package core

import (
	"context"
	"encoding/json"
	"net"
	"net/http"
	"net/http/httputil"
	"reflect"
	"sync"

	"github.com/gin-gonic/gin"

	"github.com/aler9/rtsp-simple-server/internal/conf"
	"github.com/aler9/rtsp-simple-server/internal/logger"
)

func interfaceIsEmpty(i interface{}) bool {
	return reflect.ValueOf(i).Kind() != reflect.Ptr || reflect.ValueOf(i).IsNil()
}

func fillStruct(dest interface{}, source interface{}) {
	rvsource := reflect.ValueOf(source).Elem()
	rvdest := reflect.ValueOf(dest)
	nf := rvsource.NumField()
	for i := 0; i < nf; i++ {
		fnew := rvsource.Field(i)
		if !fnew.IsNil() {
			f := rvdest.Elem().FieldByName(rvsource.Type().Field(i).Name)
			if f.Kind() == reflect.Ptr {
				f.Set(fnew)
			} else {
				f.Set(fnew.Elem())
			}
		}
	}
}

func cloneStruct(dest interface{}, source interface{}) {
	enc, _ := json.Marshal(source)
	_ = json.Unmarshal(enc, dest)
}

func generateStructWithOptionalFields(model interface{}) interface{} {
	var fields []reflect.StructField

	rt := reflect.TypeOf(model)
	nf := rt.NumField()
	for i := 0; i < nf; i++ {
		f := rt.Field(i)
		j := f.Tag.Get("json")

		if j != "-" && j != "paths" {
			fields = append(fields, reflect.StructField{
				Name: f.Name,
				Type: reflect.PtrTo(f.Type),
				Tag:  f.Tag,
			})
		}
	}

	return reflect.New(reflect.StructOf(fields)).Interface()
}

func loadConfData(ctx *gin.Context) (interface{}, error) {
	in := generateStructWithOptionalFields(conf.Conf{})
	err := json.NewDecoder(ctx.Request.Body).Decode(in)
	if err != nil {
		return nil, err
	}

	return in, err
}

func loadConfPathData(ctx *gin.Context) (interface{}, error) {
	in := generateStructWithOptionalFields(conf.PathConf{})
	err := json.NewDecoder(ctx.Request.Body).Decode(in)
	if err != nil {
		return nil, err
	}

	return in, err
}

type apiPathManager interface {
	apiPathsList(req pathAPIPathsListReq) pathAPIPathsListRes
}

type apiRTSPServer interface {
	apiSessionsList(req rtspServerAPISessionsListReq) rtspServerAPISessionsListRes
	apiSessionsKick(req rtspServerAPISessionsKickReq) rtspServerAPISessionsKickRes
}

type apiRTMPServer interface {
	apiConnsList(req rtmpServerAPIConnsListReq) rtmpServerAPIConnsListRes
	apiConnsKick(req rtmpServerAPIConnsKickReq) rtmpServerAPIConnsKickRes
}

type apiHLSServer interface {
	apiHLSMuxersList(req hlsServerAPIMuxersListReq) hlsServerAPIMuxersListRes
}

type apiParent interface {
	Log(logger.Level, string, ...interface{})
	apiConfigSet(conf *conf.Conf)
}

type api struct {
	conf        *conf.Conf
	pathManager apiPathManager
	rtspServer  apiRTSPServer
	rtspsServer apiRTSPServer
	rtmpServer  apiRTMPServer
	rtmpsServer apiRTMPServer
	hlsServer   apiHLSServer
	parent      apiParent

	ln    net.Listener
	mutex sync.Mutex
	s     *http.Server
}

func newAPI(
	address string,
	conf *conf.Conf,
	pathManager apiPathManager,
	rtspServer apiRTSPServer,
	rtspsServer apiRTSPServer,
	rtmpServer apiRTMPServer,
	rtmpsServer apiRTMPServer,
	hlsServer apiHLSServer,
	parent apiParent,
) (*api, error) {
	ln, err := net.Listen("tcp", address)
	if err != nil {
		return nil, err
	}

	a := &api{
		conf:        conf,
		pathManager: pathManager,
		rtspServer:  rtspServer,
		rtspsServer: rtspsServer,
		rtmpServer:  rtmpServer,
		rtmpsServer: rtmpsServer,
		hlsServer:   hlsServer,
		parent:      parent,
		ln:          ln,
	}

	router := gin.New()
	router.SetTrustedProxies(nil)
	router.NoRoute(a.mwLog)
	group := router.Group("/", a.mwLog)

