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

#include "bootinfo.h"
#include "symbols.h"

static struct systemid sysid = {
	.title        = "TEST TITLE                                                                                                      ",
	.maker        = "SEGA TP T-000   ",
	.product      = "T-000000G ",
	.version      = "V0.001",
	.reldate      = "20000101",
	.device       = "CD-1/1  ",
	.regions      = "          ",
	.peripherals  = "J               ",
	.bootsize     = 0xe00,
	.stack_master = 0,
	.stack_slave  = 0,
	.load_addr    = 0x06004000,
	.load_size    = 0,
};

static char ipbuf[0x7200];
static char *ipfile, *outfile;

static char *serialize_region_code(char *out, const struct symbolname *region)
{
	size_t namelen  = strlen(region->name);
	char  *tmp = out;
	char  *end = out+32;

	memcpy(tmp, "\xa0\x0e\x00\x09For ", 8); tmp += 8;
	memcpy(tmp, region->name,     namelen); tmp += namelen;
	*tmp++ = '.';
	memset(tmp, ' ', end - tmp);
	return end;
}

#define WRITE(f,p,s) fwrite(p,s,1,f)
#define WRITE32(f,v) fwrite((char[]){(v)>>24,(v)>>16,(v)>>8,(v)},4,1,f)

static int write_output(FILE *fp)
{
	static const unsigned char zeros[16];
	extern const unsigned char securitycode[];
	extern const size_t        securitycode_size;

	/* system id - 0x100 bytes */
	WRITE  (fp, "SEGA SEGASATURN ", 16);
	WRITE  (fp, sysid.maker,        16);
	WRITE  (fp, sysid.product,      10);
	WRITE  (fp, sysid.version,       6);
	WRITE  (fp, sysid.reldate,       8);
	WRITE  (fp, sysid.device,        8);
	WRITE  (fp, sysid.regions,      10);
	WRITE  (fp, "      ",            6);
	WRITE  (fp, sysid.peripherals,  16);
	WRITE  (fp, sysid.title,       112);
	WRITE  (fp, zeros,              16); /* reserved bytes */
	WRITE32(fp, sysid.bootsize);
	WRITE  (fp, zeros,               4); /* reserved bytes */
	WRITE32(fp, sysid.stack_master);
	WRITE32(fp, sysid.stack_slave);
	WRITE32(fp, sysid.load_addr);
	WRITE32(fp, sysid.load_size);
	WRITE  (fp, zeros,               8); /* reserved bytes */

	/* security code */
	WRITE(fp, securitycode, securitycode_size);

	/* initial program */
	WRITE(fp, ipbuf, sysid.bootsize - 0xe00);
	return ferror(fp) ? -1 : 0;
}

static size_t load_ip(char *filename, char *out, size_t maxsize)
{
	FILE  *fp;
	size_t size;
	const char *errprefix = "Error loading initial program";

	if (!(fp = fopen(filename, "rb"))) {
		goto fail_perror;
	}
	if ((size = fread(out, 1, maxsize, fp)) < maxsize) {
		/* read fewer than requested amount. determine if we hit error or eof */
		if (ferror(fp)) {
			goto fail_perror;
		}
	} else {
		/* successfully read the requested amount. verify we reached eof */
		if (fgetc(fp) != EOF) {
			fprintf(stderr, "%s: exceeds maximum size\n", errprefix);
			goto fail;
		}
	}

	fclose(fp);
	return size;

fail_perror:
	perror(errprefix);
fail:
	if (fp) fclose(fp);
	return -1;
}

static int append_symbol(char *list, size_t size, char symbol)
{
	for (size_t i = 0; i < size; i++) {
		if (list[i] == ' ')
			list[i] = symbol;
		if (list[i] == symbol)
			return 0;
	}
	return -1;
}

static void print_symbols(FILE *fp, int width, const struct symbolname *symbols)
{
	for (; symbols->symbol; symbols++) {
		fprintf(fp, "\t%*s%c: %s\n", width+4, "", symbols->symbol, symbols->name);
	}
}

