nj/app/lib/data/models/sync_models.dart

// 同步协议模型 — 与 Rust 端 SyncReq/SyncResp/SyncChange/ConflictInfo 一一对应
//
// 端点: POST /api/v1/diary/sync
// Rust DTO: crates/erp-diary/src/dto.rs (SyncReq, SyncResp, SyncChange, ConflictInfo)

/// 同步请求 — 与 Rust SyncReq 对应
///
/// ```rust
/// pub struct SyncReq {
///     pub last_sync_time: Option<DateTime<Utc>>,
///     pub changes: Vec<SyncChange>,
/// }
/// ```
class SyncReq {
  final DateTime? lastSyncTime;
  final List<SyncChange> changes;

  const SyncReq({this.lastSyncTime, this.changes = const []});

  Map<String, dynamic> toJson() => {
        if (lastSyncTime != null)
          'last_sync_time': lastSyncTime!.toUtc().toIso8601String(),
        'changes': changes.map((c) => c.toJson()).toList(),
      };
}

/// 同步变更条目 — 与 Rust SyncChange 枚举对应
///
/// ```rust
/// pub enum SyncChange {
///     CreateJournal { data: serde_json::Value },
///     UpdateJournal { id: Uuid, version: i32, data: serde_json::Value },
///     DeleteJournal { id: Uuid, version: i32 },
/// }
/// ```
sealed class SyncChange {
  const SyncChange();

  Map<String, dynamic> toJson();

  /// 从 JSON 反序列化
  factory SyncChange.fromJson(Map<String, dynamic> json) {
    if (json.containsKey('CreateJournal')) {
      return SyncChangeCreateJournal(
        data: json['CreateJournal']['data'] as Map<String, dynamic>,
      );
    }
    if (json.containsKey('UpdateJournal')) {
      final inner = json['UpdateJournal'] as Map<String, dynamic>;
      return SyncChangeUpdateJournal(
        id: inner['id'] as String,
        version: inner['version'] as int,
        data: inner['data'] as Map<String, dynamic>,
      );
    }
    if (json.containsKey('DeleteJournal')) {
      final inner = json['DeleteJournal'] as Map<String, dynamic>;
      return SyncChangeDeleteJournal(
        id: inner['id'] as String,
        version: inner['version'] as int,
      );
    }
    throw FormatException('Unknown SyncChange variant: $json');
  }
}

/// 创建日记变更
class SyncChangeCreateJournal extends SyncChange {
  final Map<String, dynamic> data;

  const SyncChangeCreateJournal({required this.data});

  @override
  Map<String, dynamic> toJson() => {
        'CreateJournal': {'data': data},
      };
}

/// 更新日记变更
class SyncChangeUpdateJournal extends SyncChange {
  final String id;
  final int version;
  final Map<String, dynamic> data;

  const SyncChangeUpdateJournal({
    required this.id,
    required this.version,
    required this.data,
  });

  @override
  Map<String, dynamic> toJson() => {
        'UpdateJournal': {
          'id': id,
          'version': version,
          'data': data,
        },
      };
}

/// 删除日记变更
class SyncChangeDeleteJournal extends SyncChange {
  final String id;
  final int version;

  const SyncChangeDeleteJournal({
    required this.id,
    required this.version,
  });

  @override
  Map<String, dynamic> toJson() => {
        'DeleteJournal': {
          'id': id,
          'version': version,
        },
      };
}

/// 同步响应 — 与 Rust SyncResp 对应
///
/// ```rust
/// pub struct SyncResp {
///     pub server_changes: Vec<serde_json::Value>,
///     pub conflicts: Vec<ConflictInfo>,
///     pub sync_time: DateTime<Utc>,
/// }
/// ```
class SyncResp {
  final List<Map<String, dynamic>> serverChanges;
  final List<ConflictInfo> conflicts;
  final DateTime syncTime;

  const SyncResp({
    required this.serverChanges,
    required this.conflicts,
    required this.syncTime,
  });

  factory SyncResp.fromJson(Map<String, dynamic> json) => SyncResp(
        serverChanges: (json['server_changes'] as List)
            .map((e) => Map<String, dynamic>.from(e as Map))
            .toList(),
        conflicts: (json['conflicts'] as List)
            .map((e) => ConflictInfo.fromJson(Map<String, dynamic>.from(e as Map)))
            .toList(),
        syncTime: DateTime.parse(json['sync_time'] as String),
      );
}

/// 冲突信息 — 与 Rust ConflictInfo 对应
///
/// ```rust
/// pub struct ConflictInfo {
///     pub journal_id: Uuid,
///     pub local_version: i32,
///     pub server_version: i32,
/// }
/// ```
class ConflictInfo {
  final String journalId;
  final int localVersion;
  final int serverVersion;

  const ConflictInfo({
    required this.journalId,
    required this.localVersion,
    required this.serverVersion,
  });

  factory ConflictInfo.fromJson(Map<String, dynamic> json) => ConflictInfo(
        journalId: json['journal_id'] as String,
        localVersion: json['local_version'] as int,
        serverVersion: json['server_version'] as int,
      );
}