
		
		/* source and destination overlap, don't use memcpy() */
		memmove(text->curl->line + text->curc - c_len,
		        text->curl->line + text->curc,
		        text->curl->len  - text->curc + 1);

		text->curl->len -= c_len;
		text->curc -= c_len;

		txt_pop_sel(text);
	}

	txt_make_dirty(text);
	txt_clean_text(text);
	
	if (!undoing) txt_undo_add_charop(text, UNDO_BS_1, c);
}

void txt_backspace_word(Text *text)
{
	txt_jump_left(text, true, true);
	txt_delete_sel(text);
	txt_make_dirty(text);
}

/* Max spaces to replace a tab with, currently hardcoded to TXT_TABSIZE = 4.
 * Used by txt_convert_tab_to_spaces, indent and unindent.
 * Remember to change this string according to max tab size */
static char tab_to_spaces[] = "    ";

static void txt_convert_tab_to_spaces(Text *text)
{
	/* sb aims to pad adjust the tab-width needed so that the right number of spaces
	 * is added so that the indention of the line is the right width (i.e. aligned
	 * to multiples of TXT_TABSIZE)
	 */
	const char *sb = &tab_to_spaces[text->curc % TXT_TABSIZE];
	txt_insert_buf(text, sb);
}

static bool txt_add_char_intern(Text *text, unsigned int add, bool replace_tabs)
{
	char *tmp, ch[BLI_UTF8_MAX];
	size_t add_len;

	if (!text->curl) return 0;

	if (add == '\n') {
		txt_split_curline(text);
		return true;
	}
	
	/* insert spaces rather than tabs */
	if (add == '\t' && replace_tabs) {
		txt_convert_tab_to_spaces(text);
		return true;
	}

	txt_delete_sel(text);
	
	if (!undoing) txt_undo_add_charop(text, UNDO_INSERT_1, add);

	add_len = BLI_str_utf8_from_unicode(add, ch);
	
	tmp = MEM_mallocN(text->curl->len + add_len + 1, "textline_string");
	
	memcpy(tmp, text->curl->line, text->curc);
	memcpy(tmp + text->curc, ch, add_len);
	memcpy(tmp + text->curc + add_len, text->curl->line + text->curc, text->curl->len - text->curc + 1);

	make_new_line(text->curl, tmp);
		
	text->curc += add_len;

	txt_pop_sel(text);
	
	txt_make_dirty(text);
	txt_clean_text(text);

	return 1;
}

bool txt_add_char(Text *text, unsigned int add)
{
	return txt_add_char_intern(text, add, (text->flags & TXT_TABSTOSPACES) != 0);
}

bool txt_add_raw_char(Text *text, unsigned int add)
{
	return txt_add_char_intern(text, add, 0);
}

void txt_delete_selected(Text *text)
{
	txt_delete_sel(text);
	txt_make_dirty(text);
}

bool txt_replace_char(Text *text, unsigned int add)
{
	unsigned int del;
	size_t del_size = 0, add_size;
	char ch[BLI_UTF8_MAX];

	if (!text->curl) return false;

	/* If text is selected or we're at the end of the line just use txt_add_char */
	if (text->curc == text->curl->len || txt_has_sel(text) || add == '\n') {
		return txt_add_char(text, add);
	}
	
	del = BLI_str_utf8_as_unicode_and_size(text->curl->line + text->curc, &del_size);
	add_size = BLI_str_utf8_from_unicode(add, ch);
	
	if (add_size > del_size) {
		char *tmp = MEM_mallocN(text->curl->len + add_size - del_size + 1, "textline_string");
		memcpy(tmp, text->curl->line, text->curc);
		memcpy(tmp + text->curc + add_size, text->curl->line + text->curc + del_size, text->curl->len - text->curc - del_size + 1);
		MEM_freeN(text->curl->line);
		text->curl->line = tmp;
	}
	else if (add_size < del_size) {
		char *tmp = text->curl->line;
		memmove(tmp + text->curc + add_size, tmp + text->curc + del_size, text->curl->len - text->curc - del_size + 1);
	}
	
	memcpy(text->curl->line + text->curc, ch, add_size);
	text->curc += add_size;
	text->curl->len += add_size - del_size;
	
	txt_pop_sel(text);
	txt_make_dirty(text);
	txt_clean_text(text);

