import 'dart:io';

import 'package:image/image.dart' as img;
import 'package:path_provider/path_provider.dart';

/// 上传前压缩：限制长边、JPEG 质量，减轻内存与带宽；解码失败时返回原文件。
Future<File> compressImageForUpload(
  File source, {
  int maxSide = 2048,
  int jpegQuality = 85,
}) async {
  try {
    final raw = await source.readAsBytes();
    final image = img.decodeImage(raw);
    if (image == null) return source;

    var work = image;
    if (work.width > maxSide || work.height > maxSide) {
      if (work.width >= work.height) {
        work = img.copyResize(work, width: maxSide, interpolation: img.Interpolation.linear);
      } else {
        work = img.copyResize(work, height: maxSide, interpolation: img.Interpolation.linear);
      }
    }

    final jpg = img.encodeJpg(work, quality: jpegQuality);

    final dir = await getTemporaryDirectory();
    final out = File(
      '${dir.path}/upload_${DateTime.now().millisecondsSinceEpoch}.jpg',
    );
    await out.writeAsBytes(jpg, flush: true);
    return out;
  } catch (_) {
    return source;
  }
}