package localserver

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strconv"
	sync "sync"
	"time"

	"github.com/pion/webrtc/v3"
)

const (
	ZONE_FS_WEBRTC_OFFER                 ReqType = "zone_fs_offer"
	ZONE_FS_WEBRTC_ANSWER                ReqType = "zone_fs_answer"
	ZONE_FS_WEBRTC_RENNEGOTIATION_OFFER  ReqType = "zone_fs_rennegotiation_offer"
	ZONE_FS_WEBRTC_RENNEGOTIATION_ANSWER ReqType = "zone_fs_rennegotiation_answer"
	ZONE_FS_WEBRTC_COUNTER_OFFER         ReqType = "zone_fs_webrtc_counter_offer"
	ZONE_FS_WEBRTC_CANDIDATE             ReqType = "zone_fs_webrtc_candidate"
)

type FSInstance struct {
	ZoneID                   string                                `json:"id"`
	Owner                    string                                `json:"owner"`
	Members                  []string                              `json:"members"`
	OpenFiles                map[string]*os.File                   `json:"-"`
	OpenFilesForUser         map[string][]string                   `json:"-"`
	localSD                  map[string]*webrtc.SessionDescription `json:"-"`
	rtcPeerConnections       map[string]*ZoneRTCPeerConnection     `json:"-"`
	zoneFSDataChannels       map[string]map[string]*DataChannel    `json:"-"`
	pendingCandidates        map[string][]*webrtc.ICECandidate     `json:"-"`
	middlewares              []interface{}                         `json:"-"`
	candidateFlag            *uint32                               `json:"-"`
	filesFlag                *uint32                               `json:"-"`
	rtcPeerConnectionMapFlag *uint32                               `json:"-"`
	dataChannelMapFlag       *uint32                               `json:"-"`
	localSDMapFlag           *uint32                               `json:"-"`
}

type FSInstanceOnICECandidateFunc = func(string, string, *webrtc.ICECandidate) error

func NewFSInstance(id, owner string, members []string) (audioChannel *FSInstance) {
	candidateFlag := uint32(0)
	rtcPeerConnectionMapFlag := uint32(0)
	dataChannelMapFlag := uint32(0)
	filesFlag := uint32(0)
	localSDMapFlag := uint32(0)
	audioChannel = &FSInstance{
		ZoneID:                   id,
		Owner:                    owner,
		Members:                  members,
		OpenFiles:                make(map[string]*os.File),
		OpenFilesForUser:         make(map[string][]string),
		localSD:                  make(map[string]*webrtc.SessionDescription),
		rtcPeerConnections:       make(map[string]*ZoneRTCPeerConnection),
		zoneFSDataChannels:       make(map[string]map[string]*DataChannel),
		pendingCandidates:        make(map[string][]*webrtc.ICECandidate),
		middlewares:              make([]interface{}, 0),
		candidateFlag:            &candidateFlag,
		filesFlag:                &filesFlag,
		rtcPeerConnectionMapFlag: &rtcPeerConnectionMapFlag,
		dataChannelMapFlag:       &dataChannelMapFlag,
		localSDMapFlag:           &localSDMapFlag,
	}
	return
}

