/*
 * This code provides a glue layer between PhysicsFS and Simple Directmedia
 *  Layer's (SDL) RWops i/o abstraction.
 *
 * License: this code is public domain. I make no warranty that it is useful,
 *  correct, harmless, or environmentally safe.
 *
 * This particular file may be used however you like, including copying it
 *  verbatim into a closed-source project, exploiting it commercially, and
 *  removing any trace of my name from the source (although I hope you won't
 *  do that). I welcome enhancements and corrections to this file, but I do
 *  not require you to send me patches if you make changes. This code has
 *  NO WARRANTY.
 *
 * Unless otherwise stated, the rest of PhysicsFS falls under the zlib license.
 *  Please see LICENSE.txt in the root of the source tree.
 *
 * SDL falls under the LGPL license. You can get SDL at http://www.libsdl.org/
 *
 *  This file was written by Ryan C. Gordon. (icculus@icculus.org).
 *
 *  Copyright (C) 2012  The ManaPlus Developers
 */

#include "utils/physfsrwops.h"

#include <stdio.h>  /* used for SEEK_SET, SEEK_CUR, SEEK_END ... */

#include "localconsts.h"

#include "debug.h"

static int physfsrwops_seek(SDL_RWops *rw, int offset, int whence)
{
    PHYSFS_file *const handle = static_cast<PHYSFS_file *const>(
        rw->hidden.unknown.data1);
    int pos = 0;

    if (whence == SEEK_SET)
    {
        pos = offset;
    } /* if */
    else if (whence == SEEK_CUR)
    {
        const PHYSFS_sint64 current = PHYSFS_tell(handle);
        if (current == -1)
        {
            SDL_SetError("Can't find position in file: %s",
                          PHYSFS_getLastError());
            return -1;
        } /* if */

        pos = static_cast<int>(current);
        if (static_cast<PHYSFS_sint64>(pos) != current)
        {
            SDL_SetError("Can't fit current file position in an int!");
            return -1;
        } /* if */

        if (offset == 0)  /* this is a "tell" call. We're done. */
            return pos;

        pos += offset;
    } /* else if */
    else if (whence == SEEK_END)
    {
        const PHYSFS_sint64 len = PHYSFS_fileLength(handle);
        if (len == -1)
        {
            SDL_SetError("Can't find end of file: %s", PHYSFS_getLastError());
            return -1;
        } /* if */

        pos = static_cast<int>(len);
        if (static_cast<PHYSFS_sint64>(pos) != len)
        {
            SDL_SetError("Can't fit end-of-file position in an int!");
            return -1;
        } /* if */

        pos += offset;
    } /* else if */
    else
    {
        SDL_SetError("Invalid 'whence' parameter.");
        return -1;
    } /* else */

    if ( pos < 0 )
    {
        SDL_SetError("Attempt to seek past start of file.");
        return -1;
    } /* if */

    if (!PHYSFS_seek(handle, static_cast<PHYSFS_uint64>(pos)))
    {
        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
        return -1;
    } /* if */

    return pos;
} /* physfsrwops_seek */

static int physfsrwops_read(SDL_RWops *rw, void *ptr, int size, int maxnum)
{
    PHYSFS_file *const handle = static_cast<PHYSFS_file *const>(
        rw->hidden.unknown.data1);
    const PHYSFS_sint64 rc = PHYSFS_read(handle, ptr, size, maxnum);
    if (rc != maxnum)
    {
        if (!PHYSFS_eof(handle)) /* not EOF? Must be an error. */
            SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
    } /* if */

    return static_cast<int>(rc);
} /* physfsrwops_read */

static int physfsrwops_write(SDL_RWops *rw, const void *ptr, int size, int num)
{
    PHYSFS_file *const handle = static_cast<PHYSFS_file *const>(
        rw->hidden.unknown.data1);
    const PHYSFS_sint64 rc = PHYSFS_write(handle, ptr, size, num);
    if (rc != num)
        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());

    return static_cast<int>(rc);
} /* physfsrwops_write */

static int physfsrwops_close(SDL_RWops *rw)
{
    PHYSFS_file *const handle = static_cast<PHYSFS_file*>(
        rw->hidden.unknown.data1);
    if (!PHYSFS_close(handle))
    {
        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
        return -1;
    } /* if */

    SDL_FreeRW(rw);
    return 0;
} /* physfsrwops_close */

static SDL_RWops *create_rwops(PHYSFS_file *handle)
{
    SDL_RWops *retval = nullptr;

    if (!handle)
    {
        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
    }
    else
    {
        retval = SDL_AllocRW();
        if (retval)
        {
            retval->seek  = physfsrwops_seek;
            retval->read  = physfsrwops_read;
            retval->write = physfsrwops_write;
            retval->close = physfsrwops_close;
            retval->hidden.unknown.data1 = handle;
        } /* if */
    } /* else */

    return retval;
} /* create_rwops */

SDL_RWops *PHYSFSRWOPS_makeRWops(PHYSFS_file *handle)
{
    SDL_RWops *retval = nullptr;
    if (!handle)
        SDL_SetError("NULL pointer passed to PHYSFSRWOPS_makeRWops().");
    else
        retval = create_rwops(handle);

    return retval;
} /* PHYSFSRWOPS_makeRWops */

#ifdef __APPLE__
static bool checkFilePath(char *fname)
{
    if (!fname || !*fname)
        return false;
    if (!PHYSFS_exists(fname) || PHYSFS_isDirectory(fname))
        return false;
    return true;
}
#endif

SDL_RWops *PHYSFSRWOPS_openRead(const char *fname)
{
#ifdef __APPLE__
    if (!checkFilePath(fname))
        return nullptr;
#endif
    return create_rwops(PHYSFS_openRead(fname));
} /* PHYSFSRWOPS_openRead */

SDL_RWops *PHYSFSRWOPS_openWrite(const char *fname)
{
#ifdef __APPLE__
    if (!checkFilePath(fname))
        return nullptr;
#endif
    return create_rwops(PHYSFS_openWrite(fname));
} /* PHYSFSRWOPS_openWrite */

SDL_RWops *PHYSFSRWOPS_openAppend(const char *fname)
{
#ifdef __APPLE__
    if (!checkFilePath(fname))
        return nullptr;
#endif
    return create_rwops(PHYSFS_openAppend(fname));
} /* PHYSFSRWOPS_openAppend */

/* end of physfsrwops.c ... */