#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <locale.h>
#include <wchar.h>
#include <errno.h>

#include "atables.h"

const char **table = ata2utf;
const char *inverse_on  = "\x1b[7m";
const char *inverse_off = "\x1b[0m";
const char *word_format = "%04x";
const char *byte_format = "%02x";

int verbose = 0, color = 1, disp_offset = 0, maxlen = 0;
int seek_whence = 0, seekpos = 0, filepos = 0, limit = 0;
int graphics = 0;

const char *self;

void set_self(const char *argv0) {
   char *p;

   self = argv0;
   p = strrchr(self, '/');
   if(p) self = p + 1;
}

void die(const char *msg) {
   fprintf(stderr, "%s: %s\n", self, msg);
   exit(1);
}

void print_help(void) {
	printf("Usage: %s [-i] [-l limit] [-m] [-o offset] [-s [-]seek] [-u] [-v] [file]\n", self);
	printf("With no [file], or '-', reads from stdin.\n");
}

int parse_num_arg(const char *arg) {
	int got;

	if(sscanf(arg, "0x%x", &got) != 1)
		if(sscanf(arg, "$%x", &got) != 1)
			if(sscanf(arg, "%d", &got) != 1) {
				fprintf(stderr, "%s: invalid numeric argument '%s'.", self, arg);
				exit(1);
			}

	return got;
}

void parse_seek_arg(const char *arg) {
	seek_whence = SEEK_SET;

	if(*arg == '-') {
		seek_whence = SEEK_END;
	}

	seekpos = parse_num_arg(arg);
}

int parse_offset_arg(const char *arg) {
	int got;

	got = parse_num_arg(arg);

	return got;
}

int parse_limit_arg(const char *arg) {
	int got;

	got = parse_num_arg(arg);
	if(got < 0)
		die("negative arguments to -l (limit) are not supported.");

	return got;
}

FILE *open_input(const char *file) {
	FILE *input;

	if(file[0] == '-' && file[1] == 0) {
		if(freopen(NULL, "rb", stdin)) {
			input = stdin;
		} else {
			fprintf(stderr, "%s: ", self);
			perror("(standard input)");
			return NULL;
		}
		if(verbose)
			fprintf(stderr, "%s: reading from standard input.\n", self);
	} else {
		if(!(input = fopen(file, "rb"))) {
			perror(file);
			return NULL;
		}
		if(verbose)
			fprintf(stderr, "%s: reading from file '%s'.\n", self, file);
	}

	return input;
}

const char *color_off = "\x1b[0m";

char *get_color(unsigned char c) {
	int color;
	unsigned char c7 = c & 0x7f;
	static char outbuf[32];

	if(graphics) {
		if(c < 0x20)
			color = 2;
		else if(c >= 0x20 && c < 0x60)
			color = 3;
		else if(c >= 0x60 && c < 0x80)
			color = 2;
		else if(c >= 0x80 && c < 0xa0)
			color = 1;
		else if(c >= 0xa0 && c < 0xe0)
			color = 6; /* cyan (blue is too dark on most terminals) */
		else /* c >= 0xe0 */
			color = 1;
	} else {
		if(c == 0 || c == 0x9b) {
			color = 1; /* red */
		} else if(c7 < 32 || c7 == 0x60 || c7 == 0x7b || c7 == 0x7d || c7 == 0x7e || c7 == 0x7f) {
			color = 3; /* yellow/orange */
		} else {
			color = 2; /* green */
		}
	}

	if(color) {
		sprintf(outbuf, "\x1b[0;3%dm", color);
	} else {
		outbuf[0] = '\0';
	}

	return outbuf;
}

/* in GR.1 or GR.2:
   $00-$1F get displayed in green, as $20-$2F.
   $20-$5F get displayed in orange, as themselves.
   $60-$7F get displayed in green, as $40-$5F.
   for $80-$FF, same thing, but green is red, and orange is blue.
*/
char *get_graphics(unsigned char c) {
	static char result[2];
	c &= 0x7f;
	if(c < 0x20)
		c += 0x20;
	else if(c >= 0x60)
		c -= 0x20;
	result[0] = c;
	result[1] = 0;
	return result;
}

void fake_seek(FILE *input) {
	char junkbuf[1024];
	int pos = 0, chunksize;

	if(verbose)
		fprintf(stderr, "%s: faking fseek() for stdin, skipping %d bytes.\n", self, seekpos);