func (fs *FSInstance) SetupFileUpload(path, filename, userId string) (err error) {
	concretePath := filepath.Join("data", "zones", fs.ZoneID, "fs", path, "__files__", filename)
	if _, rErr := os.ReadDir(filepath.Join("data", "zones", fs.ZoneID, "fs", path, "__files__")); os.IsNotExist(rErr) {
		if err = os.MkdirAll(filepath.Join("data", "zones", fs.ZoneID, "fs", path, "__files__"), 0700); err != nil {
			return
		}
	} else if rErr != nil {
		return rErr
	}
	if err = os.Remove(concretePath); err != nil {
		logger.Println(err)
	}
	file, err := os.OpenFile(concretePath, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0755)
	if err != nil {
		return
	}
	_ = atomicallyExecute(fs.filesFlag, func() (err error) {
		fs.OpenFiles[filename] = file
		return
	})
	setupDataChan := func(id, fileName string) (err error) {
		if pc, ok := fs.rtcPeerConnections[id]; ok {
			maxRetransmits := uint16(100)
			var dc *webrtc.DataChannel
			dc, err = pc.CreateDataChannel(fileName, &webrtc.DataChannelInit{
				MaxRetransmits: &maxRetransmits,
			})
			if err != nil {
				return
			}
			dc.OnOpen(func() {
				logger.Println("!-----------------------------!")
				logger.Printf("datachannel with id %s is now open\n", dc.Label())
				logger.Println("updated")
				logger.Println("!-----------------------------!")
			})
			dc.OnMessage(func(msg webrtc.DataChannelMessage) {
				logger.Println(msg)
				_, _ = file.Write(msg.Data)
			})
			dc.OnClose(func() {
				//fmt.Println("closing datachannel with id", dc.Label())
				_ = atomicallyExecute(fs.filesFlag, func() (err error) {
					if f, ok := fs.OpenFiles[fileName]; ok {
						err = f.Close()
					}
					delete(fs.OpenFiles, fileName)
					return
				})
				_ = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
					delete(fs.zoneFSDataChannels[userId], fileName)
					return
				})
				dc.Close()
			})
			err = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
				if _, ok := fs.zoneFSDataChannels[id]; !ok {
					fs.zoneFSDataChannels[id] = make(map[string]*DataChannel)
				}
				l := int32(0)
				fs.zoneFSDataChannels[id][dc.Label()] = &DataChannel{
					DataChannel: dc,
					l:           &l,
				}
				return
			})
		} else {
			err = fmt.Errorf("no peerconnection for id %s", id)
		}
		return
	}
	err = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
		err = setupDataChan(userId, filename)
		return
	})
	return
}

func (fs *FSInstance) FileUploadDone(path, filename, userId string) (err error) {
	err = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
		if _, ok := fs.zoneFSDataChannels[userId]; ok {
			if dc, ok := fs.zoneFSDataChannels[userId][filename]; ok {
				err = dc.DataChannel.Close()
				return
			}
		}
		return
	})
	return
}

func (fs *FSInstance) FileUploadFailed(path, filename, userId string) (err error) {
	concretePath := filepath.Join("data", "zones", fs.ZoneID, "fs", path, "__files__", filename)
	if err = os.Remove(concretePath); err != nil {
		return
	}
	err = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
		if _, ok := fs.zoneFSDataChannels[userId]; ok {
			if dc, ok := fs.zoneFSDataChannels[userId][filename]; ok {
				err = dc.DataChannel.Close()
				return
			}
		}
		return
	})
	return
}

