(function () {
  'use strict';

  var state = {
    range: '15m',
    offset: 0,
    limit: 100,
    tail: false,
    tailTimer: null,
    tailCursor: null,
    tailPaused: false,
    lastCount: 0
  };

  var SEV_CLASS = {
    fatal: 'label-danger', crit: 'label-danger', critical: 'label-danger',
    error: 'label-danger', err: 'label-danger',
    warn: 'label-warning', warning: 'label-warning',
    info: 'label-info',
    debug: 'label-default', trace: 'label-default'
  };

  function sevLabel(sev) {
    var cls = SEV_CLASS[(sev || '').toLowerCase()] || 'label-default';
    return $('<span>').addClass('label ' + cls).text(sev || '-');
  }

  function timeParams() {
    var p = {};
    if (state.range === 'custom') {
      var s = $('#since-input').val(), u = $('#until-input').val();
      if (s) p.since = new Date(s).toISOString();
      if (u) p.until = new Date(u).toISOString();
    } else {
      p.since = state.range;
    }
    return p;
  }

  function filterParams() {
    var p = {};
    var map = {
      namespace: '#f-namespace', app: '#f-app', host: '#f-host',
      pod: '#f-pod', container: '#f-container',
      severity: '#f-severity', stream: '#f-stream'
    };
    Object.keys(map).forEach(function (k) {
      var v = $(map[k]).val();
      if (v) p[k] = v;
    });
    var q = $('#q').val().trim();
    if (q) p.q = q;
    if ($('#sql-row').is(':visible')) {
      var sql = $('#sql').val().trim();
      if (sql) p.sql = sql;
    }
    return p;
  }

  function setStatus(msg, isError) {
    $('#status-text').text(msg || '').toggleClass('text-danger', !!isError);
  }

  function renderRow(row, tbody) {
    var src = (row.namespace || '-') + ' / ' + (row.pod || '-');
    var tr = $('<tr>').addClass('log-row')
      .append($('<td>').addClass('col-ts').text(row.timestamp))
      .append($('<td>').addClass('col-src').text(src))
      .append($('<td>').addClass('col-sev').append(sevLabel(row.severity)))
      .append($('<td>').addClass('msg').text(row.message));
    tr.data('row', row);
    tbody.append(tr);
  }

  function kvTable(title, obj) {
    var keys = Object.keys(obj || {});
    if (!keys.length) return null;
    var t = $('<table>').addClass('table table-condensed detail-table');
    t.append($('<caption>').text(title));
    keys.sort().forEach(function (k) {
      t.append($('<tr>').append($('<th>').text(k)).append($('<td>').text(obj[k])));
    });
    return t;
  }

  function toggleDetail(tr) {
    var next = tr.next();
    if (next.hasClass('detail-row')) { next.remove(); return; }
    var row = tr.data('row');
    var cell = $('<td>').attr('colspan', 4);
    var meta = {
      host: row.host, source: row.source, namespace: row.namespace,
      pod: row.pod, container: row.container, stream: row.stream
    };
    [kvTable('meta', meta), kvTable('labels', row.labels), kvTable('fields', row.fields)]
      .forEach(function (t) { if (t) cell.append(t); });
    tr.after($('<tr>').addClass('detail-row').append(cell));
  }

  function renderRows(rows, append) {
    var tbody = $('#log-body');
    if (!append) tbody.empty();
    rows.forEach(function (r) { renderRow(r, tbody); });
  }

  function runQuery() {
    var params = $.extend({ limit: state.limit, offset: state.offset }, timeParams(), filterParams());
    setStatus('loading...');
    $.getJSON('/api/query', params)
      .done(function (res) {
        renderRows(res.rows, false);
        state.lastCount = res.count;
        setStatus('');
        $('#result-info').text(
          res.count + ' rows (' + res.since + ' → ' + res.until + '), offset ' + res.offset);
        $('#prev-btn').prop('disabled', state.offset === 0);
        $('#next-btn').prop('disabled', res.count < state.limit);
      })
      .fail(function (xhr) {
        setStatus((xhr.responseJSON && xhr.responseJSON.error) || 'query failed', true);
      });
  }

