/*
 * Copyright (C) 2020 Emeric Poupon
 *
 * This file is part of LMS.
 *
 * LMS 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.
 *
 * LMS 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "MediaRetrieval.hpp"

#include <algorithm>
#include <chrono>

#include "core/FileResourceHandlerCreator.hpp"
#include "core/ILogger.hpp"
#include "core/IResourceHandler.hpp"
#include "core/String.hpp"

#include "audio/AudioTypes.hpp"
#include "audio/Exception.hpp"
#include "audio/IAudioFileInfo.hpp"
#include "audio/IAudioFileInfoParser.hpp"

#include "database/Session.hpp"
#include "database/objects/PodcastEpisode.hpp"
#include "database/objects/PodcastEpisodeId.hpp"
#include "database/objects/Track.hpp"
#include "database/objects/TrackLyrics.hpp"
#include "database/objects/User.hpp"

#include "services/artwork/IArtworkService.hpp"
#include "services/podcast/IPodcastService.hpp"
#include "services/transcoding/ITranscodeService.hpp"

#include "CoverArtId.hpp"
#include "ParameterParsing.hpp"
#include "RequestContext.hpp"
#include "SubsonicId.hpp"
#include "SubsonicResponse.hpp"
#include "responses/Lyrics.hpp"

namespace lms::api::subsonic
{
    namespace
    {
        std::optional<audio::OutputFormat> subsonicStreamFormatToTranscodingOutputFormat(std::string_view format)
        {
            for (const auto& [str, avFormat] : std::initializer_list<std::pair<std::string_view, audio::OutputFormat>>{
                     { "mp3", audio::OutputFormat::MP3 },
                     { "opus", audio::OutputFormat::OGG_OPUS },
                     { "vorbis", audio::OutputFormat::OGG_VORBIS },
                 })
            {
                if (core::stringUtils::stringCaseInsensitiveEqual(str, format))
                    return avFormat;
            }
            return std::nullopt;
        }

        audio::OutputFormat userTranscodeFormatToTranscodingFormat(db::TranscodingOutputFormat format)
        {
            switch (format)
            {
            case db::TranscodingOutputFormat::MP3:
                return audio::OutputFormat::MP3;
            case db::TranscodingOutputFormat::OGG_OPUS:
                return audio::OutputFormat::OGG_OPUS;
            case db::TranscodingOutputFormat::MATROSKA_OPUS:
                return audio::OutputFormat::MATROSKA_OPUS;
            case db::TranscodingOutputFormat::OGG_VORBIS:
                return audio::OutputFormat::OGG_VORBIS;
            case db::TranscodingOutputFormat::WEBM_VORBIS:
                return audio::OutputFormat::WEBM_VORBIS;
            }

            return audio::OutputFormat::OGG_OPUS;
        }

        bool isCodecCompatibleWithOutputFormat(audio::CodecType codec, audio::OutputFormat outputFormat)
        {
            switch (outputFormat)
            {
            case audio::OutputFormat::MP3:
                return codec == audio::CodecType::MP3;

            case audio::OutputFormat::OGG_OPUS:
            case audio::OutputFormat::MATROSKA_OPUS:
                return codec == audio::CodecType::Opus;

            case audio::OutputFormat::OGG_VORBIS:
            case audio::OutputFormat::WEBM_VORBIS:
                return codec == audio::CodecType::Vorbis;
            }

            return true;
        }

        struct StreamParameters
        {
            std::filesystem::path filePath;
            std::string fileMimeType; // set if known
            std::optional<audio::TranscodeParameters> transcodeParameters;
            bool estimateContentLength{};
        };

        bool isOutputFormatCompatible(const std::filesystem::path& trackPath, audio::OutputFormat outputFormat)
        {
            // TODO: put this information in db during scan
            // It is in base only for tracks, not yet for podcasts
            try
            {
                const auto parser{ audio::createAudioFileInfoParser(audio::AudioFileInfoParserBackend::FFmpeg) };

