package downloader

import (
	"context"

	"softbox.local/core/application"
)

// ApplicationPublisher is implemented by application.Runtime.
type ApplicationPublisher interface {
	Publish(context.Context, application.Event) error
}

// ApplicationObserver maps downloader events to the documented application
// event envelope and concrete payloads.
type ApplicationObserver struct {
	Publisher ApplicationPublisher
}

// PublishDownload implements Observer.
func (observer ApplicationObserver) PublishDownload(
	ctx context.Context,
	event Event,
) error {
	if observer.Publisher == nil {
		return nil
	}
	envelope := application.Event{
		RequestID: event.RequestID,
		AppID:     event.AppID,
	}
	switch event.Type {
	case EventStarted:
		envelope.Type = application.EventDownloadStarted
		envelope.Payload = application.DownloadStartedPayload{
			Attempt:    event.Attempt,
			Done:       event.Done,
			TotalKnown: event.TotalKnown,
			Total:      event.Total,
		}
	case EventProgress:
		envelope.Type = application.EventDownloadProgress
		envelope.Payload = application.DownloadProgressPayload{
			Attempt:       event.Attempt,
			Done:          event.Done,
			TotalKnown:    event.TotalKnown,
			Total:         event.Total,
			SpeedBytesSec: event.SpeedBytesSec,
		}
	case EventPaused:
		envelope.Type = application.EventDownloadPaused
		envelope.Payload = application.DownloadPausedPayload{
			Attempt: event.Attempt,
			Done:    event.Done,
		}
	case EventCompleted:
		envelope.Type = application.EventDownloadCompleted
		envelope.Payload = application.DownloadCompletedPayload{
			Attempt: event.Attempt,
			Done:    event.Done,
			Path:    event.CompletedPath,
		}
	case EventFailed:
		envelope.Type = application.EventDownloadFailed
		envelope.Payload = application.DownloadFailedPayload{
			Attempt:   event.Attempt,
			Done:      event.Done,
			ErrorCode: event.ErrorCode,
		}
	case EventCanceled:
		envelope.Type = application.EventDownloadCanceled
		envelope.Payload = application.DownloadCanceledPayload{
			Attempt: event.Attempt,
		}
	default:
		return nil
	}
	return observer.Publisher.Publish(ctx, envelope)
}