/*
filesystem.c - game filesystem based on DP fs
Copyright (C) 2003-2006 Mathieu Olivier
Copyright (C) 2000-2007 DarkPlaces contributors
Copyright (C) 2007 Uncle Mike
Copyright (C) 2015-2023 Xash3D FWGS contributors

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 3 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.
*/

#include <errno.h>
#include "common.h"
#include "library.h"
#include "platform/platform.h"

fs_api_t g_fsapi;
fs_globals_t *FI;

static pfnCreateInterface_t fs_pfnCreateInterface;
static HINSTANCE fs_hInstance;

static void COM_StripDirectorySlash( char *pname )
{
	size_t len;

	len = Q_strlen( pname );
	if( len > 0 && pname[len - 1] == '/' )
		pname[len - 1] = 0;
}

void *FS_GetNativeObject( const char *obj )
{
	if( fs_pfnCreateInterface )
		return fs_pfnCreateInterface( obj, NULL );

	return NULL;
}

static void FS_Rescan_f( void )
{
	FS_Rescan();
}

static void FS_ClearPaths_f( void )
{
	FS_ClearSearchPath();
}

static void FS_Path_f_( void )
{
	FS_Path_f();
}

static fs_interface_t fs_memfuncs =
{
	Con_Printf,
	Con_DPrintf,
	Con_Reportf,
	Sys_Error,

	_Mem_AllocPool,
	_Mem_FreePool,
	_Mem_Alloc,
	_Mem_Realloc,
	_Mem_Free,

	Sys_GetNativeObject,
};

static void FS_UnloadProgs( void )
{
	if( fs_hInstance )
	{
		COM_FreeLibrary( fs_hInstance );
		fs_hInstance = 0;
	}
}

#ifdef XASH_INTERNAL_GAMELIBS
#define FILESYSTEM_STDIO_DLL "filesystem_stdio"
#else
#define FILESYSTEM_STDIO_DLL "filesystem_stdio." OS_LIB_EXT
#endif

static qboolean FS_LoadProgs( void )
{
	const char *name = FILESYSTEM_STDIO_DLL;
	FSAPI GetFSAPI;

	fs_hInstance = COM_LoadLibrary( name, false, true );

	if( !fs_hInstance )
	{
		Sys_Error( "%s: can't load filesystem library %s: %s\n", __func__, name, COM_GetLibraryError() );
		return false;
	}

	if( !( GetFSAPI = (FSAPI)COM_GetProcAddress( fs_hInstance, GET_FS_API )))
	{
		FS_UnloadProgs();
		Sys_Error( "%s: can't find GetFSAPI entry point in %s\n", __func__, name );
		return false;
	}

	if( GetFSAPI( FS_API_VERSION, &g_fsapi, &FI, &fs_memfuncs ) != FS_API_VERSION )
	{
		FS_UnloadProgs();
		Sys_Error( "%s: can't initialize filesystem API: wrong version\n", __func__ );
		return false;
	}

	if( !( fs_pfnCreateInterface = (pfnCreateInterface_t)COM_GetProcAddress( fs_hInstance, "CreateInterface" )))
	{
		FS_UnloadProgs();
		Sys_Error( "%s: can't find CreateInterface entry point in %s\n", __func__, name );
		return false;
	}

	Con_DPrintf( "%s: filesystem_stdio successfully loaded\n", __func__ );
	return true;
}

static qboolean FS_DetermineRootDirectory( char *out, size_t size )
{
	const char *path = getenv( "XASH3D_BASEDIR" );

	if( COM_CheckString( path ))
	{
		Q_strncpy( out, path, size );
		return true;
	}

#if TARGET_OS_IOS
	Q_strncpy( out, IOS_GetDocsDir(), size );
	return true;
#elif XASH_ANDROID && XASH_SDL
	path = SDL_AndroidGetExternalStoragePath();
	if( path != NULL )
	{
		Q_strncpy( out, path, size );
		return true;
	}
	Sys_Error( "couldn't determine Android external storage path: %s", SDL_GetError( ));
	return false;
#elif XASH_PSVITA
	if( PSVita_GetBasePath( out, size ))
		return true;
	Sys_Error( "couldn't find Xash3D data directory" );
	return false;
#elif ( XASH_SDL == 2 ) && !XASH_NSWITCH // GetBasePath not impl'd in switch-sdl2
	path = SDL_GetBasePath();
	if( path != NULL )
	{
		Q_strncpy( out, path, size );
		SDL_free(( void *)path );
		return true;
	}

#if XASH_POSIX || XASH_WIN32
	if( getcwd( out, size ))
		return true;
	Sys_Error( "couldn't determine current directory: %s, getcwd: %s", SDL_GetError(), strerror( errno ));
#else // !( XASH_POSIX || XASH_WIN32 )
	Sys_Error( "couldn't determine current directory: %s", SDL_GetError( ));
#endif // !( XASH_POSIX || XASH_WIN32 )
	return false;
#else // generic case
	if( getcwd( out, size ))
		return true;

	Sys_Error( "couldn't determine current directory: %s", strerror( errno ));
	return false;
#endif // generic case
}

static qboolean FS_DetermineReadOnlyRootDirectory( char *out, size_t size )
{
	const char *env_rodir = getenv( "XASH3D_RODIR" );

	if( _Sys_GetParmFromCmdLine( "-rodir", out, size ))
		return true;

	if( COM_CheckString( env_rodir ))
	{
		Q_strncpy( out, env_rodir, size );
		return true;
	}

	return false;
}

/*
================
FS_Init
================
*/
void FS_Init( const char *basedir )
{
	string gamedir;
	char rodir[MAX_OSPATH], rootdir[MAX_OSPATH];
	rodir[0] = rootdir[0] = 0;

	if( !FS_DetermineRootDirectory( rootdir, sizeof( rootdir )) || !COM_CheckStringEmpty( rootdir ))
	{
		Sys_Error( "couldn't determine current directory (empty string)" );
		return;
	}
	COM_FixSlashes( rootdir );
	COM_StripDirectorySlash( rootdir );

	FS_DetermineReadOnlyRootDirectory( rodir, sizeof( rodir ));
	COM_FixSlashes( rodir );
	COM_StripDirectorySlash( rodir );

	if( !Sys_GetParmFromCmdLine( "-game", gamedir ))
		Q_strncpy( gamedir, basedir, sizeof( gamedir )); // gamedir == basedir

	FS_LoadProgs();
	if( !g_fsapi.InitStdio( true, rootdir, basedir, gamedir, rodir ))
	{
		Sys_Error( "Can't init filesystem_stdio!\n" );
		return;
	}

	// TODO: this function will cause engine to stop in case of fail
	// when it will have an option to return string error, restore Sys_Error
	g_fsapi.SetCurrentDirectory( rootdir );

	Cmd_AddRestrictedCommand( "fs_rescan", FS_Rescan_f, "rescan filesystem search pathes" );
	Cmd_AddRestrictedCommand( "fs_path", FS_Path_f_, "show filesystem search pathes" );
	Cmd_AddRestrictedCommand( "fs_clearpaths", FS_ClearPaths_f, "clear filesystem search pathes" );

	if( !Sys_GetParmFromCmdLine( "-dll", host.gamedll ))
		host.gamedll[0] = 0;

	if( !Sys_GetParmFromCmdLine( "-clientlib", host.clientlib ))
		host.clientlib[0] = 0;
}

/*
================
FS_Shutdown
================
*/
void FS_Shutdown( void )
{
	if( g_fsapi.ShutdownStdio )
		g_fsapi.ShutdownStdio();

	FS_UnloadProgs();
}