                audio::AudioFileInfoParseOptions parseOptions;
                parseOptions.audioPropertiesReadStyle = audio::AudioFileInfoParseOptions::AudioPropertiesReadStyle::Fast; // only coded needed
                parseOptions.readImages = false;
                parseOptions.readTags = false;
                const auto audioFile{ parser->parse(trackPath, parseOptions) };

                if (!audioFile->getAudioProperties())
                    throw RequestedDataNotFoundError{};

                return isCodecCompatibleWithOutputFormat(audioFile->getAudioProperties()->codec, outputFormat);
            }
            catch (const audio::Exception& e)
            {
                throw RequestedDataNotFoundError{};
            }
        }

        using AudioFileId = std::variant<db::TrackId, db::PodcastEpisodeId>;
        struct AudioFileInfo
        {
            std::filesystem::path path;
            std::chrono::milliseconds duration{};
            std::size_t bitrate{};
            std::string mimeType; // set if known
        };

        AudioFileInfo getAudioFileInfo(db::Session& session, AudioFileId audioFileId)
        {
            AudioFileInfo res;

            auto transaction{ session.createReadTransaction() };

            if (const db::TrackId * trackId{ std::get_if<db::TrackId>(&audioFileId) })
            {
                const db::Track::pointer track{ db::Track::find(session, *trackId) };
                if (!track)
                    throw RequestedDataNotFoundError{};

                res.path = track->getAbsoluteFilePath();
                res.duration = track->getDuration();
                res.bitrate = track->getBitrate();
            }
            else if (const db::PodcastEpisodeId * episodeId{ std::get_if<db::PodcastEpisodeId>(&audioFileId) })
            {
                const db::PodcastEpisode::pointer episode{ db::PodcastEpisode::find(session, *episodeId) };
                if (!episode)
                    throw RequestedDataNotFoundError{};

                std::filesystem::path podcastCachePath{ core::Service<podcast::IPodcastService>::get()->getCachePath() };

                res.path = podcastCachePath / episode->getAudioRelativeFilePath();
                res.duration = episode->getDuration();
                res.bitrate = episode->getEnclosureLength() / std::chrono::duration_cast<std::chrono::seconds>(episode->getDuration()).count() * 8;
                res.mimeType = episode->getEnclosureContentType();
            }

            return res;
        }

        StreamParameters getStreamParameters(RequestContext& context)
        {
            // Mandatory params
            const auto trackId{ getParameterAs<db::TrackId>(context.getParameters(), "id") };
            const auto podcastEpisodeId{ getParameterAs<db::PodcastEpisodeId>(context.getParameters(), "id") };
            if (!trackId && !podcastEpisodeId)
                throw RequiredParameterMissingError{ "id" };

            const AudioFileId audioId{ trackId ? AudioFileId{ *trackId } : AudioFileId{ *podcastEpisodeId } };

            // Optional params
            std::size_t maxBitRate{ getParameterAs<std::size_t>(context.getParameters(), "maxBitRate").value_or(0) * 1000 }; // "If set to zero, no limit is imposed", given in kpbs
            const std::string format{ getParameterAs<std::string>(context.getParameters(), "format").value_or("") };
            std::size_t timeOffset{ getParameterAs<std::size_t>(context.getParameters(), "timeOffset").value_or(0) };
            bool estimateContentLength{ getParameterAs<bool>(context.getParameters(), "estimateContentLength").value_or(false) };

            const AudioFileInfo audioFileInfo{ getAudioFileInfo(context.getDbSession(), audioId) };

            StreamParameters parameters;
            parameters.filePath = audioFileInfo.path;
            parameters.fileMimeType = audioFileInfo.mimeType;
            parameters.estimateContentLength = estimateContentLength;

            if (format == "raw")   // raw => no transcoding
                return parameters; // TODO: what if offset is not 0?

