package server

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"os/exec"
	"time"

	"git.netflux.io/rob/clipper/config"
	pbmediaset "git.netflux.io/rob/clipper/generated/pb/media_set"
	"git.netflux.io/rob/clipper/media"
	"github.com/google/uuid"
	grpcmiddleware "github.com/grpc-ecosystem/go-grpc-middleware"
	grpczap "github.com/grpc-ecosystem/go-grpc-middleware/logging/zap"
	grpcrecovery "github.com/grpc-ecosystem/go-grpc-middleware/recovery"
	"github.com/improbable-eng/grpc-web/go/grpcweb"
	"go.uber.org/zap"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"google.golang.org/protobuf/types/known/durationpb"
)

const (
	// ts-proto generates code that automatically retries for a subset of gRPC
	// response codes. To avoid invoking this behaviour, default to returning a
	// Cancelled code for now.
	// See https://github.com/stephenh/ts-proto/blob/459b94f5b2988d58d186461332e888c3e511603a/src/generate-grpc-web.ts#L293
	// and https://github.com/stephenh/ts-proto/pull/131.
	defaultResponseCode    = codes.Canceled
	defaultResponseMessage = "An unexpected error occurred"
)

const (
	getPeaksTimeout           = time.Minute * 5
	getPeaksForSegmentTimeout = time.Second * 10
	getAudioSegmentTimeout    = time.Minute * 2
	getVideoTimeout           = time.Minute * 5
)

type ResponseError struct {
	err error
	s   string
}

func (r *ResponseError) Error() string {
	return fmt.Sprintf("unexpected error: %v", r.err.Error())
}

func (r *ResponseError) Unwrap() error {
	return r.err
}

func (r *ResponseError) GRPCStatus() *status.Status {
	return status.New(defaultResponseCode, r.s)
}

func newResponseError(err error) *ResponseError {
	return &ResponseError{err: err, s: defaultResponseMessage}
}

type Options struct {
	Config        config.Config
	Timeout       time.Duration
	Store         media.Store
	YoutubeClient media.YoutubeClient
	FileStore     media.FileStore
	WorkerPool    *media.WorkerPool
	Logger        *zap.Logger
}

// mediaSetServiceController implements gRPC controller for MediaSetService
type mediaSetServiceController struct {
	pbmediaset.UnimplementedMediaSetServiceServer

	mediaSetService *media.MediaSetService
	logger          *zap.SugaredLogger
}

// Get returns a pbMediaSet.MediaSet
func (c *mediaSetServiceController) Get(ctx context.Context, request *pbmediaset.GetRequest) (*pbmediaset.MediaSet, error) {
	mediaSet, err := c.mediaSetService.Get(ctx, request.GetYoutubeId())
	if err != nil {
		return nil, newResponseError(err)
	}

	result := pbmediaset.MediaSet{
		Id:                mediaSet.ID.String(),
		YoutubeId:         mediaSet.YoutubeID,
		AudioChannels:     int32(mediaSet.Audio.Channels),
		AudioFrames:       mediaSet.Audio.Frames,
		AudioApproxFrames: mediaSet.Audio.ApproxFrames,
		AudioSampleRate:   int32(mediaSet.Audio.SampleRate),
		AudioYoutubeItag:  int32(mediaSet.Audio.YoutubeItag),
		AudioMimeType:     mediaSet.Audio.MimeType,
		VideoDuration:     durationpb.New(mediaSet.Video.Duration),
		VideoYoutubeItag:  int32(mediaSet.Video.YoutubeItag),
		VideoMimeType:     mediaSet.Video.MimeType,
	}

	return &result, nil
}

// GetPeaks returns a stream of GetPeaksProgress relating to the entire audio
// part of the MediaSet.
func (c *mediaSetServiceController) GetPeaks(request *pbmediaset.GetPeaksRequest, stream pbmediaset.MediaSetService_GetPeaksServer) error {
	// TODO: reduce timeout when fetching from S3
	ctx, cancel := context.WithTimeout(context.Background(), getPeaksTimeout)
	defer cancel()

