/**
 * ChatCore unit tests
 *
 * Tests scaffold — full implementation in Task 16.
 * Covers: new conversation, save/load/delete, provider switching,
 *         localStorage bounds (MAX_CONVERSATIONS), and streaming abort.
 */

import { describe, it, expect, beforeEach, vi } from 'vitest';
import { ChatCore } from '../core/ChatCore.js';
import type { ChatConfig } from '../types/index.js';

// ---- localStorage mock ----
const storage: Record<string, string> = {};

beforeEach(() => {
  Object.keys(storage).forEach(k => delete storage[k]);

  vi.stubGlobal('localStorage', {
    getItem: (k: string) => storage[k] ?? null,
    setItem: (k: string, v: string) => { storage[k] = v; },
    removeItem: (k: string) => { delete storage[k]; },
    clear: () => { Object.keys(storage).forEach(k => delete storage[k]); },
  });
});

const config: ChatConfig = {
  gateway: 'https://api.example.com/v1',
  apiKey: 'sk_test',
  provider: 'xai',
};

describe('ChatCore — initialisation', () => {
  it('creates a new conversation ID on construction', () => {
    const core = new ChatCore(config);
    expect(core.conversationId).toBeTruthy();
    expect(typeof core.conversationId).toBe('string');
  });

  it('defaults to xai provider', () => {
    const core = new ChatCore(config);
    expect(core.provider).toBe('xai');
  });

  it('accepts provider override', () => {
    const core = new ChatCore({ ...config, provider: 'anthropic' });
    expect(core.provider).toBe('anthropic');
  });
});

describe('ChatCore — provider switching', () => {
  it('switches provider and updates model', () => {
    const core = new ChatCore(config);
    core.setProvider('openai');
    expect(core.provider).toBe('openai');
    expect(core.model).toBeTruthy();
  });

  it('ignores unknown providers with a warning', () => {
    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
    const core = new ChatCore(config);
    const before = core.provider;
    core.setProvider('unknown-provider');
    expect(core.provider).toBe(before); // unchanged
    warn.mockRestore();
  });
});

describe('ChatCore — conversation persistence', () => {
  it('returns empty array when no conversations saved', () => {
    const core = new ChatCore(config);
    expect(core.getConversations()).toEqual([]);
  });

  it('clearHistory starts fresh conversation with new ID', () => {
    const core = new ChatCore(config);
    const oldId = core.conversationId;
    core.clearHistory();
    expect(core.conversationId).not.toBe(oldId);
    expect(core.messages.length).toBe(0);
  });

  it('deleteConversation on active conversation starts new one', () => {
    const core = new ChatCore(config);
    const id = core.conversationId!;
    core.deleteConversation(id);
    expect(core.conversationId).not.toBe(id);
  });
});

describe('ChatCore — streaming', () => {
  it('isStreaming starts as false', () => {
    const core = new ChatCore(config);
    expect(core.isStreaming).toBe(false);
  });

  it('stop() is a no-op when not streaming', () => {
    const core = new ChatCore(config);
    expect(() => core.stop()).not.toThrow();
  });
});