// Copyright (c) Athena Dev Teams - Licensed under GNU GPL
// For more information, see LICENCE in the main folder

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

#ifndef _WIN32
#include <unistd.h>
#endif

#include "grfio.h"

#define MAP_NAME_LENGTH 12
#define MAP_NAME_LENGTH_EXT 16
#define NO_WATER 1000000

char grf_list_file[256] = "conf/grf-files.txt";
char map_list_file[256] = "db/map_index.txt";
char map_cache_file[256] = "db/map_cache.dat";
int rebuild = 0;

FILE *map_cache_fp;

unsigned long file_size;

// Used internally, this structure contains the physical map cells
struct map_data {
	short xs;
	short ys;
	unsigned char *cells;
};

// This is the main header found at the very beginning of the file
struct main_header {
	unsigned long file_size;
	unsigned short map_count;
} header;

// This is the header appended before every compressed map cells info
struct map_info {
	char name[MAP_NAME_LENGTH];
	short xs;
	short ys;
	long len;
};


/*************************************
* Big-endian compatibility functions *
*************************************/

// Converts a short (16 bits) from current machine order to little-endian
short MakeShortLE(short val)
{
	unsigned char buf[2];
	buf[0] = (unsigned char)( (val & 0x00FF)         );
	buf[1] = (unsigned char)( (val & 0xFF00) >> 0x08 );
	return *((short*)buf);
}

// Converts a long (32 bits) from current machine order to little-endian
long MakeLongLE(long val)
{
	unsigned char buf[4];
	buf[0] = (unsigned char)( (val & 0x000000FF)         );
	buf[1] = (unsigned char)( (val & 0x0000FF00) >> 0x08 );
	buf[2] = (unsigned char)( (val & 0x00FF0000) >> 0x10 );
	buf[3] = (unsigned char)( (val & 0xFF000000) >> 0x18 );
	return *((long*)buf);
}

// Reads an unsigned short (16 bits) in little-endian from the buffer
unsigned short GetUShort(const unsigned char *buf)
{
	return	 ( ((unsigned short)(buf[0]))         )
			|( ((unsigned short)(buf[1])) << 0x08 );
}

// Reads a long (32 bits) in little-endian from the buffer
long GetLong(const unsigned char *buf)
{
	return	 ( ((long)(buf[0]))         )
			|( ((long)(buf[1])) << 0x08 )
			|( ((long)(buf[2])) << 0x10 )
			|( ((long)(buf[3])) << 0x18 );
}

// Reads an unsigned long (32 bits) in little-endian from the buffer
unsigned long GetULong(const unsigned char *buf)
{
	return	 ( ((unsigned long)(buf[0]))         )
			|( ((unsigned long)(buf[1])) << 0x08 )
			|( ((unsigned long)(buf[2])) << 0x10 )
			|( ((unsigned long)(buf[3])) << 0x18 );
}

// Reads a float (32 bits) from the buffer
float GetFloat(const unsigned char *buf)
{
	unsigned long val = GetULong(buf);
	return *((float*)&val);
}


// Reads a map from GRF's GAT and RSW files
int read_map(char *name, struct map_data *m)
{
	char filename[256];
	unsigned char *gat, *rsw;
	int water_height;
	size_t xy, off, num_cells;
	float height;
	unsigned long type;

	// Open map GAT
	sprintf(filename,"data\\%s.gat", name);
	gat = (unsigned char *)grfio_read(filename);
	if (gat == NULL)
		return 0;

	// Open map RSW
	sprintf(filename,"data\\%s.rsw", name);
	rsw = (unsigned char *)grfio_read(filename);

	// Read water height
	if (rsw) { 
		water_height = (int)GetFloat(rsw+166);
		free(rsw);
	} else
		water_height = NO_WATER;

	// Read map size and allocate needed memory
	m->xs = (short)GetULong(gat+6);
	m->ys = (short)GetULong(gat+10);
	num_cells = (size_t)m->xs*m->ys;
	m->cells = (unsigned char *)malloc(num_cells);

	// Set cell properties
	off = 14;
	for (xy = 0; xy < num_cells; xy++)
	{
		// Height of the bottom-left corner
		height = GetFloat( gat + off      );
		// Type of cell
		type   = GetULong( gat + off + 16 );
		off += 20;

		if (type == 0 && water_height != NO_WATER && height > water_height)
			type = 3; // Cell is 0 (walkable) but under water level, set to 3 (walkable water)

		m->cells[xy] = (unsigned char)type;
	}

	free(gat);

	return 1;
}

// Adds a map to the cache
void cache_map(char *name, struct map_data *m)
{
	struct map_info info;
	unsigned long len;
	unsigned char *write_buf;

	// Create an output buffer twice as big as the uncompressed map... this way we're sure it fits
	len = m->xs*m->ys*2;
	write_buf = (unsigned char *)malloc(len);
	// Compress the cells and get the compressed length
	encode_zip(write_buf, &len, m->cells, m->xs*m->ys);

