/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */
#include "common.h"
#include "diff.h"
#include "diff_patch.h"
#include "fileops.h"

typedef struct {
	git_diff *diff;
	git_diff_format_t format;
	git_diff_line_cb print_cb;
	void *payload;
	git_buf *buf;
	uint32_t flags;
	int oid_strlen;
	git_diff_line line;
} diff_print_info;

static int diff_print_info_init(
	diff_print_info *pi,
	git_buf *out,
	git_diff *diff,
	git_diff_format_t format,
	git_diff_line_cb cb,
	void *payload)
{
	pi->diff     = diff;
	pi->format   = format;
	pi->print_cb = cb;
	pi->payload  = payload;
	pi->buf      = out;

	if (diff)
		pi->flags = diff->opts.flags;

	if (diff && diff->opts.oid_abbrev != 0)
		pi->oid_strlen = diff->opts.oid_abbrev;
	else if (!diff || !diff->repo)
		pi->oid_strlen = GIT_ABBREV_DEFAULT;
	else if (git_repository__cvar(
		&pi->oid_strlen, diff->repo, GIT_CVAR_ABBREV) < 0)
		return -1;

	pi->oid_strlen += 1; /* for NUL byte */

	if (pi->oid_strlen < 2)
		pi->oid_strlen = 2;
	else if (pi->oid_strlen > GIT_OID_HEXSZ + 1)
		pi->oid_strlen = GIT_OID_HEXSZ + 1;

	memset(&pi->line, 0, sizeof(pi->line));
	pi->line.old_lineno = -1;
	pi->line.new_lineno = -1;
	pi->line.num_lines  = 1;

	return 0;
}

static char diff_pick_suffix(int mode)
{
	if (S_ISDIR(mode))
		return '/';
	else if (GIT_PERMS_IS_EXEC(mode)) /* -V536 */
		/* in git, modes are very regular, so we must have 0100755 mode */
		return '*';
	else
		return ' ';
}

char git_diff_status_char(git_delta_t status)
{
	char code;

	switch (status) {
	case GIT_DELTA_ADDED:     code = 'A'; break;
	case GIT_DELTA_DELETED:   code = 'D'; break;
	case GIT_DELTA_MODIFIED:  code = 'M'; break;
	case GIT_DELTA_RENAMED:   code = 'R'; break;
	case GIT_DELTA_COPIED:    code = 'C'; break;
	case GIT_DELTA_IGNORED:   code = 'I'; break;
	case GIT_DELTA_UNTRACKED: code = '?'; break;
	default:                  code = ' '; break;
	}

	return code;
}

static int callback_error(void)
{
	giterr_clear();
	return GIT_EUSER;
}

static int diff_print_one_name_only(
	const git_diff_delta *delta, float progress, void *data)
{
	diff_print_info *pi = data;
	git_buf *out = pi->buf;

	GIT_UNUSED(progress);

	if ((pi->flags & GIT_DIFF_SHOW_UNMODIFIED) == 0 &&
		delta->status == GIT_DELTA_UNMODIFIED)
		return 0;

	git_buf_clear(out);

	if (git_buf_puts(out, delta->new_file.path) < 0 ||
		git_buf_putc(out, '\n'))
		return -1;

	pi->line.origin      = GIT_DIFF_LINE_FILE_HDR;
	pi->line.content     = git_buf_cstr(out);
	pi->line.content_len = git_buf_len(out);

	if (pi->print_cb(delta, NULL, &pi->line, pi->payload))
		return callback_error();

	return 0;
}

static int diff_print_one_name_status(
	const git_diff_delta *delta, float progress, void *data)
{
	diff_print_info *pi = data;
	git_buf *out = pi->buf;
	char old_suffix, new_suffix, code = git_diff_status_char(delta->status);
	int (*strcomp)(const char *, const char *) =
		pi->diff ? pi->diff->strcomp : git__strcmp;

