/* Autocomplete for the origin/destination fields, backed by /api/stops.
   Progressive enhancement: without JS the inputs stay plain free-text fields.
   A picked stop fills the sibling hidden <input> with its id; editing the text
   afterwards clears it again, so unmatched entries save as free text. */
(function () {
  "use strict";

  var TYPE_LABEL = {
    bus: "Bus",
    tram: "Straßenbahn",
    subway: "U-Bahn",
    train: "Zug",
    bus_station: "Busbahnhof",
    other: "Haltestelle",
  };

  function debounce(fn, ms) {
    var t;
    return function () {
      var args = arguments, self = this;
      clearTimeout(t);
      t = setTimeout(function () { fn.apply(self, args); }, ms);
    };
  }

  function setup(input) {
    var wrap = input.closest(".combo");
    var hidden = wrap.querySelector(input.dataset.stopTarget);
    var hint = wrap.querySelector("[data-stop-hint]");
    if (!hidden) return;

    var list = document.createElement("div");
    list.className = "combo-list";
    list.hidden = true;
    wrap.appendChild(list);

    var items = [];
    var active = -1;
    var lastQuery = "";

    function clearMatch() {
      hidden.value = "";
      if (hint) { hint.textContent = ""; hint.classList.remove("matched"); }
    }

    function markMatch(stop) {
      hidden.value = String(stop.id);
      if (hint) {
        hint.textContent =
          "✓ " + stop.name + (stop.municipality ? ", " + stop.municipality : "");
        hint.classList.add("matched");
      }
    }

    function close() { list.hidden = true; active = -1; }

    function render() {
      list.innerHTML = "";
      if (!items.length) {
        var empty = document.createElement("div");
        empty.className = "combo-empty";
        empty.textContent =
          "Keine Haltestelle gefunden – Eingabe wird als Freitext gespeichert.";
        list.appendChild(empty);
        list.hidden = false;
        return;
      }
      items.forEach(function (stop, i) {
        var opt = document.createElement("div");
        opt.className = "combo-option" + (i === active ? " active" : "");
        var name = document.createElement("span");
        name.className = "name";
        name.textContent = stop.name;
        opt.appendChild(name);
        if (stop.municipality) {
          var muni = document.createElement("span");
          muni.className = "muni";
          muni.textContent = stop.municipality;
          opt.appendChild(muni);
        }
        var kind = document.createElement("span");
        kind.className = "kind";
        kind.textContent = TYPE_LABEL[stop.type] || "";
        opt.appendChild(kind);
        opt.addEventListener("mousedown", function (e) {
          e.preventDefault();
          choose(i);
        });
        list.appendChild(opt);
      });
      list.hidden = false;
    }

    function choose(i) {
      var stop = items[i];
      if (!stop) return;
      input.value = stop.name;
      markMatch(stop);
      close();
    }

    var search = debounce(function () {
      var q = input.value.trim();
      lastQuery = q;
      if (q.length < 2) { items = []; close(); return; }
      fetch("/api/stops?q=" + encodeURIComponent(q))
        .then(function (r) { return r.ok ? r.json() : []; })
        .then(function (data) {
          if (input.value.trim() !== lastQuery) return;
          items = data;
          active = -1;
          render();
          var exact = data.filter(function (s) {
            return s.name.toLowerCase() === lastQuery.toLowerCase();
          })[0];
          if (exact) { markMatch(exact); } else { clearMatch(); }
        })
        .catch(function () { items = []; close(); });
    }, 180);

    input.setAttribute("autocomplete", "off");
    input.addEventListener("input", function () { clearMatch(); search(); });
    input.addEventListener("focus", function () { if (items.length) render(); });
    input.addEventListener("blur", function () { setTimeout(close, 120); });
    input.addEventListener("keydown", function (e) {
      if (list.hidden) return;
      if (e.key === "ArrowDown") {
        e.preventDefault();
        active = Math.min(active + 1, items.length - 1);
        render();
      } else if (e.key === "ArrowUp") {
        e.preventDefault();
        active = Math.max(active - 1, 0);
        render();
      } else if (e.key === "Enter") {
        if (active >= 0) { e.preventDefault(); choose(active); }
      } else if (e.key === "Escape") {
        close();
      }
    });
  }

  document.querySelectorAll("[data-stop-input]").forEach(setup);
})();