/*
 * Copyright (c) 2018-2021, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/ByteBuffer.h>
#include <AK/NonnullOwnPtr.h>
#include <AK/NonnullRefPtr.h>
#include <AK/RefCounted.h>
#include <AK/RefPtr.h>
#include <AK/Result.h>
#include <AK/StringView.h>
#include <AK/Try.h>
#include <LibAudio/Buffer.h>
#include <LibAudio/LoaderError.h>
#include <LibCore/File.h>

namespace Audio {

static const String empty_string = "";
static String no_plugin_error = "No loader plugin available";

using LoaderSamples = Result<NonnullRefPtr<Buffer>, LoaderError>;
using MaybeLoaderError = Result<void, LoaderError>;

class LoaderPlugin {
public:
    virtual ~LoaderPlugin() { }

    virtual MaybeLoaderError initialize() = 0;

    virtual LoaderSamples get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) = 0;

    virtual MaybeLoaderError reset() = 0;

    virtual MaybeLoaderError seek(const int sample_index) = 0;

    // total_samples() and loaded_samples() should be independent
    // of the number of channels.
    //
    // For example, with a three-second-long, stereo, 44.1KHz audio file:
    //    num_channels() should return 2
    //    sample_rate() should return 44100 (each channel is sampled at this rate)
    //    total_samples() should return 132300 (sample_rate * three seconds)
    virtual int loaded_samples() = 0;
    virtual int total_samples() = 0;
    virtual u32 sample_rate() = 0;
    virtual u16 num_channels() = 0;

    virtual PcmSampleFormat pcm_format() = 0;
    virtual RefPtr<Core::File> file() = 0;
};

class Loader : public RefCounted<Loader> {
public:
    static Result<NonnullRefPtr<Loader>, LoaderError> create(StringView path) { return adopt_ref(*new Loader(TRY(try_create(path)))); }
    static Result<NonnullRefPtr<Loader>, LoaderError> create(ByteBuffer const& buffer) { return adopt_ref(*new Loader(TRY(try_create(buffer)))); }

    LoaderSamples get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) const { return m_plugin->get_more_samples(max_bytes_to_read_from_input); }

    MaybeLoaderError reset() const { return m_plugin->reset(); }
    MaybeLoaderError seek(const int position) const { return m_plugin->seek(position); }

    int loaded_samples() const { return m_plugin->loaded_samples(); }
    int total_samples() const { return m_plugin->total_samples(); }
    u32 sample_rate() const { return m_plugin->sample_rate(); }
    u16 num_channels() const { return m_plugin->num_channels(); }
    u16 bits_per_sample() const { return pcm_bits_per_sample(m_plugin->pcm_format()); }
    RefPtr<Core::File> file() const { return m_plugin->file(); }

private:
    static Result<NonnullOwnPtr<LoaderPlugin>, LoaderError> try_create(StringView path);
    static Result<NonnullOwnPtr<LoaderPlugin>, LoaderError> try_create(ByteBuffer const& buffer);

    explicit Loader(NonnullOwnPtr<LoaderPlugin>);

    mutable NonnullOwnPtr<LoaderPlugin> m_plugin;
};

}