/**
 * $Id$
 *
 * ***** 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) 2007 Blender Foundation.
 * All rights reserved.
 *
 * 
 * Contributor(s): Blender Foundation
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <stdlib.h>
#include <string.h>
#include <GL/glew.h>

#include "DNA_listBase.h"
#include "DNA_screen_types.h"
#include "DNA_windowmanager_types.h"
#include "DNA_userdef_types.h"
#include "DNA_view3d_types.h"

#include "MEM_guardedalloc.h"

#include "BLI_blenlib.h"

#include "BKE_context.h"
#include "BKE_global.h"
#include "BKE_utildefines.h"

#include "GHOST_C-api.h"

#include "ED_screen.h"

#include "GPU_extensions.h"

#include "WM_api.h"
#include "WM_types.h"
#include "wm.h"
#include "wm_draw.h"
#include "wm_window.h"
#include "wm_event_system.h"

/* swap */
#define WIN_NONE_OK		0
#define WIN_BACK_OK     1
#define WIN_FRONT_OK    2
#define WIN_BOTH_OK		3

/* ******************* drawing, overlays *************** */


static void wm_paintcursor_draw(bContext *C, ARegion *ar)
{
	wmWindowManager *wm= CTX_wm_manager(C);
	
	if(wm->paintcursors.first) {
		wmWindow *win= CTX_wm_window(C);
		bScreen *screen= win->screen;
		wmPaintCursor *pc;

		if(screen->subwinactive == ar->swinid) {
			for(pc= wm->paintcursors.first; pc; pc= pc->next) {
				if(pc->poll == NULL || pc->poll(C)) {
					ARegion *ar= CTX_wm_region(C);
					if (ELEM(win->grabcursor, GHOST_kGrabWrap, GHOST_kGrabHide)) {
						int x = 0, y = 0;
						wm_get_cursor_position(win, &x, &y);
						pc->draw(C, x - ar->winrct.xmin, y - ar->winrct.ymin, pc->customdata);
					} else {
						pc->draw(C, win->eventstate->x - ar->winrct.xmin, win->eventstate->y - ar->winrct.ymin, pc->customdata);
					}
				}
			}
		}
	}
}

/* ********************* drawing, swap ****************** */

static void wm_area_mark_invalid_backbuf(ScrArea *sa)
{
	if(sa->spacetype == SPACE_VIEW3D)
		((View3D*)sa->spacedata.first)->flag |= V3D_INVALID_BACKBUF;
}

/********************** draw all **************************/
/* - reference method, draw all each time                 */

static void wm_method_draw_full(bContext *C, wmWindow *win)
{
	bScreen *screen= win->screen;
	ScrArea *sa;
	ARegion *ar;

	/* draw area regions */
	for(sa= screen->areabase.first; sa; sa= sa->next) {
		CTX_wm_area_set(C, sa);

		for(ar=sa->regionbase.first; ar; ar= ar->next) {
			if(ar->swinid) {
				CTX_wm_region_set(C, ar);
				ED_region_do_draw(C, ar);
				wm_paintcursor_draw(C, ar);
				ED_area_overdraw_flush(C, sa, ar);
				CTX_wm_region_set(C, NULL);
			}
		}
		
		wm_area_mark_invalid_backbuf(sa);
		CTX_wm_area_set(C, NULL);
	}

	ED_screen_draw(win);
	ED_area_overdraw(C);

	/* draw overlapping regions */
	for(ar=screen->regionbase.first; ar; ar= ar->next) {
		if(ar->swinid) {
			CTX_wm_menu_set(C, ar);
			ED_region_do_draw(C, ar);
			CTX_wm_menu_set(C, NULL);
		}
	}

	if(screen->do_draw_gesture)
		wm_gesture_draw(win);
}

/****************** draw overlap all **********************/
/* - redraw marked areas, and anything that overlaps it   */
/* - it also handles swap exchange optionally, assuming   */
/*   that on swap no clearing happens and we get back the */
/*   same buffer as we swapped to the front               */