  function tailTick() {
    if (state.tailPaused) return;
    var params = $.extend({}, filterParams());
    if (state.tailCursor !== null) params.cursor = state.tailCursor;
    $.getJSON('/api/tail', params)
      .done(function (res) {
        state.tailCursor = res.cursor;
        if (res.rows.length) {
          renderRows(res.rows, true);
          // keep the DOM bounded during long tails
          var body = $('#log-body');
          var extra = body.children('.log-row').length - 2000;
          if (extra > 0) body.children().slice(0, extra * 2).remove();
          if (!state.tailPaused) {
            window.scrollTo(0, document.body.scrollHeight);
          }
        }
        setStatus('tailing (cursor ' + res.cursor + ')');
      })
      .fail(function (xhr) {
        setStatus((xhr.responseJSON && xhr.responseJSON.error) || 'tail failed', true);
      });
  }

  function startTail() {
    state.tail = true;
    state.tailCursor = null;
    state.tailPaused = false;
    $('#log-body').empty();
    $('#tail-toggle').addClass('active');
    $('#pager button, #page-size').prop('disabled', true);
    state.tailTimer = setInterval(tailTick, 1000);
    tailTick();
  }

  function stopTail() {
    state.tail = false;
    clearInterval(state.tailTimer);
    state.tailTimer = null;
    $('#tail-toggle').removeClass('active');
    $('#pager button, #page-size').prop('disabled', false);
    setStatus('');
  }

  function refresh() {
    if (state.tail) { stopTail(); startTail(); return; }
    state.offset = 0;
    runQuery();
  }

  function loadFacets() {
    $.getJSON('/api/facets', timeParams()).done(function (res) {
      var fill = function (sel, items, placeholder) {
        var cur = $(sel).val();
        var el = $(sel).empty().append($('<option>').val('').text(placeholder));
        (items || []).forEach(function (it) {
          el.append($('<option>').val(it.value).text(it.value + ' (' + it.count + ')'));
        });
        el.val(cur);
        if (el.val() === null) el.val('');
      };
      fill('#f-namespace', res.namespaces, 'namespace');
      fill('#f-app', res.apps, 'app');
      fill('#f-host', res.hosts, 'host');
    });
  }

  // --- events ---

  $('#range-buttons').on('click', '.range-btn', function () {
    $('.range-btn').removeClass('active');
    $(this).addClass('active');
    state.range = $(this).data('range');
    $('#custom-range').toggle(state.range === 'custom');
    if (state.range !== 'custom') { loadFacets(); refresh(); }
  });

  $('#custom-range input').on('change', function () {
    loadFacets();
    refresh();
  });

  $('#search-btn').on('click', refresh);
  $('#search-form').on('change', 'select', refresh);
  $('#search-form').on('keypress', 'input', function (e) {
    if (e.which === 13) { e.preventDefault(); refresh(); }
  });

  var debounce = null;
  $('#q').on('input', function () {
    clearTimeout(debounce);
    debounce = setTimeout(refresh, 300);
  });

  $('#sql-toggle').on('click', function () {
    $(this).toggleClass('active');
    $('#sql-row').toggle($(this).hasClass('active'));
  });

  $('#tail-toggle').on('click', function () {
    if (state.tail) stopTail(); else startTail();
  });

  $('#log-body').on('click', 'tr.log-row', function () { toggleDetail($(this)); });

  $('#prev-btn').on('click', function () {
    state.offset = Math.max(0, state.offset - state.limit);
    runQuery();
  });
  $('#next-btn').on('click', function () {
    state.offset += state.limit;
    runQuery();
  });
  $('#page-size').on('change', function () {
    state.limit = parseInt($(this).val(), 10);
    state.offset = 0;
    runQuery();
  });

  // Pause tail autoscroll when the user scrolls up; resume at the bottom.
  $(window).on('scroll', function () {
    if (!state.tail) return;
    var atBottom = window.innerHeight + window.scrollY >= document.body.scrollHeight - 40;
    state.tailPaused = !atBottom;
    if (state.tailPaused) setStatus('tail paused (scroll to bottom to resume)');
  });

  loadFacets();
  runQuery();
})();