package main

import (
	"fmt"
	"log"

	"github.com/bwmarrin/discordgo"
)

// startAsyncDownload initiates a download in a goroutine and handles progress updates
func startAsyncDownload(s *discordgo.Session, i *discordgo.InteractionCreate, url, videoFormatID, audioFormatID, outputDir, tempDir string) {
	progressChan := make(chan ProgressUpdate, 1)
	resultChan := make(chan DownloadResult, 1)

	// Start download in goroutine
	go func() {
		defer close(resultChan)
		defer func() {
			if r := recover(); r != nil {
				// Handle panic from DownloadVideo
				resultChan <- DownloadResult{
					Success: false,
					Message: fmt.Sprintf("Download failed: %v", r),
					URL:     url,
					Format:  fmt.Sprintf("video: %s, audio: %s", videoFormatID, audioFormatID),
					Error:   fmt.Errorf("%v", r),
				}
			}
		}()

		// Call DownloadVideo (it panics on error instead of returning error)
		DownloadVideo(outputDir, tempDir, url, DownloadOptions{
			EmbedThumbnail:   true,
			IncludeSubtitles: true,
			VideoFormatID:    videoFormatID,
			AudioFormatID:    audioFormatID,
		}, progressChan)

		// If we reach here, download was successful
		resultChan <- DownloadResult{
			Success: true,
			Message: "Video Downloaded Successfully!",
			URL:     url,
			Format:  fmt.Sprintf("video: %s, audio: %s", videoFormatID, audioFormatID),
			Error:   nil,
		}
	}()

	// Handle progress and results asynchronously
	go func() {
		_, err := s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{
			Content: ptr("⏬ downloading: starting..."),
		})
		if err != nil {
			log.Printf("Error updating interaction: %v", err)
		}

		for {
			select {
			case prog, ok := <-progressChan:
				if !ok {
					progressChan = nil
					continue
				}

				var content string
				if prog.Phase == "post-processing" {
					content = "⚙️ post-processing"
				} else {
					var progressStr string
					if prog.DownloadedBytes > 0 {
						progressStr = formatBytes(prog.DownloadedBytes) + " downloaded"
					} else {
						progressStr = "starting..."
					}
					content = fmt.Sprintf("Downloading Video: %s", progressStr)
				}

				_, err := s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{
					Content: ptr(content),
				})
				if err != nil {
					log.Printf("Error updating progress: %v", err)
				}

			case result := <-resultChan:
				if result.Success {
					_, err = s.FollowupMessageCreate(i.Interaction, false, &discordgo.WebhookParams{
						Content: "📥 Video downloaded: " + result.URL,
					})
					if err != nil {
						log.Printf("Error updating interaction: %v", err)
					}
				} else {
					_, err = s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{
						Content: ptr("❌ Download failed: " + result.Message),
					})
					if err != nil {
						log.Printf("Error updating interaction: %v", err)
					}
				}
				return
			}
		}
	}()
}