/*

 * 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 "git2/errors.h"

#include "common.h"

#include "diff.h"

#include "diff_driver.h"

#include "diff_xdiff.h"

#include "patch_generate.h"

static int git_xdiff_scan_int(const char **str, int *value)

{

	const char *scan = *str;

	int v = 0, digits = 0;

	/* find next digit */

	for (scan = *str; *scan && !git__isdigit(*scan); scan++);

	/* parse next number */

	for (; git__isdigit(*scan); scan++, digits++)

		v = (v * 10) + (*scan - '0');

	*str = scan;

	*value = v;

	return (digits > 0) ? 0 : -1;

}

static int git_xdiff_parse_hunk(git_diff_hunk *hunk, const char *header)

{

	/* expect something of the form "@@ -%d[,%d] +%d[,%d] @@" */

	if (*header != '@')

		goto fail;

	if (git_xdiff_scan_int(&header, &hunk->old_start) < 0)

		goto fail;

	if (*header == ',') {

		if (git_xdiff_scan_int(&header, &hunk->old_lines) < 0)

			goto fail;

	} else

		hunk->old_lines = 1;

	if (git_xdiff_scan_int(&header, &hunk->new_start) < 0)

		goto fail;

	if (*header == ',') {

		if (git_xdiff_scan_int(&header, &hunk->new_lines) < 0)

			goto fail;

	} else

		hunk->new_lines = 1;

	if (hunk->old_start < 0 || hunk->new_start < 0)

		goto fail;

	return 0;

fail:

	giterr_set(GITERR_INVALID, "malformed hunk header from xdiff");

	return -1;

}

typedef struct {

	git_xdiff_output *xo;

	git_patch_generated *patch;

	git_diff_hunk hunk;

	int old_lineno, new_lineno;

	mmfile_t xd_old_data, xd_new_data;

} git_xdiff_info;

static int diff_update_lines(

	git_xdiff_info *info,

	git_diff_line *line,

	const char *content,

	size_t content_len)

{

	const char *scan = content, *scan_end = content + content_len;

	for (line->num_lines = 0; scan < scan_end; ++scan)

		if (*scan == '\n')

			++line->num_lines;

	line->content     = content;

	line->content_len = content_len;

	/* expect " "/"-"/"+", then data */

	switch (line->origin) {

	case GIT_DIFF_LINE_ADDITION:

	case GIT_DIFF_LINE_DEL_EOFNL:

		line->old_lineno = -1;

		line->new_lineno = info->new_lineno;

		info->new_lineno += (int)line->num_lines;

		break;

	case GIT_DIFF_LINE_DELETION:

	case GIT_DIFF_LINE_ADD_EOFNL:

		line->old_lineno = info->old_lineno;

		line->new_lineno = -1;

		info->old_lineno += (int)line->num_lines;

		break;

	case GIT_DIFF_LINE_CONTEXT:

	case GIT_DIFF_LINE_CONTEXT_EOFNL:

		line->old_lineno = info->old_lineno;

		line->new_lineno = info->new_lineno;

		info->old_lineno += (int)line->num_lines;

		info->new_lineno += (int)line->num_lines;

		break;

	default:

		giterr_set(GITERR_INVALID, "unknown diff line origin %02x",

			(unsigned int)line->origin);

		return -1;

	}

	return 0;

}

static int git_xdiff_cb(void *priv, mmbuffer_t *bufs, int len)

{

	git_xdiff_info *info = priv;

	git_patch_generated *patch = info->patch;

	const git_diff_delta *delta = patch->base.delta;

	git_patch_generated_output *output = &info->xo->output;

	git_diff_line line;

	if (len == 1) {

		output->error = git_xdiff_parse_hunk(&info->hunk, bufs[0].ptr);

		if (output->error < 0)

			return output->error;

		info->hunk.header_len = bufs[0].size;

		if (info->hunk.header_len >= sizeof(info->hunk.header))

			info->hunk.header_len = sizeof(info->hunk.header) - 1;

		memcpy(info->hunk.header, bufs[0].ptr, info->hunk.header_len);

		info->hunk.header[info->hunk.header_len] = '\0';

		if (output->hunk_cb != NULL &&

			(output->error = output->hunk_cb(

				delta, &info->hunk, output->payload)))

			return output->error;

		info->old_lineno = info->hunk.old_start;

		info->new_lineno = info->hunk.new_start;