func (fs *FSInstance) SetupFileDownload(path, filename, userId string) (err error) {
	concretePath := filepath.Join("data", "zones", fs.ZoneID, "fs", path, "__files__", filename)
	file, err := os.OpenFile(concretePath, os.O_RDONLY, 0755)
	if err != nil {
		return
	}
	_ = atomicallyExecute(fs.filesFlag, func() (err error) {
		fs.OpenFiles[filename] = file
		if _, ok := fs.OpenFilesForUser[userId]; !ok {
			fs.OpenFilesForUser[userId] = []string{}
		}
		fs.OpenFilesForUser[userId] = append(fs.OpenFilesForUser[userId], filename)
		return
	})
	var dc *webrtc.DataChannel
	err = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
		if pc, ok := fs.rtcPeerConnections[userId]; ok {
			maxRetransmits := uint16(100)
			dc, err = pc.CreateDataChannel(filename, &webrtc.DataChannelInit{
				MaxRetransmits: &maxRetransmits,
			})
			if err != nil {
				return
			}
		}
		return
	})
	if dc != nil {
		dc.SetBufferedAmountLowThreshold(15000000)
		bufferedAmountLock := make(chan struct{})
		done := make(chan struct{})
		dc.OnOpen(func() {
			go func() {
				defer func() {
					close(bufferedAmountLock)
					bufferedAmountLock = nil
					_ = atomicallyExecute(fs.filesFlag, func() (err error) {
						if f, ok := fs.OpenFiles[filename]; ok {
							err = f.Close()
						}
						delete(fs.OpenFiles, filename)
						if _, ok := fs.OpenFilesForUser[userId]; ok {
							var index int
							for i, v := range fs.OpenFilesForUser[userId] {
								if v == filename {
									index = i
									break
								}
							}
							if len(fs.OpenFilesForUser[userId]) > 1 {
								fs.OpenFilesForUser[userId] = append(fs.OpenFilesForUser[userId][:index], fs.OpenFilesForUser[userId][:index+1]...)
							} else {
								delete(fs.OpenFilesForUser, userId)
							}
						}
						return
					})
				}()
				r := bufio.NewReader(file)
				buf := make([]byte, 0, 15000)
			sendingLoop:
				for {
					n, readErr := r.Read(buf[:cap(buf)])
					buf = buf[:n]
					if n == 0 {
						if err == nil {
							logger.Println("n is 0 weird")
							break
						}
						if err == io.EOF {
							break
						}
						logger.Println(readErr)
						return
					}
					if err = dc.Send(buf); err != nil {
						dc.Close()
						logger.Println(err)
						break sendingLoop
					}
					if dc.BufferedAmount() > dc.
						BufferedAmountLowThreshold() {
						<-bufferedAmountLock
					}
				}
				logger.Println("done")
				<-time.After(4*time.Second)
				_ = dc.SendText("done")
				<-time.After(time.Second)
				_ = dc.Close()
				_ = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
					if _, ok := fs.zoneFSDataChannels[userId]; ok {
						delete(fs.zoneFSDataChannels[userId], dc.Label())
					}
					return
				})
			}()
		})
		dc.OnBufferedAmountLow(func() {
			if bufferedAmountLock != nil {
				bufferedAmountLock <- struct{}{}
			}
		})
		dc.OnClose(func() {
			done <- struct{}{}
			defer close(done)
			_ = atomicallyExecute(fs.filesFlag, func() (err error) {
				if f, ok := fs.OpenFiles[filename]; ok {
					err = f.Close()
				}
				delete(fs.OpenFiles, filename)
				return
			})
		})
		err = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
			if _, ok := fs.zoneFSDataChannels[userId]; !ok {
				fs.zoneFSDataChannels[userId] = make(map[string]*DataChannel)
			}
			l := int32(0)
			fs.zoneFSDataChannels[userId][dc.Label()] = &DataChannel{
				DataChannel: dc,
				l:           &l,
			}
			return
		})
	} else {
		err = fmt.Errorf("datachannel not created")
		_ = atomicallyExecute(fs.filesFlag, func() (err error) {
			if file, ok := fs.OpenFiles[filename]; ok {
				file.Close()
			}
			delete(fs.OpenFiles, filename)
			return
		})
	}
	return
}

func (fs *FSInstance) HandleOffer(ctx context.Context, channelId, userId, sdp, hostId string, sendDCMessage SendDCMessageFunc, cb FSInstanceOnICECandidateFunc) (done chan struct{}, errCh chan error) {
	done, errCh = make(chan struct{}), make(chan error)
	go func() {
		peerConnection, err := fs.createPeerConnection(userId, fs.ZoneID, webrtc.SDPTypeAnswer, cb, sendDCMessage)
		if err != nil {
			errCh <- err
			return
		}
		_ = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
			fs.rtcPeerConnections[userId] = &ZoneRTCPeerConnection{
				PeerConnection:  peerConnection,
				makingOffer:     false,
				makingOfferLock: &sync.Mutex{},
			}
			return
		})
		offer := webrtc.SessionDescription{
			Type: webrtc.SDPTypeOffer,
			SDP:  sdp,
		}
		if err = peerConnection.SetRemoteDescription(offer); err != nil {
			errCh <- err
			return
		}
		rawAnswer, err := peerConnection.CreateAnswer(nil)
		if err != nil {
			errCh <- err
			return
		}
		if err = peerConnection.SetLocalDescription(rawAnswer); err != nil {
			errCh <- err
			return
		}
		_, _ = sendDCMessage(string(ZONE_FS_WEBRTC_ANSWER), hostId, userId, map[string]interface{}{
			"to":        userId,
			"from":      fs.ZoneID,
			"channelId": channelId,
			"sdp":       rawAnswer.SDP,
		})
		done <- struct{}{}
		logger.Println("handle offer done")
	}()
	return
}

