import * as monaco from 'monaco-editor';

function createMockModel(id: string): monaco.editor.ITextModel {
  return ({ id } as unknown) as monaco.editor.ITextModel;
}

function createMockEditor(model: monaco.editor.ITextModel | null) {
  return ({
    getModel: () => model,
  } as unknown) as monaco.editor.IStandaloneCodeEditor;
}

function createMockPosition(column: number, lineNumber = 1): monaco.Position {
  return { column, lineNumber } as monaco.Position;
}

/**
 * Simulates the filteringCompletionProvider wrapper used in ExprEditor.
 * This matches the pattern in src/expr/index.tsx.
 */
function createFilteringProvider(editorRef: { current: monaco.editor.IStandaloneCodeEditor | null }) {
  const innerProvider = {
    provideCompletionItems: jest.fn().mockResolvedValue({
      suggestions: [{ label: 'test', insertText: 'test' }],
    }),
  };

  const filteringProvider: monaco.languages.CompletionItemProvider = {
    ...innerProvider,
    provideCompletionItems: (model, position, context, token) => {
      if (editorRef.current?.getModel()?.id !== model.id) {
        return { suggestions: [] };
      }
      return innerProvider.provideCompletionItems(model, position, context, token);
    },
  };

  return { filteringProvider, innerProvider };
}

describe('Expr filteringCompletionProvider - model ownership check', () => {
  it('returns empty suggestions when model ID does NOT match the editor model', async () => {
    const editorModel = createMockModel('editor-model-1');
    const otherModel = createMockModel('other-model-2');
    const editorRef = { current: createMockEditor(editorModel) };

    const { filteringProvider, innerProvider } = createFilteringProvider(editorRef);
    const result = await filteringProvider.provideCompletionItems!(otherModel, createMockPosition(1), {} as any, {} as any);

    expect(result).toEqual({ suggestions: [] });
    expect(innerProvider.provideCompletionItems).not.toHaveBeenCalled();
  });

  it('proceeds with completions when model ID matches the editor model', async () => {
    const model = createMockModel('same-model-1');
    const editorRef = { current: createMockEditor(model) };

    const { filteringProvider, innerProvider } = createFilteringProvider(editorRef);
    const result = await filteringProvider.provideCompletionItems!(model, createMockPosition(1), {} as any, {} as any);

    expect(result).not.toEqual({ suggestions: [] });
    expect(innerProvider.provideCompletionItems).toHaveBeenCalled();
  });

  it('returns empty suggestions when editorRef.current is null', async () => {
    const model = createMockModel('some-model');
    const editorRef = { current: null };

    const { filteringProvider, innerProvider } = createFilteringProvider(editorRef);
    const result = await filteringProvider.provideCompletionItems!(model, createMockPosition(1), {} as any, {} as any);

    expect(result).toEqual({ suggestions: [] });
    expect(innerProvider.provideCompletionItems).not.toHaveBeenCalled();
  });

  it('returns empty suggestions when editor has no model', async () => {
    const model = createMockModel('some-model');
    const editorRef = { current: createMockEditor(null) };

    const { filteringProvider, innerProvider } = createFilteringProvider(editorRef);
    const result = await filteringProvider.provideCompletionItems!(model, createMockPosition(1), {} as any, {} as any);

    expect(result).toEqual({ suggestions: [] });
    expect(innerProvider.provideCompletionItems).not.toHaveBeenCalled();
  });

  it('returns empty suggestions when editor model id is undefined', async () => {
    const editorModel = ({ id: undefined } as unknown) as monaco.editor.ITextModel;
    const model = createMockModel('some-model');
    const editorRef = { current: createMockEditor(editorModel) };

    const { filteringProvider, innerProvider } = createFilteringProvider(editorRef);
    const result = await filteringProvider.provideCompletionItems!(model, createMockPosition(1), {} as any, {} as any);

    expect(result).toEqual({ suggestions: [] });
    expect(innerProvider.provideCompletionItems).not.toHaveBeenCalled();
  });
});