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

import handleStreamData from '../utils/handleStreamData.ts';

describe('handleStreamData', () => {
  // Setup mocks
  const mockController = {
    enqueue: vi.fn(),
  };
  const mockEncoder = {
    encode: vi.fn(str => str),
  };

  beforeEach(() => {
    vi.resetAllMocks();
  });

  it('should return early if data type is not "chat"', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    handler({ type: 'not-chat', data: {} });

    expect(mockController.enqueue).not.toHaveBeenCalled();
    expect(mockEncoder.encode).not.toHaveBeenCalled();
  });

  it('should return early if data is undefined', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    handler(undefined as any);

    expect(mockController.enqueue).not.toHaveBeenCalled();
    expect(mockEncoder.encode).not.toHaveBeenCalled();
  });

  it('should handle content_block_start type data', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    const data = {
      type: 'chat',
      data: {
        type: 'content_block_start',
        content_block: {
          type: 'text',
          text: 'Hello world',
        },
      },
    };

    handler(data);

    expect(mockController.enqueue).toHaveBeenCalledTimes(1);
    expect(mockEncoder.encode).toHaveBeenCalledWith(expect.stringContaining('Hello world'));

    // @ts-expect-error - mock
    const encodedData = mockEncoder.encode.mock.calls[0][0];
    const parsedData = JSON.parse(encodedData.split('data: ')[1]);

    expect(parsedData.type).toBe('chat');
    expect(parsedData.data.choices[0].delta.content).toBe('Hello world');
  });

  it('should handle delta.text type data', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    const data = {
      type: 'chat',
      data: {
        delta: {
          text: 'Hello world',
        },
      },
    };

    handler(data);

    expect(mockController.enqueue).toHaveBeenCalledTimes(1);
    expect(mockEncoder.encode).toHaveBeenCalledWith(expect.stringContaining('Hello world'));

    // @ts-expect-error - mock
    const encodedData = mockEncoder.encode.mock.calls[0][0];
    const parsedData = JSON.parse(encodedData.split('data: ')[1]);

    expect(parsedData.type).toBe('chat');
    expect(parsedData.data.choices[0].delta.content).toBe('Hello world');
  });

  it('should handle choices[0].delta.content type data', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    const data = {
      type: 'chat',
      data: {
        choices: [
          {
            index: 0,
            delta: {
              content: 'Hello world',
            },
            logprobs: null,
            finish_reason: null,
          },
        ],
      },
    };

    handler(data);

    expect(mockController.enqueue).toHaveBeenCalledTimes(1);
    expect(mockEncoder.encode).toHaveBeenCalledWith(expect.stringContaining('Hello world'));

    // @ts-expect-error - mock
    const encodedData = mockEncoder.encode.mock.calls[0][0];
    const parsedData = JSON.parse(encodedData.split('data: ')[1]);

    expect(parsedData.type).toBe('chat');
    expect(parsedData.data.choices[0].delta.content).toBe('Hello world');
    expect(parsedData.data.choices[0].finish_reason).toBe(null);
  });

  it('should pass through data with choices but no delta.content', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    const data = {
      type: 'chat',
      data: {
        choices: [
          {
            index: 0,
            delta: {},
            logprobs: null,
            finish_reason: 'stop',
          },
        ],
      },
    };

    handler(data as any);

    expect(mockController.enqueue).toHaveBeenCalledTimes(1);
    expect(mockEncoder.encode).toHaveBeenCalledWith(
      expect.stringContaining('"finish_reason":"stop"'),
    );
  });

  it('should return early for unrecognized data format', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    const data = {
      type: 'chat',
      data: {
        // No recognized properties
        unrecognized: 'property',
      },
    };

    handler(data as any);

    expect(mockController.enqueue).not.toHaveBeenCalled();
    expect(mockEncoder.encode).not.toHaveBeenCalled();
  });

  it('should use custom transform function if provided', () => {
    const handler = handleStreamData(mockController as any, mockEncoder as any);

    const data = {
      type: 'chat',
      data: {
        original: 'data',
      },
    };

    const transformFn = vi.fn().mockReturnValue({
      type: 'chat',
      data: {
        choices: [
          {
            delta: {
              content: 'Transformed content',
            },
            logprobs: null,
            finish_reason: null,
          },
        ],
      },
    });

    handler(data as any, transformFn);

    expect(transformFn).toHaveBeenCalledWith(data);
    expect(mockController.enqueue).toHaveBeenCalledTimes(1);
    expect(mockEncoder.encode).toHaveBeenCalledWith(expect.stringContaining('Transformed content'));
  });
});