package ytdlp

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/charmbracelet/log"
	ytdlp "github.com/lrstanley/go-ytdlp"

	"github.com/krau/SaveAny-Bot/config"
	"github.com/krau/SaveAny-Bot/pkg/enums/ctxkey"
)

// Execute implements core.Executable.
func (t *Task) Execute(ctx context.Context) error {
	logger := log.FromContext(ctx)
	logger.Infof("Starting yt-dlp download task %s", t.ID)

	if t.Progress != nil {
		t.Progress.OnStart(ctx, t)
	}

	// Create temporary directory for downloads
	tempDir, err := os.MkdirTemp(config.C().Temp.BasePath, "ytdlp-*")
	if err != nil {
		logger.Errorf("Failed to create temp directory: %v", err)
		if t.Progress != nil {
			t.Progress.OnDone(ctx, t, err)
		}
		return fmt.Errorf("failed to create temp directory: %w", err)
	}
	defer os.RemoveAll(tempDir) // Clean up temp directory

	logger.Debugf("Created temp directory: %s", tempDir)

	// Download files using yt-dlp
	downloadedFiles, err := t.downloadFiles(ctx, tempDir)
	if err != nil {
		logger.Errorf("yt-dlp download failed: %v", err)
		if t.Progress != nil {
			t.Progress.OnDone(ctx, t, err)
		}
		return err
	}

	if len(downloadedFiles) == 0 {
		err := errors.New("no files were downloaded")
		logger.Error(err.Error())
		if t.Progress != nil {
			t.Progress.OnDone(ctx, t, err)
		}
		return err
	}

	// Transfer downloaded files to storage
	logger.Infof("Transferring %d file(s) to storage %s", len(downloadedFiles), t.Storage.Name())
	for _, filePath := range downloadedFiles {
		if err := t.transferFile(ctx, filePath); err != nil {
			logger.Errorf("File transfer failed: %v", err)
			if t.Progress != nil {
				t.Progress.OnDone(ctx, t, err)
			}
			return err
		}
	}

	logger.Infof("yt-dlp task %s completed successfully", t.ID)
	if t.Progress != nil {
		t.Progress.OnDone(ctx, t, nil)
	}

	return nil
}

// downloadFiles downloads files using yt-dlp and returns the list of downloaded file paths
func (t *Task) downloadFiles(ctx context.Context, tempDir string) ([]string, error) {
	logger := log.FromContext(ctx)

	// Configure yt-dlp command with essential settings
	// Always set output path to ensure files go to temp directory
	cmd := ytdlp.New().
		Output(filepath.Join(tempDir, "%(title)s.%(ext)s"))

	// If no custom flags are provided, use default behavior
	if len(t.Flags) == 0 {
		cmd = cmd.
			FormatSort("res,ext:mp4:m4a").
			RecodeVideo("mp4").
			RestrictFilenames()
	}
	// Note: If custom flags are provided, users have full control over format/quality
	// The output path is always set above to ensure downloads go to the correct directory

	if t.Progress != nil {
		t.Progress.OnProgress(ctx, t, "Downloading...")
	}

	// Execute download with URLs and custom flags
	logger.Infof("Executing yt-dlp for %d URL(s) with %d custom flag(s)", len(t.URLs), len(t.Flags))

	// Combine flags and URLs as arguments (flags first, then URLs)
	// yt-dlp accepts: yt-dlp [OPTIONS] URL [URL...]
	args := append(t.Flags, t.URLs...)

	// Run with context for cancellation support
	result, err := cmd.Run(ctx, args...)
	if err != nil {
		// Check if context was canceled
		if errors.Is(err, context.Canceled) {
			return nil, err
		}
		return nil, fmt.Errorf("yt-dlp execution failed: %w", err)
	}

	if result.ExitCode != 0 {
		return nil, fmt.Errorf("yt-dlp exited with code %d: %s", result.ExitCode, result.Stderr)
	}

	// List downloaded files
	files, err := os.ReadDir(tempDir)
	if err != nil {
		return nil, fmt.Errorf("failed to read temp directory: %w", err)
	}

	var downloadedFiles []string
	for _, file := range files {
		if file.IsDir() {
			continue
		}
		fullPath := filepath.Join(tempDir, file.Name())
		downloadedFiles = append(downloadedFiles, fullPath)
		logger.Debugf("Downloaded file: %s", file.Name())
	}

	return downloadedFiles, nil
}

// transferFile transfers a single file to storage
func (t *Task) transferFile(ctx context.Context, filePath string) error {
	logger := log.FromContext(ctx)

	// Check if file exists
	fileInfo, err := os.Stat(filePath)
	if err != nil {
		if os.IsNotExist(err) {
			logger.Warnf("Downloaded file not found: %s", filePath)
			return nil // Not a fatal error
		}
		return fmt.Errorf("failed to stat file %s: %w", filePath, err)
	}

	// Open file
	f, err := os.Open(filePath)
	if err != nil {
		return fmt.Errorf("failed to open file %s: %w", filePath, err)
	}
	defer f.Close()

	// Set content length in context for storage
	ctx = context.WithValue(ctx, ctxkey.ContentLength, fileInfo.Size())

	// Save to storage
	fileName := filepath.Base(filePath)
	// Remove special characters from filename if needed
	fileName = sanitizeFilename(fileName)
	destPath := filepath.Join(t.StorPath, fileName)

	logger.Infof("Transferring file %s to %s:%s", fileName, t.Storage.Name(), destPath)

	if err := t.Storage.Save(ctx, f, destPath); err != nil {
		return fmt.Errorf("failed to save file %s to storage: %w", fileName, err)
	}

	logger.Infof("Successfully transferred file %s", fileName)

	if t.Progress != nil {
		t.Progress.OnProgress(ctx, t, fmt.Sprintf("Transferred: %s", fileName))
	}

	return nil
}

// sanitizeFilename removes or replaces problematic characters in filenames
func sanitizeFilename(name string) string {
	// yt-dlp with --restrict-filenames should already handle most cases
	// but we can do additional sanitization if needed
	name = strings.ReplaceAll(name, ":", "_")
	name = strings.ReplaceAll(name, "\"", "'")
	return name
}