Split off efa_client module

Reviewed-on: #2

.gitignore

@@ -1,3 +1,4 @@
 result
 vrnp
+main
 *.swp

README.md

@@ -2,12 +2,21 @@
 
 ## TODO
 
+### Server
+
 - [x] Use timeout for fetching departures
 - [x] Add basic auth
 - [x] Create Nix package
 - [x] Create container
-- [x] Write ESP8266 client
-- [ ] Make port configurable
 - [x] Transfer using JSON
 - [x] Correctly implement basic auth
-- [ ] Use unidecode to replace non-ascii stuff in the backend
+- [ ] Make port configurable
+- [ ] Use unidecode to replace non-ascii stuff
+- [ ] Add query parameter for selecting EFAClient
+- [ ] Return current time for displaying clock
+
+### Client
+
+- [x] Write ESP8266 client
+- [x] Add code for handling button presses
+- [ ] Add clock

client/bitmaps.h

@@ -81,3 +81,17 @@ static const uint8_t PROGMEM spinny[][8] = {
     0x00,
   },
 };
+static const uint16_t PROGMEM tiny_train_dims[] = {24, 9, 1};
+static const uint8_t PROGMEM tiny_train[][27] = {
+  {
+    0x00, 0x04, 0x00,
+    0x00, 0x02, 0x00,
+    0x01, 0xff, 0xfe,
+    0x00, 0xa4, 0x94,
+    0x01, 0x24, 0x92,
+    0x01, 0x24, 0x92,
+    0x03, 0xfc, 0xff,
+    0x03, 0xff, 0xff,
+    0x01, 0xb0, 0x36,
+  },
+};

client/client.ino

@@ -1,39 +1,300 @@
 #include <ArduinoJson.h>
-#include <ESP8266WiFi.h>
-#include <SPI.h>
-#include <Wire.h>
 #include <Adafruit_GFX.h>
-#include <Adafruit_SSD1306.h>
+#include <Adafruit_ST7735.h>
+#include <ESP8266WiFi.h>
 #include <ESP8266HTTPClient.h>
+#include <memory>
+#include <SPI.h>
 #include <WiFiClientSecureBearSSL.h>
 
 #include "bitmaps.h"
 #include "wifi_credentials.h"
 
-// Screen stuff
+#define TFT_CS D8
-#define SCREEN_WIDTH 128 // OLED display width, in pixels
+#define TFT_DC D4
-#define SCREEN_HEIGHT 64 // OLED display height, in pixels
+#define TFT_RESET D3
-#define OLED_RESET    -1 // Reset pin # (or -1 if sharing Arduino reset pin)
-#define SCREEN_ADDRESS 0x3C
 
 // Button stuff
 #define BUTTON_PIN D6
 
+// Display stuff
 #define FRAME_DELAY 80
+#define COLOR_BG (rgb(0, 0, 0))
+#define COLOR_DIVIDER (rgb(0xff, 0x60, 0x0d))
+#define COLOR_TOP (rgb(0xa0, 0xa0, 0xa0))
+#define COLOR_TEXT (rgb(0xff, 0x60, 0x0d))
+
+// Layout
+#define WIDTH 160
+#define HEIGHT 128
+
+#define CX 6
+#define CY 8
+
+#define MARGIN_LEFT 5
+#define MARGIN_RIGHT 5
+
+#define TOP_X MARGIN_LEFT
+#define TOP_Y 4
+#define TOP_WIDTH (WIDTH - 2 * MARGIN_LEFT)
+#define TOP_HEIGHT CY
+
+#define MAIN_X MARGIN_LEFT
+#define MAIN_Y 19
+#define MAIN_WIDTH (WIDTH - 2 * MARGIN_LEFT)
+#define MAIN_HEIGHT (8 * CY)
+
+#define CLOCK_X MARGIN_LEFT
+#define CLOCK_Y 113
+#define CLOCK_WIDTH (5 * CX)
+#define CLOCK_HEIGHT CY
+
+#define STATUS_X 83
+#define STATUS_Y CLOCK_Y
+#define STATUS_WIDTH (12 * CX)
+#define STATUS_HEIGHT CY
+
+struct Timetable {
+  const char *label;
+  const char *path;
+};
+
+// Selectable timetables
+Timetable timetables[] = {
+  {"Johanneskirche    Bstg. 1", "/departures?stop_id=de:08311:30104&platform=1"},
+  {"Johanneskirche    Bstg. 2", "/departures?stop_id=de:08311:30104&platform=2"},
+  {"Blumenthalstr     Bstg. A", "/departures?stop_id=de:08221:1225&platform=A"},
+  {"Blumenthalstr     Bstg. B", "/departures?stop_id=de:08221:1225&platform=B"}
+};
+size_t selectedTimetable = 0;
+
+// Function definitions
+void drawLayout();
+void clearTop();
+void clearStatus();
+void clearMain();
+void clearClock();
+uint16_t rgb(uint16_t, uint16_t, uint16_t);
+String fetchDepartures(String);
 
