/*
   Copyright (c) 2001, Loki software, inc.
   All rights reserved.

   Redistribution and use in source and binary forms, with or without modification,
   are permitted provided that the following conditions are met:

   Redistributions of source code must retain the above copyright notice, this list
   of conditions and the following disclaimer.

   Redistributions in binary form must reproduce the above copyright notice, this
   list of conditions and the following disclaimer in the documentation and/or
   other materials provided with the distribution.

   Neither the name of Loki software nor the names of its contributors may be used
   to endorse or promote products derived from this software without specific prior
   written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
   DIRECT,INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
   ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

//
// Rules:
//
// - Directories should be searched in the following order: ~/.q3a/baseq3,
//   install dir (/usr/local/games/quake3/baseq3) and cd_path (/mnt/cdrom/baseq3).
//
// - Pak files are searched first inside the directories.
// - Case insensitive.
// - Unix-style slashes (/) (windows is backwards .. everyone knows that)
//
// Leonardo Zide (leo@lokigames.com)
//

#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>

#include "cmdlib.h"
#include "filematch.h"
#include "mathlib.h"
#include "inout.h"
#include "vfs.h"
#include <unzip.h>
#include <glib.h>

typedef struct
{
	char*   name;
	unzFile zipfile;
	unz_file_pos zippos;
	guint32 size;
} VFS_PAKFILE;

// =============================================================================
// Global variables

static GSList*  g_unzFiles;
static GSList*  g_pakFiles;
static char g_strDirs[VFS_MAXDIRS][PATH_MAX + 1];
static int g_numDirs;
char g_strForbiddenDirs[VFS_MAXDIRS][PATH_MAX + 1];
int g_numForbiddenDirs = 0;
static gboolean g_bUsePak = TRUE;

// =============================================================================
// Static functions

static void vfsAddSlash( char *str ){
	int n = strlen( str );
	if ( n > 0 ) {
		if ( str[n - 1] != '\\' && str[n - 1] != '/' ) {
			strcat( str, "/" );
		}
	}
}

static void vfsFixDOSName( char *src ){
	if ( src == NULL ) {
		return;
	}

	while ( *src )
	{
		if ( *src == '\\' ) {
			*src = '/';
		}
		src++;
	}
}

//!\todo Define globally or use heap-allocated string.
#define NAME_MAX 255

static void vfsInitPakFile( const char *filename ){
	unz_global_info gi;
	unzFile uf;
	guint32 i;
	int err;

	uf = unzOpen( filename );
	if ( uf == NULL ) {
		return;
	}

	g_unzFiles = g_slist_append( g_unzFiles, uf );

	err = unzGetGlobalInfo( uf,&gi );
	if ( err != UNZ_OK ) {
		return;
	}
	unzGoToFirstFile( uf );

	for ( i = 0; i < gi.number_entry; i++ )
	{
		char filename_inzip[NAME_MAX];
		char *filename_lower;
		unz_file_info file_info;
		VFS_PAKFILE* file;

		err = unzGetCurrentFileInfo( uf, &file_info, filename_inzip, sizeof( filename_inzip ), NULL, 0, NULL, 0 );
		if ( err != UNZ_OK ) {
			break;
		}
		unz_file_pos pos;
		err = unzGetFilePos( uf, &pos );
		if ( err != UNZ_OK ) {
			break;
		}

		file = (VFS_PAKFILE*)safe_malloc( sizeof( VFS_PAKFILE ) );
		g_pakFiles = g_slist_append( g_pakFiles, file );

		vfsFixDOSName( filename_inzip );
		 //-1 null terminated string
		filename_lower = g_ascii_strdown( filename_inzip, -1 );

		file->name = strdup( filename_lower );
		file->size = file_info.uncompressed_size;
		file->zipfile = uf;
		file->zippos = pos;

		if ( ( i + 1 ) < gi.number_entry ) {
			err = unzGoToNextFile( uf );
			if ( err != UNZ_OK ) {
				break;
			}
		}
		g_free( filename_lower );
	}
}

// =============================================================================
// Global functions

// reads all pak files from a dir
void vfsInitDirectory( const char *path ){
	char filename[PATH_MAX];
	char *dirlist;
	GDir *dir;
	int j;

	for ( j = 0; j < g_numForbiddenDirs; ++j )
	{
		char* dbuf = g_strdup( path );
		if ( *dbuf && dbuf[strlen( dbuf ) - 1] == '/' ) {
			dbuf[strlen( dbuf ) - 1] = 0;
		}
		const char *p = strrchr( dbuf, '/' );
		p = ( p ? ( p + 1 ) : dbuf );
		if ( matchpattern( p, g_strForbiddenDirs[j], TRUE ) ) {
			g_free( dbuf );
			break;
		}
		g_free( dbuf );
	}
	if ( j < g_numForbiddenDirs ) {
		return;
	}

	if ( g_numDirs == VFS_MAXDIRS ) {
		return;
	}

	Sys_Printf( "VFS Init: %s\n", path );

