const canvas = document.getElementById('canvas')
const ctx = canvas.getContext('2d')

const width = canvas.width;
const height = canvas.height;

let current;
let selection = []

const tools = {
    graffity: {
        mousemove(e){
            (e.buttons & 1) && new Circle(e.clientX, e.clientY, +size.value, color.value)
        }
    },
    circle: {
        mousedown(e){
            current = new Circle(e.clientX,e.clientY, 1, color.value)
        },
        mousemove(e){
            if (!current) return;

            current.radius = current.distanceTo(e.clientX, e.clientY)
            Drawable.drawAll()
        },

        mouseup(e){
            current = null
        }
    },
    line: {
        mousedown(e){
            current = new Line(e.clientX, e.clientY, 0, 0, color.value, +size.value)
        },
        mousemove(e){
            if (!current) return;

            current.width = e.clientX - current.x
            current.height = e.clientY - current.y

            Drawable.drawAll()
        },

        mouseup(e){
            current = null
        }
    },
    rectangle: {
        mousedown(e){
            current = new Rectangle(e.clientX, e.clientY, 0, 0, color.value)
        },
        mousemove(e){
            if (!current) return;

            current.width = e.clientX - current.x
            current.height = e.clientY - current.y

            Drawable.drawAll()
        },

        mouseup(e){
            current = null
        }
    },
    ellipse: {
        mousedown(e) {
            current = new Ellipse(e.clientX, e.clientY, 0, 0, color.value)
        },
        mousemove(e) {
            if (!current) return;

            resultX = e.clientX - current.x;
            resultY = e.clientY - current.y;
            current.radiusX = resultX > 0 ? resultX : -resultX;
            current.radiusY = resultY > 0 ? resultY : - resultY;

            Drawable.drawAll()
        },

        mouseup(e) {
            current = null
        }
    },
    square: {
        mousedown(e){
            current = new Square(e.clientX, e.clientY, 0, color.value)
        },
        mousemove(e){
            if (!current) return;

            current.width = e.clientX - current.x

            Drawable.drawAll()
        },

        mouseup(e){
            current = null
        }
    },
    triangle: {
        mousedown(e){
            current = new Triangle(e.clientX, e.clientY, color.value)
        },
        mousemove(e){
            if (!current) return;
            
            current.oneX = e.clientX;
            current.oneY = e.clientY;
            current.twoX = current.x - (current.oneX - current.x);
            current.twoY = e.clientY;

            Drawable.drawAll()
        },

        mouseup(e){
            current = null
        }
    },
    select: {
        click(e){
            console.log(e)
            let found = Drawable.instances.filter(c => c.in && c.in(e.clientX, e.clientY))
            if (found.length){
                if (e.ctrlKey){
                    selection.push(found.pop())
                }
                else {
                    selection = [found.pop()]
                }
            }
            else {
                if (!e.ctrlKey) selection = []
            }

            Drawable.drawAll(selection)
        },
        mousedown(e){
            current = new Rectangle(e.clientX, e.clientY, 0, 0, color.value)
        },
        mousemove(e){
            if (!current) return;

            current.width = e.clientX - current.x
            current.height = e.clientY - current.y

            Drawable.drawAll()
        },
        mouseup(e){
            current = null // пока не додумала как обратиться внутрь поля выделения
            //x,y, w, h прямоугольника
            //selection - только те элеменеты Drawable.instances которые в границах прямоугольника.
        },
    }
}

function superHandler(evt){
    let t = tools[tool.value]
    if (typeof t[evt.type] === 'function')
        t[evt.type].call(this, evt)
}

canvas.onmousemove = superHandler
canvas.onmouseup = superHandler
canvas.onmousedown = superHandler
canvas.onclick = superHandler

function Drawable(){
   Drawable.addInstance(this);   
}

const distance = (x1,y1, x2, y2) => ((x1-x2)**2 + (y1-y2)**2)**0.5

Drawable.prototype.draw = function(){};
Drawable.prototype.distanceTo = function(x,y){
    if (typeof this.x !== 'number' ||
        typeof this.y !== 'number'){
        return NaN
    }
    return distance(this.x, this.y, x, y)
}

Drawable.instances = [];
Drawable.addInstance = function(item){
    Drawable.instances.push(item);
}