	// Fill the map header
	strncpy(info.name, name, MAP_NAME_LENGTH);
	info.xs = MakeShortLE(m->xs);
	info.ys = MakeShortLE(m->ys);
	info.len = MakeLongLE(len);

	// Append map header then compressed cells at the end of the file
	fseek(map_cache_fp, header.file_size, SEEK_SET);
	fwrite(&info, sizeof(struct map_info), 1, map_cache_fp);
	fwrite(write_buf, 1, len, map_cache_fp);
	header.file_size += sizeof(struct map_info) + len;
	header.map_count++;

	free(write_buf);
	free(m->cells);

	return;
}

// Checks whether a map is already is the cache
int find_map(char *name)
{
	int i;
	struct map_info info;

	fseek(map_cache_fp, sizeof(struct main_header), SEEK_SET);

	for(i = 0; i < header.map_count; i++) {
		fread(&info, sizeof(info), 1, map_cache_fp);
		if(strcmp(name, info.name) == 0) // Map found
			return 1;
		else // Map not found, jump to the beginning of the next map info header
			fseek(map_cache_fp, GetLong((unsigned char *)&(info.len)), SEEK_CUR);
	}

	return 0;
}

// Cuts the extension from a map name
char *remove_extension(char *mapname)
{
	char *ptr, *ptr2;
	ptr = strchr(mapname, '.');
	if (ptr) { //Check and remove extension.
		while (ptr[1] && (ptr2 = strchr(ptr+1, '.')))
			ptr = ptr2; //Skip to the last dot.
		if (strcmp(ptr,".gat") == 0)
			*ptr = '\0'; //Remove extension.
	}
	return mapname;
}

// Processes command-line arguments
void process_args(int argc, char *argv[])
{
	int i;

	for(i = 0; i < argc; i++) {
		if(strcmp(argv[i], "-grf") == 0) {
			if(++i < argc)
				strcpy(grf_list_file, argv[i]);
		} else if(strcmp(argv[i], "-list") == 0) {
			if(++i < argc)
				strcpy(map_list_file, argv[i]);
		} else if(strcmp(argv[i], "-cache") == 0) {
			if(++i < argc)
				strcpy(map_cache_file, argv[i]);
		} else if(strcmp(argv[i], "-rebuild") == 0)
			rebuild = 1;
	}

}

int main(int argc, char *argv[])
{
	FILE *list;
	char line[1024];
	struct map_data map;
	char name[MAP_NAME_LENGTH_EXT];

	// Process the command-line arguments
	process_args(argc, argv);

	printf("Initializing grfio with %s\n", grf_list_file);
	grfio_init(grf_list_file);

	// Attempt to open the map cache file and force rebuild if not found
	printf("Opening map cache: %s\n", map_cache_file);
	if(!rebuild) {
		map_cache_fp = fopen(map_cache_file, "rb");
		if(map_cache_fp == NULL) {
			printf("Existing map cache not found, forcing rebuild mode\n");
			rebuild = 1;
		} else
			fclose(map_cache_fp);
	}
	if(rebuild)
		map_cache_fp = fopen(map_cache_file, "w+b");
	else
		map_cache_fp = fopen(map_cache_file, "r+b");
	if(map_cache_fp == NULL) {
		printf("Failure when opening map cache file %s\n", map_cache_file);
		exit(EXIT_FAILURE);
	}

	// Open the map list
	printf("Opening map list: %s\n", map_list_file);
	list = fopen(map_list_file, "r");
	if(list == NULL) {
		printf("Failure when opening maps list file %s\n", map_list_file);
		exit(EXIT_FAILURE);
	}

	// Initialize the main header
	if(rebuild) {
		header.file_size = sizeof(struct main_header);
		header.map_count = 0;
	} else {
		fread(&header, sizeof(struct main_header), 1, map_cache_fp);
		header.file_size = GetULong((unsigned char *)&(header.file_size));
		header.map_count = GetUShort((unsigned char *)&(header.map_count));
	}

	// Read and process the map list
	while(fgets(line, sizeof(line), list))
	{
		if(line[0] == '/' && line[1] == '/')
			continue;

		if(sscanf(line, "%15s", name) < 1)
			continue;

		if(strcmp("map:", name) == 0 && sscanf(line, "%*s %15s", name) < 1)
			continue;

		name[MAP_NAME_LENGTH_EXT-1] = '\0';
		remove_extension(name);
		printf("%s", name);
		if(find_map(name))
			printf(" already in cache!\n");
		else if(read_map(name, &map)) {
			cache_map(name, &map);
			printf(" successfully cached\n");
		} else
			printf(" not found in GRF!\n");

	}

	printf("Closing map list: %s\n", map_list_file);
	fclose(list);

	// Write the main header and close the map cache
	printf("Closing map cache: %s\n", map_cache_file);
	fseek(map_cache_fp, 0, SEEK_SET);
	fwrite(&header, sizeof(struct main_header), 1, map_cache_fp);
	fclose(map_cache_fp);

	printf("Finalizing grfio\n");
	grfio_final();

	printf("%d maps now in cache\n", header.map_count);

	return 0;
}
