// SPDX-FileCopyrightText: 2022 Johannes Loher
//
// SPDX-License-Identifier: MIT

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

import { defaultEvaluator, Evaluator, mathEvaluator } from '../../src/expression-evaluation/evaluator';

describe('Evaluator', () => {
  it('evaluates expressions that only use identifiers according to the given predicate', () => {
    // given
    const expression = "typeof 'foo' === 'string' ? 42 : null";

    // when
    const result = defaultEvaluator.evaluate(expression);

    // then
    expect(result).toEqual(42);
  });

  it('fails to evaluate expressions that contain identifiers that are not allowed by the predicate', () => {
    // given
    const expression = "typeof 'foo' === 'string' ? 42 : function (){}";

    // when
    const evaluate = () => defaultEvaluator.evaluate(expression);

    // then
    expect(evaluate).toThrowError("'function' is not an allowed identifier.");
  });

  it('fails to evaluate expressions that contain invalid tokens', () => {
    // given
    const expression = '1;';

    // when
    const evaluate = () => defaultEvaluator.evaluate(expression);

    // then
    expect(evaluate).toThrowError('Invalid or unexpected token (1)');
  });

  it('fails to evaluate expressions that contain arrow functions', () => {
    // given
    const expression = '(() => 1)()';

    // when
    const evaluate = () => defaultEvaluator.evaluate(expression);

    // then
    expect(evaluate).toThrowError('Invalid or unexpected token (4)');
  });

  it('makes the given context available', () => {
    // given
    const context = { floor: Math.floor };
    const evaluator = new Evaluator({ context });
    const expression = 'floor(0.5)';

    // when
    const result = evaluator.evaluate(expression);

    // then
    expect(result).toEqual(0);
  });

  describe('mathEvaluator', () => {
    it('makes the given context available', () => {
      // given
      const expression = 'sqrt(sin(PI))';

      // when
      const result = mathEvaluator.evaluate(expression);

      // then
      expect(result).toEqual(Math.sqrt(Math.sin(Math.PI)));
    });

    it('does not give acces to the function constructor', () => {
      // given
      const expression = 'sqrt.constructor';

      // when
      const evaluate = () => mathEvaluator.evaluate(expression);

      // then
      expect(evaluate).toThrowError("'constructor' is not an allowed identifier.");
    });
  });
});