function d(x1, y1, x2, y2){
    return Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
}
class Segment{
    constructor(bx, by, ex, ey){
        this.bx = bx;
        this.by = by;
        this.ex = ex;
        this.ey = ey;
        this.dist = d(bx, by, ex, ey);
    }
}

class Route{
    constructor(n, color, bx=0, by=0, ex=800, ey=600){
        this.s = [];
        this.color = color;
        for (let i=0; i<n; ++i){
            let bx_, by_, ex_, ey_;
            if (i==0){
                bx_ = bx;
                by_ = by;
            }
            else {
                bx_ = this.s[i-1].ex;
                by_ = this.s[i-1].ey;
            }
            ex_ = Math.random()*800;
            ey_ = Math.random()*600;
            if (i==n-1){
                ex_ = ex;
                ey_ = ey;
            }
            this.s[i] = new Segment(bx_, by_, ex_, ey_);
        }
    }
    draw(){
        context.strokeStyle = this.color;
        context.beginPath();
        context.moveTo(this.s[0].bx, this.s[0].by);
        for (let i=0; i<this.s.length; ++i){
            context.lineTo(this.s[i].ex, this.s[i].ey);
        }
        context.stroke();
    }
}

class Enemy{
    constructor(){
        this.r_ind = Math.floor(Math.random()*r.length);
        this.s_ind = 0;
        this.d = 0;
        this.calcxy();
        this.image = duckTarget;
        this.sx = 50;
        this.sy = 50;
        this.speed = 5;
        this.finish = false;
        this.hp = 100;
    }
    calcxy(){
        if (this.finish || this.hp <= 0) return;
        this.x = r[this.r_ind].s[this.s_ind].bx;
        this.y = r[this.r_ind].s[this.s_ind].by;
        this.x += (r[this.r_ind].s[this.s_ind].ex - r[this.r_ind].s[this.s_ind].bx)*this.d/r[this.r_ind].s[this.s_ind].dist;
        this.y += (r[this.r_ind].s[this.s_ind].ey - r[this.r_ind].s[this.s_ind].by)*this.d/r[this.r_ind].s[this.s_ind].dist;
    }
    update(){
        if (this.finish || this.hp <= 0) return;
        this.d += this.speed;
        if (this.d > r[this.r_ind].s[this.s_ind].dist){
            this.d -= r[this.r_ind].s[this.s_ind].dist;
            this.s_ind++;
            if (this.s_ind >= r[this.r_ind].s.length){
                this.finish = true;
            }
        }
        this.calcxy();
    }
    draw(){
        if (this.finish || this.hp <= 0) return;
        drawImage(this.image, this.x-this.sx/2, this.y-this.sy/2, this.sx, this.sy);
    }
}

class Tower{
    constructor(x, y){
        this.x = x;
        this.y = y;
        this.r = 200;
        this.target = [];
        this.dmg = 0.5;
    }
    shoot(){
        this.target = [];
        for (let i=0; i<e.length; ++i){
            if (d(this.x, this.y, e[i].x, e[i].y) < this.r && !e[i].finish && e[i].hp > 0){
                this.target.push(i);
                e[i].hp -= this.dmg;
            }
        }
    }
    update(){
        this.shoot();
    }
    draw(){
        drawImage(crystal, this.x-25, this.y-25, 50, 50);
        context.strokeStyle = "red";
        context.beginPath();
        for (let i=0; i<this.target.length; ++i){
            context.moveTo(this.x, this.y);
            context.lineTo(e[this.target[i]].x, e[this.target[i]].y);
        }
        context.stroke();
    }
}

var r = [new Route(3, "blue"), new Route(5, "red"), new Route(7, "green")];
var e = [];
var tower = [];
var t = 0;
function update() {
    ++t;
    if (t%1==0){
        e.push(new Enemy())
    }
    for (let i=0; i<e.length; ++i){
        e[i].update();
    }
    for (let i=0; i<tower.length; ++i){
        tower[i].update();
    }
}
function draw() {
    for (let i=0; i<r.length; ++i){
        r[i].draw();
    }
    for (let i=0; i<e.length; ++i){
        e[i].draw();
    }
    for (let i=0; i<tower.length; ++i){
        tower[i].draw();
    }
};
function keyup(key) {
    // Show the pressed keycode in the console
    console.log("Pressed", key);
};
function mouseup() {
    tower.push(new Tower(mouseX, mouseY));
};