import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";

import { AgentController, SuggestionBuilder } from "./index.js";
import type { ResolvedProvider } from "./index.js";

const config: ResolvedProvider = {
  id: "test-openai",
  kind: "openai-compatible",
  baseUrl: "https://api.openai.com/v1",
  apiKey: "sk-test",
  model: "gpt-4o",
  contextWindow: 128_000,
};

let savedFetch: typeof fetch;

/** Build an SSE Response streaming a single text delta. */
function sseResponse(events: string[]): Response {
  const encoder = new TextEncoder();
  const body = new ReadableStream<Uint8Array<ArrayBuffer>>({
    start(controller) {
      for (const event of events) controller.enqueue(encoder.encode(`data: ${event}\n\n`));
      controller.enqueue(encoder.encode("data: [DONE]\n\n"));
      controller.close();
    },
  });
  return new Response(body, { status: 200, headers: { "content-type": "text/event-stream" } });
}

describe("SuggestionBuilder", () => {
  let builder: SuggestionBuilder;

  beforeEach(() => {
    savedFetch = globalThis.fetch;
  });

  afterEach(() => {
    globalThis.fetch = savedFetch;
    vi.restoreAllMocks();
  });

  it("streams a prompt and builds a pending suggestion", async () => {
    globalThis.fetch = (() =>
      sseResponse([JSON.stringify({ choices: [{ delta: { content: "Try a flashback here. It reveals the secret early." } }] })])) as unknown as typeof fetch;

    const agent = new AgentController(config);
    builder = new SuggestionBuilder(agent);

    const result = await builder.build(
      { kind: "expand", prompt: "Expand the reveal scene" },
      "sess-1",
      "msg-1",
    );

    expect(result.id).toBeTruthy();
    expect(result.sessionId).toBe("sess-1");
    expect(result.sourceMessageId).toBe("msg-1");
    expect(result.kind).toBe("expand");
    expect(result.status).toBe("pending");
    expect(result.text).toContain("flashback");
    expect(result.title.length).toBeGreaterThan(0);
    expect(result.summary.length).toBeGreaterThan(0);
    expect(result.createdAt).toBeTruthy();
  });

  it("includes the context in the system prompt", async () => {
    const calls: Array<RequestInit> = [];
    globalThis.fetch = ((_url: string, init: RequestInit) => {
      calls.push(init);
      return Promise.resolve(
        sseResponse([JSON.stringify({ choices: [{ delta: { content: "ok" } }] })]),
      );
    }) as unknown as typeof fetch;

    const agent = new AgentController(config);
    builder = new SuggestionBuilder(agent);

    await builder.build(
      {
        kind: "outline",
        prompt: "Outline chapter 3",
        context: { chapterTitle: "The Return", setting: "the capital", characters: ["Aria"] },
      },
      "sess-1",
      "msg-1",
    );

    const init = calls[0] as RequestInit;
    const body = JSON.parse(init.body as string) as Record<string, unknown>;
    const messages = body.messages as Array<{ content: string; role?: string }>;
    const system = messages.find((m) => m.role === "system")?.content ?? "";
    expect(system).toContain("The Return");
    expect(system).toContain("the capital");
    expect(system).toContain("Aria");
  });

  it("produces distinct titles per kind", async () => {
    globalThis.fetch = (() =>
      sseResponse([JSON.stringify({ choices: [{ delta: { content: "Chapter 3: The Return — Aria confronts the council about the missing supplies." } }] })])) as unknown as typeof fetch;

    const agent = new AgentController(config);
    builder = new SuggestionBuilder(agent);

    const result = await builder.build({ kind: "outline", prompt: "Outline" }, "sess-1", "msg-1");
    expect(result.title).toContain("Chapter 3");
  });
});