function __veh_pickCustomerId(){
    try { if (window.sale_items && window.sale_items.customer) {
      var c = toIntSafe(window.sale_items.customer); if (c) return c; } } catch(e){}
    var $sc = $('#searchbox_customers');
    if ($sc.length) {
      var v = $sc.val(); var c2 = toIntSafe(v);
      if (!c2 && $sc.select2) { try { var d = $sc.select2('data'); if (d && d.length) c2 = toIntSafe(d[0].id); } catch(e){} }
      if (c2) return c2;
    }
    var $c = $('#customer');
    if ($c.length) {
      var v2 = $c.val(); var c3 = toIntSafe(v2);
      if (!c3 && $c.select2) { try { var d2 = $c.select2('data'); if (d2 && d2.length) c3 = toIntSafe(d2[0].id); } catch(e){} }
      if (c3) return c3;
    }
    return 0;
    }

  function refreshVehicleHistory(v){
    v = toIntSafe(v);
    var c = __veh_pickCustomerId();   // 0 allowed
    var $tb = $('#reading_history_table tbody');
    var reqId = ++vehHistReqId;       // take a token
    $tb.empty();

    if (!v) {
      $('#prev_reading').text('—'); $('#prev_invoice').text('—'); $('#prev_date').text('—');
      return;
    }

    // last 5 (with cache buster to avoid old results)
    $.getJSON("{% url 'sales:vehicle_reading_history' %}", { vehicle_id: v, customer_id: c, limit: 5, _ts: Date.now() }, function(r){
      if (reqId !== vehHistReqId) return;  // newer request already issued — ignore this
      var items = (r && r.items) ? r.items : [];
      if (!items.length){
        $tb.append('<tr><td colspan="3" class="text-muted small">No history found.</td></tr>');
        return;
      }
      for (var i=0; i<items.length; i++){
        var it = items[i];
        var inv = toIntSafe(it.invoice_no);
        var date = it.reading_date || '-';
        var rdg  = (it.reading!=null ? it.reading : '-');
        var row  = '<tr class="hist-row" data-invoice="'+ inv +'">'+
                   '<td>'+ (inv || '-') +'</td>'+
                   '<td>'+ date +'</td>'+
                   '<td class="text-right">'+ rdg +'</td>'+
                   '</tr>';
        $tb.append(row);
      }
    });

    // single previous (for hints)
    $.getJSON("{% url 'sales:vehicle_last_reading' %}", { vehicle_id: v, customer_id: c, _ts: Date.now() }, function(r){
      if (reqId !== vehHistReqId) return;
      $('#prev_reading').text((r && r.prev_reading!=null)? r.prev_reading : '—');
      $('#prev_invoice').text((r && r.prev_invoice!=null)? r.prev_invoice : '—');
      $('#prev_date').text((r && r.prev_date)? r.prev_date : '—');
    });
    }

  function loadCustomerVehicles(){
    var cid = getCustomerId();
    var st  = getSaleType();
    var $tbody = $('#cust_vehicle_table tbody');
    var $hint  = $('#custVehHint');
    $tbody.empty();

    // show only when Credit + customer selected
    if (!cid) {
      $hint.text('Select customer to see attached vehicles.').show();
      return;
    }
    $hint.hide();  // customer mil gaya — list la do


    $.getJSON("{% url 'sales:options_customer_vehicles' %}", { customer_id: cid, limit: 300 }, function(resp){
      var rows = (resp && resp.results) ? resp.results : [];
      if (!rows.length) {
        $tbody.append('<tr><td class="text-muted small">No vehicles for this customer.</td></tr>');
        return;
      }
      for (var i=0; i<rows.length; i++){
        var r = rows[i];
        var safeText = r.text ? r.text : ('ID ' + r.id);
        var tr = $('<tr class="cust-veh-row" data-id="'+ r.id +'" data-text="'+ safeText +'"><td>'+ safeText +'</td></tr>');
        $tbody.append(tr);
      }
    });
    }