	/* Should probably create a new op for this */
	if (!undoing) {
		txt_undo_add_charop(text, UNDO_INSERT_1, add);
		text->curc -= add_size;
		txt_pop_sel(text);
		txt_undo_add_charop(text, UNDO_DEL_1, del);
		text->curc += add_size;
		txt_pop_sel(text);
	}
	return true;
}

void txt_indent(Text *text)
{
	int len, num, curc_old;
	char *tmp;

	const char *add = "\t";
	int indentlen = 1;
	
	/* hardcoded: TXT_TABSIZE = 4 spaces: */
	int spaceslen = TXT_TABSIZE;

	if (ELEM(NULL, text->curl, text->sell)) {
		return;
	}

	/* insert spaces rather than tabs */
	if (text->flags & TXT_TABSTOSPACES) {
		add = tab_to_spaces;
		indentlen = spaceslen;
	}

	curc_old = text->curc;

	num = 0;
	while (true) {

		/* don't indent blank lines */
		if (text->curl->len != 0) {
			tmp = MEM_mallocN(text->curl->len + indentlen + 1, "textline_string");

			text->curc = 0;
			if (text->curc) memcpy(tmp, text->curl->line, text->curc);  /* XXX never true, check prev line */
			memcpy(tmp + text->curc, add, indentlen);

			len = text->curl->len - text->curc;
			if (len > 0) memcpy(tmp + text->curc + indentlen, text->curl->line + text->curc, len);
			tmp[text->curl->len + indentlen] = 0;

			make_new_line(text->curl, tmp);

			text->curc += indentlen;

			txt_make_dirty(text);
			txt_clean_text(text);
		}
		
		if (text->curl == text->sell) {
			text->selc += indentlen;
			break;
		}
		else {
			text->curl = text->curl->next;
			num++;
		}
	}
	if (!curc_old) text->curc = 0;
	else text->curc = curc_old + indentlen;

	while (num > 0) {
		text->curl = text->curl->prev;
		num--;
	}
	
	if (!undoing) {
		txt_undo_add_op(text, UNDO_INDENT);
	}
}

void txt_unindent(Text *text)
{
	int num = 0;
	const char *remove = "\t";
	int indentlen = 1;
	bool unindented_first = false;
	
	/* List of lines that are already at indent level 0, to store them later into the undo buffer */
	ListBase line_index_mask = {NULL, NULL};
	int line_index_mask_len = 0;
	int curl_span_init = 0;


	/* hardcoded: TXT_TABSIZE = 4 spaces: */
	int spaceslen = TXT_TABSIZE;

	if (ELEM(NULL, text->curl, text->sell)) {
		return;
	}

	/* insert spaces rather than tabs */
	if (text->flags & TXT_TABSTOSPACES) {
		remove = tab_to_spaces;
		indentlen = spaceslen;
	}

	if (!undoing) {
		curl_span_init = txt_get_span(text->lines.first, text->curl);
	}

	while (true) {
		bool changed = false;
		if (STREQLEN(text->curl->line, remove, indentlen)) {
			if (num == 0)
				unindented_first = true;
			text->curl->len -= indentlen;
			memmove(text->curl->line, text->curl->line + indentlen, text->curl->len + 1);
			changed = true;
		}
		else {
			if (!undoing) {
				/* Create list element for 0 indent line */
				struct LinkInt *idata = MEM_mallocN(sizeof(struct LinkInt), __func__);
				idata->value = curl_span_init + num;
				BLI_assert(idata->value == txt_get_span(text->lines.first, text->curl));
				BLI_addtail(&line_index_mask, idata);
				line_index_mask_len += 1;
			}
		}
	
		txt_make_dirty(text);
		txt_clean_text(text);
		
		if (text->curl == text->sell) {
			if (changed)
				text->selc = MAX2(text->selc - indentlen, 0);
			break;
		}
		else {
			text->curl = text->curl->next;
			num++;

