/* SPDX-License-Identifier: GPL-3.0-or-later */
/* Copyright (C) 2021 KikooDX */

#include <gint/bfile.h>
#include <gint/std/stdlib.h>
#include <stdint.h>

#include "level.h"

/* globals are needed when using gint_switch() */
tile_t level[LEVEL_SIZE];
int level_id = 0;
int fatal_error = 0;
char *fatal_error_msg = "no error, happy kikoo :D";
int debug_value = 0;

static const uint16_t *filepath = u"\\\\fls0\\sample.kble";

static int read_byte(int file);
static tile_t read_merge_bytes(int file, int size);

/* Load level from storage memory. */
void level_load(void) {
	int file;
	int tile_size;
	int width;
	int height;
	int file_size;
	int i;
	char byte;
	tile_t tile;

	/* open file read only */
	file = BFile_Open(filepath, BFile_ReadOnly);
	assert(file >= 0, "can't open file "
	       "don't forget to put it on the calculator dummy");

	/* assert KBLE format version */
	byte = read_byte(file);
	assert(byte == kble_format_version,
	       "kble format version doesn't match");

	/* get tile size (in bytes) */
	tile_size = read_byte(file);
	assert(tile_size >= 0, "can't read tile size");
	assert((unsigned int)tile_size <= sizeof(tile_t),
	       "tiles are too heavy");

	/* assert than width and height are correct */
	width = read_merge_bytes(file, 2);
	height = read_merge_bytes(file, 2);
	assert(width >= 0, "can't read level width");
	assert(width == LEVEL_WIDTH, "invalid level width");
	assert(height >= 0, "can't read level height");
	assert(height == LEVEL_HEIGHT, "invalid level height");

	/* using those informations, see if the file size make sense */
	file_size = BFile_Size(file);
	assert(file_size >= 0, "can't read file size");
	assert(file_size == kble_header_len + LEVEL_SIZE * tile_size,
	       "file size doesn't make sense");

	/* read file content */
	for (i = 0; i < LEVEL_SIZE; i += 1) {
		tile = read_merge_bytes(file, tile_size);
		assert(tile != (tile_t)-1, "can't read tile");
		level[i] = tile;
	}

	/* close file */
	file = BFile_Close(file);
	assert(file >= 0, "closure failed miserably");
}

/* Save level to memory. Allocate memory to write everything at once. */
void level_save(void) {
	int file;
	unsigned int tile_size;
	unsigned int max_tile_size = 1;
	int i;
	tile_t tile;
	int data_size;
	char *data = NULL;

	/* find appropriate tile size */
	for (i = 0; i < LEVEL_SIZE; i += 1) {
		tile = level[i];
		tile_size = 1;
		while (tile >>= 8)
			tile_size += 1;
		if (tile_size > max_tile_size)
			max_tile_size = tile_size;
	}
	assert(max_tile_size <= sizeof(tile_t),
	       "computed tile size is crazy");

	/* total amount of data to write in bytes */
	data_size = kble_header_len + LEVEL_SIZE * tile_size;

	/* allocate memory */
	data = malloc(data_size);

	/* kble format version */
	data[0] = kble_format_version;
	/* tile size in bytes */
	data[1] = max_tile_size;
	/* width and height (comptime) */
	data[2] = LEVEL_WIDTH / 256;
	data[3] = LEVEL_WIDTH % 256;
	data[4] = LEVEL_HEIGHT / 256;
	data[5] = LEVEL_HEIGHT % 256;

	/* level content */
	assert(max_tile_size == 1,
	       "this editor only support tiles from 0 to 255");
	for (i = 0; i < LEVEL_SIZE; i += 1) {
		data[i + kble_header_len] = level[i];
	}

	/* open file in write mode */
	file = BFile_Open(filepath, BFile_WriteOnly);
	assert(file >= 0, "can't open file in write mode");

	/* recreate file with correct size if needed */
	if (BFile_Size(file) != data_size) {
		int data_size_copy = data_size;
		/* close file */
		file = BFile_Close(file);
		assert(file >= 0, "closure failed miserably (w)");
		/* remove file */
		file = BFile_Remove(filepath);
		assert(file >= 0, "file removal failed somehow");
		/* create file */
		file = BFile_Create(filepath, BFile_File, &data_size_copy);
		assert(file >= 0, "file creation failed :(");
		assert(data_size == data_size_copy,
		       "casio messed up my data_size variable");
		/* open file */
		file = BFile_Open(filepath, BFile_WriteOnly);
		assert(file >= 0, "can't open file in write mode");
	}

	/* write data */
	BFile_Write(file, data, data_size);

	/* close file */
	file = BFile_Close(file);
	assert(file >= 0, "closure failed miserably (w)");

	/* free memory */
	free(data);
}

/* Read a single byte. Negative value is BFile error code. */
static int read_byte(int file) {
	char byte;
	const int error = BFile_Read(file, &byte, sizeof(char), -1);
	if (error < 0)
		return error;
	else
		return byte;
}

/* Read multiple bytes and merge them as one integer.
 * Return -1 on failure. */
static tile_t read_merge_bytes(int file, int size) {
	tile_t merged = 0;
	int byte = 0;
	char *byte_ptr = (char*)&merged;
	int i = 0;
	byte_ptr += sizeof(tile_t) - size;
	for (i = 0; i < size; i += 1) {
		byte = read_byte(file);
		if (byte < 0)
			return -1;
		*byte_ptr = byte;
		byte_ptr += 1;
	}
	return merged;
}