import 'dart:io';

import 'package:dio/dio.dart';
import 'package:file_picker/file_picker.dart';
import 'package:image_picker/image_picker.dart';

class AttachmentFile {
  final String path;
  final String name;
  final int sizeBytes;
  final String extension;
  final String mimeType;

  const AttachmentFile({
    required this.path,
    required this.name,
    required this.sizeBytes,
    required this.extension,
    required this.mimeType,
  });

  /// 根据扩展名判断是否为图片
  bool get isImage {
    const imageExts = {'jpg', 'jpeg', 'png', 'gif', 'bmp', 'webp', 'heic'};
    return imageExts.contains(extension);
  }

  /// 从本地路径创建（读取文件大小）
  static Future<AttachmentFile> fromPath(String path) async {
    final name = _extractName(path);
    final ext = _extractExt(name);
    final size = await File(path).length();
    return AttachmentFile(
      path: path,
      name: name,
      sizeBytes: size,
      extension: ext,
      mimeType: _inferMimeType(ext),
    );
  }

  /// 从 FilePicker 的 PlatformFile 创建
  factory AttachmentFile.fromPlatformFile(PlatformFile file) {
    final name = file.name;
    final ext = _extractExt(name);
    return AttachmentFile(
      path: file.path ?? '',
      name: name,
      sizeBytes: file.size,
      extension: ext,
      mimeType: _inferMimeType(ext),
    );
  }

  /// 从 ImagePicker 的 XFile 创建
  static Future<AttachmentFile> fromXFile(XFile xfile) async {
    final name = _extractName(xfile.path);
    final ext = _extractExt(name);
    final size = await xfile.length();
    return AttachmentFile(
      path: xfile.path,
      name: name,
      sizeBytes: size,
      extension: ext,
      mimeType: _inferMimeType(ext),
    );
  }

  /// 转换为 Dio MultipartFile，可直接用于 FormData 上传
  Future<MultipartFile> toMultipartFile({String fieldName = 'files'}) {
    return MultipartFile.fromFile(
      path,
      filename: name,
      contentType: DioMediaType.parse(mimeType),
    );
  }

  /// 文件大小（MB）
  double get sizeMB => sizeBytes / (1024 * 1024);

  // ── 私有工具方法 ──

  static String _extractName(String path) {
    return path.split('/').last.split('\\').last;
  }

  static String _extractExt(String name) {
    return name.split('.').last.toLowerCase();
  }

  static String _inferMimeType(String ext) {
    switch (ext) {
      case 'jpg':
      case 'jpeg':
        return 'image/jpeg';
      case 'png':
        return 'image/png';
      case 'gif':
        return 'image/gif';
      case 'bmp':
        return 'image/bmp';
      case 'webp':
        return 'image/webp';
      case 'heic':
        return 'image/heic';
      case 'pdf':
        return 'application/pdf';
      case 'doc':
        return 'application/msword';
      case 'docx':
        return 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';
      case 'xls':
        return 'application/vnd.ms-excel';
      case 'xlsx':
        return 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
      case 'ppt':
        return 'application/vnd.ms-powerpoint';
      case 'pptx':
        return 'application/vnd.openxmlformats-officedocument.presentationml.presentation';
      case 'txt':
        return 'text/plain';
      default:
        return 'application/octet-stream';
    }
  }
}