	GIT_UNUSED(progress);

	if ((pi->flags & GIT_DIFF_SHOW_UNMODIFIED) == 0 && code == ' ')
		return 0;

	old_suffix = diff_pick_suffix(delta->old_file.mode);
	new_suffix = diff_pick_suffix(delta->new_file.mode);

	git_buf_clear(out);

	if (delta->old_file.path != delta->new_file.path &&
		strcomp(delta->old_file.path,delta->new_file.path) != 0)
		git_buf_printf(out, "%c\t%s%c %s%c\n", code,
			delta->old_file.path, old_suffix, delta->new_file.path, new_suffix);
	else if (delta->old_file.mode != delta->new_file.mode &&
		delta->old_file.mode != 0 && delta->new_file.mode != 0)
		git_buf_printf(out, "%c\t%s%c %s%c\n", code,
			delta->old_file.path, old_suffix, delta->new_file.path, new_suffix);
	else if (old_suffix != ' ')
		git_buf_printf(out, "%c\t%s%c\n", code, delta->old_file.path, old_suffix);
	else
		git_buf_printf(out, "%c\t%s\n", code, delta->old_file.path);

	if (git_buf_oom(out))
		return -1;

	pi->line.origin      = GIT_DIFF_LINE_FILE_HDR;
	pi->line.content     = git_buf_cstr(out);
	pi->line.content_len = git_buf_len(out);

	if (pi->print_cb(delta, NULL, &pi->line, pi->payload))
		return callback_error();

	return 0;
}

static int diff_print_one_raw(
	const git_diff_delta *delta, float progress, void *data)
{
	diff_print_info *pi = data;
	git_buf *out = pi->buf;
	char code = git_diff_status_char(delta->status);
	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];

	GIT_UNUSED(progress);

	if ((pi->flags & GIT_DIFF_SHOW_UNMODIFIED) == 0 && code == ' ')
		return 0;

	git_buf_clear(out);

	git_oid_tostr(start_oid, pi->oid_strlen, &delta->old_file.oid);
	git_oid_tostr(end_oid, pi->oid_strlen, &delta->new_file.oid);

	git_buf_printf(
		out, ":%06o %06o %s... %s... %c",
		delta->old_file.mode, delta->new_file.mode, start_oid, end_oid, code);

	if (delta->similarity > 0)
		git_buf_printf(out, "%03u", delta->similarity);

	if (delta->old_file.path != delta->new_file.path)
		git_buf_printf(
			out, "\t%s %s\n", delta->old_file.path, delta->new_file.path);
	else
		git_buf_printf(
			out, "\t%s\n", delta->old_file.path ?
			delta->old_file.path : delta->new_file.path);

	if (git_buf_oom(out))
		return -1;

	pi->line.origin      = GIT_DIFF_LINE_FILE_HDR;
	pi->line.content     = git_buf_cstr(out);
	pi->line.content_len = git_buf_len(out);

	if (pi->print_cb(delta, NULL, &pi->line, pi->payload))
		return callback_error();

	return 0;
}

static int diff_print_oid_range(
	git_buf *out, const git_diff_delta *delta, int oid_strlen)
{
	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];

	git_oid_tostr(start_oid, oid_strlen, &delta->old_file.oid);
	git_oid_tostr(end_oid, oid_strlen, &delta->new_file.oid);

	/* TODO: Match git diff more closely */
	if (delta->old_file.mode == delta->new_file.mode) {
		git_buf_printf(out, "index %s..%s %o\n",
			start_oid, end_oid, delta->old_file.mode);
	} else {
		if (delta->old_file.mode == 0) {
			git_buf_printf(out, "new file mode %o\n", delta->new_file.mode);
		} else if (delta->new_file.mode == 0) {
			git_buf_printf(out, "deleted file mode %o\n", delta->old_file.mode);
		} else {
			git_buf_printf(out, "old mode %o\n", delta->old_file.mode);
			git_buf_printf(out, "new mode %o\n", delta->new_file.mode);
		}
		git_buf_printf(out, "index %s..%s\n", start_oid, end_oid);
	}