	}

	if (len == 2 || len == 3) {

		/* expect " "/"-"/"+", then data */

		line.origin =

			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_ADDITION :

			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_DELETION :

			GIT_DIFF_LINE_CONTEXT;

		if (line.origin == GIT_DIFF_LINE_ADDITION)

			line.content_offset = bufs[1].ptr - info->xd_new_data.ptr;

		else if (line.origin == GIT_DIFF_LINE_DELETION)

			line.content_offset = bufs[1].ptr - info->xd_old_data.ptr;

		else

			line.content_offset = -1;

		output->error = diff_update_lines(

			info, &line, bufs[1].ptr, bufs[1].size);

		if (!output->error && output->data_cb != NULL)

			output->error = output->data_cb(

				delta, &info->hunk, &line, output->payload);

	}

	if (len == 3 && !output->error) {

		/* If we have a '+' and a third buf, then we have added a line

		 * without a newline and the old code had one, so DEL_EOFNL.

		 * If we have a '-' and a third buf, then we have removed a line

		 * with out a newline but added a blank line, so ADD_EOFNL.

		 */

		line.origin =

			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_DEL_EOFNL :

			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_ADD_EOFNL :

			GIT_DIFF_LINE_CONTEXT_EOFNL;

		line.content_offset = -1;

		output->error = diff_update_lines(

			info, &line, bufs[2].ptr, bufs[2].size);

		if (!output->error && output->data_cb != NULL)

			output->error = output->data_cb(

				delta, &info->hunk, &line, output->payload);

	}

	return output->error;

}

static int git_xdiff(git_patch_generated_output *output, git_patch_generated *patch)

{

	git_xdiff_output *xo = (git_xdiff_output *)output;

	git_xdiff_info info;

	git_diff_find_context_payload findctxt;

	memset(&info, 0, sizeof(info));

	info.patch = patch;

	info.xo    = xo;

	xo->callback.priv = &info;

	git_diff_find_context_init(

		&xo->config.find_func, &findctxt, git_patch_generated_driver(patch));

	xo->config.find_func_priv = &findctxt;

	if (xo->config.find_func != NULL)

		xo->config.flags |= XDL_EMIT_FUNCNAMES;

	else

		xo->config.flags &= ~XDL_EMIT_FUNCNAMES;

	/* TODO: check ofile.opts_flags to see if driver-specific per-file

	 * updates are needed to xo->params.flags

	 */

	git_patch_generated_old_data(&info.xd_old_data.ptr, &info.xd_old_data.size, patch);

	git_patch_generated_new_data(&info.xd_new_data.ptr, &info.xd_new_data.size, patch);

	if (info.xd_old_data.size > GIT_XDIFF_MAX_SIZE ||

		info.xd_new_data.size > GIT_XDIFF_MAX_SIZE) {

		giterr_set(GITERR_INVALID, "files too large for diff");

		return -1;

	}

	xdl_diff(&info.xd_old_data, &info.xd_new_data,

		&xo->params, &xo->config, &xo->callback);

	git_diff_find_context_clear(&findctxt);

	return xo->output.error;

}

void git_xdiff_init(git_xdiff_output *xo, const git_diff_options *opts)

{

	uint32_t flags = opts ? opts->flags : 0;

	xo->output.diff_cb = git_xdiff;

	xo->config.ctxlen = opts ? opts->context_lines : 3;

	xo->config.interhunkctxlen = opts ? opts->interhunk_lines : 0;

	if (flags & GIT_DIFF_IGNORE_WHITESPACE)

		xo->params.flags |= XDF_WHITESPACE_FLAGS;

	if (flags & GIT_DIFF_IGNORE_WHITESPACE_CHANGE)

		xo->params.flags |= XDF_IGNORE_WHITESPACE_CHANGE;

	if (flags & GIT_DIFF_IGNORE_WHITESPACE_EOL)

		xo->params.flags |= XDF_IGNORE_WHITESPACE_AT_EOL;

	if (flags & GIT_DIFF_PATIENCE)

		xo->params.flags |= XDF_PATIENCE_DIFF;

	if (flags & GIT_DIFF_MINIMAL)

		xo->params.flags |= XDF_NEED_MINIMAL;

	xo->callback.outf = git_xdiff_cb;

}