#include "cache.h"

#include <sys/types.h>
#include <dirent.h>

/*
 * These two functions should build up a graph in memory about
 * what objects we've referenced, and found, and types..
 *
 * Right now we don't do that kind of reachability checking. Yet.
 */
static void mark_needs_sha1(unsigned char *parent, const char * type, unsigned char *child)
{
}

static int mark_sha1_seen(unsigned char *sha1, char *tag)
{
	return 0;
}

static int fsck_tree(unsigned char *sha1, void *data, unsigned long size)
{
	while (size) {
		int len = 1+strlen(data);
		unsigned char *file_sha1 = data + len;
		char *path = strchr(data, ' ');
		if (size < len + 20 || !path)
			return -1;
		data += len + 20;
		size -= len + 20;
		mark_needs_sha1(sha1, "blob", file_sha1);
	}
	return 0;
}

static int fsck_commit(unsigned char *sha1, void *data, unsigned long size)
{
	unsigned char tree_sha1[20];
	unsigned char parent_sha1[20];

	if (memcmp(data, "tree ", 5))
		return -1;
	if (get_sha1_hex(data + 5, tree_sha1) < 0)
		return -1;
	mark_needs_sha1(sha1, "tree", tree_sha1);
	data += 5 + 40 + 1;	/* "tree " + <hex sha1> + '\n' */
	while (!memcmp(data, "parent ", 7)) {
		if (get_sha1_hex(data + 7, parent_sha1) < 0)
			return -1;
		mark_needs_sha1(sha1, "commit", parent_sha1);
		data += 7 + 40 + 1; 	/* "parent " + <hex sha1> + '\n' */
	}
	return 0;
}

static int fsck_entry(unsigned char *sha1, char *tag, void *data, unsigned long size)
{
	if (!strcmp(tag, "blob")) {
		/* Nothing to check */;
	} else if (!strcmp(tag, "tree")) {
		if (fsck_tree(sha1, data, size) < 0)
			return -1;
	} else if (!strcmp(tag, "commit")) {
		if (fsck_commit(sha1, data, size) < 0)
			return -1;
	} else
		return -1;
	return mark_sha1_seen(sha1, tag);
}

static int fsck_name(char *hex)
{
	unsigned char sha1[20];
	if (!get_sha1_hex(hex, sha1)) {
		unsigned long mapsize;
		void *map = map_sha1_file(sha1, &mapsize);
		if (map) {
			char type[100];
			unsigned long size;
			void *buffer = NULL;
			if (!check_sha1_signature(sha1, map, mapsize))
				buffer = unpack_sha1_file(map, mapsize, type, &size);
			munmap(map, mapsize);
			if (buffer && !fsck_entry(sha1, type, buffer, size))
				return 0;
		}
	}
	return -1;
}

static int fsck_dir(int i, char *path)
{
	DIR *dir = opendir(path);
	struct dirent *de;

	if (!dir) {
		fprintf(stderr, "missing sha1 directory '%s'", path);
		return -1;
	}

	while ((de = readdir(dir)) != NULL) {
		char name[100];
		int len = strlen(de->d_name);

		switch (len) {
		case 2:
			if (de->d_name[1] != '.')
				break;
		case 1:
			if (de->d_name[0] != '.')
				break;
			continue;
		case 38:
			sprintf(name, "%02x", i);
			memcpy(name+2, de->d_name, len+1);
			if (!fsck_name(name))
				continue;
		}
		fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
	}
	closedir(dir);
	return 0;
}

int main(int argc, char **argv)
{
	int i;
	char *sha1_dir;

	if (argc != 1)
		usage("fsck-cache");
	sha1_dir = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
	for (i = 0; i < 256; i++) {
		static char dir[4096];
		sprintf(dir, "%s/%02x", sha1_dir, i);
		fsck_dir(i, dir);
	}
	return 0;
}