/**
 * Chat Persistence Tests
 *
 * Unit tests for saveMessages, loadMessages, chatStorageKey, and getStableAnonId.
 * Uses a minimal localStorage mock (no jsdom needed).
 */
import { describe, it, expect, beforeEach, vi } from "vitest";
import {
  chatStorageKey,
  saveMessages,
  loadMessages,
  getStableAnonId,
} from "../src/utils/chat-persistence";

// Minimal localStorage mock
const store: Record<string, string> = {};
const localStorageMock = {
  getItem: vi.fn((key: string) => store[key] ?? null),
  setItem: vi.fn((key: string, value: string) => { store[key] = value; }),
  removeItem: vi.fn((key: string) => { delete store[key]; }),
  clear: vi.fn(() => { for (const k in store) delete store[k]; }),
  get length() { return Object.keys(store).length; },
  key: vi.fn((_i: number) => null),
};

vi.stubGlobal("localStorage", localStorageMock);

beforeEach(() => {
  localStorageMock.clear();
  vi.clearAllMocks();
});

// Factory for UIMessage-like objects
function msg(overrides: Record<string, unknown> = {}) {
  return {
    id: "m1",
    role: "user" as const,
    parts: [{ type: "text", text: "hello" }],
    content: "hello",
    createdAt: new Date("2025-06-01T12:00:00Z"),
    ...overrides,
  };
}

describe("chatStorageKey", () => {
  it("builds key from user name and scope", () => {
    expect(chatStorageKey("alice", "article")).toBe("chat:alice:article");
  });

  it("handles embed scopes", () => {
    expect(chatStorageKey("bob", "embed:banner.html")).toBe("chat:bob:embed:banner.html");
  });
});

describe("saveMessages / loadMessages round-trip", () => {
  it("saves and loads a single message", () => {
    const m = msg();
    saveMessages("alice", "article", [m as any]);

    const loaded = loadMessages("alice", "article");
    expect(loaded).toBeDefined();
    expect(loaded).toHaveLength(1);
    expect(loaded![0].id).toBe("m1");
    expect(loaded![0].role).toBe("user");
  });

  it("restores createdAt as a Date object", () => {
    const m = msg();
    saveMessages("alice", "article", [m as any]);

    const loaded = loadMessages("alice", "article")! as any;
    expect(loaded[0].createdAt).toBeInstanceOf(Date);
    expect(loaded[0].createdAt!.toISOString()).toBe("2025-06-01T12:00:00.000Z");
  });

  it("handles messages without createdAt", () => {
    const m = msg({ createdAt: undefined });
    saveMessages("alice", "article", [m as any]);

    const loaded = loadMessages("alice", "article")! as any;
    expect(loaded[0].createdAt).toBeUndefined();
  });

  it("preserves parts array", () => {
    const m = msg({ parts: [{ type: "text", text: "hi" }, { type: "text", text: "there" }] });
    saveMessages("alice", "article", [m as any]);

    const loaded = loadMessages("alice", "article")!;
    expect(loaded[0].parts).toEqual([{ type: "text", text: "hi" }, { type: "text", text: "there" }]);
  });

  it("saves multiple messages and preserves order", () => {
    const msgs = [
      msg({ id: "m1", role: "user" }),
      msg({ id: "m2", role: "assistant", content: "hey" }),
      msg({ id: "m3", role: "user", content: "thanks" }),
    ];
    saveMessages("alice", "article", msgs as any);

    const loaded = loadMessages("alice", "article")!;
    expect(loaded).toHaveLength(3);
    expect(loaded.map((m) => m.id)).toEqual(["m1", "m2", "m3"]);
    expect(loaded.map((m) => m.role)).toEqual(["user", "assistant", "user"]);
  });
});

describe("saveMessages - edge cases", () => {
  it("removes key when saving empty array", () => {
    saveMessages("alice", "article", [msg() as any]);
    expect(localStorageMock.setItem).toHaveBeenCalled();

    saveMessages("alice", "article", []);
    expect(localStorageMock.removeItem).toHaveBeenCalledWith("chat:alice:article");

    const loaded = loadMessages("alice", "article");
    expect(loaded).toBeUndefined();
  });

  it("does not throw when localStorage.setItem fails", () => {
    localStorageMock.setItem.mockImplementationOnce(() => { throw new Error("QuotaExceeded"); });
    expect(() => saveMessages("alice", "article", [msg() as any])).not.toThrow();
  });
});

describe("loadMessages - edge cases", () => {
  it("returns undefined for missing key", () => {
    expect(loadMessages("unknown", "article")).toBeUndefined();
  });

  it("returns undefined for corrupt JSON", () => {
    store["chat:alice:article"] = "not json!!!";
    expect(loadMessages("alice", "article")).toBeUndefined();
  });

  it("returns undefined for non-array JSON", () => {
    store["chat:alice:article"] = JSON.stringify({ not: "an array" });
    expect(loadMessages("alice", "article")).toBeUndefined();
  });

  it("returns undefined for empty array JSON", () => {
    store["chat:alice:article"] = JSON.stringify([]);
    expect(loadMessages("alice", "article")).toBeUndefined();
  });
});

describe("user scoping", () => {
  it("isolates messages between users", () => {
    saveMessages("alice", "article", [msg({ id: "a1" }) as any]);
    saveMessages("bob", "article", [msg({ id: "b1" }) as any]);

    expect(loadMessages("alice", "article")![0].id).toBe("a1");
    expect(loadMessages("bob", "article")![0].id).toBe("b1");
  });

  it("isolates article and embed scopes for same user", () => {
    saveMessages("alice", "article", [msg({ id: "art" }) as any]);
    saveMessages("alice", "embed:chart.html", [msg({ id: "emb" }) as any]);

    expect(loadMessages("alice", "article")![0].id).toBe("art");
    expect(loadMessages("alice", "embed:chart.html")![0].id).toBe("emb");
  });
});

describe("getStableAnonId", () => {
  it("returns a string starting with 'anon-'", () => {
    const id = getStableAnonId();
    expect(id).toMatch(/^anon-/);
  });

  it("returns the same value on subsequent calls", () => {
    const first = getStableAnonId();
    const second = getStableAnonId();
    expect(first).toBe(second);
  });

  it("persists the id in localStorage", () => {
    const id = getStableAnonId();
    expect(store["collab-editor:anon-id"]).toBe(id);
  });
});