	id, err := uuid.Parse(request.GetId())
	if err != nil {
		return newResponseError(err)
	}

	reader, err := c.mediaSetService.GetPeaks(ctx, id, int(request.GetNumBins()))
	if err != nil {
		return newResponseError(err)
	}

	for {
		progress, err := reader.Next()
		if err != nil && err != io.EOF {
			return newResponseError(err)
		}

		peaks := make([]int32, len(progress.Peaks))
		for i, p := range progress.Peaks {
			peaks[i] = int32(p)
		}

		progressPb := pbmediaset.GetPeaksProgress{
			PercentComplete: progress.PercentComplete,
			Url:             progress.URL,
			Peaks:           peaks,
		}
		stream.Send(&progressPb)

		if err == io.EOF {
			break
		}
	}

	return nil
}

// GetPeaksForSegment returns a set of peaks for a segment of an audio part of
// a MediaSet.
func (c *mediaSetServiceController) GetPeaksForSegment(ctx context.Context, request *pbmediaset.GetPeaksForSegmentRequest) (*pbmediaset.GetPeaksForSegmentResponse, error) {
	ctx, cancel := context.WithTimeout(ctx, getPeaksForSegmentTimeout)
	defer cancel()

	id, err := uuid.Parse(request.GetId())
	if err != nil {
		return nil, newResponseError(err)
	}

	peaks, err := c.mediaSetService.GetPeaksForSegment(ctx, id, request.StartFrame, request.EndFrame, int(request.GetNumBins()))
	if err != nil {
		return nil, newResponseError(err)
	}

	peaks32 := make([]int32, len(peaks))
	for i, p := range peaks {
		peaks32[i] = int32(p)
	}

	return &pbmediaset.GetPeaksForSegmentResponse{Peaks: peaks32}, nil
}

func (c *mediaSetServiceController) GetAudioSegment(request *pbmediaset.GetAudioSegmentRequest, outStream pbmediaset.MediaSetService_GetAudioSegmentServer) error {
	ctx, cancel := context.WithTimeout(context.Background(), getPeaksForSegmentTimeout)
	defer cancel()

	id, err := uuid.Parse(request.GetId())
	if err != nil {
		return newResponseError(err)
	}

	var format media.AudioFormat
	switch request.Format {
	case pbmediaset.AudioFormat_MP3:
		format = media.AudioFormatMP3
	case pbmediaset.AudioFormat_WAV:
		format = media.AudioFormatWAV
	default:
		return newResponseError(errors.New("unknown format"))
	}

	stream, err := c.mediaSetService.GetAudioSegment(ctx, id, request.StartFrame, request.EndFrame, format)
	if err != nil {
		return newResponseError(err)
	}

	for {
		progress, err := stream.Next(ctx)
		if err != nil && err != io.EOF {
			return newResponseError(err)
		}

		progressPb := pbmediaset.GetAudioSegmentProgress{
			PercentComplete: progress.PercentComplete,
			AudioData:       progress.Data,
		}

		outStream.Send(&progressPb)

		if err == io.EOF {
			break
		}
	}

	return nil
}

func (c *mediaSetServiceController) GetVideo(request *pbmediaset.GetVideoRequest, stream pbmediaset.MediaSetService_GetVideoServer) error {
	// TODO: reduce timeout when already fetched from Youtube
	ctx, cancel := context.WithTimeout(context.Background(), getVideoTimeout)
	defer cancel()

	id, err := uuid.Parse(request.GetId())
	if err != nil {
		return newResponseError(err)
	}

	reader, err := c.mediaSetService.GetVideo(ctx, id)
	if err != nil {
		return newResponseError(err)
	}

	for {
		progress, err := reader.Next()
		if err != nil && err != io.EOF {
			return newResponseError(err)
		}

		progressPb := pbmediaset.GetVideoProgress{
			PercentComplete: progress.PercentComplete,
			Url:             progress.URL,
		}
		stream.Send(&progressPb)