            std::optional<audio::OutputFormat> requestedFormat{ subsonicStreamFormatToTranscodingOutputFormat(format) };
            if (!requestedFormat)
            {
                if (context.getUser()->getSubsonicEnableTranscodingByDefault())
                    requestedFormat = userTranscodeFormatToTranscodingFormat(context.getUser()->getSubsonicDefaultTranscodingOutputFormat());
            }

            if (!requestedFormat && (maxBitRate == 0 || audioFileInfo.bitrate <= maxBitRate))
            {
                LMS_LOG(API_SUBSONIC, DEBUG, "File's bitrate is compatible with parameters => no transcoding");
                return parameters; // no transcoding needed
            }

            // scan the file to check if its format is compatible with the actual requested format
            //  same codec => apply max bitrate
            //  otherwise => apply default bitrate (because we can't really compare bitrates between formats) + max bitrate)
            std::size_t bitrate{};
            if (requestedFormat && isOutputFormatCompatible(audioFileInfo.path, *requestedFormat))
            {
                if (maxBitRate == 0 || audioFileInfo.bitrate <= maxBitRate)
                {
                    LMS_LOG(API_SUBSONIC, DEBUG, "File's bitrate and format are compatible with parameters => no transcoding");
                    return parameters; // no transcoding needed
                }
                bitrate = maxBitRate;
            }

            // Need to transcode here
            if (!requestedFormat)
                requestedFormat = userTranscodeFormatToTranscodingFormat(context.getUser()->getSubsonicDefaultTranscodingOutputFormat());
            if (!bitrate)
                bitrate = context.getUser()->getSubsonicDefaultTranscodingOutputBitrate();
            if (maxBitRate)
                bitrate = std::min<std::size_t>(bitrate, maxBitRate);

            audio::TranscodeParameters& transcodeParameters{ parameters.transcodeParameters.emplace() };

            transcodeParameters.inputParameters.filePath = audioFileInfo.path;
            transcodeParameters.inputParameters.duration = audioFileInfo.duration;
            transcodeParameters.inputParameters.offset = std::chrono::seconds{ timeOffset };
            ;

            transcodeParameters.outputParameters.bitrate = bitrate;
            transcodeParameters.outputParameters.format = *requestedFormat;
            transcodeParameters.outputParameters.stripMetadata = false; // We want clients to use metadata (offline use, replay gain, etc.)

            return parameters;
        }
    } // namespace

    Response handleGetLyrics(RequestContext& context)
    {
        std::string artistName{ getParameterAs<std::string>(context.getParameters(), "artist").value_or("") };
        std::string titleName{ getParameterAs<std::string>(context.getParameters(), "title").value_or("") };

        Response response{ Response::createOkResponse(context.getServerProtocolVersion()) };

        // best effort search, as this API is really limited
        auto transaction{ context.getDbSession().createReadTransaction() };

        db::Track::FindParameters params;
        params.setName(titleName);
        params.setArtistName(artistName);
        params.setRange(db::Range{ .offset = 0, .size = 2 });

        // Choice: we return nothing if there are too many results
        const auto tracks{ db::Track::findIds(context.getDbSession(), params) };
        if (tracks.results.size() == 1)
        {
            // Choice: we return only the first lyrics if the track has many lyrics
            db::TrackLyrics::FindParameters lyricsParams;
            lyricsParams.setTrack(tracks.results[0]);
            lyricsParams.setSortMethod(db::TrackLyricsSortMethod::ExternalFirst);
            lyricsParams.setRange(db::Range{ 0, 1 });

            db::TrackLyrics::find(context.getDbSession(), lyricsParams, [&](const db::TrackLyrics::pointer& lyrics) {
                response.addNode("lyrics", createLyricsNode(context, lyrics));
            });
        }

        return response;
    }

    Response handleGetLyricsBySongId(RequestContext& context)
    {
        // mandatory params
        db::TrackId id{ getMandatoryParameterAs<db::TrackId>(context.getParameters(), "id") };

