package nanoleaf

import (
	"bytes"
	"context"
	"encoding/binary"
	"encoding/hex"
	"encoding/json"
	"fmt"
	lucifer3 "git.aiterp.net/lucifer3/server"
	"git.aiterp.net/lucifer3/server/commands"
	"git.aiterp.net/lucifer3/server/device"
	"git.aiterp.net/lucifer3/server/events"
	"git.aiterp.net/lucifer3/server/internal/color"
	"git.aiterp.net/lucifer3/server/internal/gentools"
	"io"
	"io/ioutil"
	"log"
	"net"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"
)

type bridge struct {
	mu         sync.Mutex
	host       string
	apiKey     string
	panels     []*panel
	panelIDMap map[uint16]string
}

func (b *bridge) HardwareEvents() []lucifer3.Event {
	results := make([]lucifer3.Event, 0, len(b.panels)*2)
	for i, panel := range b.panels {
		// Find normalized RGB and intensity
		rgb := color.RGB{
			Red:   float64(panel.ColorRGBA[0]) / 255.0,
			Green: float64(panel.ColorRGBA[1]) / 255.0,
			Blue:  float64(panel.ColorRGBA[2]) / 255.0,
		}
		normalized, intensity := rgb.Normalize()
		col := color.Color{RGB: &normalized}

		shapeType, shapeTypeOK := shapeTypeMap[panel.ShapeType]
		if !shapeTypeOK {
			shapeType = "Unknown"
		}

		shapeIcon, shapeIconOK := shapeIconMap[panel.ShapeType]
		if !shapeIconOK {
			shapeIcon = "lightbulb"
		}

		state := device.State{}
		if panel.ColorRGBA != [4]byte{0, 0, 0, 0} {
			state = device.State{
				Power:     gentools.Ptr(panel.ColorRGBA[3] == 0),
				Color:     &col,
				Intensity: &intensity,
			}
		}

		results = append(results, events.HardwareState{
			ID:           panel.FullID,
			InternalName: fmt.Sprintf("%s %d (%s)", shapeType, i+1, strings.SplitN(panel.FullID, ":", 3)[2]),
			SupportFlags: device.SFlagPower | device.SFlagIntensity | device.SFlagColor,
			ColorFlags:   device.CFlagRGB,
			Buttons:      []string{"Touch"},
			State:        state,
		}, events.HardwareMetadata{
			ID:        panel.FullID,
			X:         panel.X,
			Y:         panel.Y,
			ShapeType: shapeType,
			Icon:      shapeIcon,
		})
	}

	return append(results, events.DevicesReady{
		ID: fmt.Sprintf("nanoleaf:%s", b.host),
	})
}

func (b *bridge) Refresh(ctx context.Context) (bool, error) {
	overview, err := b.Overview(ctx)
	if err != nil {
		return false, err
	}

	changed := false

	b.mu.Lock()
PanelLoop:
	for _, panelInfo := range overview.PanelLayout.Data.PositionData {
		if shapeTypeMap[panelInfo.ShapeType] == "Shapes Controller" {
			continue
		}

		for _, existingPanel := range b.panels {
			if existingPanel.ID == panelInfo.PanelID {
				existingPanel.O = panelInfo.O
				existingPanel.X = panelInfo.X
				existingPanel.Y = panelInfo.Y
				existingPanel.ShapeType = panelInfo.ShapeType

				continue PanelLoop
			}
		}

		changed = true

		idBytes := [2]byte{0, 0}
		binary.BigEndian.PutUint16(idBytes[:], panelInfo.PanelID)
		hexID := hex.EncodeToString(idBytes[:])
		fullID := fmt.Sprintf("nanoleaf:%s:%s", b.host, hexID)

		b.panelIDMap[panelInfo.PanelID] = fullID
		b.panels = append(b.panels, &panel{
			ID:           panelInfo.PanelID,
			FullID:       fullID,
			ColorRGBA:    [4]byte{0, 0, 0, 0},
			TransitionAt: time.Time{},
			O:            panelInfo.O,
			X:            panelInfo.X,
			Y:            panelInfo.Y,
			ShapeType:    panelInfo.ShapeType,
			Stale:        true,
			SlowUpdates:  5,
		})
	}
	b.mu.Unlock()

