/**
 * Task Orchestrator — 任务编排器
 *
 * 支持父子委派模式：主 Agent 委派子任务给 SubAgent。
 * 每个 SubAgent 运行在**独立的 AgentLoopEngine 实例**中，避免状态污染。
 *
 * 安全保障：
 * 1. 独立引擎实例 — SubAgent 不共享主 Agent 的引擎状态
 * 2. 递归深度限制 — 默认最大 3 层，防止无限递归
 * 3. 工具白名单隔离 — SubAgent 默认不继承 delegate_task（防止递归）
 * 4. 真正的 abort — 通过引擎引用调用 engine.abort()
 * 5. 事件隔离 — SubAgent 的流式事件不直接转发到前端，仅通过 orchestrator 事件通知
 *
 * @see docs/生产级通用 AI Agent 智能体桌面应用：完整设计与构建指南.html — 第五章
 */

import { EventEmitter } from 'events';
import { nanoid } from 'nanoid';
import { AgentLoopEngine } from '../agent-loop/engine';
import type { AgentLoopConfig } from '../agent-loop/types';
import type { MetonaMessage, MetonaSystemPrompt, MetonaToolDef } from '../types';
import type { ToolRegistry } from '../tools/registry';
import type { PreToolHook } from '../hooks/pre-tool';
import type { PostToolHook } from '../hooks/post-tool';
import log from 'electron-log';

export interface SubAgentResult {
  taskId: string;
  result: string;
  success: boolean;
  durationMs: number;
  iterations: number;
}

interface SubAgentHandle {
  taskId: string;
  description: string;
  status: 'pending' | 'running' | 'completed' | 'error';
  depth: number;
  engine?: AgentLoopEngine;
  result?: SubAgentResult;
  abort: () => void;
  getStatus: () => { taskId: string; status: string; description: string; depth: number };
}

/** 默认递归深度限制 */
const MAX_DELEGATION_DEPTH = 3;

export class TaskOrchestrator extends EventEmitter {
  private activeSubAgents = new Map<string, SubAgentHandle>();
  /** 追踪每个 session 的当前委派深度 */
  private sessionDepth = new Map<string, number>();

  constructor(
    private mainEngine: AgentLoopEngine,
    private toolRegistry?: ToolRegistry,
    private preToolHooks: PreToolHook[] = [],
    private postToolHooks: PostToolHook[] = [],
    private defaultConfig?: Partial<AgentLoopConfig>,
  ) {
    super();
  }

  /**
   * 委派子任务
   *
   * 创建一个独立的 AgentLoopEngine 实例执行子任务。
   * SubAgent 不共享主 Agent 的引擎状态，安全隔离。
   */
  async delegate(params: {
    taskId?: string;
    description: string;
    parentSessionId: string;
    maxIterations?: number;
    tools?: string[];
  }): Promise<SubAgentResult> {
    const taskId = params.taskId ?? `sub_${nanoid(8)}`;
    const startMs = Date.now();

    // ===== 递归深度检查 =====
    const currentDepth = this.sessionDepth.get(params.parentSessionId) ?? 0;
    if (currentDepth >= MAX_DELEGATION_DEPTH) {
      log.warn(`[Orchestrator] Delegation depth limit reached (${currentDepth}) for session ${params.parentSessionId}`);
      return {
        taskId,
        result: `SubAgent delegation depth limit reached (${MAX_DELEGATION_DEPTH}). Cannot delegate further.`,
        success: false,
        durationMs: 0,
        iterations: 0,
      };
    }
    const depth = currentDepth + 1;
    this.sessionDepth.set(params.parentSessionId, depth);

    this.emit('taskDelegated', { taskId, description: params.description, parentSessionId: params.parentSessionId, depth });

    // ===== 创建独立的引擎实例 =====
    const subEngine = new AgentLoopEngine(
      {
        maxIterations: params.maxIterations ?? 10,
        totalTimeoutMs: 300_000, // 子任务总超时 5 分钟
        thinkingEnabled: this.defaultConfig?.thinkingEnabled ?? true,
        thinkingEffort: this.defaultConfig?.thinkingEffort ?? 'medium',
        contextLength: this.defaultConfig?.contextLength,
        contextWindow: this.defaultConfig?.contextWindow ?? 128_000,
      },
      this.mainEngine.getAdapter(),
      this.toolRegistry,
      this.preToolHooks,
      this.postToolHooks,
    );
    subEngine.setWorkspacePath(this.mainEngine.getWorkspacePath());

    // ===== 工具白名单设置 =====
    const allowedTools = this.resolveTools(params.tools);
    subEngine.setTools(allowedTools);

    const handle: SubAgentHandle = {
      taskId,
      description: params.description,
      status: 'running',
      depth,
      engine: subEngine,
      abort: () => {
        subEngine.abort();
        handle.status = 'error';
        this.activeSubAgents.delete(taskId);
      },
      getStatus: () => ({ taskId, status: handle.status, description: handle.description, depth: handle.depth }),
    };

    this.activeSubAgents.set(taskId, handle);
    this.emit('taskStarted', { taskId, depth });

    try {
      // 构建用户消息
      const userMessage: MetonaMessage = {
        role: 'user',
        content: params.description,
        timestamp: Date.now(),
      };

