var screenshotVideo;
const defaultSound = 'https://github.com/amiad/screenshot.js/raw/master/assets/cam-click.mp3';

class Screenshot {
    constructor(args){
        this.args = args;

        if (typeof navigator.mediaDevices.getDisplayMedia == 'function'){
            if (! screenshotVideo){
                screenshotVideo = document.createElement("video");
                screenshotVideo.setAttribute('autoplay', true);
                screenshotVideo.style.top = '-9999px';
                screenshotVideo.style.position = 'absolute';
                screenshotVideo.style.marginBottom = screenshotVideo.clientHeight * -1 + 'px';
                document.body.appendChild(screenshotVideo);

                screenshotVideo.addEventListener('canplay', () => {this.takeScreenshot();});
            }
            if (! screenshotVideo.srcObject || ! screenshotVideo.srcObject.active ||args.askNewShare){
                if (screenshotVideo.srcObject){
                    let tracks =  screenshotVideo.srcObject.getTracks();
                    tracks.forEach(track => track.stop());
                    screenshotVideo.srcObject = null;
                }
                navigator.mediaDevices.getDisplayMedia({
                    audio: false
                })
                .then((record) => {
                    screenshotVideo.srcObject = record;
                })
                .catch((e) => {
                    //console.log('You need to allow screen share');
                    if (typeof this.args.noPermit == 'function'){
                        this.args.noPermit();
                    }
                });
            }
            else {
                this.takeScreenshot();
            }
        }
        else {
            //console.log('You\'re browser not support screen share');
            if (typeof this.args.noSupport == 'function'){
                this.args.noSupport();
            }
        }
    }

    takeScreenshot(){

        if (this.args.sound) {
            this.playSound();
        }

        const canvas = document.createElement("canvas");
        canvas.width = screenshotVideo.clientWidth;
        canvas.height = screenshotVideo.clientHeight;
        canvas.getContext('2d').drawImage(screenshotVideo, 0, 0, canvas.width, canvas.height);
        const img = document.createElement("img");
        img.src = canvas.toDataURL();

        if (this.args.width) {
            img.width = this.args.width;
        }
        if (this.args.height) {
            img.height = this.args.height;
        }

        img.addEventListener('load', () => {
            if (typeof this.args.success == 'function'){
                this.args.success(img);
            }
        });
    }

    playSound(){
        let sound;
        if (this.args.sound === true){
            sound = defaultSound;
        }
        else {
            sound = this.args.sound;
        }
        new Audio(sound).play();
    }
}