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


static size_t
hunk_head_part(const char *text, size_t len, size_t *first, size_t *count)
{
	size_t off, r;
	off = libpatch_get_zu__(&text[off], len - off, first);
	if (!off)
		return 0;
	if (off < len && text[off] == ',') {
		off += 1;
		off += r = libpatch_get_zu__(&text[off], len - off, count);
		if (!r)
			return 0;
	} else if (*count) {
		*count = 1;
	}
	return off;
}


int
libpatch_parse_unified_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, r, lineno1, lineno2, count1, count2;
	int in_hunk = 0, 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);
			in_hunk = 0;

		} else if (len >= 4 && !strncmp(text, "@@ -", 4)) {
			off = 4;
			off += r = hunk_head_part(&text[off], len - off, &lineno1, &count1);
			if (!r || 2 >= len - off || strncmp(&text[off], " +", 2))
				goto garbage;
			off += 2;
			off += r = hunk_head_part(&text[off], len - off, &lineno2, &count2);
			if (!r || 3 > len - off || strncmp(&text[off], " @@", 3))
				goto garbage;
			off += 3;
			APPEND_OPTSTRING(off, LIBPATCH_PATCH_HUNK);
			in_hunk = ((count1 ? 1 : 0) | (count2 ? 2 : 0));
			has_patch = 1;

		} else if (!in_hunk && len >= 3 && !strncmp(text, "---", 3)) {
			APPEND_OPTSTRING(3, LIBPATCH_PATCH_FILE1_LABEL);
			(*patch)[*patchlen - 1].lf_terminated = 0;

		} else if (!in_hunk && len >= 3 && !strncmp(text, "+++", 3)) {
			APPEND_OPTSTRING(3, LIBPATCH_PATCH_FILE2_LABEL);
			(*patch)[*patchlen - 1].lf_terminated = 0;
			has_patch = 1;

		} else if ((in_hunk & 1) && len >= 1 && text[0] == '-') {
			APPEND_OPTSTRING(1, LIBPATCH_PATCH_FILE1_ONLY);
			if (!--count1)
				in_hunk ^= 1;
			(*patch)[*patchlen - 1].file1_lineno = lineno1++;

		} else if ((in_hunk & 2) && len >= 1 && text[0] == '+') {
			APPEND_OPTSTRING(1, LIBPATCH_PATCH_FILE2_ONLY);
			if (!--count2)
				in_hunk ^= 2;
			(*patch)[*patchlen - 1].file2_lineno = lineno2++;

		} else if (in_hunk == 3 && len >= 1 && text[0] == ' ') {
			APPEND_OPTSTRING(1, LIBPATCH_PATCH_CONTEXT);
			if (!--count1)
				in_hunk ^= 1;
			if (!--count2)
				in_hunk ^= 2;
			(*patch)[*patchlen - 1].file1_lineno = lineno1++;
			(*patch)[*patchlen - 1].file2_lineno = lineno2++;

		} 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;
}