/* mark area-regions to redraw if overlapped with rect */
static void wm_flush_regions_down(bScreen *screen, rcti *dirty)
{
	ScrArea *sa;
	ARegion *ar;

	for(sa= screen->areabase.first; sa; sa= sa->next) {
		for(ar= sa->regionbase.first; ar; ar= ar->next) {
			if(BLI_isect_rcti(dirty, &ar->winrct, NULL)) {
				ar->do_draw= RGN_DRAW;
				memset(&ar->drawrct, 0, sizeof(ar->drawrct));
				ar->swap= WIN_NONE_OK;
			}
		}
	}
}

/* mark menu-regions to redraw if overlapped with rect */
static void wm_flush_regions_up(bScreen *screen, rcti *dirty)
{
	ARegion *ar;
	
	for(ar= screen->regionbase.first; ar; ar= ar->next) {
		if(BLI_isect_rcti(dirty, &ar->winrct, NULL)) {
			ar->do_draw= RGN_DRAW;
			memset(&ar->drawrct, 0, sizeof(ar->drawrct));
			ar->swap= WIN_NONE_OK;
		}
	}
}

static void wm_method_draw_overlap_all(bContext *C, wmWindow *win, int exchange)
{
	wmWindowManager *wm= CTX_wm_manager(C);
	bScreen *screen= win->screen;
	ScrArea *sa;
	ARegion *ar;
	static rcti rect= {0, 0, 0, 0};

	/* flush overlapping regions */
	if(screen->regionbase.first) {
		/* flush redraws of area regions up to overlapping regions */
		for(sa= screen->areabase.first; sa; sa= sa->next)
			for(ar= sa->regionbase.first; ar; ar= ar->next)
				if(ar->swinid && ar->do_draw)
					wm_flush_regions_up(screen, &ar->winrct);
		
		/* flush between overlapping regions */
		for(ar= screen->regionbase.last; ar; ar= ar->prev)
			if(ar->swinid && ar->do_draw)
				wm_flush_regions_up(screen, &ar->winrct);
		
		/* flush redraws of overlapping regions down to area regions */
		for(ar= screen->regionbase.last; ar; ar= ar->prev)
			if(ar->swinid && ar->do_draw)
				wm_flush_regions_down(screen, &ar->winrct);
	}

	/* flush drag item */
	if(rect.xmin!=rect.xmax) {
		wm_flush_regions_down(screen, &rect);
		rect.xmin= rect.xmax = 0;
	}
	if(wm->drags.first) {
		/* doesnt draw, fills rect with boundbox */
		wm_drags_draw(C, win, &rect);
	}
	
	/* draw marked area regions */
	for(sa= screen->areabase.first; sa; sa= sa->next) {
		CTX_wm_area_set(C, sa);

		for(ar=sa->regionbase.first; ar; ar= ar->next) {
			if(ar->swinid) {
				if(ar->do_draw) {
					CTX_wm_region_set(C, ar);
					ED_region_do_draw(C, ar);
					wm_paintcursor_draw(C, ar);
					ED_area_overdraw_flush(C, sa, ar);
					CTX_wm_region_set(C, NULL);

					if(exchange)
						ar->swap= WIN_FRONT_OK;
				}
				else if(exchange) {
					if(ar->swap == WIN_FRONT_OK) {
						CTX_wm_region_set(C, ar);
						ED_region_do_draw(C, ar);
						wm_paintcursor_draw(C, ar);
						ED_area_overdraw_flush(C, sa, ar);
						CTX_wm_region_set(C, NULL);

						ar->swap= WIN_BOTH_OK;
						printf("draws swap exchange %d\n", ar->swinid);
					}
					else if(ar->swap == WIN_BACK_OK)
						ar->swap= WIN_FRONT_OK;
					else if(ar->swap == WIN_BOTH_OK)
						ar->swap= WIN_BOTH_OK;
				}
			}
		}
		
		wm_area_mark_invalid_backbuf(sa);
		CTX_wm_area_set(C, NULL);
	}

	/* after area regions so we can do area 'overlay' drawing */
	if(screen->do_draw) {
		ED_screen_draw(win);

		if(exchange)
			screen->swap= WIN_FRONT_OK;
	}
	else if(exchange) {
		if(screen->swap==WIN_FRONT_OK) {
			ED_screen_draw(win);
			screen->swap= WIN_BOTH_OK;
		}
		else if(screen->swap==WIN_BACK_OK)
			screen->swap= WIN_FRONT_OK;
		else if(screen->swap==WIN_BOTH_OK)
			screen->swap= WIN_BOTH_OK;
	}