		if err == io.EOF {
			break
		}
	}

	return nil
}

func (c *mediaSetServiceController) GetVideoThumbnail(ctx context.Context, request *pbmediaset.GetVideoThumbnailRequest) (*pbmediaset.GetVideoThumbnailResponse, error) {
	id, err := uuid.Parse(request.GetId())
	if err != nil {
		return nil, newResponseError(err)
	}

	thumbnail, err := c.mediaSetService.GetVideoThumbnail(ctx, id)
	if err != nil {
		return nil, newResponseError(err)
	}

	response := pbmediaset.GetVideoThumbnailResponse{
		Image:  thumbnail.Data,
		Width:  int32(thumbnail.Width),
		Height: int32(thumbnail.Height),
	}

	return &response, nil
}

func Start(options Options) error {
	fetchMediaSetService := media.NewMediaSetService(
		options.Store,
		options.YoutubeClient,
		options.FileStore,
		exec.CommandContext,
		options.WorkerPool,
		options.Config,
		options.Logger.Sugar().Named("mediaSetService"),
	)

	grpcServer, err := buildGRPCServer(options.Config, options.Logger)
	if err != nil {
		return fmt.Errorf("error building server: %v", err)
	}

	mediaSetController := &mediaSetServiceController{mediaSetService: fetchMediaSetService, logger: options.Logger.Sugar().Named("controller")}
	pbmediaset.RegisterMediaSetServiceServer(grpcServer, mediaSetController)

	// TODO: configure CORS
	grpcWebServer := grpcweb.WrapServer(grpcServer, grpcweb.WithOriginFunc(func(string) bool { return true }))

	log := options.Logger.Sugar()
	fileHandler := http.NotFoundHandler()

	// Enabling the file system store disables serving assets over HTTP.
	// TODO: fix this.
	if options.Config.AssetsHTTPRoot != "" {
		log.With("root", options.Config.AssetsHTTPRoot).Info("Configured to serve assets over HTTP")
		fileHandler = http.FileServer(http.Dir(options.Config.AssetsHTTPRoot))
	}
	if options.Config.FileStoreHTTPRoot != "" {
		log.With("root", options.Config.FileStoreHTTPRoot).Info("Configured to serve file store over HTTP")
		fileHandler = http.FileServer(http.Dir(options.Config.FileStoreHTTPRoot))
	}

	httpServer := http.Server{
		Addr:         options.Config.BindAddr,
		ReadTimeout:  options.Timeout,
		WriteTimeout: options.Timeout,
		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if !grpcWebServer.IsGrpcWebRequest(r) && !grpcWebServer.IsAcceptableGrpcCorsRequest(r) {
				fileHandler.ServeHTTP(w, r)
				return
			}
			grpcWebServer.ServeHTTP(w, r)
		}),
	}

	log.Infof("Listening at %s", options.Config.BindAddr)

	if options.Config.TLSCertFile != "" && options.Config.TLSKeyFile != "" {
		return httpServer.ListenAndServeTLS(options.Config.TLSCertFile, options.Config.TLSKeyFile)
	}

	return httpServer.ListenAndServe()
}

func buildGRPCServer(c config.Config, logger *zap.Logger) (*grpc.Server, error) {
	unaryInterceptors := []grpc.UnaryServerInterceptor{
		grpczap.UnaryServerInterceptor(logger),
	}
	streamInterceptors := []grpc.StreamServerInterceptor{
		grpczap.StreamServerInterceptor(logger),
	}
	if c.Environment == config.EnvProduction {
		panicOpts := []grpcrecovery.Option{
			grpcrecovery.WithRecoveryHandler(func(p interface{}) error {
				return newResponseError(fmt.Errorf("%v", p))
			}),
		}
		unaryInterceptors = append(unaryInterceptors, grpcrecovery.UnaryServerInterceptor(panicOpts...))
		streamInterceptors = append(streamInterceptors, grpcrecovery.StreamServerInterceptor(panicOpts...))
	}

	return grpc.NewServer(
		grpc.StreamInterceptor(grpcmiddleware.ChainStreamServer(streamInterceptors...)),
		grpc.UnaryInterceptor(grpcmiddleware.ChainUnaryServer(unaryInterceptors...)),
	), nil
}