package services

import (
	"fmt"
	"io"
	"mime/multipart"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/rs/zerolog/log"

	"github.com/treytartt/mycrib-api/internal/config"
)

// StorageService handles file uploads to local filesystem
type StorageService struct {
	cfg *config.StorageConfig
}

// UploadResult contains information about an uploaded file
type UploadResult struct {
	URL      string `json:"url"`
	FileName string `json:"file_name"`
	FileSize int64  `json:"file_size"`
	MimeType string `json:"mime_type"`
}

// NewStorageService creates a new storage service
func NewStorageService(cfg *config.StorageConfig) (*StorageService, error) {
	// Ensure upload directory exists
	if err := os.MkdirAll(cfg.UploadDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create upload directory: %w", err)
	}

	// Create subdirectories for organization
	subdirs := []string{"images", "documents", "completions"}
	for _, subdir := range subdirs {
		path := filepath.Join(cfg.UploadDir, subdir)
		if err := os.MkdirAll(path, 0755); err != nil {
			return nil, fmt.Errorf("failed to create subdirectory %s: %w", subdir, err)
		}
	}

	log.Info().Str("upload_dir", cfg.UploadDir).Msg("Storage service initialized")

	return &StorageService{cfg: cfg}, nil
}

// Upload saves a file to the local filesystem
func (s *StorageService) Upload(file *multipart.FileHeader, category string) (*UploadResult, error) {
	// Validate file size
	if file.Size > s.cfg.MaxFileSize {
		return nil, fmt.Errorf("file size %d exceeds maximum allowed %d bytes", file.Size, s.cfg.MaxFileSize)
	}

	// Get MIME type
	mimeType := file.Header.Get("Content-Type")
	if mimeType == "" {
		mimeType = "application/octet-stream"
	}

	// Validate MIME type
	if !s.isAllowedType(mimeType) {
		return nil, fmt.Errorf("file type %s is not allowed", mimeType)
	}

	// Generate unique filename
	ext := filepath.Ext(file.Filename)
	if ext == "" {
		ext = s.getExtensionFromMimeType(mimeType)
	}
	newFilename := fmt.Sprintf("%s_%s%s", time.Now().Format("20060102"), uuid.New().String()[:8], ext)

	// Determine subdirectory based on category
	subdir := "images"
	switch category {
	case "document", "documents":
		subdir = "documents"
	case "completion", "completions":
		subdir = "completions"
	}

	// Full path
	destPath := filepath.Join(s.cfg.UploadDir, subdir, newFilename)

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

	// Create destination file
	dst, err := os.Create(destPath)
	if err != nil {
		return nil, fmt.Errorf("failed to create destination file: %w", err)
	}
	defer dst.Close()

	// Copy file content
	written, err := io.Copy(dst, src)
	if err != nil {
		// Clean up on error
		os.Remove(destPath)
		return nil, fmt.Errorf("failed to save file: %w", err)
	}

	// Generate URL
	url := fmt.Sprintf("%s/%s/%s", s.cfg.BaseURL, subdir, newFilename)

	log.Info().
		Str("filename", newFilename).
		Str("category", category).
		Int64("size", written).
		Str("mime_type", mimeType).
		Msg("File uploaded successfully")

	return &UploadResult{
		URL:      url,
		FileName: file.Filename,
		FileSize: written,
		MimeType: mimeType,
	}, nil
}

// Delete removes a file from storage
func (s *StorageService) Delete(fileURL string) error {
	// Convert URL to file path
	relativePath := strings.TrimPrefix(fileURL, s.cfg.BaseURL)
	relativePath = strings.TrimPrefix(relativePath, "/")
	fullPath := filepath.Join(s.cfg.UploadDir, relativePath)

	// Security check: ensure path is within upload directory
	absUploadDir, _ := filepath.Abs(s.cfg.UploadDir)
	absFilePath, _ := filepath.Abs(fullPath)
	if !strings.HasPrefix(absFilePath, absUploadDir) {
		return fmt.Errorf("invalid file path")
	}

	if err := os.Remove(fullPath); err != nil {
		if os.IsNotExist(err) {
			return nil // File already doesn't exist
		}
		return fmt.Errorf("failed to delete file: %w", err)
	}

	log.Info().Str("path", fullPath).Msg("File deleted")
	return nil
}

// isAllowedType checks if the MIME type is in the allowed list
func (s *StorageService) isAllowedType(mimeType string) bool {
	allowed := strings.Split(s.cfg.AllowedTypes, ",")
	for _, t := range allowed {
		if strings.TrimSpace(t) == mimeType {
			return true
		}
	}
	return false
}

// getExtensionFromMimeType returns a file extension for common MIME types
func (s *StorageService) getExtensionFromMimeType(mimeType string) string {
	extensions := map[string]string{
		"image/jpeg":      ".jpg",
		"image/png":       ".png",
		"image/gif":       ".gif",
		"image/webp":      ".webp",
		"application/pdf": ".pdf",
	}
	if ext, ok := extensions[mimeType]; ok {
		return ext
	}
	return ""
}

// GetUploadDir returns the upload directory path
func (s *StorageService) GetUploadDir() string {
	return s.cfg.UploadDir
}