#define _XOPEN_SOURCE 700
#include <fcntl.h>
#include <regex.h>
#include <sys/mman.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "maje.h"

#define MAX_MATCHES (2)

static struct majeflag * find_flags(const struct majefile *file, const regex_t * restrict re, struct majeflag *flags)
{
	int fd = open(file->path, O_RDONLY);
	if (fd == -1) {
		return NULL;
	}

	void *map = mmap(NULL, (size_t)file->st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	if (map == MAP_FAILED) {
		close(fd);
		return NULL;
	}

	regmatch_t match[MAX_MATCHES];
	
	void *base = map;
	while (regexec(re, base, MAX_MATCHES, match, 0) == 0) {
		if (match[1].rm_so == -1) {
			break;
		}
		char flag[FILENAME_MAX] = { 0 };
		char *start = (char*)base + match[1].rm_so;
		memcpy(flag, start, match[1].rm_eo - match[1].rm_so);
		flags = insert_flag(flags, flag);
		base = start + match[1].rm_eo;
	}

	munmap(map, file->st.st_size);
	close(fd);

	return flags;
}

struct majeflag *add_flags(const struct majefile *source, struct majeflag *flags)
{
	static regex_t re = { .re_nsub = (size_t)-1 };
	if (re.re_nsub == (size_t)-1) {
		if (regcomp(&re,
			"(MAJE_[[:upper:]]+=[^[:space:]]+)",
			REG_EXTENDED | REG_NEWLINE) != 0) {
				fprintf(stderr, "maje: regcomp(MAJE) failed\n");
				abort();
		}
	}

	struct majeflag *ret = find_flags(source, &re, flags);

	if (ret != NULL) {
		while (ret->prev != NULL) {
			ret = ret->prev;
		}
	}

	return ret;
}