package worker

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"time"

	"github.com/redis/go-redis/v9"

	"github.com/example/remote-access-platform/backend/internal/modules/sessionbroker"
)

type EventProcessor struct {
	client *redis.Client
	broker *sessionbroker.Service
}

func NewEventProcessor(client *redis.Client, broker *sessionbroker.Service) *EventProcessor {
	return &EventProcessor{client: client, broker: broker}
}

func (p *EventProcessor) Run(ctx context.Context) error {
	for {
		select {
		case <-ctx.Done():
			return nil
		default:
		}

		result, err := p.client.BLPop(ctx, 5*time.Second, "worker:events").Result()
		if err == redis.Nil {
			continue
		}
		if err != nil {
			if ctx.Err() != nil {
				return nil
			}
			return fmt.Errorf("consume worker event: %w", err)
		}
		if len(result) != 2 {
			continue
		}

		var event SessionEvent
		if err := json.Unmarshal([]byte(result[1]), &event); err != nil {
			continue
		}
		if err := p.handleEvent(ctx, event); err != nil {
			return err
		}
	}
}

func (p *EventProcessor) handleEvent(ctx context.Context, event SessionEvent) error {
	switch event.Type {
	case SessionEventConnected, SessionEventDisplayReady:
		if err := p.broker.HandleWorkerConnected(ctx, event.SessionID); err != nil {
			return err
		}
		if len(event.Payload) > 0 {
			if err := p.broker.UpdateWorkerRenderTelemetry(ctx, event.SessionID, event.Payload); err != nil && !errors.Is(err, sessionbroker.ErrSessionNotFound) {
				return err
			}
		}
		return nil
	case SessionEventHeartbeat:
		return p.broker.HandleWorkerHeartbeat(ctx, event.SessionID)
	case SessionEventRenderReady, SessionEventRenderDirty, SessionEventRenderResized, SessionEventCursorUpdated, SessionEventFrame:
		if len(event.Payload) == 0 {
			return nil
		}
		if correlationID, _ := event.Payload["input_correlation_id"].(string); correlationID != "" {
			slog.Info("worker frame event received",
				"session_id", event.SessionID,
				"worker_id", event.WorkerID,
				"frame_sequence", event.Payload["frame_sequence"],
				"correlation_id", correlationID,
				"worker_frame_captured_at", event.Payload["worker_frame_captured_at"],
				"trace_stage", "backend_frame_receive")
		}
		return p.updateRenderTelemetryWithRetry(ctx, event.SessionID, event.Payload)
	case SessionEventClipboardText:
		if len(event.Payload) == 0 {
			return nil
		}
		slog.Info("worker clipboard event received",
			"session_id", event.SessionID,
			"worker_id", event.WorkerID,
			"origin", event.Payload["origin"],
			"sequence_id", event.Payload["sequence_id"],
			"content_hash", event.Payload["content_hash"])
		return p.broker.UpdateWorkerClipboardText(ctx, event.SessionID, event.Payload)
	case SessionEventFileUploaded:
		slog.Info("worker file upload completed",
			"session_id", event.SessionID,
			"worker_id", event.WorkerID,
			"transfer_id", event.Payload["transfer_id"],
			"file_name", event.Payload["file_name"],
			"file_size", event.Payload["file_size"],
			"content_hash", event.Payload["content_hash"],
			"storage_path", event.Payload["storage_path"])
		return nil
	case SessionEventFileDownloadAvailable, SessionEventFileDownloadChunk, SessionEventFileDownloadProgress,
		SessionEventFileDownloadCompleted, SessionEventFileDownloadFailed, SessionEventFileDownloadBlocked:
		slog.Info("worker file download event received",
			"session_id", event.SessionID,
			"worker_id", event.WorkerID,
			"event_type", event.Type,
			"transfer_id", event.Payload["transfer_id"],
			"file_id", event.Payload["file_id"],
			"file_name", event.Payload["file_name"],
			"status", event.Payload["status"])
		return p.broker.UpdateWorkerFileDownloadEvent(ctx, event.SessionID, event.Type, event.Payload)
	case SessionEventFailed:
		reason, _ := event.Payload["reason"].(string)
		err := p.broker.MarkSessionFailed(ctx, sessionbroker.MarkSessionFailedCommand{
			SessionID: event.SessionID,
			Reason:    reason,
		})
		if errors.Is(err, sessionbroker.ErrSessionNotFound) || errors.Is(err, sessionbroker.ErrSessionNotTerminable) {
			return nil
		}
		return err
	case SessionEventTerminated:
		reason, _ := event.Payload["reason"].(string)
		err := p.broker.TerminateSession(ctx, sessionbroker.TerminateSessionCommand{
			SessionID: event.SessionID,
			Reason:    reason,
		})
		if errors.Is(err, sessionbroker.ErrSessionNotFound) || errors.Is(err, sessionbroker.ErrSessionNotTerminable) {
			return nil
		}
		return err
	default:
		return nil
	}
}

func (p *EventProcessor) updateRenderTelemetryWithRetry(ctx context.Context, sessionID string, payload map[string]any) error {
	var lastErr error
	for attempt := 0; attempt < 10; attempt++ {
		err := p.broker.UpdateWorkerRenderTelemetry(ctx, sessionID, payload)
		if err == nil || errors.Is(err, sessionbroker.ErrSessionNotFound) {
			return nil
		}
		lastErr = err
		time.Sleep(100 * time.Millisecond)
	}
	return lastErr
}