#include "adventure.h"

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <readline/readline.h>

/* the last 32 bits are a version number to be increased on breaking changes.
 */
static const char magic[]
	= { 0, 0, 0, 0, 'T', 'E', 'X', 'T', 'A', 'D', 'V', 0, 0, 0, 0 };

#define MLEN sizeof(magic)

/* Every object is serialized in a buffer with the following format:
 *
 *	| offset | location | weight | capacity | health |
 *
 * with each field 32 bits long, for a total of 160 bytes.  Each field is a
 * SIGNED 32 bit integer.  The meaning of the fields is as follows:
 *
 * - offset : the current object, that is objs[offset]
 * - location : the offset of the location, if NULL -1
 * - weight, capacity, health : the propriety of the object.
 *
 * This should make cheating a little bit harder.
 */

int
save(void)
{
	char *line;
	FILE *f;
	struct object *obj;

	line = readline("Save to file: ");
	if (!line || !*line) {
		printf("Invalid filename\n");

		if (line != NULL)
			free(line);

		return save();
	}

	/* b = binary mode, for windows compatibility I guess */
	if ((f = fopen(line, "wb")) == NULL) {
		printf("Cannot write file!\n");
		return 0;
	}

	/* write magic header */
	fwrite(magic, 1, MLEN, f);

	/* write the objects */
	for (obj = objs; obj < obj_end; ++obj) {
		int32_t offset, location, weight, capacity, health;

		offset = obj - objs;
		if (obj->location == NULL)
			location = -1;
		else
			location = obj->location - objs;
		weight = obj->weight;
		capacity = obj->capacity;
		health = obj->health;

		printf("saved: %d %d %d %d %d\n", offset, location, weight,
			capacity, health);

		fwrite(&offset, 4, 1, f);
		fwrite(&location, 4, 1, f);
		fwrite(&weight, 4, 1, f);
		fwrite(&capacity, 4, 1, f);
		fwrite(&health, 4, 1, f);
	}

	fclose(f);
	free(line);
	return 1;
}

int
load(void)
{
	char *line, m[MLEN];
	FILE *f;
	ssize_t r;

	line = readline("Load from file: ");
	if (!line || !*line) {
		printf("Invalid filename\n");

		if (line != NULL)
			free(line);

		return load();
	}

	if ((f = fopen(line, "rb")) == NULL) {
		printf("Cannot open file %s\n", line);
		free(line);
		return 0;
	}

	/* read the magic */
	fread(m, MLEN, 1, f);
	if (memcmp(m, magic, MLEN)) {
		printf("Wrong magic in file, cannot load.\n");
		goto err;
	}

	/* read all the objects */
	while (1) {
		int32_t offset, location, weight, capacity, health;

		if ((r = fread(&offset, 1, 4, f)) != 4)
			break;
		if ((r = fread(&location, 1, 4, f)) != 4)
			break;
		if ((r = fread(&weight, 1, 4, f)) != 4)
			break;
		if ((r = fread(&capacity, 1, 4, f)) != 4)
			break;
		if ((r = fread(&health, 1, 4, f)) != 4)
			break;

		if (objs + offset >= obj_end)
			goto err;

		if (location == -1)
			objs[offset].location = NULL;
		else {
			if (objs + location >= obj_end)
				goto err;

			objs[offset].location = objs + location;
		}

		objs[offset].weight = weight;
		objs[offset].capacity = capacity;
		objs[offset].health = health;
	}

	if (ferror(f)) {
		perror(line);
		goto err;
	}

	printf("OK!\n");
	fclose(f);
	free(line);
	return 1;

err:
	printf("Error in loading file!\n");
	fclose(f);
	free(line);
	return 0;
}