	group.GET("/v1/config/get", a.onConfigGet)
	group.POST("/v1/config/set", a.onConfigSet)
	group.POST("/v1/config/paths/add/*name", a.onConfigPathsAdd)
	group.POST("/v1/config/paths/edit/*name", a.onConfigPathsEdit)
	group.POST("/v1/config/paths/remove/*name", a.onConfigPathsDelete)

	group.GET("/v1/paths/list", a.onPathsList)

	if !interfaceIsEmpty(a.rtspServer) {
		group.GET("/v1/rtspsessions/list", a.onRTSPSessionsList)
		group.POST("/v1/rtspsessions/kick/:id", a.onRTSPSessionsKick)
	}

	if !interfaceIsEmpty(a.rtspsServer) {
		group.GET("/v1/rtspssessions/list", a.onRTSPSSessionsList)
		group.POST("/v1/rtspssessions/kick/:id", a.onRTSPSSessionsKick)
	}

	if !interfaceIsEmpty(a.rtmpServer) {
		group.GET("/v1/rtmpconns/list", a.onRTMPConnsList)
		group.POST("/v1/rtmpconns/kick/:id", a.onRTMPConnsKick)
	}

	if !interfaceIsEmpty(a.rtmpsServer) {
		group.GET("/v1/rtmpsconns/list", a.onRTMPSConnsList)
		group.POST("/v1/rtmpsconns/kick/:id", a.onRTMPSConnsKick)
	}

	if !interfaceIsEmpty(a.hlsServer) {
		group.GET("/v1/hlsmuxers/list", a.onHLSMuxersList)
	}

	a.s = &http.Server{Handler: router}

	go a.s.Serve(ln)

	a.log(logger.Info, "listener opened on "+address)

	return a, nil
}

func (a *api) close() {
	a.log(logger.Info, "listener is closing")
	a.s.Shutdown(context.Background())
	a.ln.Close() // in case Shutdown() is called before Serve()
}

func (a *api) log(level logger.Level, format string, args ...interface{}) {
	a.parent.Log(level, "[API] "+format, args...)
}

func (a *api) mwLog(ctx *gin.Context) {
	a.log(logger.Info, "[conn %v] %s %s", ctx.Request.RemoteAddr, ctx.Request.Method, ctx.Request.URL.Path)

	byts, _ := httputil.DumpRequest(ctx.Request, true)
	a.log(logger.Debug, "[conn %v] [c->s] %s", ctx.Request.RemoteAddr, string(byts))

	logw := &httpLogWriter{ResponseWriter: ctx.Writer}
	ctx.Writer = logw

	ctx.Writer.Header().Set("Server", "rtsp-simple-server")

	ctx.Next()

	a.log(logger.Debug, "[conn %v] [s->c] %s", ctx.Request.RemoteAddr, logw.dump())
}

func (a *api) onConfigGet(ctx *gin.Context) {
	a.mutex.Lock()
	c := a.conf
	a.mutex.Unlock()

	ctx.JSON(http.StatusOK, c)
}

func (a *api) onConfigSet(ctx *gin.Context) {
	in, err := loadConfData(ctx)
	if err != nil {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	a.mutex.Lock()
	defer a.mutex.Unlock()

	var newConf conf.Conf
	cloneStruct(&newConf, a.conf)
	fillStruct(&newConf, in)

	err = newConf.CheckAndFillMissing()
	if err != nil {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	a.conf = &newConf

	// since reloading the configuration can cause the shutdown of the API,
	// call it in a goroutine
	go a.parent.apiConfigSet(&newConf)

	ctx.Status(http.StatusOK)
}

func (a *api) onConfigPathsAdd(ctx *gin.Context) {
	name := ctx.Param("name")
	if len(name) < 2 || name[0] != '/' {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}
	name = name[1:]

	in, err := loadConfPathData(ctx)
	if err != nil {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	a.mutex.Lock()
	defer a.mutex.Unlock()

	var newConf conf.Conf
	cloneStruct(&newConf, a.conf)

	if _, ok := newConf.Paths[name]; ok {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	newConfPath := &conf.PathConf{}
	fillStruct(newConfPath, in)

	newConf.Paths[name] = newConfPath

	err = newConf.CheckAndFillMissing()
	if err != nil {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	a.conf = &newConf

