import { describe, expect, it } from 'vitest';
import { Point } from '@flatten-js/core';
import { LineEntity } from './LineEntity.ts';
import { TO_DEGREES } from '../App.consts.ts';
import { getActiveLayerId } from '../state.ts';

describe('getAngle', () => {
	it('should return 0 for a horizontal line', () => {
		const point1 = new Point(0, 0);
		const point2 = new Point(1, 0);
		const lineEntity = new LineEntity(getActiveLayerId(), point1, point2);
		expect(lineEntity.getAngle() * TO_DEGREES).toBeCloseTo(0);
	});

	it('should return 90 degrees for a vertical line', () => {
		const point1 = new Point(0, 0);
		const point2 = new Point(0, 1);
		const lineEntity = new LineEntity(getActiveLayerId(), point1, point2);
		expect(lineEntity.getAngle() * TO_DEGREES).toBeCloseTo(90);
	});

	it('should return 45 degrees for a slope of 1', () => {
		const point1 = new Point(0, 0);
		const point2 = new Point(1, 1);
		const lineEntity = new LineEntity(getActiveLayerId(), point1, point2);
		expect(lineEntity.getAngle() * TO_DEGREES).toBeCloseTo(45);
	});

	it('should return 135 degrees for a slope of -1', () => {
		const point1 = new Point(0, 0);
		const point2 = new Point(-1, 1);
		const lineEntity = new LineEntity(getActiveLayerId(), point1, point2);
		expect(lineEntity.getAngle() * TO_DEGREES).toBeCloseTo(135);
	});

	it('should return 30 degrees for a slope of √3/3', () => {
		const point1 = new Point(0, 0);
		const point2 = new Point(1, Math.tan(Math.PI / 6)); // tan(30°) = 1/√3 ≈ 0.577
		const lineEntity = new LineEntity(getActiveLayerId(), point1, point2);
		expect(lineEntity.getAngle() * TO_DEGREES).toBeCloseTo(30);
	});

	it('should handle NaN slope gracefully', () => {
		const point1 = new Point(0, 0);
		const point2 = new Point(0, 0);
		const lineEntity = new LineEntity(getActiveLayerId(), point1, point2); // zero-length segment
		expect(lineEntity.getAngle() * TO_DEGREES).toBeCloseTo(0);
	});
});