/* 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 *last)
{
	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, last);
		if (!r)
			return 0;
	} else {
		*last = *first;
	}
	return off;
}


int
libpatch_parse_normal_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, lineno1, lineno2, count1, count2, last;
	int in_hunk = 0, need2, type, has_patch = 0;
	char op;

	*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 >= 3 && in_hunk == 1 && need2 && !strncmp(text, "---", 3)) {
			APPEND_OPTSTRING(3, LIBPATCH_PATCH_HUNK_FILE2);
			in_hunk = 2;

		} else if (len >= 3 && in_hunk == 0 && text[1] != ' ') {
			off = hunk_head_part(&text[off], len - off, &lineno1, &last);
			if (!off || 2 > len - off)
				goto garbage;
			if (!lineno1 && last)
				goto garbage;
			else if (!lineno1)
				count1 = 0;
			else if (last < lineno1)
				goto garbage;
			else
				count1 = last - lineno1 + 1;

			op = text[off++];

			off = hunk_head_part(&text[off], len - off, &lineno2, &last);
			if (!off || 2 > len - off)
				goto garbage;
			if (!lineno2 && last)
				goto garbage;
			else if (!lineno2)
				count2 = 0;
			else if (last < lineno2)
				goto garbage;
			else
				count2 = last - lineno2 + 1;

			if (op == 'a') {
				in_hunk = 2;
			} else if (op == 'c') {
				in_hunk = 1;
				need2 = 1;
			} else if (op == 'd') {
				in_hunk = 1;
				need2 = 0;
			} else {
				goto garbage;
			}

			if (in_hunk == 1)
				APPEND_OPTSTRING(off, LIBPATCH_PATCH_HUNK_FILE1);
			else
				APPEND_OPTSTRING(off, LIBPATCH_PATCH_HUNK);

			has_patch = 1;

		} else if (len >= 2 && in_hunk == 1 && !strncmp(text, "< ", 2)) {
			type = LIBPATCH_PATCH_FILE1_ONLY;
		file1_line:
			APPEND_OPTSTRING(2, type);
			if (!--count2)
				in_hunk = 0;
			(*patch)[*patchlen - 1].file1_lineno = lineno1++;
		} else if (len >= 2 && in_hunk == 1 && !strncmp(text, "  ", 2)) {
			type = LIBPATCH_PATCH_FILE1_CONTEXT;
			goto file1_line;

		} else if (len >= 2 && in_hunk == 2 && !strncmp(text, "> ", 2)) {
			type = LIBPATCH_PATCH_FILE2_ONLY;
		file2_line:
			APPEND_OPTSTRING(2, type);
			if (!--count2)
				in_hunk = 0;
			(*patch)[*patchlen - 1].file2_lineno = lineno2++;
		} else if (len >= 2 && in_hunk == 2 && !strncmp(text, "  ", 2)) {
			type = LIBPATCH_PATCH_FILE2_CONTEXT;
			goto file2_line;

		} 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;
}