feat: add Go microservice, Dockerfile, docker-compose, and API submission endpoint

public/datetime.js

@@ -0,0 +1,152 @@
+// Datum: Kalender-Widget
+
+(function () {
+  const WEEKDAYS = ["Mo", "Di", "Mi", "Do", "Fr", "Sa", "So"];
+  const MONTHS = [
+    "Januar", "Februar", "März", "April", "Mai", "Juni",
+    "Juli", "August", "September", "Oktober", "November", "Dezember",
+  ];
+
+  const monthLabel = document.getElementById("monthLabel");
+  const weekdayRow = document.getElementById("weekdayRow");
+  const dayGrid = document.getElementById("dayGrid");
+  const prevMonthBtn = document.getElementById("prevMonthBtn");
+  const nextMonthBtn = document.getElementById("nextMonthBtn");
+  const continueBtn = document.getElementById("continueBtn");
+
+  const today = new Date();
+  today.setHours(0, 0, 0, 0);
+
+  let availableDatesMap = new Map();
+  let viewYear = today.getFullYear();
+  let viewMonth = today.getMonth();
+  let selectedDate = null;
+  let selectedDateType = "long";
+
+  WEEKDAYS.forEach((day) => {
+    const span = document.createElement("span");
+    span.textContent = day;
+    weekdayRow.appendChild(span);
+  });
+
+  function toDateKey(date) {
+    const year = date.getFullYear();
+    const month = String(date.getMonth() + 1).padStart(2, "0");
+    const day = String(date.getDate()).padStart(2, "0");
+    return `${year}-${month}-${day}`;
+  }
+
+  fetch("appsettings.json")
+    .then((response) => response.json())
+    .then((settings) => {
+      const datesList = settings.availableDates || [];
+      datesList.forEach((item) => {
+        if (typeof item === "string") {
+          availableDatesMap.set(item, { type: "long" });
+        } else if (item && item.date) {
+          availableDatesMap.set(item.date, { type: item.type || "long" });
+        }
+      });
+
+      const upcoming = Array.from(availableDatesMap.keys())
+        .map((dateKey) => new Date(`${dateKey}T00:00:00`))
+        .filter((date) => date > today)
+        .sort((a, b) => a - b);
+
+      if (upcoming.length > 0) {
+        viewYear = upcoming[0].getFullYear();
+        viewMonth = upcoming[0].getMonth();
+      }
+
+      renderCalendar();
+    })
+    .catch(() => {
+      dayGrid.textContent = "Verfügbare Termine konnten nicht geladen werden.";
+    });
+
+  function renderCalendar() {
+    monthLabel.textContent = `${MONTHS[viewMonth]} ${viewYear}`;
+    dayGrid.innerHTML = "";
+
+    const firstOfMonth = new Date(viewYear, viewMonth, 1);
+    // Montag = 0 ... Sonntag = 6
+    const leadingBlanks = (firstOfMonth.getDay() + 6) % 7;
+    const daysInMonth = new Date(viewYear, viewMonth + 1, 0).getDate();
+
+    for (let i = 0; i < leadingBlanks; i++) {
+      const blank = document.createElement("span");
+      blank.className = "day-cell is-empty";
+      dayGrid.appendChild(blank);
+    }
+
+    for (let day = 1; day <= daysInMonth; day++) {
+      const cellDate = new Date(viewYear, viewMonth, day);
+      const key = toDateKey(cellDate);
+      const button = document.createElement("button");
+      button.type = "button";
+      button.className = "day-cell";
+      button.textContent = String(day);
+
+      const dateInfo = availableDatesMap.get(key);
+      const isPastOrToday = cellDate <= today;
+      const isAvailable = Boolean(dateInfo) && !isPastOrToday;
+      const isToday = cellDate.getTime() === today.getTime();
+      const isSelected = selectedDate && cellDate.getTime() === selectedDate.getTime();
+
+      if (!isAvailable) {
+        button.classList.add("is-disabled");
+        button.disabled = true;
+      }
+      if (isToday) {
+        button.classList.add("is-today");
+      }
+      if (isSelected) {
+        button.classList.add("is-selected");
+      }
+
+      button.addEventListener("click", () => {
+        selectedDate = cellDate;
+        selectedDateType = dateInfo ? dateInfo.type : "long";
+        renderCalendar();
+        updateContinueState();
+      });
+
+      dayGrid.appendChild(button);
+    }
+
+    const isCurrentMonth = viewYear === today.getFullYear() && viewMonth === today.getMonth();
+    prevMonthBtn.disabled = isCurrentMonth;
+  }
+
+  prevMonthBtn.addEventListener("click", () => {
+    viewMonth -= 1;
+    if (viewMonth < 0) {
+      viewMonth = 11;
+      viewYear -= 1;
+    }
+    renderCalendar();
+  });
+
+  nextMonthBtn.addEventListener("click", () => {
+    viewMonth += 1;
+    if (viewMonth > 11) {
+      viewMonth = 0;
+      viewYear += 1;
+    }
+    renderCalendar();
+  });
+
+  function updateContinueState() {
+    continueBtn.disabled = !selectedDate;
+  }
+
+  continueBtn.addEventListener("click", () => {
+    if (!selectedDate) {
+      return;
+    }
+    localStorage.setItem("selectedDate", toDateKey(selectedDate));
+    localStorage.setItem("selectedDateType", selectedDateType);
+    window.location.href = "activity.html";
+  });
+
+})();