	strncpy( g_strDirs[g_numDirs], path, PATH_MAX );
	g_strDirs[g_numDirs][PATH_MAX] = 0;
	vfsFixDOSName( g_strDirs[g_numDirs] );
	vfsAddSlash( g_strDirs[g_numDirs] );
	g_numDirs++;

	if ( g_bUsePak ) {
		dir = g_dir_open( path, 0, NULL );

		if ( dir != NULL ) {
			while ( 1 )
			{
				const char* name = g_dir_read_name( dir );
				if ( name == NULL ) {
					break;
				}

				for ( j = 0; j < g_numForbiddenDirs; ++j )
				{
					const char *p = strrchr( name, '/' );
					p = ( p ? ( p + 1 ) : name );
					if ( matchpattern( p, g_strForbiddenDirs[j], TRUE ) ) {
						break;
					}
				}
				if ( j < g_numForbiddenDirs ) {
					continue;
				}

				dirlist = g_strdup( name );

				{
					char *ext = strrchr( dirlist, '.' );

					if ( ext != NULL && ( !Q_stricmp( ext, ".pk3dir" ) || !Q_stricmp( ext, ".dpkdir" ) ) ) {
						if ( g_numDirs == VFS_MAXDIRS ) {
							g_free( dirlist );
							continue;
						}
						snprintf( g_strDirs[g_numDirs], PATH_MAX, "%s/%s", path, name );
						g_strDirs[g_numDirs][PATH_MAX-1] = '\0';
						vfsFixDOSName( g_strDirs[g_numDirs] );
						vfsAddSlash( g_strDirs[g_numDirs] );
						++g_numDirs;
					}

					if ( ext == NULL || ( Q_stricmp( ext, ".pk3" ) != 0 && Q_stricmp( ext, ".dpk" ) != 0 ) ) {
						g_free( dirlist );
						continue;
					}
				}

				sprintf( filename, "%s/%s", path, dirlist );
				vfsInitPakFile( filename );

				g_free( dirlist );
			}
			g_dir_close( dir );
		}
	}
}

// frees all memory that we allocated
void vfsShutdown(){
	while ( g_unzFiles )
	{
		unzClose( (unzFile)g_unzFiles->data );
		g_unzFiles = g_slist_remove( g_unzFiles, g_unzFiles->data );
	}

	while ( g_pakFiles )
	{
		VFS_PAKFILE* file = (VFS_PAKFILE*)g_pakFiles->data;
		free( file->name );
		free( file );
		g_pakFiles = g_slist_remove( g_pakFiles, file );
	}
}

// return the number of files that match
int vfsGetFileCount( const char *filename ){
	int i, count = 0;
	char fixed[NAME_MAX], tmp[NAME_MAX];
	char *lower;
	GSList *lst;

	strcpy( fixed, filename );
	vfsFixDOSName( fixed );
	lower = g_ascii_strdown( fixed, -1 );

	for ( lst = g_pakFiles; lst != NULL; lst = g_slist_next( lst ) )
	{
		VFS_PAKFILE* file = (VFS_PAKFILE*)lst->data;

		if ( strcmp( file->name, lower ) == 0 ) {
			count++;
		}
	}

	for ( i = 0; i < g_numDirs; i++ )
	{
		strcpy( tmp, g_strDirs[i] );
		strcat( tmp, lower );
		if ( access( tmp, R_OK ) == 0 ) {
			count++;
		}
	}
	g_free( lower );
	return count;
}

static qboolean isSymlink(const unz_file_info64 *fileInfo) {
	// see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/stat.h
	// redefine so it works outside of Unices
	const unsigned long Q3MAP_S_IFMT = 00170000;
	const unsigned long Q3MAP_S_IFLNK = 0120000;
	// see https://trac.edgewall.org/attachment/ticket/8919/ZipDownload.patch
	const unsigned long PKZIP_EXTERNAL_ATTR_FILE_TYPE_SHIFT = 16;

	unsigned long attr = fileInfo->external_fa >> PKZIP_EXTERNAL_ATTR_FILE_TYPE_SHIFT;
	return (attr & Q3MAP_S_IFMT) == Q3MAP_S_IFLNK;
}

// The zip format has a maximum filename size of 64K
static const int MAX_FILENAME_BUF = 65537;

/* The symlink implementation is ported from Dæmon engine implementation by slipher which was a complete rewrite of one illwieckz did on Dæmon by taking inspiration from Darkplaces engine.

See:

- https://github.com/DaemonEngine/Daemon/blob/master/src/common/FileSystem.cpp
- https://gitlab.com/xonotic/darkplaces/-/blob/div0-stable/fs.c

Some words by slipher:

> Symlinks are a bad feature which you should not use. Therefore, the implementation is as
> slow as possible with a full iteration of the archive performed for each symlink.