        Response response{ Response::createOkResponse(context.getServerProtocolVersion()) };
        Response::Node& lyricsList{ response.createNode("lyricsList") };
        lyricsList.createEmptyArrayChild("structuredLyrics");

        auto transaction{ context.getDbSession().createReadTransaction() };
        const db::Track::pointer track{ db::Track::find(context.getDbSession(), id) };
        if (track)
        {
            db::TrackLyrics::FindParameters params;
            params.setTrack(track->getId());
            params.setExternal(true); // First try to only report external lyrics as they are often duplicate of embedded lyrics and support more features

            bool hasExternalLyrics{};
            db::TrackLyrics::find(context.getDbSession(), params, [&](const db::TrackLyrics::pointer& lyrics) {
                lyricsList.addArrayChild("structuredLyrics", createStructuredLyricsNode(context, lyrics));
                hasExternalLyrics = true;
            });

            if (!hasExternalLyrics)
            {
                params.setExternal(false);
                db::TrackLyrics::find(context.getDbSession(), params, [&](const db::TrackLyrics::pointer& lyrics) {
                    lyricsList.addArrayChild("structuredLyrics", createStructuredLyricsNode(context, lyrics));
                });
            }
        }

        return response;
    }

    void handleDownload(RequestContext& context, const Wt::Http::Request& request, Wt::Http::Response& response)
    {
        std::shared_ptr<core::IResourceHandler> resourceHandler;

        Wt::Http::ResponseContinuation* continuation{ request.continuation() };
        if (!continuation)
        {
            // Mandatory params
            db::TrackId id{ getMandatoryParameterAs<db::TrackId>(context.getParameters(), "id") };

            std::filesystem::path trackPath;
            {
                auto transaction{ context.getDbSession().createReadTransaction() };

                auto track{ db::Track::find(context.getDbSession(), id) };
                if (!track)
                    throw RequestedDataNotFoundError{};

                trackPath = track->getAbsoluteFilePath();
            }

            resourceHandler = core::createFileResourceHandler(trackPath);
        }
        else
        {
            resourceHandler = Wt::cpp17::any_cast<std::shared_ptr<core::IResourceHandler>>(continuation->data());
        }

        continuation = resourceHandler->processRequest(request, response);
        if (continuation)
            continuation->setData(resourceHandler);
    }

    void handleStream(RequestContext& context, const Wt::Http::Request& request, Wt::Http::Response& response)
    {
        std::shared_ptr<core::IResourceHandler> resourceHandler;

        try
        {
            Wt::Http::ResponseContinuation* continuation = request.continuation();
            if (!continuation)
            {
                StreamParameters streamParameters{ getStreamParameters(context) };
                if (streamParameters.transcodeParameters)
                    resourceHandler = core::Service<transcoding::ITranscodeService>::get()->createTranscodeResourceHandler(*streamParameters.transcodeParameters, streamParameters.estimateContentLength);
                else
                    resourceHandler = core::createFileResourceHandler(streamParameters.filePath, streamParameters.fileMimeType);
            }
            else
            {
                resourceHandler = Wt::cpp17::any_cast<std::shared_ptr<core::IResourceHandler>>(continuation->data());
            }

            continuation = resourceHandler->processRequest(request, response);
            if (continuation)
                continuation->setData(resourceHandler);
        }
        catch (const audio::Exception& e)
        {
            response.setStatus(404); // report not found if something wrong happened
            LMS_LOG(API_SUBSONIC, ERROR, "Caught Av exception: " << e.what());
        }
    }

    void handleGetCoverArt(RequestContext& context, const Wt::Http::Request& /*request*/, Wt::Http::Response& response)
    {
        // Mandatory params
        const CoverArtId coverArtId{ getMandatoryParameterAs<CoverArtId>(context.getParameters(), "id") };

        std::optional<std::size_t> size{ getParameterAs<std::size_t>(context.getParameters(), "size") };
        if (size)
            *size = std::clamp(*size, std::size_t{ 32 }, std::size_t{ 2048 });

        std::shared_ptr<image::IEncodedImage> image{ core::Service<artwork::IArtworkService>::get()->getImage(coverArtId.id, size) };
        if (!image)
        {
            response.setStatus(404);
            return;
        }

        response.out().write(reinterpret_cast<const char*>(image->getData().data()), image->getData().size());
        response.setMimeType(std::string{ image->getMimeType() });
    }

} // namespace lms::api::subsonic