		}
		
	}

	if (unindented_first)
		text->curc = MAX2(text->curc - indentlen, 0);

	while (num > 0) {
		text->curl = text->curl->prev;
		num--;
	}
	
	if (!undoing) {
		txt_undo_add_unindent_op(text, &line_index_mask, line_index_mask_len);
	}

	BLI_freelistN(&line_index_mask);
}

void txt_comment(Text *text)
{
	int len, num;
	char *tmp;
	char add = '#';

	if (!text->curl) return;
	if (!text->sell) return;  // Need to change this need to check if only one line is selected to more than one

	num = 0;
	while (true) {
		tmp = MEM_mallocN(text->curl->len + 2, "textline_string");
		
		text->curc = 0; 
		if (text->curc) memcpy(tmp, text->curl->line, text->curc);
		tmp[text->curc] = add;
		
		len = text->curl->len - text->curc;
		if (len > 0) memcpy(tmp + text->curc + 1, text->curl->line + text->curc, len);
		tmp[text->curl->len + 1] = 0;

		make_new_line(text->curl, tmp);
			
		text->curc++;
		
		txt_make_dirty(text);
		txt_clean_text(text);
		
		if (text->curl == text->sell) {
			text->selc = text->sell->len;
			break;
		}
		else {
			text->curl = text->curl->next;
			num++;
		}
	}
	text->curc = 0;
	while (num > 0) {
		text->curl = text->curl->prev;
		num--;
	}
	
	if (!undoing) {
		txt_undo_add_op(text, UNDO_COMMENT);
	}
}

void txt_uncomment(Text *text)
{
	int num = 0;
	char remove = '#';

	if (!text->curl) return;
	if (!text->sell) return;

	while (true) {
		int i = 0;
		
		if (text->curl->line[i] == remove) {
			while (i < text->curl->len) {
				text->curl->line[i] = text->curl->line[i + 1];
				i++;
			}
			text->curl->len--;
		}
			 
	
		txt_make_dirty(text);
		txt_clean_text(text);
		
		if (text->curl == text->sell) {
			text->selc = text->sell->len;
			break;
		}
		else {
			text->curl = text->curl->next;
			num++;
		}
		
	}
	text->curc = 0;
	while (num > 0) {
		text->curl = text->curl->prev;
		num--;
	}
	
	if (!undoing) {
		txt_undo_add_op(text, UNDO_UNCOMMENT);
	}
}

void txt_move_lines(struct Text *text, const int direction)
{
	TextLine *line_other;

	BLI_assert(ELEM(direction, TXT_MOVE_LINE_UP, TXT_MOVE_LINE_DOWN));

	if (!text->curl || !text->sell) return;
	
	txt_order_cursors(text, false);

	line_other =  (direction == TXT_MOVE_LINE_DOWN) ? text->sell->next : text->curl->prev;
	
	if (!line_other) return;
		
