package app

import (
	"context"
	"fmt"
	"log"
	"os"
	"sync"
	"time"

	"git.az-it.net/az/morz-infoboard/player/agent/internal/config"
	"git.az-it.net/az/morz-infoboard/player/agent/internal/statusreporter"
)

type Status string

type Connectivity string

const (
	StatusStarting Status = "starting"
	StatusRunning  Status = "running"
	StatusStopped  Status = "stopped"

	ConnectivityUnknown  Connectivity = "unknown"
	ConnectivityOnline   Connectivity = "online"
	ConnectivityDegraded Connectivity = "degraded"
	ConnectivityOffline  Connectivity = "offline"
)

const offlineFailureThreshold = 3

type HealthSnapshot struct {
	Status             Status
	ServerConnectivity Connectivity
	ScreenID           string
	ServerBaseURL      string
	MQTTBroker         string
	HeartbeatEvery     int
	StartedAt          time.Time
	LastHeartbeatAt    time.Time
}

type App struct {
	Config   config.Config
	logger   *log.Logger
	now      func() time.Time
	reporter statusSender

	mu                        sync.RWMutex
	status                    Status
	serverConnectivity        Connectivity
	consecutiveReportFailures int
	startedAt                 time.Time
	lastHeartbeatAt           time.Time
}

type statusSender interface {
	Send(ctx context.Context, snapshot statusreporter.Snapshot) error
}

func New() (*App, error) {
	cfg, err := config.Load()
	if err != nil {
		return nil, err
	}

	logger := log.New(os.Stdout, "agent ", log.LstdFlags|log.LUTC)

	return newApp(cfg, logger, time.Now, statusreporter.New(cfg.ServerBaseURL, nil, time.Now)), nil
}

func newApp(cfg config.Config, logger *log.Logger, now func() time.Time, reporter statusSender) *App {
	if logger == nil {
		logger = log.New(os.Stdout, "agent ", log.LstdFlags|log.LUTC)
	}

	if now == nil {
		now = time.Now
	}

	return &App{
		Config:             cfg,
		logger:             logger,
		now:                now,
		reporter:           reporter,
		status:             StatusStarting,
		serverConnectivity: ConnectivityUnknown,
	}
}

func (a *App) Snapshot() HealthSnapshot {
	a.mu.RLock()
	defer a.mu.RUnlock()

	return HealthSnapshot{
		Status:             a.status,
		ServerConnectivity: a.serverConnectivity,
		ScreenID:           a.Config.ScreenID,
		ServerBaseURL:      a.Config.ServerBaseURL,
		MQTTBroker:         a.Config.MQTTBroker,
		HeartbeatEvery:     a.Config.HeartbeatEvery,
		StartedAt:          a.startedAt,
		LastHeartbeatAt:    a.lastHeartbeatAt,
	}
}

func (a *App) Run(ctx context.Context) error {
	if a.Config.ScreenID == "" {
		return fmt.Errorf("screen id is required")
	}

	select {
	case <-ctx.Done():
		a.mu.Lock()
		a.status = StatusStopped
		a.mu.Unlock()
		return nil
	default:
	}

	a.mu.Lock()
	a.startedAt = a.now()
	a.mu.Unlock()

	a.logger.Printf(
		"event=agent_configured screen_id=%s server_url=%s mqtt_broker=%s heartbeat_every_seconds=%d",
		a.Config.ScreenID,
		a.Config.ServerBaseURL,
		a.Config.MQTTBroker,
		a.Config.HeartbeatEvery,
	)
	a.emitHeartbeat()
	a.mu.Lock()
	a.status = StatusRunning
	a.mu.Unlock()

	ticker := time.NewTicker(time.Duration(a.Config.HeartbeatEvery) * time.Second)
	defer ticker.Stop()

	reportTicker := time.NewTicker(time.Duration(a.Config.StatusReportEvery) * time.Second)
	defer reportTicker.Stop()
	a.reportStatus(ctx)

	for {
		select {
		case <-ctx.Done():
			a.mu.Lock()
			a.status = StatusStopped
			a.mu.Unlock()
			a.logger.Printf("event=agent_stopped screen_id=%s", a.Config.ScreenID)
			return nil
		case <-ticker.C:
			a.emitHeartbeat()
		case <-reportTicker.C:
			a.reportStatus(ctx)
		}
	}
}

func (a *App) emitHeartbeat() {
	now := a.now()

	a.mu.Lock()
	a.lastHeartbeatAt = now
	a.mu.Unlock()

	a.logger.Printf("event=heartbeat_tick screen_id=%s", a.Config.ScreenID)
}

func (a *App) reportStatus(ctx context.Context) {
	if a.reporter == nil {
		return
	}

	snapshot := a.Snapshot()

	err := a.reporter.Send(ctx, statusreporter.Snapshot{
		Status:                string(snapshot.Status),
		ScreenID:              snapshot.ScreenID,
		ServerBaseURL:         snapshot.ServerBaseURL,
		MQTTBroker:            snapshot.MQTTBroker,
		HeartbeatEverySeconds: snapshot.HeartbeatEvery,
		StartedAt:             snapshot.StartedAt,
		LastHeartbeatAt:       snapshot.LastHeartbeatAt,
	})
	if err != nil {
		a.mu.Lock()
		a.consecutiveReportFailures++
		a.serverConnectivity = ConnectivityDegraded
		if a.consecutiveReportFailures >= offlineFailureThreshold {
			a.serverConnectivity = ConnectivityOffline
		}
		a.mu.Unlock()
		a.logger.Printf("event=status_report_failed screen_id=%s error=%v", a.Config.ScreenID, err)
		return
	}

	a.mu.Lock()
	a.consecutiveReportFailures = 0
	a.serverConnectivity = ConnectivityOnline
	a.mu.Unlock()
	a.logger.Printf("event=status_report_sent screen_id=%s", a.Config.ScreenID)
}