static void usage(const char *progname)
{
	const int width = 20;

	fprintf(stderr, "usage: %s -h\n", progname);
	fprintf(stderr, "       %s -io[r]\n\n", progname);
	fprintf(stderr, "\t%-*s%s\n", width, "-h",              "Show this help text");
	fprintf(stderr, "\t%-*s%s\n", width, "-i ip.bin",       "Initial program code file");
	fprintf(stderr, "\t%-*s%s\n", width, "-o output",       "Output file");
	fprintf(stderr, "\t%-*s%s\n", width, "-r regions",      "Geographical regions (default all):");
	print_symbols(stderr, width, regiondefs);
}

#define ERR_UNKNOWN_OPTION   0
#define ERR_MISSING_OPTION   1
#define ERR_DUPLICATE_INPUT  2
#define ERR_DUPLICATE_OUTPUT 3
#define ERR_REGION_OVERFLOW  4

static const char *errmsgs[] = {
	"Unknown extra argument",
	"Missing required option",
	"Duplicate -i parameter",
	"Duplicate -o parameter",
	"Too many regions specified (max 10)",
};

static int show_arg_error(const char *progname, int prev_errors, int error)
{
	if (!(prev_errors & 1 << error))
		fprintf(stderr, "%s: %s\n", progname, errmsgs[error]);
	return prev_errors | 1 << error;
}

static int process_args(int argc, char **argv)
{
	int errors = 0, fail = 0, help = 0;
	int opt;

	extern char *optarg;
	extern int optind, optopt;
	while ((opt = getopt(argc, argv, "hi:o:r:")) != -1) {
		switch (opt) {
		case 'h':
			help = 1;
			break;

		case 'i':
			if (ipfile)
				errors = show_arg_error(argv[0], errors, ERR_DUPLICATE_INPUT);
			else
				ipfile = optarg;
			break;

		case 'o':
			if (outfile)
				errors = show_arg_error(argv[0], errors, ERR_DUPLICATE_OUTPUT);
			else
				outfile = optarg;
			break;

		case 'r':
			for (; *optarg; optarg++) {
				if (append_symbol(sysid.regions, sizeof sysid.regions, *optarg)) {
					errors = show_arg_error(argv[0], errors, ERR_REGION_OVERFLOW);
					break;
				}
			}
			break;

		default:
			fail = 1;
		}
	}

	if (help) {
		usage(argv[0]);
	} else if (!fail) {
		if (argv[optind])
			errors = show_arg_error(argv[0], errors, ERR_UNKNOWN_OPTION);
		if (!ipfile || !outfile)
			errors = show_arg_error(argv[0], errors, ERR_MISSING_OPTION);
		fail = errors;
	}

	if (fail) {
		fprintf(stderr, "\nUse -h option for help on correct usage.\n");
	}

	return fail | help;
}

int main(int argc, char **argv)
{
	FILE  *outfp = NULL;
	char  *ipout = ipbuf;
	size_t ipsize;

	if (process_args(argc, argv)) {
		return 1;
	}

	if (sysid.regions[0] == ' ') strcpy(sysid.regions, "JTUBKAEL");
	for (int i = 0; i < 10 && sysid.regions[i] != ' '; i++) {
		const struct symbolname *region = find_symbol(regiondefs, sysid.regions[i]);
		if (region) ipout = serialize_region_code(ipout, region);
	}

	if ((ipsize = load_ip(ipfile, ipout, sizeof ipbuf - (ipout - ipbuf))) == -1) {
		goto fail;
	}
	sysid.bootsize += ipsize;

	if (!(outfp = fopen(outfile, "wb"))) {
		perror("Error opening output file");
		goto fail;
	}

	if (write_output(outfp)) {
		perror("Error writing output");
		goto fail;
	}

	fclose(outfp);
	return 0;

fail:
	if (outfp) fclose(outfp);
	return 1;
}