	ED_area_overdraw(C);

	/* draw marked overlapping regions */
	for(ar=screen->regionbase.first; ar; ar= ar->next) {
		if(ar->swinid && ar->do_draw) {
			CTX_wm_menu_set(C, ar);
			ED_region_do_draw(C, ar);
			CTX_wm_menu_set(C, NULL);
		}
	}

	if(screen->do_draw_gesture)
		wm_gesture_draw(win);
	
	/* needs pixel coords in screen */
	if(wm->drags.first) {
		wm_drags_draw(C, win, NULL);
	}
}

#if 0
/******************** draw damage ************************/
/* - not implemented                                      */

static void wm_method_draw_damage(bContext *C, wmWindow *win)
{
	wm_method_draw_all(C, win);
}
#endif

/****************** draw triple buffer ********************/
/* - area regions are written into a texture, without any */
/*   of the overlapping menus, brushes, gestures. these   */
/*   are redrawn each time.                               */
/*                                                        */
/* - if non-power of two textures are supported, that is  */
/*   used. if not, multiple smaller ones are used, with   */
/*   worst case wasted space being 23.4% for 3x3 textures */

#define MAX_N_TEX 3

typedef struct wmDrawTriple {
	GLuint bind[MAX_N_TEX*MAX_N_TEX];
	int x[MAX_N_TEX], y[MAX_N_TEX];
	int nx, ny;
	GLenum target;
} wmDrawTriple;

static int is_pow2(int n)
{
	return ((n)&(n-1))==0;
}

static int smaller_pow2(int n)
{
	while (!is_pow2(n))
		n= n&(n-1);

	return n;
}

static int larger_pow2(int n)
{
	if (is_pow2(n))
		return n;

	while(!is_pow2(n))
		n= n&(n-1);

	return n*2;
}

static void split_width(int x, int n, int *splitx, int *nx)
{
	int a, newnx, waste;

	/* if already power of two just use it */
	if(is_pow2(x)) {
		splitx[0]= x;
		(*nx)++;
		return;
	}

	if(n == 1) {
		/* last part, we have to go larger */
		splitx[0]= larger_pow2(x);
		(*nx)++;
	}
	else {
		/* two or more parts to go, use smaller part */
		splitx[0]= smaller_pow2(x);
		newnx= ++(*nx);
		split_width(x-splitx[0], n-1, splitx+1, &newnx);

		for(waste=0, a=0; a<n; a++)
			waste += splitx[a];

		/* if we waste more space or use the same amount,
		 * revert deeper splits and just use larger */
		if(waste >= larger_pow2(x)) {
			splitx[0]= larger_pow2(x);
			memset(splitx+1, 0, sizeof(int)*(n-1));
		}
		else
			*nx= newnx;
	}
}

static void wm_draw_triple_free(wmWindow *win)
{
	if(win->drawdata) {
		wmDrawTriple *triple= win->drawdata;

		glDeleteTextures(triple->nx*triple->ny, triple->bind);
		MEM_freeN(triple);

		win->drawdata= NULL;
	}
}

static void wm_draw_triple_fail(bContext *C, wmWindow *win)
{
	wm_draw_window_clear(win);

	win->drawfail= 1;
	wm_method_draw_overlap_all(C, win, 0);
}

static int wm_triple_gen_textures(wmWindow *win, wmDrawTriple *triple)
{
	GLint maxsize;
	int x, y;

