/**
 * Workspace Service — 工作空间管理
 *
 * 负责：
 * 1. 工作空间目录的创建和验证
 * 2. 4 个必需磁盘文件的加载和自动创建
 * 3. MEMORY.md 格式校验和自动修正
 *
 * @see docs/MetonaAI-Desktop 架构与交互设计.html — 工作空间
 * @see standard/开发规范.md — 使用 fs/path 内置模块（非第三方库）
 */

import { join } from 'path';
import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'fs';
import { app } from 'electron';
import log from 'electron-log';

// ===== 类型定义 =====

export interface WorkspaceFiles {
  soul: string;
  agents: string;
  memory: string;
  users: string;
}

export interface WorkspaceInfo {
  path: string;
  files: WorkspaceFiles;
  isValid: boolean;
  missingFiles: string[];
}

// ===== 常量 =====

const REQUIRED_FILES = ['SOUL.md', 'AGENTS.md', 'MEMORY.md', 'USERS.md'] as const;

const AUTO_CREATED_DIRS = ['logs', 'traces', '.metona'] as const;

const MEMORY_TEMPLATE = `# MEMORY.md — AI 持久记忆

> 创建时间: __CREATED_AT__
> 最后更新: __UPDATED_AT__
> 工作空间: __WORKSPACE_PATH__

## 用户偏好

## 项目上下文

## 重要决策

## 待办事项

## 已知问题
`;

// ===== 服务类 =====

export class WorkspaceService {
  private workspacePath: string;
  private files: WorkspaceFiles = { soul: '', agents: '', memory: '', users: '' };

  constructor(workspacePath?: string) {
    this.workspacePath = workspacePath ?? join(app.getPath('userData'), 'MetonaWorkspaces', 'default');
  }

  /**
   * 初始化工作空间
   *
   * 1. 创建目录结构
   * 2. 验证/创建 4 个必需文件
   * 3. 加载文件内容
   */
  initialize(): WorkspaceInfo {
    log.info(`Initializing workspace: ${this.workspacePath}`);

    // 创建工作空间目录
    this.ensureDirectory(this.workspacePath);

    // 创建自动目录（logs/, traces/, .metona/）
    for (const dir of AUTO_CREATED_DIRS) {
      this.ensureDirectory(join(this.workspacePath, dir));
    }

    // 验证/创建必需文件
    const missingOnStart: string[] = [];
    for (const fileName of REQUIRED_FILES) {
      const filePath = join(this.workspacePath, fileName);
      if (!existsSync(filePath)) {
        missingOnStart.push(fileName);
        this.createFile(fileName);
      }
    }

    // 加载文件内容（在自动创建之后）
    this.loadFiles();

    // 校验 MEMORY.md 格式
    this.validateMemoryFormat();

    // isValid: 所有文件均已就绪（包含刚自动创建的）
    const isValid = true;
    if (missingOnStart.length > 0) {
      log.info(`Auto-created missing files: ${missingOnStart.join(', ')}`);
    }

    log.info(`Workspace initialized: ${this.workspacePath} (valid: ${isValid})`);

    return {
      path: this.workspacePath,
      files: { ...this.files },
      isValid,
      missingFiles: missingOnStart,
    };
  }

  /**
   * 获取工作空间路径
   */
  getPath(): string {
    return this.workspacePath;
  }

  /**
   * 获取文件内容
   */
  getFiles(): WorkspaceFiles {
    return { ...this.files };
  }

  /**
   * 重新加载文件（用户可能在外部编辑）
   */
  reload(): WorkspaceFiles {
    this.loadFiles();
    this.validateMemoryFormat();
    return { ...this.files };
  }

  /**
   * 更新 MEMORY.md 的最后更新时间戳
   */
  updateMemoryTimestamp(): void {
    const memoryPath = join(this.workspacePath, 'MEMORY.md');
    if (!existsSync(memoryPath)) return;

    let content = readFileSync(memoryPath, 'utf-8');
    const now = new Date().toISOString();

    content = content.replace(
      /> 最后更新: .*/,
      `> 最后更新: ${now}`,
    );

    writeFileSync(memoryPath, content, 'utf-8');
    this.files.memory = content;
    log.info('MEMORY.md timestamp updated');
  }

  /**
   * 追加记忆到 MEMORY.md
   */
  appendMemory(section: string, entry: string): void {
    const memoryPath = join(this.workspacePath, 'MEMORY.md');
    if (!existsSync(memoryPath)) return;

    let content = readFileSync(memoryPath, 'utf-8');

    // 查找目标 section
    const sectionRegex = new RegExp(`## ${section}\\b`);
    const sectionMatch = content.match(sectionRegex);

    if (sectionMatch) {
      // 在 section 末尾追加
      const sectionIndex = content.indexOf(sectionMatch[0]) + sectionMatch[0].length;
      const nextSectionIndex = content.indexOf('\n## ', sectionIndex);
      const insertPoint = nextSectionIndex === -1 ? content.length : nextSectionIndex;

      const before = content.slice(0, insertPoint).trimEnd();
      const after = content.slice(insertPoint);
      content = `${before}\n- ${entry}\n${after}`;
    } else {
      // section 不存在，追加到文件末尾
      content += `\n## ${section}\n- ${entry}\n`;
    }