 // Peripherals
 
-Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
+Adafruit_ST7735 display(TFT_CS, TFT_DC, TFT_RESET);
 
-// App state
+// App state interface
+
+//           init                                                   
+//             │                                                    
+//             │                                                   
+//             │                                                    
+//             │      ┌───┐                                         
+//          ┌──▼──────▼┐  │                                         
+//          │Connecting│  │!connected                               
+//          └──┬───▲──┬┘  │                                         
+//             │   │  └───┘                                         
+//             │   │                                                
+//    connected│   │!connected                                      
+//             │   │                                                
+//             │   │                                                
+//             │   │                             ┌───┐              
+//          ┌──▼───┴─┐   timeout (3s)   ┌────────▼┐  │              
+//          │Fetching◄──────────────────┤Selecting│  │              
+//          └──┬───▲─┘                  └────▲───┬┘  │button pressed
+//             │   │                         │   └───┘              
+// got response│   │timeout (25s)            │                      
+//             │   │                         │                      
+//             │   │                         │                      
+//             │   │                         │button pressed        
+//        ┌────▼───┴─────────┐               │                      
+//        │Showing Departures│───────────────┘                      
+//        └──────────────────┘                                      
+
+class State {
+public:
+  // When the state is entered
+  virtual void enter();
+  // Called in the business loop
+  virtual void tick();
+  // Called when the button is pushed
+  virtual void button();
+  virtual ~State() = default;
+};
+
+class StateConnecting : public State {
+public:
+  void enter() override;
+  void tick() override;
+};
+
+class StateFetching : public State {
+public:
+  void enter() override;
+};
+
+class StateShowingDepartures : public State {
+private:
+  // Todo: discard JsonDocument asap, parse into better format
+  JsonDocument departures;
+  unsigned long entered;
+public:
+  StateShowingDepartures(String&);
+  void enter() override;
+  void tick() override;
+  void button() override;
+};
+
+class StateSelecting : public State {
+private:
+  unsigned long entered;
+public:
+  void enter() override;
+  void tick() override;
+  void button() override;
+};
+
+// Empty default implementations
+
+void State::enter() {}
+void State::tick() {}
+void State::button() {}
+
+// App state implementation
+
+uint64_t currentTick = 0;
+// Initially true so that enter() of the initial state is called.
+bool stateChanged = true;
+std::unique_ptr<State> state = std::make_unique<StateConnecting>();
+
+template <typename StateType, typename... Args>
+void setState(Args&&... args) {
+  state = std::make_unique<StateType>(std::forward<Args>(args)...);
+  stateChanged = true;
+}
+
+void StateConnecting::enter() {
+  Serial.println("Entering StateConnecting");
+
+  display.fillRect(STATUS_X, STATUS_Y, STATUS_WIDTH, STATUS_HEIGHT, COLOR_BG);