	while(pos < seekpos) {
		chunksize = seekpos - pos;
		if(chunksize > 1024) chunksize = 1024;
		if(fread(junkbuf, 1, chunksize, input) != chunksize)
			die("can't seek past end of input");
		pos += chunksize;
	}
}

void seek_input(FILE *input) {
	if(verbose)
		fprintf(stderr, "%s: seeking %d bytes (whence = %d) in input.\n", self, seekpos, seek_whence);
	if(input == stdin) {
		/* can't fseek() a stream, fake it */
		if(seek_whence != SEEK_SET)
			die("can't seek from the end of standard input.");
		fake_seek(input);
	} else {
		if(fseek(input, seekpos, seek_whence) < 0) {
			fprintf(stderr, "%s: ", self);
			perror("fseek() failed");
			exit(1);
		}
		if((filepos = ftell(input)) < 0) {
			fprintf(stderr, "%s: ", self);
			perror("ftell() failed");
			exit(1);
		}
	}
}

void dump_line(const unsigned char *buf, int len) {
	char hex[1024], asc[1024];
	int hpos = 0, apos = 0, count = len;
	unsigned char c, inv;

	memset(hex, 0, sizeof(hex));
	memset(asc, 0, sizeof(asc));

	printf(word_format, filepos + disp_offset);
	fputs(":  ", stdout);

	while(len) {
		c = *buf;
		inv = !graphics && (c & 0x80);

		if(color) hpos += sprintf(hex + hpos, "%s", get_color(c));
		if(inv) hpos += sprintf(hex + hpos, "%s", inverse_on);
		hpos += sprintf(hex + hpos, byte_format, c);
		if(color || inv) hpos += sprintf(hex + hpos, "%s", color_off);
		hex[hpos++] = ' ';
		if(count - len == 7) hex[hpos++] = ' ';

		if(color) apos += sprintf(asc + apos, "%s", get_color(c));
		if(inv) apos += sprintf(asc + apos, "%s", inverse_on);
		apos += sprintf(asc + apos, "%s", (graphics ? get_graphics(c) : table[c & 0x7f]));
		if(color || inv) apos += sprintf(asc + apos, "%s", color_off);

		filepos++;
		buf++;
		len--;
	}
	printf("%s", hex);

	/* what shall we use to fill the empty spaces? */
	if(count < 8) putchar(' ');
	for(; count < 16; count++) fputs("   ", stdout);

	printf(" %s\n", asc);
}

int a8xd(const char *file) {
	FILE *input;
	int c, len = 0, count = 0;
	unsigned char buf[16];

	if( !(input = open_input(file)) )
		return 1;

	if(seekpos) seek_input(input);

	while( (c = fgetc(input)) != EOF ) {
		if(limit && (count == limit)) break;
		count++;
		if(len && (len % 16 == 0)) {
			dump_line(buf, len);
			len = 0;
		}
		buf[len++] = c;
	}

	if(len) dump_line(buf, len);

	if(verbose)
		fprintf(stderr, "%s: dumped %d (0x%04x) bytes from '%s'.\n", self, count, count, file);

	fclose(input);
	return 0;
}

int main(int argc, char **argv) {
	int opt, result = 0;

	set_self(argv[0]);

	if(argc > 1 && strcmp(argv[1], "--help") == 0) {
		print_help();
		exit(0);
	}

	if(argc > 1 && strcmp(argv[1], "--version") == 0) {
		printf("%s %s\n", self, VERSION);
		exit(0);
	}

	while( (opt = getopt(argc, argv, "vhimus:o:l:g")) != -1) {
		switch(opt) {
			case 'v': verbose = 1; break;
			case 'h': print_help(); exit(0); break;
			case 'i': table = ics2utf; break;
			case 'm': color = 0; break;
			case 'u': word_format = "%04X"; byte_format = "%02X"; break;
			case 's': parse_seek_arg(optarg); break;
			case 'o': disp_offset = parse_offset_arg(optarg); break;
			case 'l': limit = parse_limit_arg(optarg); break;
			case 'g': graphics = 1; break;
			default: print_help(); exit(1); break;
		}
	}

	if(optind < argc - 1)
		die("Only one filename is supported.");

	if(optind >= argc)
		result = a8xd("-");
	else
		result = a8xd(argv[optind]);

	exit(result);
}