func (fs *FSInstance) HandleCounterOffer(ctx context.Context, userId string, sendDCMessage SendDCMessageFunc) (err error) {
	// if err = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
	// 	if _, ok := fs.rtcPeerConnections[userId]; !ok {
	// 		err = fmt.Errorf("no field corresponding peer connection for id %s", userId)
	// 		return
	// 	}
	// 	logger.Println("handling counter offer")
	// 	connection := fs.rtcPeerConnections[userId]
	// 	err = atomicallyExecute(fs.localSDMapFlag, func() (err error) {
	// 		err = connection.SetLocalDescription(*fs.localSD[userId])
	// 		return
	// 	})
	// 	return
	// }); err != nil {
	// 	return
	// }
	// _ = atomicallyExecute(fs.localSDMapFlag, func() (err error) {
	// 	delete(fs.localSD, userId)
	// 	return
	// })
	if err = atomicallyExecute(fs.candidateFlag, func() (err error) {
		for _, candidate := range fs.pendingCandidates[userId] {
			logger.Println("sending candidate to", userId, candidate)
			d, e := sendDCMessage(string(ZONE_FS_WEBRTC_CANDIDATE), "", userId, map[string]interface{}{
				"from":          fs.ZoneID,
				"to":            userId,
				"candidate":     candidate.ToJSON().Candidate,
				"sdpMid":        *candidate.ToJSON().SDPMid,
				"sdpMLineIndex": strconv.Itoa(int(*candidate.ToJSON().SDPMLineIndex)),
			})
			select {
			case <-d:
			case err = <-e:
				return
			}
		}
		delete(fs.pendingCandidates, userId)
		return
	}); err != nil {
		return
	}
	return
}

func (fs *FSInstance) HandleRennegotiationOffer(from, sdp string, sendDCMessage SendDCMessageFunc) (err error) {
	err = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
		if _, ok := fs.rtcPeerConnections[from]; !ok {
			err = fmt.Errorf("no corresponding peer connection for id %s", from)
			return
		}
		// fs.rtcPeerConnections[from].makingOfferLock.Lock()
		// if fs.rtcPeerConnections[from].makingOffer {
		// 	fs.rtcPeerConnections[from].makingOfferLock.Unlock()
		// 	return fmt.Errorf("already making an offer or state is stable")
		// }
		// fs.rtcPeerConnections[from].makingOfferLock.Unlock()
		if err = fs.rtcPeerConnections[from].SetRemoteDescription(webrtc.SessionDescription{SDP: sdp, Type: webrtc.SDPTypeOffer}); err != nil {
			return
		}
		localSd, err := fs.rtcPeerConnections[from].CreateAnswer(nil)
		if err != nil {
			return
		}
		if err = fs.rtcPeerConnections[from].SetLocalDescription(localSd); err != nil {
			return
		}
		d, e := sendDCMessage(string(ZONE_FS_WEBRTC_RENNEGOTIATION_ANSWER), fs.ZoneID, from, map[string]interface{}{
			"from": fs.ZoneID,
			"to":   from,
			"sdp":  localSd.SDP,
		})
		select {
		case <-d:
		case err = <-e:
		}
		return
	})
	return
}

