/* See LICENSE file for copyright and license details. */
#include "common.h"


static size_t
hunk_head(const char *text, size_t len, const char *suffix, size_t *first, size_t *last)
{
	size_t off = 4, r;
	off += r = libpatch_get_zu__(&text[off], len - off, first);
	if (!r)
		return 0;
	if (off < len && text[off] == ',') {
		off += 1;
		off += r = libpatch_get_zu__(&text[off], len - off, last);
		if (!r)
			return 0;
	} else {
		*last = *first;
	}
	if (5 < len - off && strncmp(&text[off], suffix, 5))
		return 0;
	off += 5;
	return off;
}


int
libpatch_parse_copied_patch(const char *text, size_t textlen, size_t *textend,
                            struct libpatch_patch **patch, size_t *patchlen)
{
	const char *patchtext = text;
	size_t len = 0, size = 0, off, lineno, last, count;
	int need_hunk = 0, in_hunk = 0, type, has_patch = 0;

	*patch = NULL;
	*patchlen = 0;

	while ((len = libpatch_next_line__(&text, &textlen, len))) {
		if (len >= 5 && !strncmp(text, "diff ", 5)) {
			if (has_patch && textend)
				break;
			APPEND_STRING(5, LIBPATCH_PATCH_DIFF_LINE);
			need_hunk = 0;
			in_hunk = 0;

		} else if (len >= 15 && !strncmp(text, "***************", 15)) {
			APPEND_OPTSTRING(15, LIBPATCH_PATCH_HUNK);
			need_hunk = 1;
			in_hunk = 0;
			has_patch = 1;

		} else if (len >= 3 && !strncmp(text, "***", 3)) {
			if (!need_hunk) {
				APPEND_OPTSTRING(3, LIBPATCH_PATCH_FILE1_LABEL);
				(*patch)[*patchlen - 1].lf_terminated = 0;
			} else if (need_hunk == 1 && len > 9 && text[3] == ' ') {
				off = hunk_head(text, len, " ****", &lineno, &last);
				if (!off)
					goto garbage;
				APPEND_OPTSTRING(off, LIBPATCH_PATCH_HUNK_FILE1);
				if (!lineno && last)
					goto garbage;
				else if (!lineno)
					count = 0;
				else if (last < lineno)
					goto garbage;
				else
					count = last - lineno + 1;
				need_hunk = 2;
				in_hunk = lineno > 0 ? 1 : 0;
			} else {
				goto garbage;
			}

		} else if (len >= 3 && !strncmp(text, "---", 3)) {
			if (!need_hunk) {
				APPEND_OPTSTRING(3, LIBPATCH_PATCH_FILE2_LABEL);
				(*patch)[*patchlen - 1].lf_terminated = 0;
				has_patch = 1;
			} else if (need_hunk == 2 && len > 9 && text[3] == ' ') {
				off = hunk_head(text, len, " ----", &lineno, &last);
				if (!off)
					goto garbage;
				APPEND_OPTSTRING(off, LIBPATCH_PATCH_HUNK_FILE2);
				count = 0;
				if (!lineno && last)
					goto garbage;
				else if (!lineno)
					count = 0;
				else if (last < lineno)
					goto garbage;
				else
					count = last - lineno + 1;
				need_hunk = 0;
				in_hunk = lineno > 0 ? 2 : 0;
			} else {
				goto garbage;
			}

		} else if (len >= 2 && in_hunk == 1 && !strncmp(text, "- ", 2)) {
			type = LIBPATCH_PATCH_FILE1_ONLY;
			goto file1_line;
		} else if (len >= 2 && in_hunk == 1 && !strncmp(text, "! ", 2)) {
			type = LIBPATCH_PATCH_PRECHANGE;
			goto file1_line;
		} else if (len >= 2 && in_hunk == 1 && !strncmp(text, "  ", 2)) {
			type = LIBPATCH_PATCH_FILE1_CONTEXT;
		file1_line:
			APPEND_OPTSTRING(2, type);
			if (!--count)
				in_hunk = 0;
			(*patch)[*patchlen - 1].file1_lineno = lineno++;

		} else if (len >= 2 && in_hunk == 2 && !strncmp(text, "+ ", 2)) {
			type = LIBPATCH_PATCH_FILE2_ONLY;
			goto file2_line;
		} else if (len >= 2 && in_hunk == 2 && !strncmp(text, "! ", 2)) {
			type = LIBPATCH_PATCH_POSTCHANGE;
			goto file2_line;
		} else if (len >= 2 && in_hunk == 2 && !strncmp(text, "  ", 2)) {
			type = LIBPATCH_PATCH_FILE2_CONTEXT;
		file2_line:
			APPEND_OPTSTRING(2, type);
			if (!--count)
				in_hunk = 0;
			(*patch)[*patchlen - 1].file2_lineno = lineno++;

		} else if (len >= 1 && !strncmp(text, "\\", 1) && *patchlen) {
			if (IS_LINE((*patch)[*patchlen - 1].type) ||
			    !(*patch)[*patchlen - 1].lf_terminated)
				goto garbage;
			(*patch)[*patchlen - 1].lf_terminated = 0;
			APPEND_NO_TEXT(LIBPATCH_PATCH_SYNTACTICAL);

		} else {
		garbage:
			APPEND_STRING(0, LIBPATCH_PATCH_GARBAGE);
			if (len == textlen)
				(*patch)[*patchlen - 1].lf_terminated = 0;
		}
	}

	if (textend)
		*textend = (size_t)(text - patchtext);

	return 0;

fail:
	free(*patch);
	*patch = NULL;
	*patchlen = 0;
	return -1;
}