	if (git_buf_oom(out))
		return -1;

	return 0;
}

static int diff_delta_format_with_paths(
	git_buf *out,
	const git_diff_delta *delta,
	const char *oldpfx,
	const char *newpfx,
	const char *template)
{
	const char *oldpath = delta->old_file.path;
	const char *newpath = delta->new_file.path;

	if (git_oid_iszero(&delta->old_file.oid)) {
		oldpfx = "";
		oldpath = "/dev/null";
	}
	if (git_oid_iszero(&delta->new_file.oid)) {
		newpfx = "";
		newpath = "/dev/null";
	}

	return git_buf_printf(out, template, oldpfx, oldpath, newpfx, newpath);
}

int git_diff_delta__format_file_header(
	git_buf *out,
	const git_diff_delta *delta,
	const char *oldpfx,
	const char *newpfx,
	int oid_strlen)
{
	if (!oldpfx)
		oldpfx = DIFF_OLD_PREFIX_DEFAULT;
	if (!newpfx)
		newpfx = DIFF_NEW_PREFIX_DEFAULT;
	if (!oid_strlen)
		oid_strlen = GIT_ABBREV_DEFAULT + 1;

	git_buf_clear(out);

	git_buf_printf(out, "diff --git %s%s %s%s\n",
		oldpfx, delta->old_file.path, newpfx, delta->new_file.path);

	if (diff_print_oid_range(out, delta, oid_strlen) < 0)
		return -1;

	if ((delta->flags & GIT_DIFF_FLAG_BINARY) == 0)
		diff_delta_format_with_paths(
			out, delta, oldpfx, newpfx, "--- %s%s\n+++ %s%s\n");

	return git_buf_oom(out) ? -1 : 0;
}

static int diff_print_patch_file(
	const git_diff_delta *delta, float progress, void *data)
{
	diff_print_info *pi = data;
	const char *oldpfx =
		pi->diff ? pi->diff->opts.old_prefix : DIFF_OLD_PREFIX_DEFAULT;
	const char *newpfx =
		pi->diff ? pi->diff->opts.new_prefix : DIFF_NEW_PREFIX_DEFAULT;

	GIT_UNUSED(progress);

	if (S_ISDIR(delta->new_file.mode) ||
		delta->status == GIT_DELTA_UNMODIFIED ||
		delta->status == GIT_DELTA_IGNORED ||
		(delta->status == GIT_DELTA_UNTRACKED &&
		 (pi->flags & GIT_DIFF_SHOW_UNTRACKED_CONTENT) == 0))
		return 0;

	if (git_diff_delta__format_file_header(
			pi->buf, delta, oldpfx, newpfx, pi->oid_strlen) < 0)
		return -1;

	pi->line.origin      = GIT_DIFF_LINE_FILE_HDR;
	pi->line.content     = git_buf_cstr(pi->buf);
	pi->line.content_len = git_buf_len(pi->buf);

	if (pi->print_cb(delta, NULL, &pi->line, pi->payload))
		return callback_error();

	if ((delta->flags & GIT_DIFF_FLAG_BINARY) == 0)
		return 0;

	git_buf_clear(pi->buf);

	if (diff_delta_format_with_paths(
			pi->buf, delta, oldpfx, newpfx,
			"Binary files %s%s and %s%s differ\n") < 0)
		return -1;

	pi->line.origin      = GIT_DIFF_LINE_BINARY;
	pi->line.content     = git_buf_cstr(pi->buf);
	pi->line.content_len = git_buf_len(pi->buf);
	pi->line.num_lines   = 1;

	if (pi->print_cb(delta, NULL, &pi->line, pi->payload))
		return callback_error();

	return 0;
}

static int diff_print_patch_hunk(
	const git_diff_delta *d,
	const git_diff_hunk *h,
	void *data)
{
	diff_print_info *pi = data;

