const { atan2, cos, PI, sin } = Math;

export default class UnitCircle {

constructor(drawCallBack) {

this.draw = drawCallBack;

this.snapping = false;

this.showRadians = false;

this.showSnapPoints = false;

this.snapPoints = [];

this.createSnapPoints();

}

createSnapPoints() {

// Add every multiple of 30°

let max = 360 / 30 + 1;

for (let i = 0; i < max; ++i) {

this.snapPoints.push(i * PI / 6);

}

// Add multiples of 45° (skipping multiples of 90°)

max = 360 / 45;

for (let i = 1; i < max; i += 2) {

this.snapPoints.push(i * PI / 4);

}

this.snapPoints.sort();

}

update({x, y}) {

this.angle = (atan2(y, x) + (2 * PI)) % (2 * PI);

if (this.snapping) {

const snapIndex = this.snapPoints.findIndex((point) => {

return point > this.angle;

});

const a = this.snapPoints[snapIndex - 1];

const b = this.snapPoints[snapIndex];

const middle = a + ((b - a) / 2);

if (middle < this.angle) {

this.angle = this.snapPoints[snapIndex];

} else {

this.angle = this.snapPoints[snapIndex - 1];

}

}

this.draw();

}

getSin() {

return sin(this.angle);

}

getCos() {

return cos(this.angle);

}

getAngleDegrees() {

const angle = (this.angle * 180 / PI);

return {

angle,

angleAlt: -360 + angle,

};

}

toggleSnapping() {

this.snapping = !this.snapping;

this.draw();

}

toggleSnapPoints() {

this.showSnapPoints = !this.showSnapPoints;

this.draw();

}

toggleRadians() {

this.showRadians = !this.showRadians;

this.draw();

}

}