> The symlink path `relative` must be relative to the symlink's location.
> Only supports paths consisting of "../" 0 or more times, followed by non-magical path components.
*/
void resolveSymlinkPath( const char* base, const char* relative, char* resolved ){

	base = g_path_get_dirname( base );

	while( g_str_has_prefix( relative, "../" ) )
	{
		if ( base[0] == '\0' )
		{
			Sys_FPrintf( SYS_WRN, "Error while reading symbolic link: \"%s\": no such directory\n", base );
			resolved[0] = '\0';
			return;
		}

		base = g_path_get_dirname( base );
		relative += 3;
	}

	snprintf( resolved, MAX_FILENAME_BUF, "%s/%s", base, relative);
}

// NOTE: when loading a file, you have to allocate one extra byte and set it to \0
int vfsLoadFile( const char *filename, void **bufferptr, int index ){
	int i, count = 0;
	char tmp[NAME_MAX], fixed[NAME_MAX];
	char *lower;
	GSList *lst;

	// filename is a full path
	if ( index == -1 ) {
		long len;
		FILE *f;

		f = fopen( filename, "rb" );
		if ( f == NULL ) {
			return -1;
		}

		fseek( f, 0, SEEK_END );
		len = ftell( f );
		rewind( f );

		*bufferptr = safe_malloc( len + 1 );
		if ( *bufferptr == NULL ) {
			fclose( f );
			return -1;
		}

		if ( fread( *bufferptr, 1, len, f ) != (size_t) len ) {
			fclose( f );
			return -1;
		}
		fclose( f );

		// we need to end the buffer with a 0
		( (char*) ( *bufferptr ) )[len] = 0;

		return len;
	}

	*bufferptr = NULL;
	strncpy( fixed, filename, sizeof( fixed ) );
	vfsFixDOSName( fixed );
	lower = g_ascii_strdown( fixed, -1 );

	for ( i = 0; i < g_numDirs; i++ )
	{
		strcpy( tmp, g_strDirs[i] );
		strcat( tmp, filename );
		if ( access( tmp, R_OK ) == 0 ) {
			if ( count == index ) {
				long len;
				FILE *f;

				f = fopen( tmp, "rb" );
				if ( f == NULL ) {
					return -1;
				}

				fseek( f, 0, SEEK_END );
				len = ftell( f );
				rewind( f );

				*bufferptr = safe_malloc( len + 1 );
				if ( *bufferptr == NULL ) {
					fclose( f );
					return -1;
				}

				if ( fread( *bufferptr, 1, len, f ) != (size_t) len ) {
					fclose( f );
					return -1;
				}
				fclose( f );

				// we need to end the buffer with a 0
				( (char*) ( *bufferptr ) )[len] = 0;

				return len;
			}

			count++;
		}
	}

	// Do not resolve more than 5 recursive symbolic links to
	// prevent circular symbolic links.
	int max_symlink_depth = 5;

	openSymlinkTarget:
	for ( lst = g_pakFiles; lst != NULL; lst = g_slist_next( lst ) )
	{
		VFS_PAKFILE* file = (VFS_PAKFILE*)lst->data;

		if ( strcmp( file->name, lower ) != 0 ) {
			continue;
		}

		if ( count == index ) {

		if ( unzGoToFilePos( file->zipfile, &file->zippos ) != UNZ_OK ) {
			return -1;
		}
			if ( unzOpenCurrentFile( file->zipfile ) != UNZ_OK ) {
				return -1;
			}

			unz_file_info64 fileInfo;
			if ( unzGetCurrentFileInfo64( file->zipfile, &fileInfo, filename, sizeof(filename), NULL, 0, NULL, 0 ) != UNZ_OK ) {
				return -1;
			}

			*bufferptr = safe_malloc( file->size + 1 );
			// we need to end the buffer with a 0
			( (char*) ( *bufferptr ) )[file->size] = 0;

			i = unzReadCurrentFile( file->zipfile, *bufferptr, file->size );
			unzCloseCurrentFile( file->zipfile );

			if ( isSymlink( &fileInfo ) ) {
				Sys_FPrintf( SYS_VRB, "Found symbolic link: \"%s\"\n", filename );

				if ( max_symlink_depth == 0 ) {
					Sys_FPrintf( SYS_WRN, "Maximum symbolic link depth reached\n" );
					g_free( lower );
					return -1;
				}

				max_symlink_depth--;

				const char* relative = (const char*) *bufferptr;
				char resolved[MAX_FILENAME_BUF];

				resolveSymlinkPath( file->name, relative, resolved );

				Sys_FPrintf( SYS_VRB, "Resolved symbolic link: \"%s\"\n", resolved );

				g_free( lower );
				strncpy( fixed, resolved, sizeof( fixed ) );
				vfsFixDOSName( fixed );
				lower = g_ascii_strdown( fixed, -1 );

				// slow as possible full iteration of the archive
				goto openSymlinkTarget;
			}

			if ( i < 0 ) {
				g_free( lower );
				return -1;
			}
			else{
				g_free( lower );
				return file->size;
			}
		}

		count++;
	}

	g_free( lower );
	return -1;
}