	return changed, nil
}

func (b *bridge) Overview(ctx context.Context) (*Overview, error) {
	req, err := http.NewRequest("GET", b.URL(), nil)
	if err != nil {
		return nil, err
	}

	res, err := http.DefaultClient.Do(req.WithContext(ctx))
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()

	switch res.StatusCode {
	case 400, 403, 500, 503:
		return nil, lucifer3.ErrUnexpectedResponse
	case 401:
		return nil, lucifer3.ErrIncorrectToken
	}

	overview := Overview{}
	err = json.NewDecoder(res.Body).Decode(&overview)
	if err != nil {
		return nil, err
	}

	return &overview, nil
}

func (b *bridge) URL(resource ...string) string {
	return fmt.Sprintf("http://%s:16021/api/v1/%s/%s", b.host, b.apiKey, strings.Join(resource, "/"))
}

func (b *bridge) Update(id string, change device.State) {
	transitionTime := time.Now().Add(time.Millisecond * 255)

	b.mu.Lock()
	for _, panel := range b.panels {
		if panel.FullID == id {
			panel.apply(change, transitionTime)
			break
		}
	}
	b.mu.Unlock()
}

func (b *bridge) UpdateBatch(batch commands.SetStateBatch) {
	transitionTime := time.Now().Add(time.Millisecond * 255)

	b.mu.Lock()
	for _, panel := range b.panels {
		if change, ok := batch[panel.FullID]; ok {
			panel.apply(change, transitionTime)
		}
	}
	b.mu.Unlock()
}

func (b *bridge) Run(ctx context.Context, bus *lucifer3.EventBus) error {
	err := b.updateEffect(ctx)
	if err != nil {
		return err
	}

	conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
		IP:   net.ParseIP(b.host),
		Port: 60222,
	})
	if err != nil {
		return err
	}
	defer conn.Close()

	// Notify connections and disconnections
	bus.RunEvent(events.DeviceConnected{
		Prefix: fmt.Sprintf("nanoleaf:%s", b.host),
	})

	_, err = b.Refresh(ctx)
	if err != nil {
		return err
	}

	// Start touch listener. This one should go down together with this one, though, so it needs a new context.
	ctx2, cancel := context.WithCancel(ctx)
	defer cancel()
	go b.runTouchListener(ctx2, bus)

	go func() {
		ticker := time.NewTicker(time.Second * 5)
		hadErrors := false
		for {
			select {
			case <-ticker.C:
			case <-ctx2.Done():
				return
			}

			reqTimeout, cancel := context.WithTimeout(ctx2, time.Second*4)
			err := b.updateEffect(reqTimeout)
			cancel()
			if err != nil {
				log.Println("Failed to update effects:", err, "This error is non-fatal, and it will be retried shortly.")
				hadErrors = true
			} else if hadErrors {
				b.mu.Lock()
				for _, panel := range b.panels {
					panel.Stale = true
					panel.SlowUpdates = 3
					panel.TicksUntilSlowUpdate = 10
				}
				b.mu.Unlock()

				hadErrors = false
			}
		}
	}()

	ticker := time.NewTicker(time.Millisecond * 100)
	defer ticker.Stop()

	strikes := 0

	for _, event := range b.HardwareEvents() {
		bus.RunEvent(event)
	}

	for range ticker.C {
		if ctx.Err() != nil {
			break
		}

		panelUpdate := make(PanelUpdate, 2)

		b.mu.Lock()
		for _, panel := range b.panels {
			if !panel.Stale {
				if panel.SlowUpdates > 0 {
					panel.TicksUntilSlowUpdate -= 1
					if panel.TicksUntilSlowUpdate > 0 {
						continue
					}

					panel.TicksUntilSlowUpdate = 10
					panel.SlowUpdates -= 1
				} else {
					continue
				}
			} else {
				panel.Stale = false
			}

