/*
This Source Code Form is subject to the
terms of the Mozilla Public License, v.
2.0. If a copy of the MPL was not
distributed with this file, You can
obtain one at
http://mozilla.org/MPL/2.0/.
*/

#include "stdafx.h"

#include "audio.h"
#include "globals.h"
#include "mczapkie/mctools.h"

#define DR_WAV_IMPLEMENTATION
#include "dr_wav.h"
#define DR_FLAC_IMPLEMENTATION
#include "dr_flac.h"

namespace audio {

openal_buffer::openal_buffer( std::string const &Filename ) :
    name( Filename ) {

    ::alGenBuffers( 1, &id );
    // fetch audio data
    if( Filename.substr( Filename.rfind( '.' ) ) == ".wav" ) {
        // .wav file
        auto *file { drwav_open_file( Filename.c_str() ) };
        rate = file->sampleRate;
        auto const samplecount { static_cast<std::size_t>( file->totalSampleCount ) };
        data.resize( samplecount );
        drwav_read_s16(
            file,
            samplecount,
            &data[ 0 ] );
        if( file->channels > 1 ) {
            narrow_to_mono( file->channels );
            data.resize( samplecount / file->channels );
        }
        // we're done with the disk data
        drwav_close( file );
    }
    else {
        // .flac or .ogg file
        auto *file { drflac_open_file( Filename.c_str() ) };
        rate = file->sampleRate;
        auto const samplecount{ static_cast<std::size_t>( file->totalSampleCount ) };
        data.resize( samplecount );
        drflac_read_s16(
            file,
            samplecount,
            &data[ 0 ] );
        if( file->channels > 1 ) {
            narrow_to_mono( file->channels );
            data.resize( samplecount / file->channels );
        }
        // we're done with the disk data
        drflac_close( file );
    }
    // send the data to openal side
    ::alBufferData( id, AL_FORMAT_MONO16, data.data(), data.size() * sizeof( std::int16_t ), rate );
    // and get rid of the source, we shouldn't need it anymore
    // TBD, TODO: delay data fetching and transfers until the buffer is actually used?
    std::vector<std::int16_t>().swap( data );
}

// mix specified number of interleaved multi-channel data, down to mono
void
openal_buffer::narrow_to_mono( std::uint16_t const Channelcount ) {
 
    std::size_t monodataindex { 0 };
    std::int32_t accumulator { 0 };
    auto channelcount { Channelcount };

    for( auto const channeldata : data ) {

        accumulator += channeldata;
        if( --channelcount == 0 ) {

            data[ monodataindex++ ] = accumulator / Channelcount;
            accumulator = 0;
            channelcount = Channelcount;
        }
    }
}



buffer_manager::~buffer_manager() {

    for( auto &buffer : m_buffers ) {
        if( buffer.id != null_resource ) {
            ::alDeleteBuffers( 1, &( buffer.id ) );
        }
    }
}

// creates buffer object out of data stored in specified file. returns: handle to the buffer or null_handle if creation failed
audio::buffer_handle
buffer_manager::create( std::string const &Filename ) {

    auto filename { ToLower( Filename ) };

    auto const dotpos { filename.rfind( '.' ) };
    if( ( dotpos != std::string::npos )
     && ( dotpos != filename.rfind( ".." ) + 1 ) ) {
        // trim extension if there's one, but don't mistake folder traverse for extension
        filename.erase( dotpos );
    }
    // convert slashes
    std::replace(
        std::begin( filename ), std::end( filename ),
        '\\', '/' );

    audio::buffer_handle lookup { null_handle };
    std::string filelookup;
    if( false == Global::asCurrentDynamicPath.empty() ) {
        // try dynamic-specific sounds first
        lookup = find_buffer( Global::asCurrentDynamicPath + filename );
        if( lookup != null_handle ) {
            return lookup;
        }
        filelookup = find_file( Global::asCurrentDynamicPath + filename );
        if( false == filelookup.empty() ) {
            return emplace( filelookup );
        }
    }
    // if dynamic-specific lookup finds nothing, try the default sound folder
    lookup = find_buffer( szSoundPath + filename );
    if( lookup != null_handle ) {
        return lookup;
    }
    filelookup = find_file( szSoundPath + filename );
    if( false == filelookup.empty() ) {
        return emplace( filelookup );
    }
    // if we still didn't find anything, give up
    return null_handle;
}

// provides direct access to a specified buffer
audio::openal_buffer const &
buffer_manager::buffer( audio::buffer_handle const Buffer ) const {

    return m_buffers[ Buffer ];
}

// places in the bank a buffer containing data stored in specified file. returns: handle to the buffer
audio::buffer_handle
buffer_manager::emplace( std::string Filename ) {

    buffer_handle const handle { m_buffers.size() };
    m_buffers.emplace_back( Filename );

    // NOTE: we store mapping without file type extension, to simplify lookups
    m_buffermappings.emplace(
        Filename.erase( Filename.rfind( '.' ) ),
        handle );

    return handle;
}

audio::buffer_handle
buffer_manager::find_buffer( std::string const &Buffername ) const {

    auto lookup = m_buffermappings.find( Buffername );
    if( lookup != m_buffermappings.end() )
        return lookup->second;
    else
        return null_handle;
}


std::string
buffer_manager::find_file( std::string const &Filename ) const {

    std::vector<std::string> const extensions { ".wav", ".flac", ".ogg" };

    for( auto const &extension : extensions ) {
        if( FileExists( Filename + extension ) ) {
            // valid name on success
            return Filename + extension;
        }
    }
    return {}; // empty string on failure
}

} // audio

//---------------------------------------------------------------------------