package bridge

import (
	"errors"
	"log/slog"
	"sync/atomic"
	"time"

	mqtt "github.com/eclipse/paho.mqtt.golang"

	"gitea.berezovskyi.dev/oleksandr/ezcoo-usb-control/pkg/ezcoo"
)

var ErrShutdown = errors.New("bridge: shutdown requested")

type Device interface {
	SetOutput(out, in int)
	GetStatus() ezcoo.State
}

type Bridge struct {
	cfg       Config
	client    mqtt.Client
	dev       Device
	done      <-chan struct{}
	available atomic.Bool
}

func New(cfg Config, dev Device, done <-chan struct{}) *Bridge {
	b := &Bridge{cfg: cfg, dev: dev, done: done}
	opts := mqtt.NewClientOptions().
		AddBroker(cfg.Broker).
		SetClientID(cfg.ClientID).
		SetUsername(cfg.Username).
		SetPassword(cfg.Password).
		SetAutoReconnect(true).
		SetWill(b.availTopic(), "offline", 1, true).
		SetOnConnectHandler(func(c mqtt.Client) {
			slog.Info("MQTT connected")
			b.onConnect(c)
		}).
		SetConnectionLostHandler(func(_ mqtt.Client, err error) {
			slog.Warn("MQTT connection lost", "err", err)
		})
	b.client = mqtt.NewClient(opts)
	return b
}

func (b *Bridge) OnState(s ezcoo.State) {
	if !b.client.IsConnected() {
		return
	}
	for out := 1; out <= numOutputs; out++ {
		in := s[out-1]
		if in >= 1 && in <= numInputs {
			b.client.Publish(b.stateTopic(out), 1, true, inputLabel(in))
			slog.Debug("state update", "output", out, "input", in)
		}
	}
}

func (b *Bridge) SetAvailable(online bool) {
	b.available.Store(online)
	if b.client.IsConnected() {
		b.client.Publish(b.availTopic(), 1, true, b.availPayload())
		slog.Info("availability", "online", online)
	}
}

func (b *Bridge) Connect() error {
	for {
		tok := b.client.Connect()
		if tok.WaitTimeout(5 * time.Second) {
			if tok.Error() == nil {
				return nil
			}
			slog.Warn("MQTT connect failed, retrying in 5s", "err", tok.Error())
		} else {
			slog.Warn("MQTT connect timed out, retrying in 5s")
		}
		select {
		case <-b.done:
			return ErrShutdown
		case <-time.After(5 * time.Second):
		}
	}
}

func (b *Bridge) Run() {
	<-b.done
	tok := b.client.Publish(b.availTopic(), 1, true, "offline")
	tok.WaitTimeout(2 * time.Second)
	b.client.Disconnect(500)
}