			panelUpdate.Add(panel.message())
			if panelUpdate.Len() > 150 {
				break
			}
		}
		b.mu.Unlock()

		if panelUpdate.Len() == 0 {
			continue
		}

		_, err := conn.Write(panelUpdate)
		if err != nil {
			strikes++
			if strikes >= 3 {
				return err
			}
		} else {
			strikes = 0
		}
	}

	return nil
}

func (b *bridge) updateEffect(ctx context.Context) error {
	overview, err := b.Overview(ctx)
	if err != nil {
		return err
	}

	if overview.Effects.Select == "*Dynamic*" && overview.State.ColorMode == "effect" {
		return nil
	}

	req, err := http.NewRequest("PUT", b.URL("effects"), bytes.NewReader(httpMessage))
	if err != nil {
		return err
	}

	res, err := http.DefaultClient.Do(req.WithContext(ctx))
	if err != nil {
		return err
	}
	defer res.Body.Close()

	if res.StatusCode != 204 {
		return lucifer3.ErrUnexpectedResponse
	}

	b.mu.Lock()
	for _, panel := range b.panels {
		panel.Stale = true
	}
	b.mu.Unlock()

	return nil
}

func (b *bridge) runTouchListener(ctx context.Context, bus *lucifer3.EventBus) {
	cooldownID := ""
	cooldownUntil := time.Now()

	message := make(PanelEventMessage, 65536)
	reqCloser := io.Closer(nil)

	for {
		// Set up touch event receiver
		touchListener, err := net.ListenUDP("udp4", &net.UDPAddr{
			Port: 0,
			IP:   net.IPv4(0, 0, 0, 0),
		})
		if err != nil {
			log.Println("Socket error:", err)
			goto teardownAndRetry
		}

		{
			// Create touch event sender on the remote end.
			req, err := http.NewRequest("GET", fmt.Sprintf("http://%s:16021/api/v1/%s/events?id=4", b.host, b.apiKey), nil)
			if err != nil {
				log.Println("HTTP error:", err)
				goto teardownAndRetry
			}
			req.Header["TouchEventsPort"] = []string{strconv.Itoa(touchListener.LocalAddr().(*net.UDPAddr).Port)}
			res, err := http.DefaultClient.Do(req.WithContext(ctx))
			if err != nil {
				log.Println("HTTP error:", err)
				goto teardownAndRetry
			}

			// Discard all data coming over http.
			reqCloser = res.Body
			go io.Copy(ioutil.Discard, res.Body)

			for {
				if ctx.Err() != nil {
					goto teardownAndRetry
				}

				// Check in with the context every so often
				_ = touchListener.SetReadDeadline(time.Now().Add(time.Second))
				n, _, err := touchListener.ReadFromUDP(message)
				if err != nil {
					if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
						continue
					} else if ctx.Err() == nil {
						log.Println("UDP error:", err)
					}

					goto teardownAndRetry
				}

				if !message[:n].ValidateLength() {
					log.Println("Bad message length field")
					continue
				}

				for i := 0; i < message.Count(); i += 1 {
					b.mu.Lock()
					id, hasID := b.panelIDMap[message.PanelID(i)]
					swipedFromID := b.panelIDMap[message.SwipedFromPanelID(i)]
					b.mu.Unlock()

					if !hasID || (id == cooldownID && time.Now().Before(cooldownUntil)) {
						continue
					}

					bus.RunEvent(events.ButtonPressed{
						ID:       id,
						SwipedID: swipedFromID,
						Name:     "Touch",
					})

					cooldownID = id
					cooldownUntil = time.Now().Add(time.Second)
				}
			}
		}

	teardownAndRetry:
		if touchListener != nil {
			_ = touchListener.Close()
		}

		if reqCloser != nil {
			_ = reqCloser.Close()
			reqCloser = nil
		}

		select {
		case <-time.After(time.Second * 3):
		case <-ctx.Done():
			return
		}
	}
}