class Boid {

    constructor(radius, color, x, y, direction, id, scene_width, scene_height) {
        // Boid properties
        this.radius = radius;
        this.color = color;
        this.x = x;
        this.y = y;
        this.direction = direction;
        this.id = id;

        // World properties
        this.scene_width = scene_width;
        this.scene_height = scene_height;

        // Boid "dynamic" properties
        this.rayLength = 40;
        this.turnStepAmount = 20;
        this.stepAmount = 4;
        this.fieldOfView = 270;
        this.boidBuffer = 20;
    }

    move(boids) {
        // this.direction += Math.random() * (2 * this.turnStepAmount) - this.turnStepAmount

        this.direction = this.findNextRay(boids);

        var vector = this.findPoint(this.x, this.y, this.stepAmount, this.direction);
        this.x = vector.x;
        this.y = vector.y;
    }

    buildRays() {
        let rays = new Array();

        let rayInteval = 2;
        let noOfSteps = this.fieldOfView / rayInteval;
        for (let i = 0; i < noOfSteps / 2; i++) {
            if (i != 0) {
                rays.push(rayInteval * -i);
            }
            rays.push(rayInteval * i);
        }

        return rays;
    }

    findNextRay(boids) {
        let rays = this.buildRays();

        for (let i = 0; i < rays.length; i++) {
            let tweakAngle = 0;
            // if (Math.random() > 0.95) {
            //     tweakAngle = this.turnStepAmount * Math.random() - (this.turnStepAmount / 2);
            // }

            let rayAngle = tweakAngle + this.direction + rays[i];

            if (i == 0 && this.detectBoid(rayAngle, boids)) {
                continue;
            }

            if (this.detectBox(this.scene_width, this.scene_height, rayAngle)) {
                continue;
            }

            return rayAngle;
        }
        console.log(this.x, this.y);
        console.log('cannot find suitable ray');
    }

    detectBoid(direction, boids) {
        for (let i = 0; i < boids.length; i++) {
            // rule out ourselves
            if (this.id == boids[i].id) {
                continue;
            }

            let thisFututrePosition = this.findPoint(this.x, this.y, this.boidBuffer, direction);
            let thisPath = {
                x1: this.x,
                y1: this.y,
                x2: thisFututrePosition.x,
                y2: thisFututrePosition.y
            };

            let boidFuturePosition = this.findPoint(boids[i].x, boids[i].y, boids[i].boidBuffer, boids[i].direction);
            let boidPath = {
                x1: boids[i].x,
                y1: boids[i].y,
                x2: boidFuturePosition.x,
                y2: boidFuturePosition.y
            };

            let thisIntersectsBoid = this.pathsIntersect(
                thisPath.x1, thisPath.y1, thisPath.x2, thisPath.y2, boidPath.x1, boidPath.y1, boidPath.x2, boidPath.y2
            );

            if (thisIntersectsBoid) {
                return true;
            }
        }

        return false;
    }

    pathsIntersect(x1, y1, x2, y2, x3, y3, x4, y4) {
        // Check if none of the lines are of length 0
        if ((x1 === x2 && y1 === y2) || (x3 === x4 && y3 === y4)) {
            return false
        }

        let denominator = ((y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1))

        // // Lines are parallel
        // if (denominator === 0) {
        //     return false
        // }

        let ua = ((x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3)) / denominator
        let ub = ((x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3)) / denominator

        // is the intersection along the segments
        if (ua < 0 || ua > 1 || ub < 0 || ub > 1) {
            return false
        }

        // Return a object with the x and y coordinates of the intersection
        let x = x1 + ua * (x2 - x1)
        let y = y1 + ua * (y2 - y1)

        return {
            x,
            y
        }
    }

    detectBox(width, height, direction) {
        let point = this.findPoint(this.x, this.y, this.rayLength, direction);

        if (point.x - this.radius < 0 ||
            point.y - this.radius < 0 ||
            point.x + this.radius > width - 0 ||
            point.y + this.radius > height - 0
        ) {
            return true;
        }

        return false;
    }

    findPoint(x1, y1, length, angle) {
        angle *= Math.PI / 180;

        var x2 = x1 + length * Math.cos(angle),
            y2 = y1 + length * Math.sin(angle);

        return {
            x: x2,
            y: y2
        };
    }

    draw(context) {
        this.drawBoid(context);
        this.drawRay(context, this.x, this.y, this.rayLength, this.direction);
    }

    drawBoid(context) {
        context.beginPath();
        context.fillStyle = "blue";
        context.arc(this.x, this.y, this.radius, 0, 2 * Math.PI);
        context.stroke();
        context.restore();
    }

    drawRay(context, x, y, perceptionDistance, direction) {
        let point = this.findPoint(x, y, perceptionDistance, direction);
        context.lineWidth = 1;
        context.beginPath();
        context.moveTo(x, y);
        context.lineTo(point.x, point.y);
        context.stroke();
        context.restore();
    }
}

class Flock {
    constructor() {
        this.boids = [];
    }

    run() {
        for (let i = 0; i < this.boids.length; i++) {
            this.boids[i].run(boids);
        }
    }

    addBoid(boid) {
        this.boids.push(boid);
    }
}

class GameArea {

    constructor(canvas_width, canvas_height) {
        this.canvas = document.createElement("canvas");
        this.canvas_width = canvas_width;
        this.canvas_height = canvas_height;
    }

    init() {
        this.canvas.width = this.canvas_width;
        this.canvas.height = this.canvas_height;
        this.context = this.canvas.getContext("2d");
        document.getElementById('container').appendChild(this.canvas);
    }

    clear() {
        this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
    }

}

class Scene {

    // boid radius
    // no of boids
    // scene width
    // scene height
    constructor(boid_radius, no_of_boids) {
        this.boid_radius = boid_radius;
        this.no_of_boids = no_of_boids;
        this.boids = [];
        this.gameArea = {};
        this.started = false;
        this.width = 600;
        this.height = 600;

        this.initGameArea();
        this.initBoids();
    }

    initBoids() {
        let boids = [];
        for (let i = 0; i < this.no_of_boids; i++) {
            boids.push(new Boid(
                this.boid_radius,
                "black",
                300, 300, Math.random() * 360,
                // Math.random() * (this.gameArea.canvas.width - 100) + 50,
                // Math.random() * (this.gameArea.canvas.height - 100) + 50,
                // Math.random() * 360,
                i,
                this.width,
                this.height
            ));
        }

        this.boids = boids;
    }

    initGameArea() {
        this.gameArea = new GameArea(this.width, this.height);
        this.gameArea.init()
    }

    start() {
        if (this.started) {
            return;
        }

        // Kinda annoying, setInterval is a piece of shite and is always run from global scope
        // Therefore "this.update" will be undefined unless we bind it
        const updateMe = this.update.bind(this);
        this.interval = setInterval(updateMe, 20);
        // updateMe();
        this.started = true;
    }

    update() {
        this.gameArea.clear();
        for (let i = 0; i < this.no_of_boids; i++) {
            this.boids[i].move(this.boids);
            this.boids[i].draw(this.gameArea.context);
        }
    }

    stop() {
        if (!this.started) {
            return;
        }

        clearInterval(this.interval);
        this.interval = null;
        this.started = false;
    }

    reset() {
        if (this.started) {
            this.stop();
        }
        this.boids = new Array;
        this.initBoids();
        this.gameArea.clear();
        this.started = false;
    }

}

let scene = new Scene(5, 2);

function stop() {
    scene.stop();
}

function start() {
    scene.start();
}

function reset() {
    scene.reset();
}