import { afterEach, describe, expect, it, onTestFinished, vi } from "vitest";
import { onAgentEventForRun, type AgentEventPayload } from "../../infra/agent-events.js";
import {
  clearAgentRunContext,
  getAgentRunContext,
  registerAgentRunContext,
  resetAgentRunRegistryForTest,
  resolveProjectedAgentRunModel,
} from "../../infra/agent-run-registry.js";
import type { AgentRunContext } from "../../infra/agent-run-registry.types.js";
import { createAssistantMessageEventStream } from "../../llm/utils/event-stream.js";
import {
  MODEL,
  PROVIDER,
  SESSION_ID,
  SESSION_KEY,
  finalMessage,
  params,
  request,
  sessionEntry,
  setup,
  type Execution,
} from "./inference-runtime.test-support.js";

const RUN_ID = request().runId;
const REROUTED_MODEL = "fixture-rerouted";
const runContext = {
  sessionId: SESSION_ID,
  sessionKey: SESSION_KEY,
  agentId: "runtime-agent",
  projectSessionActive: true,
} satisfies AgentRunContext;

function projectedModel() {
  return resolveProjectedAgentRunModel({ agentId: "runtime-agent", sessionId: SESSION_ID });
}

function startInference(
  options: {
    context?: AgentRunContext;
    afterModelPreparation?: () => void;
  } = {},
) {
  registerAgentRunContext(RUN_ID, options.context ?? runContext);
  const runtime = setup(sessionEntry, options);
  const stream = createAssistantMessageEventStream();
  const message = finalMessage();
  message.content = [{ type: "text", text: "Held response" }];
  runtime.stream.mockReturnValue(stream);
  const modelEvents: AgentEventPayload[] = [];
  const unsubscribe = onAgentEventForRun(RUN_ID, (event) => {
    if (event.stream === "lifecycle" && event.data.phase === "model") {
      modelEvents.push(event);
    }
  });
  const emit = vi.fn<Execution["emit"]>();
  const abort = new AbortController();
  let current = true;
  const execution = params(request(), emit);
  execution.signal = abort.signal;
  execution.isCurrent = () => current;
  const pending = runtime.executor(execution);
  onTestFinished(async () => {
    stream.end(message);
    await pending;
    unsubscribe();
  });
  return {
    runtime,
    stream,
    message,
    modelEvents,
    emit,
    abort,
    revoke: () => {
      current = false;
    },
    pending,
  };
}

afterEach(() => resetAgentRunRegistryForTest());

describe("worker.inference.start executing model", () => {
  it("publishes the configured model, then a responseModel reroute from a lean delta while held", async () => {
    const inference = startInference();
    inference.stream.push({ type: "start", partial: inference.message });
    await vi.waitFor(() => expect(projectedModel()).toEqual({ provider: PROVIDER, model: MODEL }));

    inference.message.responseModel = REROUTED_MODEL;
    inference.stream.push({ type: "text_delta", contentIndex: 0, delta: "Held response" });
    await vi.waitFor(() => expect(inference.emit).toHaveBeenCalledTimes(2));

    expect(projectedModel()).toEqual({ provider: PROVIDER, model: REROUTED_MODEL });
    expect(inference.modelEvents.map((event) => event.data)).toEqual([
      { phase: "model", provider: PROVIDER, model: MODEL },
      { phase: "model", provider: PROVIDER, model: REROUTED_MODEL },
    ]);
    expect(inference.modelEvents).toEqual([
      expect.objectContaining({ runId: RUN_ID, sessionId: SESSION_ID, sessionKey: SESSION_KEY }),
      expect.objectContaining({ runId: RUN_ID, sessionId: SESSION_ID, sessionKey: SESSION_KEY }),
    ]);
    expect(inference.runtime.releaseRuntime).not.toHaveBeenCalled();
    expect(inference.emit).toHaveBeenCalledWith({
      type: "text_delta",
      contentIndex: 0,
      delta: "Held response",
    });