func (fs *FSInstance) HandleRennegotiationAnswer(from, sdp string) (err error) {
	logger.Println("---------------------handling rennego answer")
	err = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
		err = fs.rtcPeerConnections[from].SetRemoteDescription(webrtc.SessionDescription{SDP: sdp, Type: webrtc.SDPTypeAnswer})
		return
	})
	return
}

func (fs *FSInstance) AddCandidate(candidate *webrtc.ICECandidateInit, from string) (err error) {
	logger.Println("adding ice candidate", candidate)
	err = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
		if _, ok := fs.rtcPeerConnections[from]; ok && candidate != nil {
			err = fs.rtcPeerConnections[from].AddICECandidate(*candidate)
		}
		return
	})
	return
}

func (fs *FSInstance) createPeerConnection(target, from string, peerType webrtc.SDPType, cb FSInstanceOnICECandidateFunc, sendDCMessage SendDCMessageFunc) (peerConnection *webrtc.PeerConnection, err error) {
	defer func() {
		if r := recover(); err != nil {
			logger.Printf("recover from panic : %v\n", r)
		}
	}()
	config := webrtc.Configuration{
		ICEServers: []webrtc.ICEServer{
			{
				URLs: []string{"stun:stun.l.google.com:19302", "stun:stunserver.org:3478"},
			},
		},
		SDPSemantics: webrtc.SDPSemanticsUnifiedPlanWithFallback,
	}

	peerConnection, err = webrtc.NewPeerConnection(config)
	if err != nil {
		return
	}
	logger.Println("---------------------------------------------------")
	if peerType == webrtc.SDPTypeAnswer {
		maxRetransmits := uint16(100)
		channel, err := peerConnection.CreateDataChannel("data", &webrtc.DataChannelInit{
			MaxRetransmits: &maxRetransmits,
		})
		if err != nil {
			return nil, err
		}
		channel.OnOpen(func() {
			logger.Println("channel opened")
			if chanErr := channel.SendText("yooo man this is open"); chanErr != nil {
				logger.Println(chanErr)
			}
		})
		channel.OnMessage(func(msg webrtc.DataChannelMessage) {
			var event CallEvent
			if err := json.Unmarshal(msg.Data, &event); err != nil {
				logger.Println(err)
				return
			}
			if e := fs.HandleDataChannelEvents(event.From, event.EventId, event.Payload); e != nil {
				logger.Println("*-------------- datachannel error: ", e)
			}
		})
		logger.Println("new channel for target : ", target)
		channel.SetBufferedAmountLowThreshold(bufferedAmountLowThreshold)
		channel.OnBufferedAmountLow(func() {

