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

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

static struct systemid sysid = {
	.magic        = "SEGA SEGASATURN ",
	.maker        = "SEGA TP T-000   ",
	.product      = "T-000000G ",
	.version      = "V0.001",
	.reldate      = "20000101",
	.device       = "CD-1/1  ",
	.regions      = "          ",
	.peripherals  = "                ",
	.padding1     = "      ",
	.title        = "TEST TITLE                                                                                                      ",
	.bootsize     = 0xe00,
	.stack_master = 0,
	.stack_slave  = 0,
	.load_addr    = 0x06004000,
	.load_size    = 0,
};

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

static void serialize_region_code(char *out, const struct symbolname *region)
{
	static const char defcode[32] = "\xa0\x0e\x00\x09" "For                         ";
	size_t namelen = region ? strlen(region->name) : 0;

	memcpy(out, defcode, sizeof defcode);
	if (namelen) memcpy(out+8, region->name, namelen);
	out[8+namelen] = '.';
}

#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)
{
	extern const unsigned char securitycode[];
	extern const size_t        securitycode_size;

	/* system id - 0x100 bytes */
	WRITE  (fp, &sysid, offsetof(struct systemid, bootsize));
	WRITE32(fp, sysid.bootsize);
	WRITE32(fp, 0); /* reserved bytes */
	WRITE32(fp, sysid.stack_master);
	WRITE32(fp, sysid.stack_slave);
	WRITE32(fp, sysid.load_addr);
	WRITE32(fp, sysid.load_size);
	WRITE32(fp, 0); /* reserved bytes */
	WRITE32(fp, 0); /* 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 default_ip(char *out)
{
	size_t size = 0;

	out[size++] = 0xd0;                          /* mov.l addr, r0 */
	out[size++] = 0x01;
	out[size++] = 0x40;                          /* jmp   @r0 */
	out[size++] = 0x2b;
	out[size++] = 0x00;                          /* nop */
	out[size++] = 0x09;
	out[size++] = 0x00;                          /* nop */
	out[size++] = 0x09;
	out[size++] = sysid.load_addr >> 24 & 0xff;  /* addr: .long <sysid.load_addr> */
	out[size++] = sysid.load_addr >> 16 & 0xff;
	out[size++] = sysid.load_addr >>  8 & 0xff;
	out[size++] = sysid.load_addr >>  0 & 0xff;

	return size;
}

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 -o[iprms]\n\n", progname);
	fprintf(stderr, "\t%-*s%s\n", width, "-h",              "Show this help text");
	fprintf(stderr, "\t%-*s%s\n", width, "-o output",       "Output file");
	fprintf(stderr, "\t%-*s%s\n", width, "-i ip.bin",       "Initial program code file");
	fprintf(stderr, "\t%-*s%s\n", width, "-p peripherals",  "Supported peripherals (default: control pad):");
	print_symbols(stderr, width, peripheraldefs);
	fprintf(stderr, "\t%-*s%s\n", width, "-r regions",      "Geographical regions (default: all):");
	print_symbols(stderr, width, regiondefs);
	fprintf(stderr, "\t%-*s%s\n", width, "-m master_stack", "Master stack address (default 0x06002000)");
	fprintf(stderr, "\t%-*s%s\n", width, "-s slave_stack",  "Slave stack address (default 0x06001000)");
}

#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
#define ERR_PERIPHERAL_OVERFLOW 5
#define ERR_DUPLICATE_MASTER    6
#define ERR_DUPLICATE_SLAVE     7
#define ERR_INVALID_MASTER      8
#define ERR_INVALID_SLAVE       9

static const char *errmsgs[] = {
	"Unknown extra argument",
	"Missing required option",
	"Duplicate -i parameter",
	"Duplicate -o parameter",
	"Too many regions specified (max 10)",
	"Too many peripherals specified (max 16)",
	"Duplicate -m parameter",
	"Duplicate -s parameter",
	"Invalid master stack address",
	"Invalid slave stack address",
};

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 void process_symbols(const char *progname, char *list, size_t size, const char *arg, int *errors, int overflow)
{
	for (; *arg; arg++) {
		if (append_symbol(list, size, *arg)) {
			*errors = show_arg_error(progname, *errors, overflow);
			return;
		}
	}
}

static int process_address(const char *progname, uint32_t *addr, const char *arg, int *errors, int bad_addr)
{
	char *end;
	errno = 0;
	unsigned long val = strtoul(arg, &end, 16);
	if (end == arg || *end || errno || val > (uint32_t)-1) {
		*errors = show_arg_error(progname, *errors, bad_addr);
		return 0;
	}

	*addr = val;
	return 1;
}

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

	int have_master = 0;
	int have_slave  = 0;

	extern char *optarg;
	extern int optind, optopt;
	while ((opt = getopt(argc, argv, "hi:o:p:r:m:s:")) != -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 'm':
			if (have_master)
				errors = show_arg_error(argv[0], errors, ERR_DUPLICATE_MASTER);
			else
				have_master = process_address(argv[0], &sysid.stack_master, optarg, &errors, ERR_INVALID_MASTER);
			break;

		case 's':
			if (have_slave)
				errors = show_arg_error(argv[0], errors, ERR_DUPLICATE_SLAVE);
			else
				have_slave = process_address(argv[0], &sysid.stack_slave, optarg, &errors, ERR_INVALID_SLAVE);
			break;

		case 'p':
			process_symbols(argv[0], sysid.peripherals, sizeof sysid.peripherals, optarg, &errors, ERR_PERIPHERAL_OVERFLOW);
			break;

		case 'r':
			process_symbols(argv[0], sysid.regions, sizeof sysid.regions, optarg, &errors, ERR_REGION_OVERFLOW);
			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 (!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");
	if (sysid.peripherals[0] == ' ') sysid.peripherals[0] = 'J';

	for (int i = 0; i < 8; i++) {
		serialize_region_code(ipout, find_symbol(regiondefs, sysid.regions[i]));
		ipout          += 32;
		sysid.bootsize += 32;
	}

	ipsize = ipfile
		? load_ip(ipfile, ipout, sizeof ipbuf - (ipout - ipbuf))
		: default_ip(ipout);
	if (ipsize == -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;
}