improve ui

include/date_utils.h

@@ -0,0 +1,66 @@
+#pragma once
+#include <Arduino.h>
+
+// No NTP/network time used, purely computed from date strings coming from
+// the calendar API itself, as specified.
+namespace DateUtils {
+
+inline const char *weekdayShortDE(int isoWeekday /* 0=Mon..6=Sun */) {
+    static const char *names[7] = {"Mo", "Di", "Mi", "Do", "Fr", "Sa", "So"};
+    if (isoWeekday < 0 || isoWeekday > 6) return "??";
+    return names[isoWeekday];
+}
+
+// Sakamoto's algorithm, returns 0=Monday..6=Sunday
+inline int computeWeekdayMonBased(int year, int month, int day) {
+    static const int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
+    int y = year;
+    if (month < 3) y -= 1;
+    int w = (y + y / 4 - y / 100 + y / 400 + t[month - 1] + day) % 7; // 0=Sun
+    return (w + 6) % 7; // convert to 0=Mon
+}
+
+struct ParsedDateTime {
+    bool valid = false;
+    int year = 0, month = 0, day = 0, hour = 0, minute = 0;
+};
+
+inline ParsedDateTime parseIso(const String &iso) {
+    ParsedDateTime r;
+    if (iso.length() < 10) return r;
+
+    int y = iso.substring(0, 4).toInt();
+    int mo = iso.substring(5, 7).toInt();
+    int d = iso.substring(8, 10).toInt();
+
+    int h = 0, mi = 0;
+    int tIdx = iso.indexOf('T');
+    if (tIdx > 0 && iso.length() >= tIdx + 6) {
+        h = iso.substring(tIdx + 1, tIdx + 3).toInt();
+        mi = iso.substring(tIdx + 4, tIdx + 6).toInt();
+    }
+
+    if (y == 0 || mo == 0 || d == 0) return r;
+
+    r.valid = true;
+    r.year = y; r.month = mo; r.day = d; r.hour = h; r.minute = mi;
+    return r;
+}
+
+// "Mo 3.8. 14:00" for timed events, "Mo 3.8." for all-day events.
+inline String formatShortDE(const String &iso, bool allDay) {
+    ParsedDateTime p = parseIso(iso);
+    if (!p.valid) return iso;
+
+    int wd = computeWeekdayMonBased(p.year, p.month, p.day);
+    String out = String(weekdayShortDE(wd)) + " " + String(p.day) + "." + String(p.month) + ".";
+
+    if (!allDay) {
+        char buf[8];
+        snprintf(buf, sizeof(buf), " %02d:%02d", p.hour, p.minute);
+        out += buf;
+    }
+    return out;
+}
+
+} // namespace DateUtils

include/text_utils.h

@@ -1,35 +1,27 @@
 #pragma once
 #include <Arduino.h>
 
-// The M5Stack default font does not correctly render UTF-8 encoded German
-// umlauts (ä, ö, ü, ß), they show up as garbled characters or boxes.
-// This helper replaces them with their common ASCII transliteration
-// (ö -> oe, ä -> ae, ü -> ue, ß -> ss) before printing to the display.
-// This is the simplest, most robust fix without needing a custom font.
+// M5Stack default font can't render UTF-8 German umlauts correctly.
+// Transliterate them to ASCII before printing.
 inline String sanitizeGermanText(const String &input) {
     String out;
     out.reserve(input.length());
-
     for (size_t i = 0; i < input.length(); i++) {
         unsigned char c1 = input[i];
-
-        // UTF-8 two-byte sequences for German umlauts start with 0xC3
         if (c1 == 0xC3 && i + 1 < input.length()) {
             unsigned char c2 = input[i + 1];
             switch (c2) {
-                case 0xA4: out += "ae"; i++; continue; // ä
-                case 0xB6: out += "oe"; i++; continue; // ö
-                case 0xBC: out += "ue"; i++; continue; // ü
-                case 0x84: out += "Ae"; i++; continue; // Ä
-                case 0x96: out += "Oe"; i++; continue; // Ö
-                case 0x9C: out += "Ue"; i++; continue; // Ü
-                case 0x9F: out += "ss"; i++; continue; // ß
+                case 0xA4: out += "ae"; i++; continue;
+                case 0xB6: out += "oe"; i++; continue;
+                case 0xBC: out += "ue"; i++; continue;
+                case 0x84: out += "Ae"; i++; continue;
+                case 0x96: out += "Oe"; i++; continue;
+                case 0x9C: out += "Ue"; i++; continue;
+                case 0x9F: out += "ss"; i++; continue;
                 default: break;
             }
         }
-
         out += (char)c1;
     }
-
     return out;
 }

include/theme.h

@@ -1,23 +1,21 @@
 #pragma once
 #include <M5Stack.h>
 
-// "iPhone Dark Mode" inspired theme: near-black background, white text,
-// desaturated accent colors used sparingly.
-
 namespace Theme {
-    constexpr uint16_t BG        = 0x0000; // near-black background
-    constexpr uint16_t BG_CARD   = 0x1082; // slightly lighter card background (dark gray)
-    constexpr uint16_t TEXT      = 0xFFFF; // white
-    constexpr uint16_t TEXT_DIM  = 0x8410; // light gray, secondary text
+    constexpr uint16_t BG        = 0x0000;
+    constexpr uint16_t BG_CARD   = 0x1082;
+    constexpr uint16_t TEXT      = 0xFFFF;
+    constexpr uint16_t TEXT_DIM  = 0x8410;
 
-    constexpr uint16_t ACCENT_WEATHER = 0x051D; // muted blue
-    constexpr uint16_t ACCENT_SUN     = 0xFEA0; // warm yellow
-    constexpr uint16_t ACCENT_RAIN    = 0x03BF; // muted cyan/blue
-    constexpr uint16_t ACCENT_CALENDAR= 0x7BEF; // muted lavender/gray
-    constexpr uint16_t ACCENT_UBAHN   = 0x0410; // U-Bahn blue (muted)
-    constexpr uint16_t ACCENT_SBAHN   = 0x0540; // S-Bahn green (muted)
-    constexpr uint16_t ACCENT_WARN    = 0xFB00; // muted orange for delays/warnings
-    constexpr uint16_t ACCENT_ERROR   = 0xF800; // red for errors/cancellations
+    constexpr uint16_t ACCENT_WEATHER = 0x051D;
+    constexpr uint16_t ACCENT_SUN     = 0xFEA0;
+    constexpr uint16_t ACCENT_RAIN    = 0x03BF;
+    constexpr uint16_t ACCENT_CALENDAR= 0x7BEF;
+    constexpr uint16_t ACCENT_UBAHN   = 0x0410;
+    constexpr uint16_t ACCENT_SBAHN   = 0x0540;
+    constexpr uint16_t ACCENT_WARN    = 0xFB00;
+    constexpr uint16_t ACCENT_ERROR   = 0xF800;
+    constexpr uint16_t ACCENT_STORM   = 0xFD20;
 
     constexpr int SCREEN_W = 320;
     constexpr int SCREEN_H = 240;