import { describe, expect, it } from "bun:test";
import { createSession, deleteSession, listSessions, sendMessage } from "./assistant-client.ts";

// ── Helper ─────────────────────────────────────────────────────────────

function withMockFetch<T>(mock: typeof fetch, fn: () => Promise<T>): Promise<T> {
  const original = globalThis.fetch;
  globalThis.fetch = mock;
  return fn().finally(() => { globalThis.fetch = original; });
}

// ── createSession tests ────────────────────────────────────────────────

describe("createSession", () => {
  it("returns session id on success", async () => {
    const result = await withMockFetch(
      (async () => new Response(JSON.stringify({ id: "sess_42" }), { status: 200 })) as typeof fetch,
      () => createSession({ baseUrl: "http://assistant" }, "title"),
    );
    expect(result).toBe("sess_42");
  });

  it("throws on non-200 response", async () => {
    await withMockFetch(
      (async () => new Response("bad", { status: 500 })) as typeof fetch,
      async () => {
        await expect(createSession({ baseUrl: "http://assistant" }, "t")).rejects.toThrow("session creation failed");
      },
    );
  });

  it("throws on invalid session id", async () => {
    await withMockFetch(
      (async () => new Response(JSON.stringify({ id: "../bad" }), { status: 200 })) as typeof fetch,
      async () => {
        await expect(createSession({ baseUrl: "http://assistant" }, "t")).rejects.toThrow("Invalid session ID");
      },
    );
  });
});

describe("listSessions", () => {
  it("returns valid session summaries", async () => {
    const result = await withMockFetch(
      (async () => new Response(JSON.stringify([
        { id: "sess_1", title: "discord/thread-1" },
        { id: "bad/id", title: "ignored" },
        { id: "sess_2", title: 123 },
      ]), { status: 200 })) as typeof fetch,
      () => listSessions({ baseUrl: "http://assistant" }),
    );

    expect(result).toEqual([{ id: "sess_1", title: "discord/thread-1" }]);
  });

  it("throws on invalid response body", async () => {
    await withMockFetch(
      (async () => new Response(JSON.stringify({ nope: true }), { status: 200 })) as typeof fetch,
      async () => {
        await expect(listSessions({ baseUrl: "http://assistant" })).rejects.toThrow("Invalid session list");
      },
    );
  });
});

describe("deleteSession", () => {
  it("returns true on success", async () => {
    const result = await withMockFetch(
      (async () => new Response("true", { status: 200 })) as typeof fetch,
      () => deleteSession({ baseUrl: "http://assistant" }, "sess_1"),
    );
    expect(result).toBe(true);
  });

  it("returns false on 404", async () => {
    const result = await withMockFetch(
      (async () => new Response("missing", { status: 404 })) as typeof fetch,
      () => deleteSession({ baseUrl: "http://assistant" }, "sess_1"),
    );
    expect(result).toBe(false);
  });

  it("throws on invalid session id", async () => {
    await expect(
      deleteSession({ baseUrl: "http://assistant" }, "../escape"),
    ).rejects.toThrow("Invalid session ID");
  });
});

// ── sendMessage tests ──────────────────────────────────────────────────

describe("sendMessage", () => {
  it("returns joined text parts", async () => {
    const result = await withMockFetch(
      (async () => new Response(JSON.stringify({
        parts: [{ type: "text", text: "a" }, { type: "text", text: "b" }],
      }), { status: 200 })) as typeof fetch,
      () => sendMessage({ baseUrl: "http://assistant" }, "sess1", "prompt"),
    );
    expect(result).toBe("a\nb");
  });

  it("returns (no response) when parts are empty", async () => {
    const result = await withMockFetch(
      (async () => new Response(JSON.stringify({ parts: [] }), { status: 200 })) as typeof fetch,
      () => sendMessage({ baseUrl: "http://assistant" }, "sess1", "prompt"),
    );
    expect(result).toBe("(no response)");
  });

  it("throws on non-200 response", async () => {
    await withMockFetch(
      (async () => new Response("err", { status: 502 })) as typeof fetch,
      async () => {
        await expect(sendMessage({ baseUrl: "http://assistant" }, "sess1", "p")).rejects.toThrow("message failed");
      },
    );
  });
});