#include "tag.h"
#include "cache.h"

const char *tag_type = "tag";

struct tag *lookup_tag(unsigned char *sha1)
{
        struct object *obj = lookup_object(sha1);
        if (!obj) {
                struct tag *ret = xmalloc(sizeof(struct tag));
                memset(ret, 0, sizeof(struct tag));
                created_object(sha1, &ret->object);
                ret->object.type = tag_type;
                return ret;
        }
        if (obj->type != tag_type) {
                error("Object %s is a %s, not a tree", 
                      sha1_to_hex(sha1), obj->type);
                return NULL;
        }
        return (struct tag *) obj;
}

int parse_tag(struct tag *item)
{
        char type[20];
        void *data, *bufptr;
        unsigned long size;
	int typelen, taglen;
	unsigned char object[20];
	const char *type_line, *tag_line, *sig_line;

        if (item->object.parsed)
                return 0;
        item->object.parsed = 1;
        data = bufptr = read_sha1_file(item->object.sha1, type, &size);
        if (!data)
                return error("Could not read %s",
                             sha1_to_hex(item->object.sha1));
        if (strcmp(type, tag_type)) {
		free(data);
                return error("Object %s not a tag",
                             sha1_to_hex(item->object.sha1));
	}

	if (size < 64)
		goto err;
	if (memcmp("object ", data, 7) || get_sha1_hex(data + 7, object))
		goto err;

	item->tagged = parse_object(object);

	type_line = data + 48;
	if (memcmp("\ntype ", type_line-1, 6))
		goto err;

	tag_line = strchr(type_line, '\n');
	if (!tag_line || memcmp("tag ", ++tag_line, 4))
		goto err;

	sig_line = strchr(tag_line, '\n');
	if (!sig_line)
		goto err;
	sig_line++;

	typelen = tag_line - type_line - strlen("type \n");
	if (typelen >= 20)
		goto err;
	taglen = sig_line - tag_line - strlen("tag \n");
	item->tag = xmalloc(taglen + 1);
	memcpy(item->tag, tag_line + 4, taglen);
	item->tag[taglen] = '\0';

	free(data);
	return 0;

err:
	free(data);
	return -1;
}