/*
 * Gallery bulk uploader.
 *
 * Per file, one request:
 *   1. draw a small JPEG thumbnail on a canvas (browser-side)
 *   2. POST the original + thumbnail to admin/api.php as multipart/form-data
 *   3. the webhost streams both to S3 and registers the image
 *
 * One file per request keeps each PHP process small, so the size of the whole
 * gallery upload never matters — only the largest single image. The browser
 * never sees an S3 URL or credential for writing.
 */
(function () {
    'use strict';

    var zone = document.getElementById('dropzone');
    if (!zone) return;

    var input = document.getElementById('file-input');
    var list = document.getElementById('upload-list');
    var countEl = document.getElementById('img-count');

    var api = zone.dataset.api;
    var slug = zone.dataset.slug;
    var csrf = zone.dataset.csrf;
    // Guest upload links pass a per-gallery key; the admin edit page sets none.
    var uploadKey = zone.dataset.key || '';
    var thumbSize = parseInt(zone.dataset.thumbSize, 10) || 600;
    var thumbQuality = parseFloat(zone.dataset.thumbQuality) || 0.8;

    var queue = [];
    var busy = false;

    zone.addEventListener('click', function () { input.click(); });
    input.addEventListener('change', function () { enqueue(input.files); input.value = ''; });

    ['dragenter', 'dragover'].forEach(function (ev) {
        zone.addEventListener(ev, function (e) { e.preventDefault(); zone.classList.add('drag'); });
    });
    ['dragleave', 'drop'].forEach(function (ev) {
        zone.addEventListener(ev, function (e) { e.preventDefault(); zone.classList.remove('drag'); });
    });
    zone.addEventListener('drop', function (e) { enqueue(e.dataTransfer.files); });

    window.addEventListener('beforeunload', function (e) {
        if (busy || queue.length) { e.preventDefault(); e.returnValue = ''; }
    });

    function enqueue(files) {
        Array.prototype.forEach.call(files, function (file) {
            var row = document.createElement('div');
            row.className = 'upload-item';
            row.innerHTML = '<span class="name"></span><span class="bar"><i></i></span><span class="state">queued</span>';
            row.querySelector('.name').textContent = file.name;
            list.appendChild(row);
            queue.push({ file: file, row: row });
        });
        pump();
    }

    function pump() {
        if (busy || !queue.length) return;
        busy = true;
        var job = queue.shift();
        uploadOne(job.file, job.row)
            .then(function () { setState(job.row, 'done', 'done'); bumpCount(); })
            .catch(function (err) {
                setState(job.row, 'failed', 'error');
                job.row.title = String(err);
                var retry = document.createElement('a');
                retry.href = '#';
                retry.textContent = ' retry';
                retry.addEventListener('click', function (e) {
                    e.preventDefault();
                    retry.remove();
                    setState(job.row, 'queued', '');
                    queue.push(job);
                    pump();
                });
                job.row.appendChild(retry);
            })
            .finally(function () { busy = false; pump(); });
    }

    function setState(row, text, cls) {
        var el = row.querySelector('.state');
        el.textContent = text;
        el.className = 'state ' + (cls || '');
    }

    function bumpCount() {
        if (countEl) countEl.textContent = String(parseInt(countEl.textContent, 10) + 1);
    }

    /* POST multipart to the webhost with upload progress (fetch has none → XHR). */
    function sendForm(form, onProgress) {
        return new Promise(function (resolve, reject) {
            var xhr = new XMLHttpRequest();
            xhr.open('POST', api);
            xhr.setRequestHeader('X-CSRF-Token', csrf);
            // Let the browser set Content-Type (with the multipart boundary).
            xhr.upload.addEventListener('progress', function (e) {
                if (e.lengthComputable && onProgress) onProgress(e.loaded / e.total);
            });
            xhr.addEventListener('load', function () {
                var data = {};
                try { data = JSON.parse(xhr.responseText); } catch (err) {}
                if (xhr.status >= 200 && xhr.status < 300 && data.ok) resolve(data);
                else reject(new Error((data && data.error) || ('Upload failed (' + xhr.status + ')')));
            });
            xhr.addEventListener('error', function () { reject(new Error('Network error during upload')); });
            xhr.send(form);
        });
    }

    /* Thumbnail as JPEG blob; null when the browser cannot decode the file
       (e.g. RAW) — the original still uploads untouched. */
    function makeThumb(file) {
        var decode = window.createImageBitmap
            ? createImageBitmap(file, { imageOrientation: 'from-image' })
            : new Promise(function (resolve, reject) {
                var img = new Image();
                img.onload = function () { resolve(img); };
                img.onerror = reject;
                img.src = URL.createObjectURL(file);
            });

        return decode.then(function (src) {
            var w = src.width, h = src.height;
            var scale = Math.min(1, thumbSize / Math.max(w, h));
            var canvas = document.createElement('canvas');
            canvas.width = Math.max(1, Math.round(w * scale));
            canvas.height = Math.max(1, Math.round(h * scale));
            canvas.getContext('2d').drawImage(src, 0, 0, canvas.width, canvas.height);
            if (src.close) src.close();
            return new Promise(function (resolve) {
                canvas.toBlob(function (blob) { resolve(blob); }, 'image/jpeg', thumbQuality);
            });
        }).catch(function () { return null; });
    }

    function uploadOne(file, row) {
        var bar = row.querySelector('.bar i');
        setState(row, 'thumbnail');

        return makeThumb(file).then(function (thumbBlob) {
            setState(row, 'uploading');
            var form = new FormData();
            form.append('slug', slug);
            if (uploadKey) form.append('key', uploadKey);
            form.append('original', file, file.name);
            if (thumbBlob) form.append('thumb', thumbBlob, 'thumb.jpg');
            return sendForm(form, function (f) {
                bar.style.width = Math.round(f * 100) + '%';
            });
        });
    }
})();