+  display.setCursor(STATUS_X, STATUS_Y);
+  display.setTextColor(COLOR_TEXT);
+  display.printf("connecting");
+}
+
+void StateConnecting::tick() {
+  if (WiFi.status() != WL_CONNECTED) {
+    display.fillRect(STATUS_X + 11 * CX, STATUS_Y, CX, CY, COLOR_BG);
+    display.setCursor(STATUS_X + 11 * CX, STATUS_Y);
+    display.setTextColor(COLOR_TEXT);
+    display.print("|/-\\"[currentTick % 4]);
+    delay(125);
+    return;
+  }
+
+  setState<StateFetching>();
+}
+
+// Fetching is a bit of an ugly duckling; it performs all its logic in enter().
+// This is because the request it does is synchronous.
+// Sadly this means no animation is possible right now.
+// At least the fetch call still does yield() under the hood :)
+void StateFetching::enter() {
+  Serial.println("Entering StateFetching");
+
+  if (WiFi.status() != WL_CONNECTED) {
+    setState<StateConnecting>();
+    return;
+  }
+  display.fillRect(STATUS_X, STATUS_Y, STATUS_WIDTH, STATUS_HEIGHT, COLOR_BG);
+  display.setTextColor(COLOR_TEXT);
+  display.setCursor(STATUS_X, STATUS_Y);
+  display.print("    fetching");
+  
+  String departuresRaw = fetchDepartures(timetables[selectedTimetable].path);
+  
+  setState<StateShowingDepartures>(departuresRaw);
+};
+
+StateShowingDepartures::StateShowingDepartures(String &departuresRaw) {
+  deserializeJson(departures, departuresRaw);
+}
+
+void StateShowingDepartures::enter() {
+  Serial.println("Entering StateShowingDepartures");
+  entered = millis();
+
+  clearStatus();
+  clearMain();
+
+  // draw timetable
+  display.setTextColor(COLOR_TEXT);
+  int line = 0;
+  for (JsonVariant departure : departures["departures"].as<JsonArray>()) {
+    if (line > 8) {
+      break;
+    }
+
+    char symbol[3] = {0};
+    char direction[16] = {0};
+
+    utf8ToCP437German(departure["symbol"].as<const char *>(), symbol, std::size(symbol));
+    utf8ToCP437German(departure["direction"].as<const char *>(), direction, std::size(direction));
+
+    display.setCursor(MAIN_X, MAIN_Y + (CY + 3) * line);
+    display.printf("%2s %-15.15s ", symbol, direction);
+    if (departure["leaving"].as<String>().equals("sofort")) {
+      int16_t x = display.getCursorX();
+      int16_t y = display.getCursorY();
+      display.drawBitmap(x + 6 * CX - tiny_train_dims[0], y, tiny_train[0], tiny_train_dims[0], tiny_train_dims[1], COLOR_TEXT);
+    } else {
+      display.printf("%6s", departure["leaving"].as<const char*>());
+    }
+
+    line++;
+  }
+
+  clearClock();
+  display.setCursor(CLOCK_X, CLOCK_Y);
+  display.printf("%5s", departures["serverTime"].as<const char *>());
+}
+
+void StateShowingDepartures::tick() {
+  unsigned long elapsed = millis() - entered;
+  if (elapsed > 25000) {
+    setState<StateFetching>();
+  }
+}
+
+void StateShowingDepartures::button() {
+  setState<StateSelecting>();
+}
+
+void StateSelecting::enter() {
+  Serial.println("Entering StateSelecting");
+  entered = millis();
+  
+  clearMain();
+  clearStatus();
+}
+
+void StateSelecting::tick() {
+  unsigned long elapsed = millis() - entered;
+  if (elapsed > 3000) {
+    setState<StateFetching>();
+  }
+}
+
+void StateSelecting::button() {
+  entered = millis();
+  selectedTimetable = (selectedTimetable + 1) % (sizeof timetables / sizeof timetables[0]);
+  clearTop();
+  display.setCursor(TOP_X, TOP_Y);
+  display.setTextColor(COLOR_TOP);
+  display.print(timetables[selectedTimetable].label);
+}
+
+// button ISR setup
 
