function findGetParameter(parameterName) {
    var result = null, tmp = [];

    location.search
        .substr(1)
        .split('&')
        .forEach(function(item) {
            tmp = item.split('=');
            if (tmp[0] === parameterName) result = decodeURIComponent(tmp[1]);
        });
    return result;
}

const Events = [
    'Transition -> slide',
    'Transition -> demo',
    'Transition -> new viewpoint',
    'Build Up',
    'Animation',
    'Pointer',
    'Live annotation',
];

class Annotator {
    constructor(root, annotations) {
        this.root = root;
        this.annotations = annotations;

        this.maxIndex = Object.keys(this.annotations).length - 1;

        let img1Id = 'img-1';
        let img2Id = 'img-2'
        let annotationsId = 'annotations';

        this.img1Element = document.getElementById(img1Id);
        this.img1IndexElement = document.getElementById(img1Id + '-index');
        this.img2Element = document.getElementById(img2Id);
        this.img2IndexElement = document.getElementById(img2Id + '-index');
        this.annotationElement = document.getElementById(annotationsId);
        this.navbar = document.getElementById('navbar');
        this.shortcutsIndex = document.getElementById('shortcuts-index');
        this.shortcutsValue = document.getElementById('shortcuts-value');

        this.setNavbar();
        this.setShortcutsInfo();
        this.setIndex(0);
        this.addShortcuts();
    }

    setShortcutsInfo() {
        for (let index = 1; index <= Events.length; index++) {
            let elt = document.createElement('td');
            elt.innerHTML = index;
            this.shortcutsIndex.appendChild(elt);

            elt = document.createElement('td');
            elt.innerHTML = Events[index - 1];
            this.shortcutsValue.appendChild(elt);
        }
    }

    setNavbar() {
        for (let frame in this.annotations) {
            let div = document.createElement('div');
            div.classList.add('column10');
            div.classList.add('notselected');
            div.id = 'thumbnail-' + frame;

            let img = document.createElement('img');
            img.setAttribute('src', this.root + '/' + frame + '.jpg');

            let text = document.createElement('p');
            text.classList.add('centered');
            text.innerHTML = frame;

            div.appendChild(img);
            div.appendChild(text);

            div.addEventListener('click', () => {
                this.setIndex(frame);
            });

            this.navbar.appendChild(div);
        }
    }

    formatIndex(index) {
        index += '';
        return index.padStart(4, '0');
    }

    getUrl(index) {
        return this.root + '/' + this.formatIndex(index) + '.jpg';
    }

    setIndex(index) {

        // If index is undefined, we only want a refresh
        if (index !== undefined) {
            this.index = index;
            this.index = Math.max(0, this.index);
            this.index = Math.min(this.index, this.maxIndex);

            // Refrsh images
            this.img1Element.src = this.getUrl(this.index);
            this.img2Element.src = this.getUrl(this.index + 1);

            // Refresh headers
            this.img1IndexElement.innerHTML = this.index + '/' + this.maxIndex;
            this.img2IndexElement.innerHTML = this.index + 1 + '/' + this.maxIndex;
        }

        let formattedIndex = this.formatIndex(this.index + 1);

        // Refresh navbar
        for (let key of Object.keys(this.annotations)) {
            document.getElementById('thumbnail-' + key).classList.remove('selected');
            document.getElementById('thumbnail-' + key).classList.add('notselected');
        }

        let current = document.getElementById('thumbnail-' + formattedIndex);
        current.classList.add('selected');
        current.classList.remove('notselected');
        current.scrollIntoView({ behavior: 'smooth', block: 'center', inline: 'center' });

        // Refresh annotations list
        let currentAnnotations = this.annotations[formattedIndex];

        if (currentAnnotations.length === 0) {
            this.annotationElement.innerHTML = 'There is no annotation for this frame';
        } else {
            this.annotationElement.innerHTML = '<ul>';
            for (let annotation of currentAnnotations) {
                this.annotationElement.innerHTML += '<li>' + annotation + '</li>';
            }
            this.annotationElement.innerHTML += '</ul>';
        }

    }

    increment(by = 1) {
        this.setIndex(this.index + by);
    }

    decrement(by = 1) {
        this.setIndex(this.index - by);
    }

    addShortcuts() {
        document.addEventListener('keyup', async (e) => {
            switch (e.code) {
                case 'ArrowRight': this.increment(e.ctrlKey ? 10 : 1); break;
                case 'ArrowLeft': this.decrement(e.ctrlKey ? 10 : 1); break;
            }

            if (e.code.startsWith('Numpad') || e.code.startsWith('Digit')) {
                let key = parseInt(e.code[e.code.length - 1], 10);
                await this.toggle(key);
            }
        });
    }

    async toggle(key) {
        let event = Events[key];
        if (event === undefined) {
            return;
        }

        let events = this.annotations[this.formatIndex(this.index + 1)];
        let search = events.indexOf(event);

        if (search === -1) {
            events.push(event);
        } else {
            events.splice(search, 1);
        }

        await this.sync();
        this.setIndex();
    }

    async sync() {
        await fetch('/data', {
            method: 'POST',
            headers: {
                'Accept': 'application/json',
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({
                root: this.root,
                annotations: this.annotations,
            }),
        });
    }
}
async function main() {
    const root = findGetParameter('root');
    let annotations = await fetch(root + '/annotations.json');
    annotations = await annotations.json();
    const annotator = new Annotator(root, annotations, );
}

main();