paper.install(window);


function gen_tree(pos, maxheight) {
    var baum = new Branch();

    baum.length = 0.15 * maxheight + 0.15 * maxheight * Math.random();

    var shapernd = Math.random() * 3;
    if(shapernd < 1) {
        baum.crown = new KiteCrown(
            0.49 * maxheight + 0.21 * maxheight * Math.random(),
            0.4 + Math.random() * 0.2,
            {bisect: 0.2 + Math.random() * 0.2},
        );
    } else if(shapernd < 2) {
        baum.crown = new TriangleCrown(
            0.49 * maxheight + 0.21 * maxheight * Math.random(),
            0.4 + Math.random() * 0.2,
        );
    } else {
        baum.crown = new EllipseCrown(
            0.49 * maxheight + 0.21 * maxheight * Math.random(),
            0.4 + Math.random() * 0.2,
            {bisect: 0.1 + Math.random() * 0.4},
        );
    }

    baum.angle = Math.PI / 2;
    if(Math.random() < 0.3) {
        baum.angle += Math.random() * 0.2 - 0.1;
    }

    if((baum.crown.shape != "triangle") && (Math.random() < 0.5)) {
        var b = {
            length: baum.length * 0.4,
            angle: Math.PI / 2,
            crown: baum.crown.clone()
        };
        b.crown.length *= 0.4;
        b.crown.width = 0.8;
        baum.forks = [{
            pos: 0.2 + Math.random() * 0.4,
            branch: new Branch(b),
        }];

        baum.draw(pos);
        var step = (Math.random() < 0.5) ? -0.1 : 0.1;
        while(baum.collides_crown(baum.forks[0].branch)) {
            baum.forks[0].branch.angle += step;
            baum.draw(pos);
        }

        var range = 4*Math.PI/9 - Math.abs(Math.PI/2 - baum.forks[0].branch.angle);
        if(step > 0) {
            baum.forks[0].branch.angle += range * (0.1 + 0.9 * Math.random());
        } else {
            baum.forks[0].branch.angle -= range * (0.1 + 0.9 * Math.random());
        }
        baum.draw(pos);

    }

    baum.draw(pos);
    return baum;
}


class Crown {
    constructor(length, width, shape) {
        this.width = width;
        this.length = length;
        this.shape = shape;
    }

    undraw() {
        if(typeof this._path !== "undefined") {
            this._path.removeSegments();
            delete this._path;
        }
    }

    collides(other) {
        return this._path.intersects(other._path);
    }

    get bounds() {
        return this._path.bounds;
    }
}


class KiteCrown extends Crown {
    constructor(length, width, {bisect = 0.3}={}) {
        super(length, width, 'kite');
        this.bisect = bisect;
    }

    clone() {
        return new KiteCrown(this.length, this.width, {bisect: this.bisect});
    }

    draw(branch, bvec, cpos) {
        this.undraw();
        var cvec = bvec.multiply(1/bvec.length * this.length);
        var bswidth = this.length * this.width;
        var bsvec = new Point(Math.sin(branch.angle) * bswidth / 2,
                              Math.cos(branch.angle) * bswidth / 2);
        this._path = new Path();
        this._path.strokeColor = 'black';
        this._path.fillColor = 'white';
        this._path.strokeWidth = 2;
        this._path.closed = true;
        this._path.add(cpos);
        this._path.add(cpos.add(cvec.multiply(this.bisect)).add(bsvec));
        this._path.add(cpos.add(cvec));
        this._path.add(cpos.add(cvec.multiply(this.bisect)).subtract(bsvec));
    }
}


class TriangleCrown extends Crown {
    constructor(length, width) {
        super(length, width, 'triangle');
    }

    clone() {
        return new TriangleCrown(this.length, this.width);
    }

    draw(branch, bvec, cpos) {
        this.undraw();
        var cvec = bvec.multiply(1/bvec.length * this.length);
        var bswidth = this.length * this.width;
        var bsvec = new Point(Math.sin(branch.angle) * bswidth / 2,
                              Math.cos(branch.angle) * bswidth / 2);
        this._path = new Path();
        this._path.strokeColor = 'black';
        this._path.fillColor = 'white';
        this._path.strokeWidth = 2;
        this._path.closed = true;
        this._path.add(cpos.add(bsvec));
        this._path.add(cpos.add(cvec));
        this._path.add(cpos.subtract(bsvec));
    }
}