	/* compute texture sizes */
	if(GLEW_ARB_texture_rectangle || GLEW_NV_texture_rectangle || GLEW_EXT_texture_rectangle) {
		triple->target= GL_TEXTURE_RECTANGLE_ARB;
		triple->nx= 1;
		triple->ny= 1;
		triple->x[0]= win->sizex;
		triple->y[0]= win->sizey;
	}
	else if(GPU_non_power_of_two_support()) {
		triple->target= GL_TEXTURE_2D;
		triple->nx= 1;
		triple->ny= 1;
		triple->x[0]= win->sizex;
		triple->y[0]= win->sizey;
	}
	else {
		triple->target= GL_TEXTURE_2D;
		triple->nx= 0;
		triple->ny= 0;
		split_width(win->sizex, MAX_N_TEX, triple->x, &triple->nx);
		split_width(win->sizey, MAX_N_TEX, triple->y, &triple->ny);
	}

	/* generate texture names */
	glGenTextures(triple->nx*triple->ny, triple->bind);

	if(!triple->bind[0]) {
		/* not the typical failure case but we handle it anyway */
		printf("WM: failed to allocate texture for triple buffer drawing (glGenTextures).\n");
		return 0;
	}

	for(y=0; y<triple->ny; y++) {
		for(x=0; x<triple->nx; x++) {
			/* proxy texture is only guaranteed to test for the cases that
			 * there is only one texture in use, which may not be the case */
			glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxsize);

			if(triple->x[x] > maxsize || triple->y[y] > maxsize) {
				glBindTexture(triple->target, 0);
				printf("WM: failed to allocate texture for triple buffer drawing (texture too large for graphics card).\n");
				return 0;
			}

			/* setup actual texture */
			glBindTexture(triple->target, triple->bind[x + y*triple->nx]);
			glTexImage2D(triple->target, 0, GL_RGB8, triple->x[x], triple->y[y], 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
			glTexParameteri(triple->target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
			glTexParameteri(triple->target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
			// glColor still used with this enabled?
			// glTexEnvi(triple->target, GL_TEXTURE_ENV_MODE, GL_REPLACE);
			glBindTexture(triple->target, 0);

			/* not sure if this works everywhere .. */
			if(glGetError() == GL_OUT_OF_MEMORY) {
				printf("WM: failed to allocate texture for triple buffer drawing (out of memory).\n");
				return 0;
			}
		}
	}

	return 1;
}

static void wm_triple_draw_textures(wmWindow *win, wmDrawTriple *triple)
{
	float halfx, halfy, ratiox, ratioy;
	int x, y, sizex, sizey, offx, offy;

	glEnable(triple->target);

	for(y=0, offy=0; y<triple->ny; offy+=triple->y[y], y++) {
		for(x=0, offx=0; x<triple->nx; offx+=triple->x[x], x++) {
			sizex= (x == triple->nx-1)? win->sizex-offx: triple->x[x];
			sizey= (y == triple->ny-1)? win->sizey-offy: triple->y[y];

			/* wmOrtho for the screen has this same offset */
			ratiox= sizex;
			ratioy= sizey;
			halfx= 0.375f;
			halfy= 0.375f;

			/* texture rectangle has unnormalized coordinates */
			if(triple->target == GL_TEXTURE_2D) {
				ratiox /= triple->x[x];
				ratioy /= triple->y[y];
				halfx /= triple->x[x];
				halfy /= triple->y[y];
			}

			glBindTexture(triple->target, triple->bind[x + y*triple->nx]);

			glColor3f(1.0f, 1.0f, 1.0f);
			glBegin(GL_QUADS);
				glTexCoord2f(halfx, halfy);
				glVertex2f(offx, offy);

				glTexCoord2f(ratiox+halfx, halfy);
				glVertex2f(offx+sizex, offy);

				glTexCoord2f(ratiox+halfx, ratioy+halfy);
				glVertex2f(offx+sizex, offy+sizey);

				glTexCoord2f(halfx, ratioy+halfy);
				glVertex2f(offx, offy+sizey);
			glEnd();
		}
	}

