/* Autocomplete helpers for the "Neue Fahrt" form.
   - origin/destination: stop lookup from /api/stops, fills a hidden *_stop_id
     when the text matches a known Austrian stop (free text still allowed).
   - line: suggestions from /api/lines, scoped to the chosen origin/destination
     stops. Always free text; when exactly one line is possible and the field is
     untouched it is pre-filled.
   Progressive enhancement: without JS every field stays a plain input. */
(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);
    };
  }

  /* Shared dropdown: owns the list element, keyboard nav and open/close.
     opts: { fetchItems(query) -> Promise<item[]>,
             fillOption(item, el), onChoose(item), minChars, onInput() } */
  function attachCombo(input, opts) {
    var wrap = input.closest(".combo");
    var list = document.createElement("div");
    list.className = "combo-list";
    list.hidden = true;
    wrap.appendChild(list);

    var items = [];
    var active = -1;
    var lastQuery = null;
    var minChars = opts.minChars != null ? opts.minChars : 2;

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

    function render() {
      list.innerHTML = "";
      if (!items.length) {
        if (opts.emptyText) {
          var empty = document.createElement("div");
          empty.className = "combo-empty";
          empty.textContent = opts.emptyText;
          list.appendChild(empty);
          list.hidden = false;
        } else {
          close();
        }
        return;
      }
      items.forEach(function (item, i) {
        var el = document.createElement("div");
        el.className = "combo-option" + (i === active ? " active" : "");
        opts.fillOption(item, el);
        el.addEventListener("mousedown", function (e) { e.preventDefault(); choose(i); });
        list.appendChild(el);
      });
      list.hidden = false;
    }

    function choose(i) {
      if (!items[i]) return;
      opts.onChoose(items[i]);
      close();
    }

    var run = debounce(function () {
      var q = input.value.trim();
      lastQuery = q;
      if (q.length < minChars && minChars > 0) { items = []; close(); return; }
      Promise.resolve(opts.fetchItems(q))
        .then(function (data) {
          if (input.value.trim() !== lastQuery) return;
          items = data || [];
          active = -1;
          render();
          if (opts.afterFetch) opts.afterFetch(items, lastQuery);
        })
        .catch(function () { items = []; close(); });
    }, 160);

    input.setAttribute("autocomplete", "off");
    input.addEventListener("input", function () {
      if (opts.onInput) opts.onInput();
      run();
    });
    input.addEventListener("focus", function () {
      if (items.length) render(); else run();
    });
    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" && active >= 0) { e.preventDefault(); choose(active); }
      else if (e.key === "Escape") { close(); }
    });

    return { refresh: run, closeList: close };
  }

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

    function clearMatch() {
      delete hidden.dataset.stopType;
      delete hidden.dataset.stopLat;
      delete hidden.dataset.stopLon;
      if (!hidden.value) return;
      hidden.value = "";
      if (hint) { hint.textContent = ""; hint.classList.remove("matched"); }
      form.dispatchEvent(new CustomEvent("stopchange"));
    }
    function markMatch(stop) {
      hidden.value = String(stop.id);
      hidden.dataset.stopType = stop.type;
      hidden.dataset.stopLat = stop.lat;
      hidden.dataset.stopLon = stop.lon;
      if (hint) {
        hint.textContent = "✓ " + stop.name +
          (stop.municipality ? ", " + stop.municipality : "");
        hint.classList.add("matched");
      }
      form.dispatchEvent(new CustomEvent("stopchange"));
    }

    attachCombo(input, {
      emptyText: "Keine Haltestelle gefunden – Eingabe wird als Freitext gespeichert.",
      onInput: clearMatch,
      fetchItems: function (q) {
        return fetch("/api/stops?q=" + encodeURIComponent(q))
          .then(function (r) { return r.ok ? r.json() : []; });
      },
      fillOption: function (stop, el) {
        var name = document.createElement("span");
        name.className = "name";
        name.textContent = stop.name;
        el.appendChild(name);
        if (stop.municipality) {
          var m = document.createElement("span");
          m.className = "muni";
          m.textContent = stop.municipality;
          el.appendChild(m);
        }
        var kind = document.createElement("span");
        kind.className = "kind";
        kind.textContent = TYPE_LABEL[stop.type] || "";
        el.appendChild(kind);
      },
      onChoose: function (stop) { input.value = stop.name; markMatch(stop); },
      afterFetch: function (data, q) {
        var exact = data.filter(function (s) {
          return s.name.toLowerCase() === q.toLowerCase();
        })[0];
        if (exact) markMatch(exact); else clearMatch();
      },
    });
  }

  function setupLineCombo(input, form) {
    var touched = false;
    var hint = input.closest(".combo").querySelector("[data-line-hint]");
    input.addEventListener("input", function () { touched = true; });

    function context() {
      var o = form.querySelector("#origin_stop_id");
      var d = form.querySelector("#destination_stop_id");
      return {
        origin_stop_id: (o && o.value) || "",
        destination_stop_id: (d && d.value) || "",
      };
    }