	BLI_remlink(&text->lines, line_other);

	if (direction == TXT_MOVE_LINE_DOWN) {
		BLI_insertlinkbefore(&text->lines, text->curl, line_other);
	}
	else {
		BLI_insertlinkafter(&text->lines, text->sell, line_other);
	}

	txt_make_dirty(text);
	txt_clean_text(text);
	
	if (!undoing) {
		txt_undo_add_op(text, (direction == TXT_MOVE_LINE_DOWN) ? UNDO_MOVE_LINES_DOWN : UNDO_MOVE_LINES_UP);
	}
}

int txt_setcurr_tab_spaces(Text *text, int space)
{
	int i = 0;
	int test = 0;
	const char *word = ":";
	const char *comm = "#";
	const char indent = (text->flags & TXT_TABSTOSPACES) ? ' ' : '\t';
	static const char *back_words[] = {"return", "break", "continue", "pass", "yield", NULL};

	if (!text->curl) return 0;

	while (text->curl->line[i] == indent) {
		//we only count those tabs/spaces that are before any text or before the curs;
		if (i == text->curc) {
			return i;
		}
		else {
			i++;
		}
	}
	if (strstr(text->curl->line, word)) {
		/* if we find a ':' on this line, then add a tab but not if it is:
		 *  1) in a comment
		 *  2) within an identifier
		 *	3) after the cursor (text->curc), i.e. when creating space before a function def [#25414] 
		 */
		int a;
		bool is_indent = false;
		for (a = 0; (a < text->curc) && (text->curl->line[a] != '\0'); a++) {
			char ch = text->curl->line[a];
			if (ch == '#') {
				break;
			}
			else if (ch == ':') {
				is_indent = 1;
			}
			else if (ch != ' ' && ch != '\t') {
				is_indent = 0;
			}
		}
		if (is_indent) {
			i += space;
		}
	}

	for (test = 0; back_words[test]; test++) {
		/* if there are these key words then remove a tab because we are done with the block */
		if (strstr(text->curl->line, back_words[test]) && i > 0) {
			if (strcspn(text->curl->line, back_words[test]) < strcspn(text->curl->line, comm)) {
				i -= space;
			}
		}
	}
	return i;
}

/*******************************/
/* Character utility functions */
/*******************************/

int text_check_bracket(const char ch)
{
	int a;
	char opens[] = "([{";
	char close[] = ")]}";

	for (a = 0; a < (sizeof(opens) - 1); a++) {
		if (ch == opens[a])
			return a + 1;
		else if (ch == close[a])
			return -(a + 1);
	}
	return 0;
}

/* TODO, have a function for operators - http://docs.python.org/py3k/reference/lexical_analysis.html#operators */
bool text_check_delim(const char ch)
{
	int a;
	char delims[] = "():\"\' ~!%^&*-+=[]{};/<>|.#\t,@";

	for (a = 0; a < (sizeof(delims) - 1); a++) {
		if (ch == delims[a])
			return true;
	}
	return false;
}

bool text_check_digit(const char ch)
{
	if (ch < '0') return false;
	if (ch <= '9') return true;
	return false;
}

bool text_check_identifier(const char ch)
{
	if (ch < '0') return false;
	if (ch <= '9') return true;
	if (ch < 'A') return false;
	if (ch <= 'Z' || ch == '_') return true;
	if (ch < 'a') return false;
	if (ch <= 'z') return true;
	return false;
}

bool text_check_identifier_nodigit(const char ch)
{
	if (ch <= '9') return false;
	if (ch < 'A') return false;
	if (ch <= 'Z' || ch == '_') return true;
	if (ch < 'a') return false;
	if (ch <= 'z') return true;
	return false;
}

#ifndef WITH_PYTHON
int text_check_identifier_unicode(const unsigned int ch)
{
	return (ch < 255 && text_check_identifier((unsigned int)ch));
}

int text_check_identifier_nodigit_unicode(const unsigned int ch)
{
	return (ch < 255 && text_check_identifier_nodigit((char)ch));
}
#endif  /* WITH_PYTHON */

bool text_check_whitespace(const char ch)
{
	if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n')
		return true;
	return false;
}

int text_find_identifier_start(const char *str, int i)
{
	if (UNLIKELY(i <= 0)) {
		return 0;
	}

	while (i--) {
		if (!text_check_identifier(str[i])) {
			break;
		}
	}
	i++;
	return i;
}