	if (S_ISDIR(d->new_file.mode))
		return 0;

	pi->line.origin      = GIT_DIFF_LINE_HUNK_HDR;
	pi->line.content     = h->header;
	pi->line.content_len = h->header_len;

	if (pi->print_cb(d, h, &pi->line, pi->payload))
		return callback_error();

	return 0;
}

static int diff_print_patch_line(
	const git_diff_delta *delta,
	const git_diff_hunk *hunk,
	const git_diff_line *line,
	void *data)
{
	diff_print_info *pi = data;

	if (S_ISDIR(delta->new_file.mode))
		return 0;

	if (pi->print_cb(delta, hunk, line, pi->payload))
		return callback_error();

	return 0;
}

/* print a git_diff to an output callback */
int git_diff_print(
	git_diff *diff,
	git_diff_format_t format,
	git_diff_line_cb print_cb,
	void *payload)
{
	int error;
	git_buf buf = GIT_BUF_INIT;
	diff_print_info pi;
	git_diff_file_cb print_file = NULL;
	git_diff_hunk_cb print_hunk = NULL;
	git_diff_line_cb print_line = NULL;

	switch (format) {
	case GIT_DIFF_FORMAT_PATCH:
		print_file = diff_print_patch_file;
		print_hunk = diff_print_patch_hunk;
		print_line = diff_print_patch_line;
		break;
	case GIT_DIFF_FORMAT_PATCH_HEADER:
		print_file = diff_print_patch_file;
		break;
	case GIT_DIFF_FORMAT_RAW:
		print_file = diff_print_one_raw;
		break;
	case GIT_DIFF_FORMAT_NAME_ONLY:
		print_file = diff_print_one_name_only;
		break;
	case GIT_DIFF_FORMAT_NAME_STATUS:
		print_file = diff_print_one_name_status;
		break;
	default:
		giterr_set(GITERR_INVALID, "Unknown diff output format (%d)", format);
		return -1;
	}

	if (!(error = diff_print_info_init(
			&pi, &buf, diff, format, print_cb, payload)))
		error = git_diff_foreach(
			diff, print_file, print_hunk, print_line, &pi);

	git_buf_free(&buf);

	return error;
}

/* print a git_patch to an output callback */
int git_patch_print(
	git_patch *patch,
	git_diff_line_cb print_cb,
	void *payload)
{
	int error;
	git_buf temp = GIT_BUF_INIT;
	diff_print_info pi;

	assert(patch && print_cb);

	if (!(error = diff_print_info_init(
			&pi, &temp, git_patch__diff(patch),
			GIT_DIFF_FORMAT_PATCH, print_cb, payload)))
		error = git_patch__invoke_callbacks(
			patch, diff_print_patch_file, diff_print_patch_hunk,
			diff_print_patch_line, &pi);

	git_buf_free(&temp);

	return error;
}

static int diff_print_to_buffer_cb(
	const git_diff_delta *delta,
	const git_diff_hunk *hunk,
	const git_diff_line *line,
	void *payload)
{
	git_buf *output = payload;
	GIT_UNUSED(delta); GIT_UNUSED(hunk);

	if (line->origin == GIT_DIFF_LINE_ADDITION ||
		line->origin == GIT_DIFF_LINE_DELETION ||
		line->origin == GIT_DIFF_LINE_CONTEXT)
		git_buf_putc(output, line->origin);

	return git_buf_put(output, line->content, line->content_len);
}

/* print a git_patch to a string buffer */
int git_patch_to_str(
	char **string,
	git_patch *patch)
{
	int error;
	git_buf output = GIT_BUF_INIT;

	error = git_patch_print(patch, diff_print_to_buffer_cb, &output);

	/* GIT_EUSER means git_buf_put in print_to_buffer_cb returned -1,
	 * meaning a memory allocation failure, so just map to -1...
	 */
	if (error == GIT_EUSER)
		error = -1;

	*string = git_buf_detach(&output);

	return error;
}