/**
 * BatchOverlay — shared full-screen progress overlay.
 *
 * Usage:
 *   BatchOverlay.show(title, total, options)
 *     options: { unit: 'documents', color: '#dc3545' }
 *
 *   BatchOverlay.update(done, total, currentItem)
 *     Advances the bar and ETA. currentItem shown in the sub-line.
 *
 *   BatchOverlay.done(message, onClose)
 *     Switches to "complete" state — green checkmark + Done button.
 *     onClose fires when the user dismisses.
 *
 *   BatchOverlay.hide()
 *     Force-hides (use for error bail-outs before done is reached).
 */
var BatchOverlay = (function () {

    var _startMs  = 0;
    var _onClose  = null;
    var _unit     = 'items';
    var _color    = '#0d6efd';
    var _injected = false;

    var _HTML = '<div id="bos-wrap" style="display:none;position:fixed;inset:0;z-index:9999;' +
        'background:rgba(0,0,0,0.55);align-items:center;justify-content:center;">' +
        '<div class="card shadow-lg p-4 text-center" style="min-width:380px;max-width:480px;width:90%;">' +
        '<div id="bos-spinner" class="spinner-border mx-auto mb-3" role="status" style="width:2.5rem;height:2.5rem;"></div>' +
        '<div id="bos-icon" class="mx-auto mb-3" style="display:none;font-size:2.5rem;color:#198754;"><i class="ti ti-circle-check"></i></div>' +
        '<div class="fw-semibold fs-6 mb-1" id="bos-title">Processing…</div>' +
        '<div class="text-muted small mb-4" id="bos-sub"></div>' +
        '<div id="bos-pct" style="font-size:3rem;font-weight:700;line-height:1;letter-spacing:-1px;">0%</div>' +
        '<div class="text-muted small mb-3" id="bos-count"></div>' +
        '<div class="progress mb-2" style="height:10px;border-radius:6px;">' +
        '<div id="bos-bar" class="progress-bar progress-bar-striped progress-bar-animated"' +
        ' role="progressbar" style="width:0%;border-radius:6px;"' +
        ' aria-valuenow="0" aria-valuemin="0" aria-valuemax="100"></div>' +
        '</div>' +
        '<div class="text-muted small" id="bos-eta">&nbsp;</div>' +
        '<button id="bos-close" class="btn btn-success mt-3" style="display:none;">' +
        '<i class="ti ti-check me-1"></i>Done' +
        '</button>' +
        '</div></div>';

    function _inject() {
        if (_injected) return;
        $('body').append(_HTML);
        $('#bos-close').on('click', function () {
            _resetState();
            $('#bos-wrap').hide();
            if (_onClose) { _onClose(); _onClose = null; }
        });
        _injected = true;
    }

    function _resetState() {
        $('#bos-spinner').show().css('color', _color);
        $('#bos-icon').hide();
        $('#bos-pct').css('color', _color);
        $('#bos-bar')
            .addClass('progress-bar-striped progress-bar-animated')
            .removeClass('bg-success')
            .css('background-color', _color)
            .css('width', '0%').attr('aria-valuenow', 0);
        $('#bos-close').hide();
        $('#bos-eta').html('&nbsp;');
    }

    function show(title, total, options) {
        options  = options || {};
        _unit    = options.unit    || 'items';
        _color   = options.color   || '#0d6efd';
        _onClose = options.onClose || null;
        _startMs = Date.now();

        _inject();
        _resetState();

        $('#bos-title').text(title);
        $('#bos-sub').text('Starting…');
        $('#bos-pct').text('0%');
        $('#bos-count').text('0 / ' + total + ' ' + _unit);
        $('#bos-wrap').css('display', 'flex');
    }

    function update(done, total, currentItem) {
        var pct     = Math.round(done / total * 100);
        var elapsed = (Date.now() - _startMs) / 1000;
        var eta     = '&nbsp;';
        if (done > 0) {
            var remaining = Math.round((elapsed / done) * (total - done));
            eta = remaining > 0 ? ('~' + remaining + 's remaining') : 'almost done…';
        }
        $('#bos-pct').text(pct + '%');
        $('#bos-bar').css('width', pct + '%').attr('aria-valuenow', pct);
        $('#bos-count').text(done + ' / ' + total + ' ' + _unit);
        if (currentItem !== undefined) $('#bos-sub').text('Processing ' + currentItem + '…');
        $('#bos-eta').html(eta);
    }

    function done(message, onClose) {
        _onClose = onClose || null;
        $('#bos-spinner').hide();
        $('#bos-icon').show();
        $('#bos-pct').text('100%').css('color', '#198754');
        $('#bos-bar')
            .removeClass('progress-bar-striped progress-bar-animated')
            .css('background-color', '').addClass('bg-success')
            .css('width', '100%').attr('aria-valuenow', 100);
        $('#bos-sub').text(message || 'Complete.');
        $('#bos-eta').html('&nbsp;');
        $('#bos-close').show();
    }

    function hide() {
        if (_injected) $('#bos-wrap').hide();
    }

    return { show: show, update: update, done: done, hide: hide };

})();