/**
 * 快照管理器 - 管理文件的 Base/Suggest 双版本
 */

import { v4 as uuidv4 } from 'uuid';
import { Snapshot, DiffChunk, ChunkStatus } from '../models/types';

export class SnapshotManager {
  private snapshots: Map<string, Snapshot> = new Map();
  private filePathIndex: Map<string, string> = new Map(); // filePath -> snapshotId

  /**
   * 创建 Base 快照
   */
  createBaseSnapshot(filePath: string, baseContent: string): string {
    const id = uuidv4();
    const snapshot: Snapshot = {
      id,
      filePath,
      baseContent,
      suggestContent: '',
      timestamp: Date.now(),
      chunks: [],
      status: 'active',
    };

    this.snapshots.set(id, snapshot);
    this.filePathIndex.set(filePath, id);

    return id;
  }

  /**
   * 应用 AI 生成的 Patch
   */
  applyPatch(snapshotId: string, patch: string, chunks: DiffChunk[]): void {
    const snapshot = this.snapshots.get(snapshotId);
    if (!snapshot) {
      throw new Error(`快照不存在: ${snapshotId}`);
    }

    snapshot.suggestContent = patch;
    snapshot.chunks = chunks;
  }

  /**
   * 获取快照
   */
  getSnapshot(snapshotId: string): Snapshot | undefined {
    return this.snapshots.get(snapshotId);
  }

  /**
   * 根据文件路径获取快照
   */
  getSnapshotByFilePath(filePath: string): Snapshot | undefined {
    const snapshotId = this.filePathIndex.get(filePath);
    if (!snapshotId) return undefined;
    return this.snapshots.get(snapshotId);
  }

  /**
   * 更新变更块状态
   */
  updateChunkStatus(snapshotId: string, chunkId: string, status: ChunkStatus): void {
    const snapshot = this.snapshots.get(snapshotId);
    if (!snapshot) return;

    const chunk = snapshot.chunks.find(c => c.id === chunkId);
    if (chunk) {
      chunk.status = status;
    }
  }

  /**
   * 批量更新变更块状态
   */
  updateAllChunksStatus(snapshotId: string, status: ChunkStatus): void {
    const snapshot = this.snapshots.get(snapshotId);
    if (!snapshot) return;

    snapshot.chunks.forEach(chunk => {
      chunk.status = status;
    });
  }

  /**
   * 标记快照完成
   */
  completeSnapshot(snapshotId: string): void {
    const snapshot = this.snapshots.get(snapshotId);
    if (!snapshot) return;

    snapshot.status = 'completed';
    this.filePathIndex.delete(snapshot.filePath);
  }

  /**
   * 取消快照
   */
  cancelSnapshot(snapshotId: string): void {
    const snapshot = this.snapshots.get(snapshotId);
    if (!snapshot) return;

    snapshot.status = 'cancelled';
    this.filePathIndex.delete(snapshot.filePath);
  }

  /**
   * 删除快照
   */
  deleteSnapshot(snapshotId: string): void {
    const snapshot = this.snapshots.get(snapshotId);
    if (snapshot) {
      this.filePathIndex.delete(snapshot.filePath);
    }
    this.snapshots.delete(snapshotId);
  }

  /**
   * 获取所有活跃快照
   */
  getActiveSnapshots(): Snapshot[] {
    return Array.from(this.snapshots.values()).filter(s => s.status === 'active');
  }

  /**
   * 检查文件是否有活跃快照
   */
  hasActiveSnapshot(filePath: string): boolean {
    const snapshotId = this.filePathIndex.get(filePath);
    if (!snapshotId) return false;
    const snapshot = this.snapshots.get(snapshotId);
    return snapshot?.status === 'active';
  }

  /**
   * 清理已完成或取消的快照
   */
  cleanup(): void {
    for (const [id, snapshot] of this.snapshots.entries()) {
      if (snapshot.status !== 'active') {
        this.filePathIndex.delete(snapshot.filePath);
        this.snapshots.delete(id);
      }
    }
  }
}