    inference.stream.push({ type: "done", reason: "stop", message: inference.message });
    await expect(inference.pending).resolves.toMatchObject({
      type: "done",
      message: { model: MODEL, responseModel: REROUTED_MODEL },
    });
    expect(inference.modelEvents).toHaveLength(2);
    expect(projectedModel()).toEqual({ provider: PROVIDER, model: REROUTED_MODEL });
    clearAgentRunContext(RUN_ID);
    expect(projectedModel()).toBeUndefined();
  });

  it.each([
    { name: "session ID", mismatch: { sessionId: "foreign-session" } },
    { name: "session key", mismatch: { sessionKey: "agent:runtime-agent:foreign" } },
    { name: "agent", mismatch: { agentId: "foreign-agent" } },
  ])("ignores a run with a different $name", async ({ mismatch }) => {
    const inference = startInference({ context: { ...runContext, ...mismatch } });
    inference.message.responseModel = REROUTED_MODEL;
    inference.stream.push({ type: "start", partial: inference.message });
    inference.stream.push({ type: "done", reason: "stop", message: inference.message });

    await expect(inference.pending).resolves.toMatchObject({ type: "done" });
    expect(inference.modelEvents).toEqual([]);
    expect(getAgentRunContext(RUN_ID)?.activeModel).toBeUndefined();
  });

  it("does not bind to a replacement run context after model preparation awaits", async () => {
    let originalContext: AgentRunContext | undefined;
    const inference = startInference({
      afterModelPreparation: () => {
        originalContext = getAgentRunContext(RUN_ID);
        clearAgentRunContext(RUN_ID);
        registerAgentRunContext(RUN_ID, runContext);
      },
    });
    inference.stream.push({ type: "start", partial: inference.message });
    inference.stream.push({ type: "done", reason: "stop", message: inference.message });

    await expect(inference.pending).resolves.toMatchObject({ type: "done" });
    expect(originalContext).toBeDefined();
    expect(getAgentRunContext(RUN_ID)).not.toBe(originalContext);
    expect(inference.modelEvents).toEqual([]);
    expect(projectedModel()).toBeNull();
  });

  it("does not publish a held reroute into a replacement run with the same identifiers", async () => {
    const inference = startInference();
    inference.stream.push({ type: "start", partial: inference.message });
    await vi.waitFor(() => expect(projectedModel()).toEqual({ provider: PROVIDER, model: MODEL }));
    const originalContext = getAgentRunContext(RUN_ID);
    clearAgentRunContext(RUN_ID);
    registerAgentRunContext(RUN_ID, runContext);
    inference.message.responseModel = REROUTED_MODEL;
    inference.stream.push({ type: "text_delta", contentIndex: 0, delta: "Late response" });
    await vi.waitFor(() => expect(inference.emit).toHaveBeenCalledTimes(2));

    expect(getAgentRunContext(RUN_ID)).not.toBe(originalContext);
    expect(projectedModel()).toBeNull();
    expect(inference.modelEvents).toHaveLength(1);
    inference.stream.push({ type: "done", reason: "stop", message: inference.message });
    await expect(inference.pending).resolves.toMatchObject({ type: "done" });
    expect(projectedModel()).toBeNull();
    expect(inference.modelEvents).toHaveLength(1);
  });

  it.each(["revocation", "abort"] as const)(
    "stops held reroute publication after %s",
    async (cancellation) => {
      const inference = startInference();
      inference.stream.push({ type: "start", partial: inference.message });
      await vi.waitFor(() =>
        expect(projectedModel()).toEqual({ provider: PROVIDER, model: MODEL }),
      );
      if (cancellation === "abort") {
        inference.abort.abort();
      } else {
        inference.revoke();
      }
      inference.message.responseModel = REROUTED_MODEL;
      inference.stream.push({ type: "text_delta", contentIndex: 0, delta: "Late response" });

      await expect(inference.pending).resolves.toMatchObject({
        type: "error",
        reason: "cancelled",
      });
      expect(inference.modelEvents).toHaveLength(1);
      expect(projectedModel()).toEqual({ provider: PROVIDER, model: MODEL });
      expect(inference.emit.mock.calls.map(([event]) => event.type)).toEqual(["start"]);
      expect(inference.runtime.releaseRuntime).toHaveBeenCalledOnce();
    },
  );
});