package main

import (
	"encoding/binary"
	"gopkg.in/mgo.v2"
	"net"
	"os"
	"os/signal"
	"syscall"

	"fmt"
	"gen/ledd"
	"github.com/golang/protobuf/proto"
	"github.com/lucasb-eyer/go-colorful"
	"github.com/op/go-logging"
	"gopkg.in/yaml.v2"
	"io/ioutil"
)

// CONSTANTS

const VERSION = "0.1"
const LOG_BACKEND = "BH"
const LOG_CLIENTS = "CH"

// STRUCTS

type Config struct {
	Name string
	Daemon struct {
		Frontend struct {
			Host string
			Port int
		}
		Backend struct {
			Host string
			Port int
		}
	}
	Mongodb struct {
		Host     string
		Port     int
		Database string
	}
}

type BackendManager struct {
	backends   map[string]*Backend
	broadcast  chan []byte
	register   chan *Backend
	unregister chan *Backend
}

type Backend struct {
	name         string
	platformType string
	version      string
	channel      int32
	resolution   int32
	socket       net.Conn
	data         chan []byte
}

type ClientManager struct {
	clients    map[*Client]bool
	broadcast  chan []byte
	register   chan *Client
	unregister chan *Client
}

type Client struct {
	platform string
	socket   net.Conn
	data     chan []byte
}

type LED struct {
	name    string
	channel []int32
	backend string
	color   chan colorful.Color
}

type LEDManager struct {
	leds      map[string]*LED
	broadcast chan colorful.Color
	add       chan *LED
	remove    chan *LED
}

// GLOBAL VARS

var log = logging.MustGetLogger("LedD")
var backManager = BackendManager{}
var clientManager = ClientManager{}
var ledManager = LEDManager{}
var LEDCollection = &mgo.Collection{}
var config = Config{}

// SOCKET SETUP

func setupSocket(host string, port int, logTag string, backend bool) (func(), error) {
	ln, err := net.Listen("tcp4", fmt.Sprintf("%s:%d", host, port))
	if err != nil {
		return nil, err
	}
	log.Infof("[%s] Ready to handle connections.", logTag)

	return func() {
		for {
			conn, err := ln.Accept()
			if err != nil {
				log.Warningf("%s", err)
			}
			log.Infof("[%s] New connection from %s", logTag, conn.RemoteAddr())
			if backend {
				backend := &Backend{socket: conn, data: make(chan []byte)}
				go backManager.receive(backend)
				go backManager.send(backend)
			} else {
				client := &Client{socket: conn, data: make(chan []byte)}
				go clientManager.receive(client)
				go clientManager.send(client)
			}
		}
	}, nil
}

// LED MANAGER

func (manager *LEDManager) start() {
	for {
		select {
		case led := <-manager.add:
			log.Debugf("[%s] Request to add led: %s", led.backend, led.name)
			manager.leds[led.name] = led
			go manager.color(led)
			err := LEDCollection.Insert(led)
			if err != nil {
				log.Warning("[%s] Error while adding LED to database: %s", LOG_BACKEND, err)
			}
		case led := <-manager.remove:
			if _, ok := manager.leds[led.name]; ok {
				log.Debugf("[%s] Request to remove led %s", led.backend, led.name)
				delete(manager.leds, led.name)
			}
		case color := <-manager.broadcast:
			for _, led := range manager.leds {
				select {
				case led.color <- color:
				}
			}
		}
	}
}

func (manager *LEDManager) color(led *LED) {
	for {
		select {
		case color := <-led.color:
			led.setColor(color)
		}
	}
}

// BACKEND HANDLER

func (manager *BackendManager) start() {
	for {
		select {
		case backend := <-manager.register:
			manager.backends[backend.name] = backend
			log.Debugf("[%s] New backend: %s", LOG_BACKEND, backend.niceName())
			wrapperMsg := &ledd.BackendWrapperMessage{
				Msg: &ledd.BackendWrapperMessage_MLedd{
					MLedd: &ledd.LedD{
						Name: config.Name,
					},
				},
			}

			data, err := proto.Marshal(wrapperMsg)
			if err != nil {
				log.Warningf("[%s] Failed to encode protobuf: %s", backend.niceName(), err)
			}

