package service

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"mime/multipart"
	"strings"

	"path/filepath"
	"tss-rocks-be/ent"
	"tss-rocks-be/internal/storage"
	"tss-rocks-be/pkg/imageutil"
)

type MediaService interface {
	// Upload uploads a new file and creates a media record
	Upload(ctx context.Context, file *multipart.FileHeader, userID int) (*ent.Media, error)

	// Get retrieves a media file by ID
	Get(ctx context.Context, id int) (*ent.Media, error)

	// Delete deletes a media file
	Delete(ctx context.Context, id int, userID int) error

	// List lists media files with pagination
	List(ctx context.Context, limit, offset int) ([]*ent.Media, error)

	// GetFile gets the file content and info
	GetFile(ctx context.Context, id int) (io.ReadCloser, *storage.FileInfo, error)
}

type mediaService struct {
	client  *ent.Client
	storage storage.Storage
}

func NewMediaService(client *ent.Client, storage storage.Storage) MediaService {
	return &mediaService{
		client:  client,
		storage: storage,
	}
}

// isValidFilename checks if a filename is valid
func isValidFilename(filename string) bool {
	// Check for illegal characters
	if strings.Contains(filename, "../") ||
		strings.Contains(filename, "./") ||
		strings.Contains(filename, "\\") {
		return false
	}

	return true
}

func (s *mediaService) Upload(ctx context.Context, file *multipart.FileHeader, userID int) (*ent.Media, error) {
	// Validate filename
	if !isValidFilename(file.Filename) {
		return nil, fmt.Errorf("invalid filename: %s", file.Filename)
	}

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

	// Read file content for processing
	fileBytes, err := io.ReadAll(src)
	if err != nil {
		return nil, fmt.Errorf("failed to read file: %w", err)
	}

	contentType := file.Header.Get("Content-Type")
	filename := file.Filename
	var processedBytes []byte

	// Process image if it's an image file
	if imageutil.IsImageFormat(contentType) {
		opts := imageutil.DefaultOptions()
		processedBytes, err = imageutil.ProcessImage(bytes.NewReader(fileBytes), opts)
		if err != nil {
			return nil, fmt.Errorf("failed to process image: %w", err)
		}

		// Update content type and filename for WebP
		contentType = "image/webp"
		filename = strings.TrimSuffix(filename, filepath.Ext(filename)) + ".webp"
	} else {
		processedBytes = fileBytes
	}

	// Save the processed file
	fileInfo, err := s.storage.Save(ctx, filename, contentType, bytes.NewReader(processedBytes))
	if err != nil {
		return nil, fmt.Errorf("failed to save file: %w", err)
	}

	// Create media record in database
	media, err := s.client.Media.Create().
		SetStorageID(fileInfo.ID).
		SetOriginalName(filename).
		SetMimeType(contentType).
		SetSize(int64(len(processedBytes))).
		SetURL(fmt.Sprintf("/api/media/%s", fileInfo.ID)).
		SetCreatedBy(fmt.Sprint(userID)).
		Save(ctx)
	if err != nil {
		// Try to cleanup the stored file if database operation fails
		_ = s.storage.Delete(ctx, fileInfo.ID)
		return nil, fmt.Errorf("failed to create media record: %w", err)
	}

	return media, nil
}

func (s *mediaService) Get(ctx context.Context, id int) (*ent.Media, error) {
	media, err := s.client.Media.Get(ctx, id)
	if err != nil {
		if ent.IsNotFound(err) {
			return nil, fmt.Errorf("media not found: %d", id)
		}
		return nil, fmt.Errorf("failed to get media: %w", err)
	}
	return media, nil
}

func (s *mediaService) Delete(ctx context.Context, id int, userID int) error {
	media, err := s.Get(ctx, id)
	if err != nil {
		return err
	}

	// Check ownership
	if media.CreatedBy != fmt.Sprintf("%d", userID) {
		return fmt.Errorf("unauthorized to delete media")
	}

	// Delete from storage
	if err := s.storage.Delete(ctx, media.StorageID); err != nil {
		return fmt.Errorf("failed to delete file from storage: %w", err)
	}

	// Delete from database
	if err := s.client.Media.DeleteOne(media).Exec(ctx); err != nil {
		return fmt.Errorf("failed to delete media record: %w", err)
	}

	return nil
}

func (s *mediaService) List(ctx context.Context, limit, offset int) ([]*ent.Media, error) {
	media, err := s.client.Media.Query().
		Order(ent.Desc("created_at")).
		Limit(limit).
		Offset(offset).
		All(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to list media: %w", err)
	}
	return media, nil
}

func (s *mediaService) GetFile(ctx context.Context, id int) (io.ReadCloser, *storage.FileInfo, error) {
	media, err := s.Get(ctx, id)
	if err != nil {
		return nil, nil, err
	}

	reader, info, err := s.storage.Get(ctx, media.StorageID)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to get file from storage: %w", err)
	}

	return reader, info, nil
}