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

#include "misc.h"

#define ESCAPED_REPL_LEN 6


// Unreserved HTML characters, only " ' & < and > are to be escaped
static unsigned char unreserved[256] =
{
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
};

void htmlencode(const char *restrict in, char *restrict out, size_t len)
{
	for (size_t i = 0; i < len; ++i)
	{
		if (unreserved[(unsigned char)in[i]])
		{
			*(out++) = in[i];
		}
		else
		{
			sprintf(out, "&#x%02X;", in[i]);
			out += ESCAPED_REPL_LEN;
		}
	}
	*out = '\0';
}

NORETURN void usage(int exit_status)
{
	printf(
		"NAME\n"
		"    %s - HTML encode strings\n"
		"\n"
		"SYNOPSIS\n"
		"    %s [OPTIONS] [URL...]\n"
		"\n"
		"DESCRIPTION\n"
		"    HTML encode the arguments and print them to stdout separated by newlines.\n"
		"    If there is no argument or the only argument is '-', stdin is read as a \n"
		"    newline separated argument list.\n"
		"\n"
		"OPTIONS\n"
		"    -a\n"
		"        Only encode \" and ', to be used as attribute value.\n"
		"\n"
		"    -e\n"
		"        Only encode <, > and &, to be used as element content.\n"
		"\n"
		"    -h\n"
		"        Print this help message and exit.\n"
		"\n"
		"    -v\n"
		"        Print the version and exit.\n"
		"\n",
		PROG_NAME, PROG_NAME);
	exit(exit_status);
}


int main(int argc, char **argv)
{
	signals_nointerrupt();

	for (int opt; (opt = getopt(argc, argv, "aehv")) != -1;)
	{
		switch (opt)
		{
			case 'a':
				unreserved['&'] = 1;
				unreserved['<'] = 1;
				unreserved['>'] = 1;
				break;

			case 'e':
				unreserved['"'] = 1;
				unreserved['\''] = 1;
				break;

			case 'h':
				usage(EXIT_SUCCESS);
				break;

			case 'v':
			    puts(PROG_VERSION);
				exit(EXIT_SUCCESS);

			default:
				exit(EXIT_FAILURE);
		}
	}
	argc -= optind;
	argv += optind;

	if (argc == 0 || (argc == 1 && !strcmp(argv[0], "-")))
	{
		char *buf = NULL, *line = NULL;
		size_t buflen = 0, linealloc = 0;

		for (ssize_t read; (read = xgetline(&line, &linealloc, stdin)) != -1; )
		{
			//Use ESCAPED_REPL_LEN time the input size (no need to check size
			//when sprinting, this way)
			if ((size_t)read > (SIZE_MAX - 1) / ESCAPED_REPL_LEN)
			{
				die("Input string is too big (lim: %zu)",
					(SIZE_MAX - 1) / ESCAPED_REPL_LEN);
			}
			if (buflen < (size_t)read * ESCAPED_REPL_LEN + 1)
			{
				buflen = read * ESCAPED_REPL_LEN + 1;
				buf = xrealloc(buf, buflen);
			}
			htmlencode(line, buf, read);
			puts(buf);
		}
		free(buf);
		free(line);
	}
	else
	{
		char *buf = NULL;
		size_t buflen = 0;

		for (int i = 0; i < argc; ++i)
		{
			const size_t arglen = strlen(argv[i]);
			if (arglen > (SIZE_MAX - 1) / ESCAPED_REPL_LEN)
			{
				die("Input string is too big (lim: %zu)",
					(SIZE_MAX - 1) / ESCAPED_REPL_LEN);
			}
			if (buflen < arglen * ESCAPED_REPL_LEN + 1)
			{
				buflen = arglen * ESCAPED_REPL_LEN + 1;
				buf = xrealloc(buf, buflen);
			}
			htmlencode(argv[i], buf, arglen);
			puts(buf);
		}
		free(buf);
	}
	return EXIT_SUCCESS;
}