      // 构建 System Prompt（子 Agent 专用）
      const systemPrompt = this.buildSubAgentPrompt(params.description, depth);

      // 运行 Agent Loop（同步等待完成）
      const output = await subEngine.runStream(
        userMessage,
        taskId,
        [],  // 子 Agent 无历史
        systemPrompt,
      );

      const durationMs = Date.now() - startMs;
      const success = output.terminationReason === 'completed';
      const result: SubAgentResult = {
        taskId,
        result: output.finalAnswer,
        success,
        durationMs,
        iterations: output.iterations.length,
      };

      handle.status = success ? 'completed' : 'error';
      handle.result = result;
      this.activeSubAgents.delete(taskId);
      // v0.3.0 修复: 深度恢复为 0 时删除条目，避免 sessionDepth Map 随会话累积
      if (currentDepth === 0) {
        this.sessionDepth.delete(params.parentSessionId);
      } else {
        this.sessionDepth.set(params.parentSessionId, currentDepth);
      }
      this.emit('taskCompleted', result);

      log.info(`[Orchestrator] SubAgent "${taskId}" (depth=${depth}) ${success ? 'completed' : 'failed'} in ${durationMs}ms, ${output.iterations.length} iterations`);

      return result;
    } catch (error) {
      const durationMs = Date.now() - startMs;
      const errMsg = (error as Error).message;
      const result: SubAgentResult = {
        taskId,
        result: errMsg,
        success: false,
        durationMs,
        iterations: 0,
      };

      handle.status = 'error';
      handle.result = result;
      this.activeSubAgents.delete(taskId);
      // v0.3.0 修复: 深度恢复为 0 时删除条目，避免 sessionDepth Map 随会话累积
      if (currentDepth === 0) {
        this.sessionDepth.delete(params.parentSessionId);
      } else {
        this.sessionDepth.set(params.parentSessionId, currentDepth);
      }
      this.emit('taskError', { taskId, error: errMsg });

      log.error(`[Orchestrator] SubAgent "${taskId}" (depth=${depth}) error: ${errMsg}`);

      return result;
    }
  }

  /**
   * 解析工具白名单
   *
   * - 如果指定了 tools，使用白名单（自动排除 delegate_task 防止递归）
   * - 如果未指定，使用所有已启用工具（同样排除 delegate_task）
   */
  private resolveTools(toolNames?: string[]): MetonaToolDef[] {
    if (!this.toolRegistry) return [];

    // 始终排除 delegate_task 防止递归（除非深度为 1 且显式要求）
    const EXCLUDE_TOOLS = new Set(['delegate_task']);

    if (toolNames && toolNames.length > 0) {
      // 使用白名单模式
      const resolved: MetonaToolDef[] = [];
      const notFound: string[] = [];

      for (const name of toolNames) {
        if (EXCLUDE_TOOLS.has(name)) continue; // 静默排除
        const tool = this.toolRegistry.get(name);
        if (tool) {
          resolved.push(tool.definition);
        } else {
          notFound.push(name);
        }
      }

      if (notFound.length > 0) {
        log.warn(`[Orchestrator] Tools not found: ${notFound.join(', ')}`);
      }

      return resolved;
    }

    // 未指定白名单 — 使用所有已启用工具（排除 delegate_task）
    return this.toolRegistry.listTools().filter((t) => !EXCLUDE_TOOLS.has(t.name));
  }

  /**
   * 构建 SubAgent 的 System Prompt
   */
  private buildSubAgentPrompt(description: string, depth: number): MetonaSystemPrompt {
    return {
      roleDefinition: `You are a SubAgent (delegation depth: ${depth}) executing a specific sub-task delegated by the parent Agent.\nYour goal is to complete the assigned task efficiently and return a clear, concise result.\nFocus only on the task at hand. Do not delegate further.`,
      outputConstraints: `Complete the task and provide a clear summary of your findings or actions.\nRespond in the same language as the task description.\nKeep your response focused and relevant — the parent Agent will use your result to continue its work.`,
      safetyGuidelines: `Do not access files outside the workspace.\nDo not execute dangerous commands.\nIf the task cannot be completed, explain why clearly.`,
    };
  }

  /**
   * 中断指定子任务
   */
  abortTask(taskId: string): boolean {
    const handle = this.activeSubAgents.get(taskId);
    if (handle && handle.status === 'running') {
      handle.abort();
      return true;
    }
    return false;
  }

  /**
   * 完成子任务（外部触发，保留接口兼容）
   */
  completeTask(taskId: string, result: string, success: boolean): void {
    const handle = this.activeSubAgents.get(taskId);
    if (handle && handle.status === 'running') {
      handle.status = success ? 'completed' : 'error';
      handle.result = { taskId, result, success, durationMs: 0, iterations: 0 };
      this.activeSubAgents.delete(taskId);
      this.emit('taskCompleted', handle.result);
    }
  }

  getActiveAgentsStatus(): Array<{ taskId: string; status: string; description: string; depth: number }> {
    return Array.from(this.activeSubAgents.values()).map((a) => a.getStatus());
  }

  /**
   * 中断所有子任务
   */
  abortAll(): void {
    for (const agent of this.activeSubAgents.values()) {
      agent.abort();
    }
    this.activeSubAgents.clear();
    this.sessionDepth.clear();
  }
}