/*

 * 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, *s;

	const char *p;

	int check_dotdot, len;

	struct razor_uri ru;

	uri = malloc(5 + (4 - 3) + 4 + 3 * strlen(path) + 1);

	strcpy(uri, "file:");

	s = uri + 5;

#ifdef MSWIN_API

	check_dotdot = path[0] != '/' && path[0] != '\\';

#else

	check_dotdot = path[0] != '/';

#endif

	p = path;

#ifdef MSWIN_API

	/*

	 * Under MS-Windows, c:/xxx maps to a path of /c:/xxx

	 * Relative paths that include a drive letter (eg., c:xxx)

	 * can't be handled directly and have to be converted

	 * to absolute form.

	 */

	if (is_alpha(p[0]) && p[1] == ':') {

		if (p[2] == '/' || p[2] == '\\') {

			*s++ = '/';

			*s++ = p[0];

			*s++ = ':';

			*s++ = '/';

			p += 3;

			/*

			 * We need to take care that ".." segments don't remove

			 * the drive letter (eg., c:/../xxx -> file:/c:/../xxx

			 * which normalizes to file:/xxx).

			 */

			check_dotdot = 2;

		} else {

			s = razor_abspath(p);

			uri = razor_path_to_uri(s);

			free(s);

			return uri;

		}

	}

#endif

	/*

	 * Relative paths are complicated. URIs can't have dot segments

	 * so these will be removed during normalization. That often does

	 * the right thing, but where a relative path traverses up the

	 * tree then the result is a URI that points to somewhere quite

	 * different to path: eg., file:../dir normalizes to file:dir

	 * We solve this by inserting a sentinel segment at the beginning.

	 * If the segment is still present after normalization, then it

	 * can just be removed. If it is missing, then we need to create

	 * an absolute path and redo the conversion.

	 */

	if (check_dotdot) {

		*s++ = '%';

		*s++ = '2';

		*s++ = 'F';

		*s++ = '/';

	}

	while(*p) {

		if (*p == '/' || is_unreserved(*p) || is_sub_delim(*p) ||

		    *p == ':' || *p == '@')

			*s++ = *p;

#ifdef MSWIN_API

		else if (*p == '\\')

			*s++ = '/';

#endif

		else {

			*s++ = '%';

			*s++ = "0123456789ABCDEF"[(*(unsigned char *)p)/16];

			*s++ = "0123456789ABCDEF"[(*(unsigned char *)p)%16];

		}

		p++;

	}

	*s++ = '\0';

	if (razor_uri_parse(&ru, uri, NULL) < 0) {

		free(uri);

		return NULL;

	}

	free(uri);

	razor_uri_normalize(&ru);

	uri = razor_uri_recompose(&ru);

	razor_uri_destroy(&ru);

	if (check_dotdot == 2) {

		s = strdup("file:/x:/%2F/");

		s[6] = path[0];

		if (str_has_prefix(uri, s)) {

			free(s);

			memmove(uri + 5 + 3, uri + 9 + 3,

				strlen(uri + 9 + 3) + 1);

			uri = realloc(uri, strlen(uri) + 1);

		} else {

			free(s);

			free(uri);

			s = razor_abspath(path);

			uri = razor_path_to_uri(s);

			free(s);

		}

	} else if (check_dotdot) {

		if (str_has_prefix(uri, "file:%2F/")) {

			memmove(uri + 5, uri + 9, strlen(uri + 9) + 1);

			uri = realloc(uri, strlen(uri) + 1);

		} else {

			free(uri);

			s = razor_abspath(path);

			uri = razor_path_to_uri(s);

			free(s);

		}

	}

	return 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;

}