patbond-flutter/lib/features/community/media_compression.dart

import 'dart:typed_data';

import 'package:flutter_image_compress/flutter_image_compress.dart';
import 'package:patbond_flutter/features/community/media_picking.dart';

/// 压缩产物（直传本体）。mimeType 与直传 PUT 的 Content-Type、
/// createUpload 登记值三处必须一致（Content-Type 已签进预签名签名）。
class CompressedMediaImage {
  const CompressedMediaImage({required this.bytes, required this.mimeType});

  final Uint8List bytes;
  final String mimeType;

  int get byteSize => bytes.length;
}

/// 压缩抽象：quality 由 MediaUploader 的降质阶梯驱动（80 → 60），
/// 单测注入假实现控制产物大小。
abstract class MediaImageCompressor {
  Future<CompressedMediaImage> compress(
    PickedMediaImage source, {
    required int quality,
  });
}

/// 基于 flutter_image_compress 的原生压缩实现（03 号评估 §4.1 选型）。
///
/// 策略（03 号 §4.1 + 13 号报告偏差 #6）：长边 ≤2048 重采样、统一转码
/// JPEG（服务端 mime 白名单不收 HEIC，客户端统一出 jpeg）；
/// autoCorrectionAngle 矫正方向后不保留 EXIF——顺带剥离 GPS 定位隐私，
/// **不要开 keepExif**。
class NativeMediaImageCompressor implements MediaImageCompressor {
  const NativeMediaImageCompressor({this.maxLongEdge = 2048});

  final int maxLongEdge;

  @override
  Future<CompressedMediaImage> compress(
    PickedMediaImage source, {
    required int quality,
  }) async {
    final bytes = await FlutterImageCompress.compressWithList(
      source.bytes,
      minWidth: maxLongEdge,
      minHeight: maxLongEdge,
      quality: quality,
      format: CompressFormat.jpeg,
      autoCorrectionAngle: true,
      keepExif: false,
    );
    return CompressedMediaImage(bytes: bytes, mimeType: 'image/jpeg');
  }
}