/**
 * A2A 内部客户端
 *
 * 替代 collaboration.ts 的 invokeAgent()，提供与原接口兼容的
 * agent 间调用能力，底层走 A2A Service 层。
 *
 * 设计原则：
 * - 接口签名与 invokeAgent 完全兼容，便于无缝替换
 * - 递归深度、超时、自调用阻断通过 A2AInvocationContext 传递
 * - 未来可切换为真实 HTTP 调用本机 A2A 端点（接口不变）
 */

import type { AgentInvocation, AgentInvocationResult } from "../agent/types";
import { getAgentBySlug } from "../agent/agent";
import { createTask, sendTask } from "./service";
import { textToA2AMessage, a2aMessageToText } from "./converter";
import { DEFAULT_A2A_CONFIG, JSONRPC_ERROR_CODES } from "./types";
import type { A2AInvocationContext } from "./types";
import log4js from "logger";

const logger = log4js.getLogger("APP");

export async function invokeAgentViaA2A(
  invocation: AgentInvocation,
  options?: {
    maxRecursionDepth?: number;
    timeoutMs?: number;
    maxOutputTokens?: number;
  },
): Promise<AgentInvocationResult> {
  const { agentSlug, input, context } = invocation;
  const maxRecursionDepth = options?.maxRecursionDepth ?? DEFAULT_A2A_CONFIG.maxRecursionDepth;
  const timeoutMs = options?.timeoutMs ?? DEFAULT_A2A_CONFIG.timeoutMs;
  const maxOutputTokens = options?.maxOutputTokens ?? DEFAULT_A2A_CONFIG.maxOutputTokens;

  const userId = context?.userId ?? null;
  const callerAgentId = context?.callerAgentId ?? null;
  const recursionDepth = context?.recursionDepth ?? 0;

  const agent = await getAgentBySlug(agentSlug);
  if (!agent) {
    return { agentSlug, output: "", ok: false, error: `agent not found: ${agentSlug}` };
  }

  if (!agent.isCallable) {
    return { agentSlug, output: "", ok: false, error: `agent not callable: ${agentSlug}` };
  }

  if (callerAgentId !== null && callerAgentId === agent.id) {
    return { agentSlug, output: "", ok: false, error: `self-invocation blocked: agent ${agentSlug} cannot invoke itself` };
  }

  if (recursionDepth >= maxRecursionDepth) {
    return {
      agentSlug,
      output: "",
      ok: false,
      error: `max recursion depth (${maxRecursionDepth}) reached`,
    };
  }

  const message = textToA2AMessage(input, "user");

  try {
    const { task } = await createTask({
      calleeAgentSlug: agentSlug,
      message,
      callerAgentId,
      userId,
    });

    const a2aContext: A2AInvocationContext = {
      callerAgentId,
      calleeAgentId: agent.id,
      calleeAgentSlug: agentSlug,
      userId,
      sessionId: task.sessionId,
      recursionDepth,
      maxRecursionDepth,
      timeoutMs,
      maxOutputTokens,
    };

    const completedTask = await sendTask(task.id, a2aContext);

    const output = completedTask.message
      ? a2aMessageToText(completedTask.message)
      : "";

    logger.info(
      "[A2A-CLIENT] invokeAgentViaA2A done agentSlug=%s taskId=%s outputLen=%d",
      agentSlug,
      task.id,
      output.length,
    );

    return { agentSlug, output, ok: true };
  } catch (err) {
    const errorMsg = err instanceof Error ? err.message : String(err);
    logger.error("[A2A-CLIENT] invokeAgentViaA2A error agentSlug=%s error=%s", agentSlug, errorMsg);
    return { agentSlug, output: "", ok: false, error: errorMsg };
  }
}