Drawable.drawAll = function(selection=[]){
    ctx.clearRect(0,0,width,height);
    Drawable.forAll(item => item.draw())
    selection.forEach(item  => item.draw(true))
}

Drawable.forAll = function(callback){
    for(var i = 0; i<Drawable.instances.length;i++){
        callback(Drawable.instances[i])
    }
}

class Circle extends Drawable {
    constructor(x, y, radius, color){
        super()
        this.x = x;
        this.y = y;
        this.radius = radius;
        this.color = color;

        this.draw(); 
    }

    draw(){
        ctx.beginPath();
        ctx.arc(this.x, this.y, this.radius, 0, 2 * Math.PI);
        ctx.closePath();
        ctx.fillStyle = this.color;
        ctx.fill(); // рисует закрашенный circle
        // ctx.stroke(); // рисует границы circle 
    }

    in(x,y){
        return this.distanceTo(x,y) < this.radius
    }

    inBounds(x,y,w,h){
        return this.x >= x && this.x <= x + w &&
               this.y >= y && this.y <= y + h 
    }
}

class Line extends Drawable {
    constructor(x,y, width, height, color, lineWidth){
        super()
        this.x = x;
        this.y = y;
        this.width = width;
        this.height = height;
        this.color = color;
        this.lineWidth = lineWidth;

        this.draw(); 
    }
    
    draw(){
        ctx.beginPath();
        ctx.moveTo(this.x, this.y);
        ctx.lineTo(this.x + this.width, this.y + this.height);
        ctx.closePath();
        ctx.strokeStyle = this.color;
        ctx.lineWidth = this.lineWidth
        ctx.stroke();
    }
}

class Rectangle extends Drawable {
    constructor(x, y, width, height, color){
        super()
        this.x = x;
        this.y = y;
        this.width = width;
        this.height = height;
        this.color = color;

        this.draw(); 
    }
    
    draw(){
        ctx.beginPath();
        ctx.strokeRect(this.x, this.y, this.width, this.height); // рисует границы rectangle
        // ctx.fillRect(this.x, this.y, this.width, this.height); // рисует закрашенный rectangle
        ctx.fillStyle = this.color;
        ctx.fill();
    }
}

class Ellipse extends Drawable {
    constructor(x, y, radiusX, radiusY, color) {
        super()
        this.x = x;
        this.y = y;
        this.radiusX = radiusX;
        this.radiusY = radiusY;
        this.color = color;

        
        this.draw();
    }

    draw() {
        ctx.beginPath();
        ctx.ellipse(this.x, this.y, this.radiusX, this.radiusY, 0, 0, 2 * Math.PI);
        ctx.closePath();
        ctx.fillStyle = this.color;
        // ctx.fill(); // рисует закрашенный ellipse
        ctx.stroke(); // рисует границы ellipse
    }
}

class Square extends Drawable {
    constructor(x, y, width, color){
        super()
        this.x = x;
        this.y = y;
        this.width = width;
        this.color = color;

        this.draw(); 
    }
    
    draw(){
        ctx.beginPath();
        ctx.strokeRect(this.x, this.y, this.width, this.width); // рисует границы square
        // ctx.fillRect(this.x, this.y, this.width, this.width); // рисует закрашенный square
        ctx.fillStyle = this.color;
        ctx.fill();
    }
}

class Triangle extends Drawable {
    constructor(x, y, color){
        super()
        this.x = x;
        this.y = y;
        this.oneX = x;
        this.oneY = y;
        this.twoX = x;
        this.twoY = y;
        this.color = color;

        this.draw(); 
    }
    
    draw(){
        ctx.beginPath();
        ctx.moveTo(this.x, this.y);
        ctx.lineTo(this.twoX, this.twoY);
        ctx.lineTo(this.oneX, this.oneY);
        ctx.closePath();
        // ctx.stroke(); // рисует границы triangle
        ctx.fill(); // рисует закрашенный triangle
        ctx.fillStyle = this.color;
    }
}

color.onchange = () => {
    selection.forEach(c => c.color = color.value)
    Drawable.drawAll(selection)
}

document.getElementById('delete').onclick = () =>{
    Drawable.instances = Drawable.instances.filter(item => !selection.includes(item))
    selection = []
    Drawable.instances = []; // очищение массива полностью
    Drawable.drawAll()
}

undo.onclick = function () {
    Drawable.instances.pop(); // удаление последнего элемента в массиве
    Drawable.drawAll()
}