    // 更新时间戳
    content = content.replace(
      /> 最后更新: .*/,
      `> 最后更新: ${new Date().toISOString()}`,
    );

    writeFileSync(memoryPath, content, 'utf-8');
    this.files.memory = content;
    log.info(`MEMORY.md: appended to section "${section}"`);
  }

  /**
   * 校验 MEMORY.md 格式
   *
   * 简化规则：
   * 1. 元数据头 — 用 > 引用语法，包含创建时间、最后更新、工作空间
   * 2. 分区结构 — 包含用户偏好、项目上下文、重要决策（其余可选）
   * 3. 时间戳自动更新
   */
  validateMemoryFormat(): boolean {
    const memoryPath = join(this.workspacePath, 'MEMORY.md');
    if (!existsSync(memoryPath)) return false;

    let content = readFileSync(memoryPath, 'utf-8');
    let modified = false;

    // 规则 1: 元数据头（> 引用语法）
    const requiredMeta: Array<{ key: string; line: string }> = [
      { key: '> 创建时间', line: `> 创建时间: ${new Date().toISOString()}` },
      { key: '> 最后更新', line: `> 最后更新: ${new Date().toISOString()}` },
      { key: '> 工作空间', line: `> 工作空间: ${this.workspacePath}` },
    ];
    for (const meta of requiredMeta) {
      if (!content.includes(meta.key)) {
        // v0.3.0 修复: 检查 # MEMORY 标题是否存在，不存在则在文件开头插入
        const memoryTitleIdx = content.indexOf('# MEMORY');
        let titleEnd: number;
        if (memoryTitleIdx === -1) {
          // 标题不存在，在开头插入
          titleEnd = 0;
        } else {
          titleEnd = content.indexOf('\n', memoryTitleIdx) + 1;
          // 如果没有换行符（文件只有一行），titleEnd 为 0，在末尾插入
          if (titleEnd === 0) titleEnd = content.length;
        }
        content = content.slice(0, titleEnd) + meta.line + '\n' + content.slice(titleEnd);
        modified = true;
        log.info(`MEMORY.md: auto-added missing metadata "${meta.key}"`);
      }
    }

    // 规则 2: 核心分区
    const requiredSections = ['## 用户偏好', '## 项目上下文', '## 重要决策'];
    for (const section of requiredSections) {
      if (!content.includes(section)) {
        content += `\n${section}\n`;
        modified = true;
        log.info(`MEMORY.md: auto-added missing section "${section}"`);
      }
    }

    // 规则 3: 时间戳更新
    const now = new Date().toISOString();
    content = content.replace(/> 最后更新: .*/, `> 最后更新: ${now}`);

    if (modified) {
      writeFileSync(memoryPath, content, 'utf-8');
      this.files.memory = content;
      log.info('MEMORY.md: format validation completed, auto-corrected');
    }

    return !modified;
  }

  // ===== 私有方法 =====

  /**
   * 确保目录存在
   */
  private ensureDirectory(dirPath: string): void {
    if (!existsSync(dirPath)) {
      mkdirSync(dirPath, { recursive: true });
      log.debug(`Created directory: ${dirPath}`);
    }
  }

  /**
   * 创建必需文件
   */
  private createFile(fileName: string): void {
    const filePath = join(this.workspacePath, fileName);

    switch (fileName) {
      case 'MEMORY.md': {
        const now = new Date().toISOString();
        const content = MEMORY_TEMPLATE
          .replace('__WORKSPACE_PATH__', this.workspacePath)
          .replace('__CREATED_AT__', now)
          .replace('__UPDATED_AT__', now);
        writeFileSync(filePath, content, 'utf-8');
        break;
      }
      case 'SOUL.md':
        writeFileSync(filePath, '# SOUL.md — AI 灵魂定义\n\n# 用户可在此定义 Agent 的身份、性格和核心价值观\n', 'utf-8');
        break;
      case 'AGENTS.md':
        writeFileSync(filePath, '# AGENTS.md — AI 行为定义\n\n# 用户可在此定义 Agent 的行为规则和边界\n', 'utf-8');
        break;
      case 'USERS.md':
        writeFileSync(filePath, '# USERS.md — 用户信息画像\n\n# 用户可在此描述自己的背景、技能和偏好\n', 'utf-8');
        break;
    }

    log.info(`Auto-created file: ${fileName}`);
  }

  /**
   * 加载所有文件内容
   */
  private loadFiles(): void {
    this.files.soul = this.readFile('SOUL.md');
    this.files.agents = this.readFile('AGENTS.md');
    this.files.memory = this.readFile('MEMORY.md');
    this.files.users = this.readFile('USERS.md');
  }

  /**
   * 读取单个文件
   */
  private readFile(fileName: string): string {
    const filePath = join(this.workspacePath, fileName);
    try {
      return readFileSync(filePath, 'utf-8');
    } catch {
      log.warn(`Failed to read file: ${filePath}`);
      return '';
    }
  }
}