-enum {
-  CONNECTING,
-  SHOWING_DEPARTURES
-} state = CONNECTING;
-int frame = 0;
 int buttonPushed = false;
-JsonDocument departures;
 
 void ICACHE_RAM_ATTR onButtonFalling() {
   buttonPushed = true;
@@ -42,47 +303,83 @@ void ICACHE_RAM_ATTR onButtonFalling() {
 void setup() {
   Serial.begin(9600);
 
-  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
+  Serial.println("serial init");
-  if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
+  display.initR();
-    Serial.println("SSD1306 allocation failed");
+  display.setSPISpeed(40000000);
-    for(;;); // Don't proceed, loop forever
+  display.cp437(true);
-  }
+  display.setRotation(3);
-  Serial.println("SSD1306 initialized");
+  Serial.println("display initialized");
-  display.clearDisplay();
+  Serial.printf("display dimensions: %" PRId16 "x%" PRId16 "\n", display.width(), display.height());
+
+  drawLayout();
+  display.setCursor(TOP_X, TOP_Y);
+  display.setTextColor(COLOR_TOP);
+  display.print(timetables[selectedTimetable].label);
 
   WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
   
   pinMode(BUTTON_PIN, INPUT_PULLUP);
   attachInterrupt(BUTTON_PIN, onButtonFalling, FALLING);
 
-  display.setTextColor(SSD1306_INVERSE);
+  state = std::make_unique<StateConnecting>();
-  display.setTextSize(1);
-  display.setCursor(0, 0);
-  display.printf("Connecting to\n%s\n", WIFI_SSID);
-  display.display();
-  /*
-  display.print(" 5 Mannheim    sofort\n"
-                "26 Kirchheim    9 min\n"
-                " 5 Weinheim     20:13");
-  */
 }
 
-void drawSpinner(int frame) {
+void loop() {
-  display.fillRect(120, 56, spinny_dims[0], spinny_dims[1], SSD1306_BLACK);
+  if (stateChanged) {
-  display.drawBitmap(120, 56, spinny[frame % spinny_dims[2]], spinny_dims[0], spinny_dims[1], SSD1306_WHITE);
+    stateChanged = false;
+    // Note: enter() may call setState(). In that case we want to end up right back here.
+    state->enter();
+  } else if (buttonPushed) {
+    // "Handle" jitter
+    delay(100);
+    buttonPushed = false;
+    state->button();
+  } else {
+    state->tick();
+    currentTick++;
+  }
+  // Let background system do its thing
+  yield();
+}
+
+uint16_t rgb(uint16_t r, uint16_t g, uint16_t b) {
+  // Color layout: RRRRRGGGGGGBBBBB (5, 6, 5)
+  return ((b >> 3) & 0b11111) << 11 | ((g >> 2) & 0b111111) << 5 | ((r >> 3) & 0b11111);
+}
+
+void clearTop() {
+  display.fillRect(TOP_X, TOP_Y, TOP_WIDTH, TOP_HEIGHT, COLOR_BG);
+}
+
+void clearMain() {
+  display.fillRect(MAIN_X, MAIN_Y, MAIN_WIDTH, MAIN_HEIGHT, COLOR_BG);
+}
+
+void clearStatus() {
+  display.fillRect(STATUS_X, STATUS_Y, STATUS_WIDTH, STATUS_HEIGHT, COLOR_BG);
+}
+
+void clearClock() {
+  display.fillRect(CLOCK_X, CLOCK_Y, CLOCK_WIDTH, CLOCK_HEIGHT, COLOR_BG);
+}
+
+void drawLayout() {
+  display.fillScreen(COLOR_BG);
+  display.drawFastHLine(5, 15, 150, COLOR_DIVIDER);
+  display.drawFastHLine(5, 109, 150, COLOR_DIVIDER);
+  display.drawFastHLine(5, 123, 150, COLOR_DIVIDER);
 }
 
