// lib/metadata/metadata_normalizer.dart
import 'metadata_model.dart';

class MetadataNormalizer {
  /// 标准化原始数据（清洗空格、推断、fallback）
  NormalizedMetadata normalize(RawMetadata raw,
      {String fileName = '', String filePath = ''}) {
    // 1. 修剪空格
    final title = raw.title.trim();
    final artist = raw.artist.trim();
    final album = raw.album.trim();
    final albumArtist = raw.albumArtist.trim();

    // 2. 如果 title 为空，尝试从文件名推断
    final finalTitle =
        title.isNotEmpty ? title : _inferTitleFromFileName(fileName);

    // 3. 如果 artist 为空，尝试从路径推断或使用默认值
    final finalArtist =
        artist.isNotEmpty ? artist : _inferArtistFromPath(filePath);

    return NormalizedMetadata(
      title: finalTitle,
      artist: finalArtist,
      album: album,
      albumArtist: albumArtist,
      composer: raw.composer.trim(),
      genre: raw.genre.trim(),
      year: raw.year,
      trackNumber: raw.trackNumber,
      discNumber: raw.discNumber,
      artwork: raw.artwork,
    );
  }

  String _inferTitleFromFileName(String fileName) {
    // 去掉扩展名
    final dotIndex = fileName.lastIndexOf('.');
    if (dotIndex > 0) {
      return fileName.substring(0, dotIndex).trim();
    }
    return fileName.trim();
  }

  String _inferArtistFromPath(String filePath) {
    // 简单推断：尝试从路径中的文件夹名获取
    final parts = filePath.split(RegExp(r'[/\\]'));
    if (parts.length >= 2) {
      // 倒数第二个文件夹可能是艺术家
      final candidate = parts[parts.length - 2].trim();
      if (candidate.isNotEmpty && !candidate.contains(' ')) {
        return candidate;
      }
    }
    return '未知艺术家';
  }

  /// 评估候选元数据（第一阶段：直接接受，不纠错）
  CandidateMetadata evaluate(
      NormalizedMetadata normalized, List<Map<String, dynamic>> history) {
    // 第一阶段：置信度固定为 0.8（文件名+标签混合）
    return CandidateMetadata(
      metadata: normalized,
      confidence: 0.8,
      evidence: {'normalized': 0.8},
    );
  }

  /// 决策是否修正（第一阶段：直接接受）
  FinalMetadata decide(CandidateMetadata candidate, {double threshold = 0.6}) {
    return FinalMetadata(
      title: candidate.metadata.title,
      artist: candidate.metadata.artist,
      album: candidate.metadata.album,
      albumArtist: candidate.metadata.albumArtist,
      composer: candidate.metadata.composer,
      genre: candidate.metadata.genre,
      year: candidate.metadata.year,
      trackNumber: candidate.metadata.trackNumber,
      discNumber: candidate.metadata.discNumber,
      artwork: candidate.metadata.artwork,
      source: 'normalized',
    );
  }
}