(function () {
  const loginView = document.getElementById("loginView");
  const adminView = document.getElementById("adminView");
  const loginForm = document.getElementById("loginForm");
  const passwordInput = document.getElementById("passwordInput");
  const loginMessage = document.getElementById("loginMessage");
  const addDateForm = document.getElementById("addDateForm");
  const dateInput = document.getElementById("dateInput");
  const addDateMessage = document.getElementById("addDateMessage");
  const datesList = document.getElementById("datesList");
  const dateCount = document.getElementById("dateCount");
  const emptyDates = document.getElementById("emptyDates");
  const logoutBtn = document.getElementById("logoutBtn");

  let dates = [];

  function setMessage(element, message, success) {
    element.textContent = message;
    element.classList.toggle("is-success", Boolean(success));
  }

  function todayKey() {
    const today = new Date();
    const year = today.getFullYear();
    const month = String(today.getMonth() + 1).padStart(2, "0");
    const day = String(today.getDate()).padStart(2, "0");
    return `${year}-${month}-${day}`;
  }

  function formatDate(date) {
    return new Date(`${date}T00:00:00`).toLocaleDateString("de-DE", {
      weekday: "short",
      day: "2-digit",
      month: "2-digit",
      year: "numeric",
    });
  }

  async function request(path, options) {
    const response = await fetch(path, {
      ...options,
      headers: {
        "Content-Type": "application/json",
        ...(options && options.headers),
      },
    });
    const data = await response.json().catch(() => ({}));
    if (!response.ok) {
      const error = new Error(data.message || "Die Anfrage ist fehlgeschlagen.");
      error.status = response.status;
      throw error;
    }
    return data;
  }

  function showLogin(message) {
    adminView.classList.add("hidden");
    loginView.classList.remove("hidden");
    if (message) {
      setMessage(loginMessage, message, false);
    }
    passwordInput.focus();
  }

  function renderDates() {
    datesList.innerHTML = "";
    dateCount.textContent = `${dates.length} ${dates.length === 1 ? "Termin" : "Termine"}`;
    emptyDates.classList.toggle("hidden", dates.length !== 0);

    dates.forEach((date) => {
      const row = document.createElement("li");
      row.className = "date-row";

      const label = document.createElement("span");
      label.className = "date-label";
      label.textContent = formatDate(date.date);

      const typeSelect = document.createElement("select");
      typeSelect.className = "date-type-select";
      typeSelect.setAttribute("aria-label", `Tagestyp für ${formatDate(date.date)}`);
      [["short", "Kurz"], ["long", "Lang"]].forEach(([value, text]) => {
        const option = document.createElement("option");
        option.value = value;
        option.textContent = text;
        option.selected = date.type === value;
        typeSelect.appendChild(option);
      });
      typeSelect.addEventListener("change", async () => {
        typeSelect.disabled = true;
        try {
          await request("/api/admin/dates", {
            method: "PUT",
            body: JSON.stringify({ date: date.date, type: typeSelect.value }),
          });
          date.type = typeSelect.value;
          setMessage(addDateMessage, "Tagestyp aktualisiert.", true);
        } catch (error) {
          if (error.status === 401) {
            showLogin("Deine Anmeldung ist abgelaufen.");
            return;
          }
          typeSelect.value = date.type;
          setMessage(addDateMessage, error.message, false);
        } finally {
          typeSelect.disabled = false;
        }
      });

      const deleteButton = document.createElement("button");
      deleteButton.className = "delete-date-btn";
      deleteButton.type = "button";
      deleteButton.textContent = "Löschen";
      deleteButton.addEventListener("click", async () => {
        if (!window.confirm(`${formatDate(date.date)} wirklich löschen?`)) {
          return;
        }
        deleteButton.disabled = true;
        try {
          await request("/api/admin/dates", {
            method: "DELETE",
            body: JSON.stringify({ date: date.date }),
          });
          dates = dates.filter((item) => item.date !== date.date);
          renderDates();
          setMessage(addDateMessage, "Datum gelöscht.", true);
        } catch (error) {
          if (error.status === 401) {
            showLogin("Deine Anmeldung ist abgelaufen.");
            return;
          }
          setMessage(addDateMessage, error.message, false);
          deleteButton.disabled = false;
        }
      });

      row.append(label, typeSelect, deleteButton);
      datesList.appendChild(row);
    });
  }

  async function loadDates() {
    try {
      dates = await request("/api/admin/dates", { method: "GET" });
      dates.sort((first, second) => first.date.localeCompare(second.date));
      loginView.classList.add("hidden");
      adminView.classList.remove("hidden");
      renderDates();
    } catch (error) {
      if (error.status === 401) {
        showLogin();
        return;
      }
      showLogin("Die Termine konnten nicht geladen werden.");
    }
  }

  loginForm.addEventListener("submit", async (event) => {
    event.preventDefault();
    setMessage(loginMessage, "", false);
    try {
      await request("/api/admin/login", {
        method: "POST",
        body: JSON.stringify({ password: passwordInput.value }),
      });
      passwordInput.value = "";
      await loadDates();
    } catch (error) {
      setMessage(loginMessage, error.message, false);
    }
  });

  addDateForm.addEventListener("submit", async (event) => {
    event.preventDefault();
    const type = addDateForm.elements.dateType.value;
    setMessage(addDateMessage, "", false);
    try {
      await request("/api/admin/dates", {
        method: "POST",
        body: JSON.stringify({ date: dateInput.value, type }),
      });
      dates.push({ date: dateInput.value, type });
      dates.sort((first, second) => first.date.localeCompare(second.date));
      renderDates();
      setMessage(addDateMessage, "Datum hinzugefügt.", true);
      addDateForm.reset();
      dateInput.min = todayKey();
    } catch (error) {
      if (error.status === 401) {
        showLogin("Deine Anmeldung ist abgelaufen.");
        return;
      }
      setMessage(addDateMessage, error.message, false);
    }
  });

  logoutBtn.addEventListener("click", async () => {
    try {
      await request("/api/admin/logout", { method: "POST" });
    } finally {
      showLogin();
    }
  });

  dateInput.min = todayKey();
  loadDates();
})();