package server

import (
	"context"
	"fmt"
	"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"
)

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 MediaSetService interface {
	Get(context.Context, string) (*media.MediaSet, error)
	GetAudioSegment(context.Context, uuid.UUID, int64, int64, media.AudioFormat) (media.AudioSegmentStream, error)
	GetPeaks(context.Context, uuid.UUID, int) (media.GetPeaksProgressReader, error)
	GetPeaksForSegment(context.Context, uuid.UUID, int64, int64, int) ([]int16, error)
	GetVideo(context.Context, uuid.UUID) (media.GetVideoProgressReader, error)
	GetVideoThumbnail(context.Context, uuid.UUID) (media.VideoThumbnail, error)
}

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
}

func Start(options Options) error {
	conf := options.Config

	mediaSetService := media.NewMediaSetService(
		options.Store,
		options.YoutubeClient,
		options.FileStore,
		exec.CommandContext,
		options.WorkerPool,
		conf,
		options.Logger.Sugar().Named("mediaSetService"),
	)

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

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

	// TODO: convert CORSAllowedOrigins to a map[string]struct{}
	originChecker := func(origin string) bool {
		for _, s := range conf.CORSAllowedOrigins {
			if origin == s {
				return true
			}
		}
		return false
	}
	grpcHandler := grpcweb.WrapServer(grpcServer, grpcweb.WithOriginFunc(originChecker))
	httpHandler := newHTTPHandler(grpcHandler, mediaSetService, conf, options.Logger.Sugar().Named("httpHandler"))

	httpServer := http.Server{
		Addr:         conf.BindAddr,
		ReadTimeout:  options.Timeout,
		WriteTimeout: options.Timeout,
		Handler:      httpHandler,
	}

	log := options.Logger.Sugar()
	log.Infof("Listening at %s", options.Config.BindAddr)

	if conf.TLSCertFile != "" && conf.TLSKeyFile != "" {
		return httpServer.ListenAndServeTLS(conf.TLSCertFile, conf.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
}