/**
 * Pre-Tool Hooks — 工具执行前钩子
 *
 * @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 type { MetonaToolCall } from '../types';
import type { PolicyEngine } from '../sandbox/permissions';

export interface HookResult {
  blocked: boolean;
  reason?: string;
  modifiedArgs?: Record<string, unknown>;
}

export interface PreToolHook {
  beforeExecute(toolCall: MetonaToolCall, sessionId: string): Promise<HookResult>;
}

/** 权限校验钩子 — 集成 PolicyEngine */
export class PermissionCheckHook implements PreToolHook {
  constructor(private policyEngine: PolicyEngine) {}

  async beforeExecute(toolCall: MetonaToolCall, _sessionId: string): Promise<HookResult> {
    const result = this.policyEngine.checkAuthorization(toolCall.name, toolCall.args);
    if (!result.authorized) {
      return { blocked: true, reason: result.reason };
    }
    return { blocked: false };
  }
}

/** 速率限制钩子 */
export class RateLimitHook implements PreToolHook {
  private callCounts = new Map<string, { count: number; resetTime: number }>();

  constructor(private maxCallsPerMinute: number = 20) {}

  async beforeExecute(toolCall: MetonaToolCall, _sessionId: string): Promise<HookResult> {
    const key = toolCall.name;
    const now = Date.now();
    const entry = this.callCounts.get(key);
    if (entry && entry.resetTime >= now) {
      if (entry.count >= this.maxCallsPerMinute) {
        return { blocked: true, reason: `Rate limit exceeded for tool "${toolCall.name}"` };
      }
      entry.count++;
    } else {
      this.callCounts.set(key, { count: 1, resetTime: now + 60_000 });
    }
    return { blocked: false };
  }
}