		})
		_ = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
			logger.Println(target)
			l := int32(0)
			if _, ok := fs.zoneFSDataChannels[target]; !ok {
				fs.zoneFSDataChannels[target] = make(map[string]*DataChannel)
			}
			fs.zoneFSDataChannels[target][channel.Label()] = &DataChannel{
				DataChannel: channel,
				l:           &l,
			}
			return
		})
	} else {
		peerConnection.OnDataChannel(func(dc *webrtc.DataChannel) {
			_ = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
				l := int32(0)
				if _, ok := fs.zoneFSDataChannels[target]; !ok {
					fs.zoneFSDataChannels[target] = make(map[string]*DataChannel)
				}
				fs.zoneFSDataChannels[target][dc.Label()] = &DataChannel{
					DataChannel: dc,
					l:           &l,
				}
				return
			})
			dc.OnOpen(func() {
				logger.Printf("got a new open datachannel %s\n", dc.Label())
			})
			dc.OnMessage(func(msg webrtc.DataChannelMessage) {
				var event CallEvent
				if err := json.Unmarshal(msg.Data, &event); err != nil {
					logger.Println(err)
					return
				}
				if e := fs.HandleDataChannelEvents(event.From, event.EventId, event.Payload); e != nil {
					logger.Println("*-------------- datachannel error: ", e)
				}
			})
		})
	}
	peerConnection.OnConnectionStateChange(func(pcs webrtc.PeerConnectionState) {
		if pcs == webrtc.PeerConnectionStateClosed || pcs == webrtc.PeerConnectionStateDisconnected || pcs == webrtc.PeerConnectionStateFailed {
			logger.Println(pcs)
			//fs.HandleLeavingMember(target)
		}
	})
	peerConnection.OnICEConnectionStateChange(func(is webrtc.ICEConnectionState) {
		logger.Printf("ICE connection state has changed %s\n", is.String())
		if is == webrtc.ICEConnectionStateDisconnected || is == webrtc.ICEConnectionStateFailed {
			logger.Println(is)
		}
	})
	peerConnection.OnICECandidate(func(i *webrtc.ICECandidate) {
		if i == nil {
			return
		}
		_ = atomicallyExecute(fs.candidateFlag, func() (err error) {
			desc := peerConnection.RemoteDescription()
			if desc == nil {
				logger.Println("generated candidate appended to list : ", i)
				fs.pendingCandidates[target] = append(fs.pendingCandidates[target], i)
			} else {
				logger.Println("generated candidate : ", i)
				if iceCandidateErr := cb(from, target, i); iceCandidateErr != nil {
					logger.Println(iceCandidateErr)
				}
			}
			return
		})
	})
	// peerConnection.OnNegotiationNeeded(func() {
	// 	logger.Println("---------------- rennego is needed -----------")
	// 	_ = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
	// 		logger.Println("----------------- sending renego to peer with id", target)
	// 		if peerConnection.SignalingState() == webrtc.SignalingStateStable {
	// 			localSd, localSdErr := peerConnection.CreateOffer(nil)
	// 			if localSdErr != nil {
	// 				logger.Println(localSdErr)
	// 				return localSdErr
	// 			}
	// 			if err = peerConnection.SetLocalDescription(localSd); err != nil {
	// 				logger.Println(err)
	// 				return
	// 			}
	// 			d, e := sendDCMessage(string(ZONE_FS_WEBRTC_RENNEGOTIATION_OFFER), fs.ZoneID, target, map[string]interface{}{
	// 				"from": fs.ZoneID,
	// 				"to":   target,
	// 				"sdp":  localSd.SDP,
	// 			})
	// 			select {
	// 			case <-d:
	// 			case err = <-e:
	// 				logger.Println(err)
	// 			}
	// 		}
	// 		return
	// 	})
	// })
	return
}

func (fs *FSInstance) HandleLeavingMember(id string) {
	_ = atomicallyExecute(fs.dataChannelMapFlag, func() (err error) {
		if _, ok := fs.zoneFSDataChannels[id]; ok {
			for _, dc := range fs.zoneFSDataChannels[id] {
				dc.DataChannel.Close()
			}
		}
		delete(fs.zoneFSDataChannels, id)
		return
	})
	logger.Println("chatfs datachannels cleaned")
	_ = atomicallyExecute(fs.rtcPeerConnectionMapFlag, func() (err error) {
		if pc, ok := fs.rtcPeerConnections[id]; ok {
			if closeErr := pc.Close(); closeErr != nil {
				err = closeErr
				logger.Println("peer connection close error", closeErr)
			}
		}
		delete(fs.rtcPeerConnections, id)
		return
	})
	logger.Println("chats perrconnections cleaned")
	_ = atomicallyExecute(fs.candidateFlag, func() (err error) {
		delete(fs.pendingCandidates, id)
		return
	})
	_ = atomicallyExecute(fs.filesFlag, func() (err error) {
		for _, openFile := range fs.OpenFilesForUser[id] {
			if f, ok := fs.OpenFiles[openFile]; ok {
				_ = f.Close()
			}
			delete(fs.OpenFiles, openFile)
		}
		delete(fs.OpenFilesForUser, id)
		return
	})
}

func (fs *FSInstance) HandleDataChannelEvents(from, eventId string, payload map[string]interface{}) (err error) {
	switch eventId {
	}
	return
}