  $('#custVehSearch').on('input', function(){
    var term = ($(this).val() || '').toLowerCase();
    $('#cust_vehicle_table tbody tr').each(function(){
      var txt = ($(this).text() || '').toLowerCase();
      $(this).toggle(txt.indexOf(term) >= 0);
    });
    });

  $(document).on('click', '#cust_vehicle_table tbody tr.cust-veh-row', function(){
    var id = toIntSafe($(this).attr('data-id') || 0);
    var label = $(this).attr('data-text') || ('ID ' + id);
    if (!id) return;

    var $sel = $('#vehicle_select');
    // Set selected without firing another change handler
    var opt = new Option(label, id, true, true);
    $sel.append(opt).trigger('change.select2'); // select2 UI sync (fires change once)
    refreshVehicleHistory(id);                  // we still call once, guarded by reqId
    });

  $(document).on('change', '#vehicle_select', function(){
    var v = toIntSafe($(this).val() || 0);
    refreshVehicleHistory(v);
    });

  $('#applyVehicle').on('click', function(){
    var v  = parseInt($('#vehicle_select').val() || 0);
    var cr = parseFloat($('#current_reading').val() || 0);
    if (!window.sale_items) window.sale_items = {};
    window.sale_items.vehicle = v || 0;
    window.sale_items.vehicle_reading = isNaN(cr) ? 0 : cr;
    $('#veh_hidden_id').val(window.sale_items.vehicle);
    $('#veh_hidden_reading').val(window.sale_items.vehicle_reading);
    $('#vehicleModal').modal('hide');
    });

  $(document).on('change', '#searchbox_customers, #customer, #saletype, input[name="saletype"]', function(){
    if ($('#vehicleModal').is(':visible')) loadCustomerVehicles();
    });
  
  $(document).on('select2:select select2:clear', '#searchbox_customers, #customer', function(){
    if ($('#vehicleModal').is(':visible')) loadCustomerVehicles();
    });
  
  $(document).off('change', '#vehicle_select').on('change', '#vehicle_select', function(){
    var v = toIntSafe($(this).val() || 0);
    refreshVehicleHistory(v);
    });

  $(document).on('click', '#reading_history_table tbody tr.hist-row', function(){
    var inv = toIntSafe($(this).data('invoice'));
    if (!inv) inv = toIntSafe($(this).find('td').eq(0).text());
    if (!inv) return;
    window.open(INVOICE_URL_BASE + inv+"/view", '_blank');
    });

  var VEH_AJAX_URL   = "{% url 'sales:options_vehicles' %}";
  var VEH_BY_CUST    = "{% url 'sales:options_customer_vehicles' %}";
  var LAST_READING   = "{% url 'sales:vehicle_last_reading' %}";
  var HISTORY_URL    = "{% url 'sales:vehicle_reading_history' %}";
  var vehicleSelectInited = false;

  document.getElementById('btnVehicle').addEventListener('click', function(){
    $('#vehicleModal').modal('show');
    });
  $('#vehicleModal').on('shown.bs.modal', function(){
    var $sel = $('#vehicle_select');

    if (!vehicleSelectInited) {
      $sel.select2({
        ajax: {
          url: "{% url 'sales:options_vehicles' %}",
          dataType: 'json',
          delay: 250,
          data: function (params) { return { q: params.term || "" }; },
          processResults: function (data) { return data; },
          cache: true
        },
        dropdownParent: $('#vehicleModal'),
        width: '100%',
        placeholder: 'Search vehicle',
        allowClear: true,
        minimumInputLength: 0
      });
      vehicleSelectInited = true;
    }

    // LEFT list refresh each open
    loadCustomerVehicles();

    // auto-open + focus in the search box
    try { $sel.select2('open'); } catch(e) {}
    setTimeout(function(){
      var $f = $('.select2-container--open .select2-search__field');
      if ($f.length) $f.focus();
    }, 0);
    });