	glBindTexture(triple->target, 0);
	glDisable(triple->target);
}

static void wm_triple_copy_textures(wmWindow *win, wmDrawTriple *triple)
{
	int x, y, sizex, sizey, offx, offy;

	for(y=0, offy=0; y<triple->ny; offy+=triple->y[y], y++) {
		for(x=0, offx=0; x<triple->nx; offx+=triple->x[x], x++) {
			sizex= (x == triple->nx-1)? win->sizex-offx: triple->x[x];
			sizey= (y == triple->ny-1)? win->sizey-offy: triple->y[y];

			glBindTexture(triple->target, triple->bind[x + y*triple->nx]);
			glCopyTexSubImage2D(triple->target, 0, 0, 0, offx, offy, sizex, sizey);
		}
	}

	glBindTexture(triple->target, 0);
}

static void wm_method_draw_triple(bContext *C, wmWindow *win)
{
	wmWindowManager *wm= CTX_wm_manager(C);
	wmDrawTriple *triple;
	bScreen *screen= win->screen;
	ScrArea *sa;
	ARegion *ar;
	int copytex= 0;

	if(win->drawdata) {
		glClearColor(0, 0, 0, 0);
		glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

		wmSubWindowSet(win, screen->mainwin);

		wm_triple_draw_textures(win, win->drawdata);

		triple= win->drawdata;
	}
	else {
		win->drawdata= MEM_callocN(sizeof(wmDrawTriple), "wmDrawTriple");

		if(!wm_triple_gen_textures(win, win->drawdata)) {
			wm_draw_triple_fail(C, win);
			return;
		}
	}

	triple= win->drawdata;

	/* draw marked area regions */
	for(sa= screen->areabase.first; sa; sa= sa->next) {
		CTX_wm_area_set(C, sa);

		for(ar=sa->regionbase.first; ar; ar= ar->next) {
			if(ar->swinid && ar->do_draw) {
				CTX_wm_region_set(C, ar);
				ED_region_do_draw(C, ar);
				ED_area_overdraw_flush(C, sa, ar);
				CTX_wm_region_set(C, NULL);
				copytex= 1;
			}
		}
		
		wm_area_mark_invalid_backbuf(sa);
		CTX_wm_area_set(C, NULL);
	}

	if(copytex) {
		wmSubWindowSet(win, screen->mainwin);
		ED_area_overdraw(C);

		wm_triple_copy_textures(win, triple);
	}

	/* after area regions so we can do area 'overlay' drawing */
	ED_screen_draw(win);

	/* draw overlapping regions */
	for(ar=screen->regionbase.first; ar; ar= ar->next) {
		if(ar->swinid) {
			CTX_wm_menu_set(C, ar);
			ED_region_do_draw(C, ar);
			CTX_wm_menu_set(C, NULL);
		}
	}

	if(screen->do_draw_gesture)
		wm_gesture_draw(win);

	if(wm->paintcursors.first) {
		for(sa= screen->areabase.first; sa; sa= sa->next) {
			for(ar=sa->regionbase.first; ar; ar= ar->next) {
				if(ar->swinid == screen->subwinactive) {
					CTX_wm_area_set(C, sa);
					CTX_wm_region_set(C, ar);

					/* make region ready for draw, scissor, pixelspace */
					ED_region_set(C, ar);
					wm_paintcursor_draw(C, ar);

					CTX_wm_region_set(C, NULL);
					CTX_wm_area_set(C, NULL);
				}
			}
		}

		wmSubWindowSet(win, screen->mainwin);
	}
	
	/* needs pixel coords in screen */
	if(wm->drags.first) {
		wm_drags_draw(C, win, NULL);
	}