	// since reloading the configuration can cause the shutdown of the API,
	// call it in a goroutine
	go a.parent.apiConfigSet(&newConf)

	ctx.Status(http.StatusOK)
}

func (a *api) onConfigPathsEdit(ctx *gin.Context) {
	name := ctx.Param("name")
	if len(name) < 2 || name[0] != '/' {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}
	name = name[1:]

	in, err := loadConfPathData(ctx)
	if err != nil {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	a.mutex.Lock()
	defer a.mutex.Unlock()

	var newConf conf.Conf
	cloneStruct(&newConf, a.conf)

	newConfPath, ok := newConf.Paths[name]
	if !ok {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	fillStruct(newConfPath, in)

	err = newConf.CheckAndFillMissing()
	if err != nil {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	a.conf = &newConf

	// since reloading the configuration can cause the shutdown of the API,
	// call it in a goroutine
	go a.parent.apiConfigSet(&newConf)

	ctx.Status(http.StatusOK)
}

func (a *api) onConfigPathsDelete(ctx *gin.Context) {
	name := ctx.Param("name")
	if len(name) < 2 || name[0] != '/' {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}
	name = name[1:]

	a.mutex.Lock()
	defer a.mutex.Unlock()

	var newConf conf.Conf
	cloneStruct(&newConf, a.conf)

	if _, ok := newConf.Paths[name]; !ok {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	delete(newConf.Paths, name)

	err := newConf.CheckAndFillMissing()
	if err != nil {
		ctx.AbortWithStatus(http.StatusBadRequest)
		return
	}

	a.conf = &newConf

	// since reloading the configuration can cause the shutdown of the API,
	// call it in a goroutine
	go a.parent.apiConfigSet(&newConf)

	ctx.Status(http.StatusOK)
}

func (a *api) onPathsList(ctx *gin.Context) {
	res := a.pathManager.apiPathsList(pathAPIPathsListReq{})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusInternalServerError)
		return
	}

	ctx.JSON(http.StatusOK, res.data)
}

func (a *api) onRTSPSessionsList(ctx *gin.Context) {
	res := a.rtspServer.apiSessionsList(rtspServerAPISessionsListReq{})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusInternalServerError)
		return
	}

	ctx.JSON(http.StatusOK, res.data)
}

func (a *api) onRTSPSessionsKick(ctx *gin.Context) {
	id := ctx.Param("id")

	res := a.rtspServer.apiSessionsKick(rtspServerAPISessionsKickReq{id: id})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusNotFound)
		return
	}

	ctx.Status(http.StatusOK)
}

func (a *api) onRTSPSSessionsList(ctx *gin.Context) {
	res := a.rtspsServer.apiSessionsList(rtspServerAPISessionsListReq{})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusInternalServerError)
		return
	}

	ctx.JSON(http.StatusOK, res.data)
}

func (a *api) onRTSPSSessionsKick(ctx *gin.Context) {
	id := ctx.Param("id")

	res := a.rtspsServer.apiSessionsKick(rtspServerAPISessionsKickReq{id: id})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusNotFound)
		return
	}

	ctx.Status(http.StatusOK)
}

func (a *api) onRTMPConnsList(ctx *gin.Context) {
	res := a.rtmpServer.apiConnsList(rtmpServerAPIConnsListReq{})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusInternalServerError)
		return
	}

	ctx.JSON(http.StatusOK, res.data)
}

func (a *api) onRTMPConnsKick(ctx *gin.Context) {
	id := ctx.Param("id")

	res := a.rtmpServer.apiConnsKick(rtmpServerAPIConnsKickReq{id: id})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusNotFound)
		return
	}

	ctx.Status(http.StatusOK)
}

func (a *api) onRTMPSConnsList(ctx *gin.Context) {
	res := a.rtmpsServer.apiConnsList(rtmpServerAPIConnsListReq{})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusInternalServerError)
		return
	}

	ctx.JSON(http.StatusOK, res.data)
}

func (a *api) onRTMPSConnsKick(ctx *gin.Context) {
	id := ctx.Param("id")

	res := a.rtmpsServer.apiConnsKick(rtmpServerAPIConnsKickReq{id: id})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusNotFound)
		return
	}

	ctx.Status(http.StatusOK)
}

func (a *api) onHLSMuxersList(ctx *gin.Context) {
	res := a.hlsServer.apiHLSMuxersList(hlsServerAPIMuxersListReq{})
	if res.err != nil {
		ctx.AbortWithStatus(http.StatusInternalServerError)
		return
	}

	ctx.JSON(http.StatusOK, res.data)
}

// confReload is called by core.
func (a *api) confReload(conf *conf.Conf) {
	a.mutex.Lock()
	defer a.mutex.Unlock()
	a.conf = conf
}