index.html

<!doctype html>
<head>
    <meta charset="utf-8" />
    <title>JSON Schema Builder</title>
    <link rel="stylesheet" href="style.css" />
    <!--link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.8.0/styles/gruvbox-dark.min.css"-->
    <!--link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.8.0/styles/gruvbox-light.min.css"-->
    <!--link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/solarized-light.min.css"-->
    <!--script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.8.0/highlight.min.js"></script-->
<style>
.deletable .delete-me {
    visibility: hidden;
}
.deletable:hover .delete-me {
    visibility: visible;
    cursor: pointer;
}
</style>
</head>

<body>
    <script src="elm.js"></script>
    <script>
let initValue = null;

try {
    initValue = localStorage.editMe ? JSON.parse(localStorage.editMe) : {}
} catch(e) {
    initValue = {};
}

const elm = Elm.Main.fullscreen(initValue);

elm.ports.select.subscribe(id => {
    setTimeout(() => {
        // console.log('attempt to select', id);
        const x = document.getElementById(id);
        // console.log(x);
        if (x) {
            x.select();
        }
    }, 100);
});

elm.ports.download.subscribe(x => {
    const a = document.createElement('a');
    const blob = new Blob([JSON.stringify(x, null, '    ')], { type: 'application/json' });
    const url = URL.createObjectURL(blob);
    a.setAttribute('href', url);
    a.download = 'JSON Schema';
    a.click();
});

// this is hack to update url and highlight menu
// TODO: discover the right way of doing this
setTimeout(() => {

    document.body.addEventListener('dragstart', () => {
        console.log('drag started');
    });
    document.body.addEventListener('dragover', e => {
        const b = e.dataTransfer.effectAllowed;
        e.dataTransfer.dropEffect = ('move' === b || 'linkMove' === b ||
                'copyMove' === b) ? 'move' : 'copy';
        // console.log('drag over');
        return cancel(e);
    });
    document.body.addEventListener('dragenter', e => {
        elm.ports.dragOver.send(true);
        return cancel(e);
    });
    document.body.addEventListener('dragleave', e => {
        elm.ports.dragOver.send(false);
        return cancel(e);
    });
    document.body.addEventListener('drop', drop);
    document.body.addEventListener('dragdrop', drop);

    function drop(e) {
        cancel(e);
        if (e.dataTransfer.types.includes('Files')) {
            const files = e.dataTransfer.files;
            elm.ports.dragOver.send(false);
            [].forEach.call(files, file => readContents(file));
        } else if (e.dataTransfer.types.includes('text/uri-list')) {
            elm.ports.dragOver.send(false);
            fetch(e.dataTransfer.getData('text/uri-list'))
                .then(x => x.text())
                .then(load);
        }
    }


    function readContents(file) {
        const reader = new FileReader();
        reader.readAsText(file);
        reader.addEventListener('loadend', () => {
            try {
                load(reader.result);
            } catch(e) {
                console.error(e);
            }
        });
    }

    function load(text) {
        const data = JSON.parse(text);
        localStorage.editMe = text;
        elm.ports.editSchema.send(data);
    }

    const content = document.querySelector('#content');
    if (content) {
        const headers = content.querySelectorAll('div[tabindex] > h1');
        // TODO: recalc on window resize
        const checkpoints = Array.from(headers).map(el => ({
            hash: '#' + el.parentNode.id,
            offsetTop: offsetTop(el, content) - 100,
        })).reverse();
        let timeout = null;
        let hash = location.hash;

        if (hash && hash.length > 1) {
            const el = document.querySelector('#' + CSS.escape(hash.substr(1)));
            if (el) {
                el.focus();
            }
        }

        content.addEventListener('scroll', ({ target }) => {
            clearTimeout(timeout);
            timeout = setTimeout(() => {
                const found = checkpoints.filter(x => x.offsetTop < target.scrollTop )[0];
                if (found) {
                    if (hash !== found.hash) {
                        hash = found.hash
                        // elm.ports.activeSection.send(found.hash);
                        // history.replaceState({}, "", found.hash);
                    }
                }
            }, 200);
        });
    }

    function offsetTop(el, limit) {
        if (el === limit) {
            return 0;
        } else {
            return el.offsetTop + offsetTop(el.parentNode, limit);
        }
    }
}, 100);

    function cancel(e) {
        if (e.preventDefault) {
            e.preventDefault();
        }
        return false;
    }
    </script>
</body>