/*
 * Copyright (C) 2014, 2016  J. Ali Harlow <ali@juiblex.co.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "razor.h"
#include "razor-internal.h"
#include "uri.h"

static int valid_unicode(unsigned unicode)
{
	/*
	 * Within the U+0000..U+10FFFF range defined by RFC3629
	 * but not in the U+D800..U+DFFF range prohibited in UTF-8.
	 */
	return unicode < 0xD800 || (unicode >= 0xE000 && unicode < 0x110000);
}

char *razor_path_from_parsed_uri(const struct razor_uri *ru,
  struct razor_error **error)
{
	int continuation_bytes = 0;
	char *path, *p, *s, *uri;
	unsigned char c;
	unsigned unicode;

	if (!ru->scheme) {
		uri = razor_uri_recompose(ru);
		razor_set_error(error, RAZOR_GENERAL_ERROR,
				RAZOR_GENERAL_ERROR_BAD_URI, uri,
				"URI does not include a scheme");
		free(uri);
		return NULL;
	}

	if (strcmp(ru->scheme, "file")) {
		uri = razor_uri_recompose(ru);
		razor_set_error(error, RAZOR_GENERAL_ERROR,
				RAZOR_GENERAL_ERROR_UNSUPPORTED_URI, uri,
				"Not a file URI");
		free(uri);
		return NULL;
	}

	if (ru->host && *ru->host && strcmp(ru->host, "localhost") ||
	    ru->userinfo || ru->port) {
		uri = razor_uri_recompose(ru);
		razor_set_error(error, RAZOR_GENERAL_ERROR,
				RAZOR_GENERAL_ERROR_UNSUPPORTED_URI, uri,
				"URI refers to a non-local file");
		free(uri);
		return NULL;
	}

	s = ru->path;
#ifdef MSWIN_API
	/*
	 * Under MS-Windows, a path of /c:/xxx maps to c:/xxx
	 * Note that PathCreateFromUrl converts / to \ as well.
	 */
	if (s[0] == '/' && is_alpha(s[1]) && s[2] == ':' && s[3] == '/')
		s++;
#endif

	p = path = malloc(strlen(s) + 1);

	while (*s) {
		if (*s >= 0x7F || *s < 0x20)
			break;
		else if (*s != '%') {
			if (continuation_bytes)
				break;
			else
				*p++ = *s++;
		} else {
			c = pchar_get_char(s);
#ifdef MSWIN_API
			if (c == '/' || c == '\\')
#else
			if (c == '/')
#endif
				break;
			else if (!continuation_bytes) {
				if (c >= 0xF5 || c == 0xC0 || c == 0xC1)
					break;
				else if (c >= 0xF0) {
					unicode = c & 7;
					continuation_bytes = 3;
				} else if (c >= 0xE0) {
					unicode = c & 3;
					continuation_bytes = 2;
				} else if (c >= 0xC0) {
					unicode = c & 1;
					continuation_bytes = 1;
				}
			} else if ((c & 0xC0) != 0x80)
				break;
			else {
				unicode <<= 6;
				unicode |= (c & 0x3F);

				if (!--continuation_bytes &&
				    !valid_unicode(unicode))
					break;
			}

			*p++ = c;
			s += 3;
		}
	}

	if (*s || continuation_bytes) {
		uri = razor_uri_recompose(ru);
		razor_set_error(error, RAZOR_GENERAL_ERROR,
				RAZOR_GENERAL_ERROR_BAD_URI,
				uri, "Illegal character in file URI path");
		free(uri);
		free(path);
		return NULL;
	}

	*p++ = '\0';

	return realloc(path, p - path);
}

RAZOR_EXPORT char *razor_path_from_uri(const char *uri,
  struct razor_error **error)
{
	struct razor_uri ru;
	char *path;

	if (razor_uri_parse(&ru, uri, error))
		return NULL;

	path = razor_path_from_parsed_uri(&ru, error);

	razor_uri_destroy(&ru);

	return path;
}

RAZOR_EXPORT char *razor_path_to_uri(const char *path)
{
	char *uri, *p;

	uri = malloc(6 + 3 * strlen(path) + 1);

	strcpy(uri, "file:");

	p = uri + 5;

#ifdef MSWIN_API
	/*
	 * Under MS-Windows, c:/xxx maps to a path of /c:/xxx
	 */
	if (is_alpha(path[0]) && path[1] == ':' && path[2] == '/')
		*p++ = '/';
#endif

	while(*path) {
		if (*path == '/' || is_unreserved(*path) ||
		    is_sub_delim(*path) || *path == ':' || *path == '@')
			*p++ = *path;
#ifdef MSWIN_API
		else if (*path == '\\')
			*p++ = '/';
#endif
		else {
			*p++ = '%';
			*p++ = "0123456789ABCDEF"[(*(unsigned char *)path)/16];
			*p++ = "0123456789ABCDEF"[(*(unsigned char *)path)%16];
		}
		path++;
	}
	*p++ = '\0';

	return realloc(uri, p - uri);
}

RAZOR_EXPORT char *
razor_path_relative_to_uri(const char *uri, const char *path,
			   struct razor_error **error)
{
	char *rel_uri, *result;

	/* Strictly wrong if uri isn't a file URI, but probably okay */
	rel_uri = razor_path_to_uri(path);

	result = razor_resolve_uri_root(uri, rel_uri + 5, 1, error);

	free(rel_uri);

	return result;
}