/*
 * Copyright (c) 2007 Vreixo Formoso
 * 
 * This file is part of the libisofs project; you can redistribute it and/or 
 * modify it under the terms of the GNU General Public License version 2 as 
 * published by the Free Software Foundation. See COPYING file for details.
 */
#ifndef LIBISO_STREAM_H_
#define LIBISO_STREAM_H_

/*
 * Definitions of streams.
 */
#include "fsource.h"

/** 
 * serial number to be used when you can't get a valid id for a Stream by other
 * means. If you use this, both fs_id and dev_id should be set to 0.
 * This must be incremented each time you get a reference to it.
 */
extern ino_t serial_id;

/*
 * Some functions here will be moved to libisofs.h when we expose 
 * Streams.
 */

typedef struct Iso_Stream IsoStream;

typedef struct IsoStream_Iface
{
    /**
     * Opens the stream.
     * 
     * TODO it would be great to return a different success code if the
     * underlying source size has changed.
     * @return 
     *     1 on success, < 0 on error
     */
    int (*open)(IsoStream *stream);

    /**
     * Close the Stream.
     * @return 1 on success, < 0 on error
     */
    int (*close)(IsoStream *stream);

    /**
     * Get the size (in bytes) of the stream. This function should always 
     * return the same size, even if the underlying source size changes.
     */
    off_t (*get_size)(IsoStream *stream);

    /**
     * Attempts to read up to count bytes from the given stream into
     * the buffer starting at buf.
     * 
     * The stream must be open() before calling this, and close() when no 
     * more needed. 
     * 
     * @return 
     *     number of bytes read, 0 if EOF, < 0 on error
     */
    int (*read)(IsoStream *stream, void *buf, size_t count);

    /**
     * Whether this Stram can be read several times, with the same results. 
     * For example, a regular file is repeatable, you can read it as many
     * times as you want. However, a pipe isn't. 
     * 
     * This function doesn't take into account if the file has been modified
     * between the two reads. 
     * 
     * @return
     *     1 if stream is repeatable, 0 if not, < 0 on error
     */
    int (*is_repeatable)(IsoStream *stream);

    /**
     * Get an unique identifier for the IsoStream.
     */
    void (*get_id)(IsoStream *stream, unsigned int *fs_id, dev_t *dev_id,
                  ino_t *ino_id);

    /**
     * Get a name that identifies the Stream contents. It is used only for
     * informational or debug purposes, so you can return anything you 
     * consider suitable for identification of the source, such as the path.
     */
    char *(*get_name)(IsoStream *stream);

    /**
     * Free implementation specific data. Should never be called by user.
     * Use iso_stream_unref() instead.
     */
    void (*free)(IsoStream *stream);
} IsoStreamIface;

struct Iso_Stream
{
    IsoStreamIface *class;
    int refcount;
    void *data;
};

void iso_stream_ref(IsoStream *stream);
void iso_stream_unref(IsoStream *stream);

extern inline
int iso_stream_open(IsoStream *stream)
{
    return stream->class->open(stream);
}

extern inline
int iso_stream_close(IsoStream *stream)
{
    return stream->class->close(stream);
}

extern inline
off_t iso_stream_get_size(IsoStream *stream)
{
    return stream->class->get_size(stream);
}

extern inline
int iso_stream_read(IsoStream *stream, void *buf, size_t count)
{
    return stream->class->read(stream, buf, count);
}

extern inline
int iso_stream_is_repeatable(IsoStream *stream)
{
    return stream->class->is_repeatable(stream);
}

extern inline
void iso_stream_get_id(IsoStream *stream, unsigned int *fs_id, dev_t *dev_id,
                      ino_t *ino_id)
{
    stream->class->get_id(stream, fs_id, dev_id, ino_id);
}

extern inline
char *iso_stream_get_name(IsoStream *stream)
{
    return stream->class->get_name(stream);
}

/**
 * Create a stream to read from a IsoFileSource.
 * The stream will take the ref. to the IsoFileSource, so after a successfully
 * exectution of this function, you musn't unref() the source, unless you
 * take an extra ref.
 * 
 * @return
 *      1 sucess, < 0 error
 *      Possible errors:
 * 
 */
int iso_file_source_stream_new(IsoFileSource *src, IsoStream **stream);

/**
 * Create a stream for reading from a arbitrary memory buffer.
 * When the Stream refcount reach 0, the buffer is free(3).
 * 
 * @return
 *      1 sucess, < 0 error
 */
int iso_memory_stream_new(unsigned char *buf, size_t size, IsoStream **stream);

#endif /*STREAM_H_*/