class EllipseCrown extends Crown {
    constructor(length, width, {bisect = 0.5}={}) {
        super(length, width, 'ellipse');
        this.bisect = bisect;
    }

    clone() {
        return new EllipseCrown(this.length, this.width, {bisect: this.bisect});
    }

    draw(branch, bvec, cpos) {
        this.undraw();
        var cvec = bvec.multiply(1/bvec.length * this.length);
        var bswidth = this.length * this.width;
        var bsvec = new Point(Math.sin(branch.angle) * bswidth / 2,
                              Math.cos(branch.angle) * bswidth / 2);
        this._path = new Path();
        this._path.strokeColor = 'black';
        this._path.fillColor = 'white';
        this._path.strokeWidth = 2;
        this._path.closed = true;
        var cmid = cpos.add(cvec.multiply(this.bisect));
        this._path.add(new Segment(cpos,
                                   bsvec.multiply(0.5),
                                   bsvec.multiply(-0.5),
                                   ));
        this._path.add(new Segment(cmid.subtract(bsvec),
                                   bvec.multiply(-0.5),
                                   bvec.multiply(0.5),
                                   ));
        this._path.add(new Segment(cpos.add(cvec),
                                   bsvec.multiply(-0.5),
                                   bsvec.multiply(0.5),
                                   ));
        this._path.add(new Segment(cmid.add(bsvec),
                                   bvec.multiply(0.5),
                                   bvec.multiply(-0.5),
                                   ));
    }
}


class Branch {
    constructor(data) {
        Object.assign(this, data);
        if(typeof this.forks !== "undefined") {
            for (let fork of this.forks) {
                fork.branch = new Branch(fork.branch, this);
            }
        }
    }

    draw(pos) {
        if(typeof this._branch !== "undefined") {
            this._branch.removeSegments();
            delete this._branch;
        }

        this._branch = new Path();
        var bvec = new Point(Math.cos(this.angle) * this.length,
                                  -1 * Math.sin(this.angle) * this.length);
        var end = pos.add(bvec);
        this._branch.strokeColor = 'black';
        this._branch.strokeWidth = 2;
        this._branch.add(pos);
        this._branch.add(end);

        if(typeof this.crown !== "undefined") {
            this.crown.draw(this, bvec, end);
        }

        if(typeof this.forks !== "undefined") {
            for (let fork of this.forks) {
                fork.branch.draw(pos.add(bvec.multiply(fork.pos)));
            }
        }

    }
    collides_crown(other) {
        return this.crown.collides(other.crown);
    }

    get bounds() {
        var b = this._branch.bounds;
        b = b.unite(this.crown.bounds);
        if(typeof this.forks !== "undefined") {
            for (let fork of this.forks) {
                b = b.unite(fork.branch.bounds);
                /*
                var r = new Path.Rectangle({
                    point: fork.branch.bounds.point,
                    size: fork.branch.bounds.size,
                    strokeWidth: 1,
                    strokeColor: 'green'});
                */
            }
        }
        return b;
    }
}


function draw() {
    var canvas = document.getElementById('canvas');
    paper.setup(canvas);

    var width = 148 * 5;
    var height = 105 * 5;
    var rows = 3;
    var rowspace = 20;
    var inspace = 30;
    var outspace = 10;

    var maxh = (height - (rows-1)*rowspace - 2*outspace - 2*inspace) / rows;

    var outline = new Path.Rectangle({
        point: new Point(outspace, outspace),
        size: new Size(width - 2*outspace, height - 2*outspace),
        strokeWidth: 2,
        strokeColor: 'black'
    });

    for(var row=0; row<rows; row++) {
        var y = outspace + inspace + maxh * (row + 1) + rowspace * row;
        var x = outspace + inspace + 20; // TODO approx width
        var prev;
        while(x < width - outspace - inspace - 60) { // TODO approx width
            var yy = y + Math.random() * 40 - 20;
            x += Math.random() * 10; // TODO approx width
            var t = gen_tree(new Point(x, yy), maxh);
            if(typeof prev !== 'undefined') {
                while(prev.bounds.intersects(t.bounds)) {
                    x += 15;
                    t.draw(new Point(x, y));
                    console.log('intersects');
                }
            }
            prev = t;
        }
    }
}