import { generateText, stepCountIs } from "ai";
import type { AgentInvocation, AgentInvocationResult } from "./types";
import { getAgentBySlug } from "./agent";
import { getAgentToolsForChatByAgentId } from "#server/service/agent-tool";
import { resolveModelForUser, resolveModelAny, toLanguageModel } from "#server/service/llm/model-resolver";
import { getConfigGlobal } from "#server/utils/context";
import log4js from "logger";

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

const DEFAULT_MAX_RECURSION_DEPTH = 3;
const DEFAULT_TIMEOUT_MS = 60_000;
const DEFAULT_MAX_OUTPUT_TOKENS = 8192;

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

  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 globalDefaultModelId = (await getConfigGlobal("agentDefaultModelId")) ?? null;
  const targetModelId = agent.defaultModelId ?? globalDefaultModelId;
  if (!targetModelId) {
    return { agentSlug, output: "", ok: false, error: `agent ${agentSlug} has no defaultModelId and no global default model configured` };
  }

  const resolved = userId
    ? await resolveModelForUser(targetModelId, userId)
    : await resolveModelAny(targetModelId);
  if (!resolved) {
    return { agentSlug, output: "", ok: false, error: `model ${targetModelId} not resolvable for agent ${agentSlug}` };
  }

  const languageModel = toLanguageModel(resolved);

  const enableTools = agent.enableTools === 1;
  const { tools } = await getAgentToolsForChatByAgentId({
    agentId: agent.id,
    userId,
    userRole: null,
    enableTools,
    recursionDepth,
  });

  const maxSteps = agent.maxStepCount ?? 8;

  logger.info(
    "[COLLAB] invokeAgent agentSlug=%s agentId=%d callerAgentId=%s recursionDepth=%d tools=%d maxSteps=%d",
    agentSlug,
    agent.id,
    callerAgentId,
    recursionDepth,
    Object.keys(tools).length,
    maxSteps,
  );

  try {
    const result = await generateText({
      model: languageModel,
      system: agent.systemPrompt,
      prompt: input,
      ...(Object.keys(tools).length > 0
        ? {
            tools,
            stopWhen: stepCountIs(maxSteps),
          }
        : {}),
      maxOutputTokens,
      abortSignal: AbortSignal.timeout(timeoutMs),
    });

    const output = result.text ?? "";

    logger.info(
      "[COLLAB] invokeAgent done agentSlug=%s outputLen=%d usage=%j",
      agentSlug,
      output.length,
      result.usage,
    );

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