}

/****************** main update call **********************/

/* quick test to prevent changing window drawable */
static int wm_draw_update_test_window(wmWindow *win)
{
	ScrArea *sa;
	ARegion *ar;
	
	if(win->screen->do_refresh)
		return 1;
	if(win->screen->do_draw)
		return 1;
	if(win->screen->do_draw_gesture)
		return 1;
	if(win->screen->do_draw_paintcursor)
		return 1;
	if(win->screen->do_draw_drag)
		return 1;
	
	for(ar= win->screen->regionbase.first; ar; ar= ar->next)
		if(ar->swinid && ar->do_draw)
			return 1;
		
	for(sa= win->screen->areabase.first; sa; sa= sa->next)
		for(ar=sa->regionbase.first; ar; ar= ar->next)
			if(ar->swinid && ar->do_draw)
				return 1;

	return 0;
}

static int wm_automatic_draw_method(wmWindow *win)
{
	if(win->drawmethod == USER_DRAW_AUTOMATIC) {
		/* ATI opensource driver is known to be very slow at this */
		if(GPU_type_matches(GPU_DEVICE_ATI, GPU_OS_UNIX, GPU_DRIVER_OPENSOURCE))
			return USER_DRAW_OVERLAP;
		/* Windows software driver darkens color on each redraw */
		else if(GPU_type_matches(GPU_DEVICE_SOFTWARE, GPU_OS_WIN, GPU_DRIVER_SOFTWARE))
			return USER_DRAW_OVERLAP_FLIP;
		else if(!GPU_24bit_color_support())
			return USER_DRAW_OVERLAP;
		else
			return USER_DRAW_TRIPLE;
	}
	else
		return win->drawmethod;
}

void wm_tag_redraw_overlay(wmWindow *win, ARegion *ar)
{
	/* for draw triple gestures, paint cursors don't need region redraw */
	if(ar && win && wm_automatic_draw_method(win) != USER_DRAW_TRIPLE)
		ED_region_tag_redraw(ar);
}

void wm_draw_update(bContext *C)
{
	wmWindowManager *wm= CTX_wm_manager(C);
	wmWindow *win;
	int drawmethod;
	
	for(win= wm->windows.first; win; win= win->next) {
		if(win->drawmethod != U.wmdrawmethod) {
			wm_draw_window_clear(win);
			win->drawmethod= U.wmdrawmethod;
		}

		if(wm_draw_update_test_window(win)) {
			CTX_wm_window_set(C, win);
			
			/* sets context window+screen */
			wm_window_make_drawable(C, win);

			/* notifiers for screen redraw */
			if(win->screen->do_refresh)
				ED_screen_refresh(wm, win);

			drawmethod= wm_automatic_draw_method(win);

			if(win->drawfail)
				wm_method_draw_overlap_all(C, win, 0);
			else if(drawmethod == USER_DRAW_FULL)
				wm_method_draw_full(C, win);
			else if(drawmethod == USER_DRAW_OVERLAP)
				wm_method_draw_overlap_all(C, win, 0);
			else if(drawmethod == USER_DRAW_OVERLAP_FLIP)
				wm_method_draw_overlap_all(C, win, 1);
			else // if(drawmethod == USER_DRAW_TRIPLE)
				wm_method_draw_triple(C, win);

			win->screen->do_draw_gesture= 0;
			win->screen->do_draw_paintcursor= 0;
			win->screen->do_draw_drag= 0;
		
			wm_window_swap_buffers(win);

			CTX_wm_window_set(C, NULL);
		}
	}
}

void wm_draw_window_clear(wmWindow *win)
{
	bScreen *screen= win->screen;
	ScrArea *sa;
	ARegion *ar;
	int drawmethod= wm_automatic_draw_method(win);

	if(drawmethod == USER_DRAW_TRIPLE)
		wm_draw_triple_free(win);

	/* clear screen swap flags */
	if(screen) {
		for(sa= screen->areabase.first; sa; sa= sa->next)
			for(ar=sa->regionbase.first; ar; ar= ar->next)
				ar->swap= WIN_NONE_OK;
		
		screen->swap= WIN_NONE_OK;
	}
}

void wm_draw_region_clear(wmWindow *win, ARegion *ar)
{
	int drawmethod= wm_automatic_draw_method(win);

	if(ELEM(drawmethod, USER_DRAW_OVERLAP, USER_DRAW_OVERLAP_FLIP))
		wm_flush_regions_down(win->screen, &ar->winrct);

	win->screen->do_draw= 1;
}