			backend.data <- data
		case backend := <-manager.unregister:
			if _, ok := manager.backends[backend.name]; ok {
				log.Debugf("[%s] Backend %s removed: connection terminated", LOG_BACKEND, backend.socket.RemoteAddr())
				close(backend.data)
				delete(manager.backends, backend.name)
			}
		case message := <-manager.broadcast:
			for _, backend := range manager.backends {
				select {
				case backend.data <- message:
				default:
					close(backend.data)
					delete(manager.backends, backend.name)
				}
			}
		}
	}
}

func (manager *BackendManager) stop() {
	for _, backend := range manager.backends {
		close(backend.data)
	}
}

func (manager *BackendManager) send(backend *Backend) {
	defer backend.socket.Close()
	for {
		select {
		case message, ok := <-backend.data:
			if !ok {
				return
			}
			backend.socket.Write(message)
		}
	}
}

func (manager *BackendManager) receive(backend *Backend) {
	for {
		message := make([]byte, 4096)

		length, err := backend.socket.Read(message)
		if err != nil {
			log.Warningf("[%s] Read failed: %s", backend.niceName(), err)
			manager.unregister <- backend
			backend.socket.Close()
			break
		}

		if length > 0 {
			msgLen := binary.BigEndian.Uint32(message[0:3])

			log.Debugf("[%s] Read %d bytes, first protobuf is %d long", backend.niceName(), length, msgLen)

			backendMsg := &ledd.BackendWrapperMessage{}
			err = proto.Unmarshal(message[4:msgLen], backendMsg)
			if err != nil {
				log.Warningf("[%s] Couldn't decode protobuf msg!", backend.niceName())
				continue
			}

			switch msg := backendMsg.Msg.(type) {
			case *ledd.BackendWrapperMessage_MBackend:
				nBackend := msg.MBackend
				backend.name = nBackend.Name
				backend.channel = nBackend.Channel
				backend.resolution = nBackend.Resolution
				backend.platformType = nBackend.Type
				backend.version = nBackend.Version
				log.Infof("[%s] %s is now identified as %s", LOG_BACKEND, backend.socket.RemoteAddr(), backend.niceName())
				backManager.register <- backend
			}
		}
	}
}

// CLIENT HANDLER

func (manager *ClientManager) start() {
	for {
		select {
		case client := <-manager.register:
			manager.clients[client] = true
			log.Debugf("[%s] New frontend (%s)", LOG_CLIENTS, client.socket.RemoteAddr(), client.platform)
		case client := <-manager.unregister:
			if _, ok := manager.clients[client]; ok {
				log.Debugf("[%s] Removed client (%s)", LOG_CLIENTS, client.socket.RemoteAddr(), client.platform)
				close(client.data)
				delete(manager.clients, client)
			}
		case message := <-manager.broadcast:
			for connection := range manager.clients {
				select {
				case connection.data <- message:
				default:
					close(connection.data)
					delete(manager.clients, connection)
				}
			}
		}
	}
}

func (manager *ClientManager) send(client *Client) {
	defer client.socket.Close()
	for {
		select {
		case message, ok := <-client.data:
			if !ok {
				return
			}
			client.socket.Write(message)
		}
	}
}

func (manager *ClientManager) receive(client *Client) {
	for {
		message := make([]byte, 4096)
		length, err := client.socket.Read(message)
		if err != nil {
			log.Warningf("[%s] Read failed: %s", client.socket.RemoteAddr(), err)
			manager.unregister <- client
			client.socket.Close()
			break
		}
		if length > 0 {
			msgLen := binary.BigEndian.Uint32(message[0:3])

			log.Debugf("[%s] Read %d bytes, first protobuf is %d long", client.socket.RemoteAddr(), length, msgLen)

			clientMsg := &ledd.ClientWrapperMessage{}
			err = proto.Unmarshal(message[4:msgLen], clientMsg)
			if err != nil {
				log.Warningf("[%s] Couldn't decode protobuf msg!", client.socket.RemoteAddr())
				continue
			}

			switch msg := clientMsg.Msg.(type) {
			case *ledd.ClientWrapperMessage_MClient:
				client.platform = msg.MClient.Type
				log.Infof("[%s] %s is now identified as client (%s)", LOG_CLIENTS, client.socket.RemoteAddr(), client.platform)
				clientManager.register <- client
			case *ledd.ClientWrapperMessage_MGetLed:
				allLED := make([]*ledd.LED, 0)

				for _, led := range ledManager.leds {
					allLED = append(allLED, &ledd.LED{Name: led.name})
				}