    var combo = attachCombo(input, {
      minChars: 0,
      onInput: function () { touched = true; },
      fetchItems: function (q) {
        var ctx = context();
        if (!ctx.origin_stop_id && !ctx.destination_stop_id) return [];
        var qs = "origin_stop_id=" + encodeURIComponent(ctx.origin_stop_id) +
          "&destination_stop_id=" + encodeURIComponent(ctx.destination_stop_id) +
          "&q=" + encodeURIComponent(q);
        return fetch("/api/lines?" + qs).then(function (r) { return r.ok ? r.json() : []; });
      },
      fillOption: function (line, el) {
        var ref = document.createElement("span");
        ref.className = "name";
        ref.textContent = line.ref;
        el.appendChild(ref);
        if (line.both) {
          var tag = document.createElement("span");
          tag.className = "kind";
          tag.textContent = "beide Halte";
          el.appendChild(tag);
        }
      },
      onChoose: function (line) { input.value = line.ref; touched = true; },
    });

    // Re-scope suggestions when a stop is picked/cleared; pre-fill an
    // unambiguous line into an untouched field.
    form.addEventListener("stopchange", function () {
      var ctx = context();
      if (!ctx.origin_stop_id && !ctx.destination_stop_id) return;
      var qs = "origin_stop_id=" + encodeURIComponent(ctx.origin_stop_id) +
        "&destination_stop_id=" + encodeURIComponent(ctx.destination_stop_id);
      fetch("/api/lines?" + qs)
        .then(function (r) { return r.ok ? r.json() : []; })
        .then(function (lines) {
          if (!touched && input.value.trim() === "" && lines.length === 1) {
            input.value = lines[0].ref;
          }
          if (hint) {
            hint.textContent = lines.length
              ? lines.length + " Linie(n) an den gewählten Halten"
              : "Keine Linien bekannt – Freitext";
          }
          if (document.activeElement === input) combo.refresh();
        })
        .catch(function () {});
    });
  }

  // Which "Verkehrsmittel" options make sense for a given origin stop type.
  // Rail stops aren't narrowed further (OSM doesn't tell S-Bahn from Fernzug).
  var MODES_FOR_STOP_TYPE = {
    bus: ["Bus"],
    bus_station: ["Bus"],
    tram: ["Straßenbahn"],
    subway: ["U-Bahn"],
    train: ["S-Bahn", "Regionalzug", "Fernzug (ÖBB/Railjet/WESTbahn)"],
  };

  function setupModeFilter(form) {
    var select = form.querySelector("#transport_mode");
    var originHidden = form.querySelector("#origin_stop_id");
    if (!select || !originHidden) return;
    var hint = form.querySelector("[data-mode-hint]");

    function apply() {
      var allowed = MODES_FOR_STOP_TYPE[originHidden.dataset.stopType || ""] || null;
      var firstVisible = null;
      Array.prototype.forEach.call(select.options, function (opt) {
        var ok = !allowed || allowed.indexOf(opt.value) !== -1;
        opt.hidden = !ok;
        opt.disabled = !ok;
        if (ok && !firstVisible) firstVisible = opt;
      });
      if (allowed && firstVisible && allowed.indexOf(select.value) === -1) {
        select.value = firstVisible.value;
      }
      if (hint) {
        hint.textContent = allowed
          ? "Eingeschränkt auf das Verkehrsmittel der gewählten Haltestelle."
          : "";
      }
    }

    form.addEventListener("stopchange", apply);
    apply(); // e.g. an already-matched origin when editing a trip
  }

  // "Fahrplan öffnen": opens Google Maps transit directions for the chosen
  // stops (exact coordinates when matched, else the typed name) so the user
  // can look up the real departure and copy it into the "Kurs" field.
  function setupTimetableLink(form) {
    var link = form.querySelector("[data-timetable-link]");
    var originText = form.querySelector("#origin");
    var destText = form.querySelector("#destination");
    var originHidden = form.querySelector("#origin_stop_id");
    var destHidden = form.querySelector("#destination_stop_id");
    if (!link || !originText || !destText || !originHidden || !destHidden) return;

    function locationParam(textInput, hiddenInput) {
      var lat = hiddenInput.dataset.stopLat, lon = hiddenInput.dataset.stopLon;
      if (lat && lon) return lat + "," + lon;
      var name = textInput.value.trim();
      return name ? name + ", Österreich" : "";
    }

    function apply() {
      var origin = locationParam(originText, originHidden);
      var destination = locationParam(destText, destHidden);
      if (!origin || !destination) {
        link.removeAttribute("href");
        link.setAttribute("aria-disabled", "true");
        return;
      }
      link.href = "https://www.google.com/maps/dir/?api=1" +
        "&origin=" + encodeURIComponent(origin) +
        "&destination=" + encodeURIComponent(destination) +
        "&travelmode=transit";
      link.removeAttribute("aria-disabled");
    }

    form.addEventListener("stopchange", apply);
    originText.addEventListener("input", apply);
    destText.addEventListener("input", apply);
    apply();
  }

  document.querySelectorAll("form").forEach(function (form) {
    form.querySelectorAll("[data-stop-input]").forEach(function (i) { setupStopCombo(i, form); });
    form.querySelectorAll("[data-line-input]").forEach(function (i) { setupLineCombo(i, form); });
    setupModeFilter(form);
    setupTimetableLink(form);
  });
})();