				data, err := proto.Marshal(&ledd.ClientWrapperMessage{Leds: allLED})
				if err != nil {
					log.Errorf("[%s] Error encoding protobuf: %s", client.socket.RemoteAddr(), err)
				}

				client.data <- data
			case *ledd.ClientWrapperMessage_MAddLed:
				backend, ok := backManager.backends[msg.MAddLed.Backend]
				if !ok {
					log.Warningf("[%s] Can't add LED for non-existing backend %s", client.socket.RemoteAddr(), msg.MAddLed.Backend)
				}

				nLED := &LED{
					name:    msg.MAddLed.Name,
					channel: msg.MAddLed.Channel,
					backend: backend.name,
				}

				ledManager.add <- nLED
			case *ledd.ClientWrapperMessage_MSetLed:
				led, ok := ledManager.leds[msg.MSetLed.Name]
				if !ok {
					log.Warningf("[%s] Failed to set LED %s: LED not found", client.socket.RemoteAddr(), msg.MSetLed.Name)
				}

				led.color <- colorful.Hcl(msg.MSetLed.Colour.Hue, msg.MSetLed.Colour.Chroma, msg.MSetLed.Colour.Light)
			}
		}
	}
}

// HELPER

func check(e error) {
	if e != nil {
		panic(e)
	}
}

func (backend *Backend) niceName() string {
	if backend.name != "" {
		return backend.name
	} else {
		return backend.socket.RemoteAddr().String()
	}
}

func (led *LED) setColor(color colorful.Color) {
	backend := backManager.backends[led.backend]

	if len(led.channel) != 3 {
		log.Warningf("[%s] Currently only RGB LEDs are supported", led.name)
		return
	}

	cMap := make(map[int32]int32)

	cMap[led.channel[0]] = int32(color.R * float64(backend.resolution))
	cMap[led.channel[1]] = int32(color.G * float64(backend.resolution))
	cMap[led.channel[2]] = int32(color.B * float64(backend.resolution))

	wrapperMsg := &ledd.BackendWrapperMessage{
		Msg: &ledd.BackendWrapperMessage_MSetChannel{
			MSetChannel: &ledd.BackendSetChannel{
				NewChannelValues: cMap}}}

	data, err := proto.Marshal(wrapperMsg)
	if err != nil {
		log.Warningf("[%s] Failed to encode protobuf msg to %s: %s", led.name, backend.name, err)
	}

	backend.data <- data
}

// MAIN

func main() {
	killSignals := make(chan os.Signal, 1)
	signal.Notify(killSignals, syscall.SIGINT, syscall.SIGTERM)

	log.Info("LedD", VERSION)

	content, err := ioutil.ReadFile("ledd.yaml")
	check(err)

	err = yaml.Unmarshal(content, &config)
	check(err)

	session, err := mgo.Dial(fmt.Sprintf("%s:%d", config.Mongodb.Host, config.Mongodb.Port))
	check(err)
	defer session.Close()

	LEDCollection = session.DB(config.Mongodb.Database).C("led")

	backManager = BackendManager{
		backends:   make(map[string]*Backend),
		broadcast:  make(chan []byte),
		register:   make(chan *Backend),
		unregister: make(chan *Backend),
	}

	go backManager.start()

	clientManager = ClientManager{
		clients:    make(map[*Client]bool),
		broadcast:  make(chan []byte),
		register:   make(chan *Client),
		unregister: make(chan *Client),
	}

	go clientManager.start()

	ledManager = LEDManager{
		leds:      make(map[string]*LED),
		broadcast: make(chan colorful.Color),
		add:       make(chan *LED),
		remove:    make(chan *LED),
	}

	go ledManager.start()

	var dbLEDs = make([]LED, 0)
	err = LEDCollection.Find(nil).All(&dbLEDs)
	if err != nil {
		log.Notice("Failed to load LEDs from db. If there should be LEDs, check db connection")
	}

	for _, l := range dbLEDs {
		ledManager.add <- &l
	}

	backendThread, err := setupSocket(config.Daemon.Backend.Host, config.Daemon.Backend.Port, LOG_BACKEND, true)
	check(err)
	go backendThread()

	frontendThread, err := setupSocket(config.Daemon.Frontend.Host, config.Daemon.Frontend.Port, LOG_CLIENTS, false)
	check(err)
	go frontendThread()

	log.Infof("All connection handler ready.")

	<-killSignals

	backManager.stop()
}