 // TODO: Error handling
-String fetchDepartures() {
+String fetchDepartures(String path) {
   std::unique_ptr<BearSSL::WiFiClientSecure> https(new BearSSL::WiFiClientSecure);
   https->setInsecure();
   
   HTTPClient client;
-  if (!client.begin(*https, "vrnp.beany.club", 443, "/departures?stop_id=de:08221:1225&platform=A")) {
+  if (!client.begin(*https, "vrnp.beany.club", 443, path)) {
-    display.clearDisplay();
+    display.fillScreen(COLOR_BG);
     display.setCursor(0, 0);
     display.print("begin failed");
-    display.display();
     for (;;);
   }
 
@@ -90,88 +387,78 @@ String fetchDepartures() {
   client.addHeader("Accept", "application/json");
   int statusCode = client.GET();
   if (statusCode != 200) {
-    display.clearDisplay();
+    display.fillScreen(COLOR_BG);
     display.setCursor(0, 0);
     display.printf("http non-ok: %d\n", statusCode);
-    display.display();
     for (;;);
   }
 
   return client.getString();
 }
 
-void loop() {
+char mapUtf8CodepointToCP437German(uint32_t codepoint) {
-  switch (state) {
+  switch (codepoint) {
-    case CONNECTING: {
+    case 0x00e4: return 0x84; // ä
-      if (WiFi.status() != WL_CONNECTED) {
+    case 0x00c4: return 0x8e; // Ä
-        drawSpinner(frame++);
+    case 0x00f6: return 0x94; // ö
-        display.display();
+    case 0x00d6: return 0x99; // Ö
-        delay(FRAME_DELAY);
+    case 0x00fc: return 0x81; // ü
-        return;
+    case 0x00dc: return 0x9a; // Ü
-      }
+    case 0x00df: return 0xe1; // ß
-      
+    default: return '?';
-      display.clearDisplay();
-      display.fillRect(0, 56, 128, 8, SSD1306_INVERSE);
-      display.setCursor(0, 56);
-      display.print("requesting departures");
-      display.display();
-
-      String departuresRaw = fetchDepartures();
-      deserializeJson(departures, departuresRaw);
-      
-      state = SHOWING_DEPARTURES;
-      frame = 0;
-      return;
-    }
-      
-    case SHOWING_DEPARTURES:
-      if (WiFi.status() != WL_CONNECTED) {
-        state = CONNECTING;
-        return;
-      }
-
-      /*
-      if (buttonPushed) {
-        buttonPushed = false;
-        delay(FRAME_DELAY);
-        return;
-      }
-      */
-
-      // Marquee effect for direction strings longer than 11 characters
-      // Neither particularly efficient nor legible
-      // (This could use some love)
-
-      int availableWidth = 11;
-
-      display.clearDisplay();
-      display.setCursor(0, 0);
-      for (JsonVariant departure : departures["departures"].as<JsonArray>()) {
-        const char *directionStr = departure["direction"].as<const char *>();
-
-        char buf[128] = {0};
-        const char *dirStart;
-
-        if (strlen(directionStr) <= availableWidth || (strlen(directionStr) + 3 + availableWidth) > 127) {
-          dirStart = directionStr;
-        } else {
-          memcpy(buf, directionStr, strlen(directionStr));
-          memcpy(buf + strlen(directionStr), "   ", 3);
-          memcpy(buf + strlen(directionStr) + 3, directionStr, availableWidth);
-          buf[strlen(directionStr) + 3 + availableWidth] = '\0';
-          dirStart = buf + frame % (strlen(directionStr) + 3);
-        }
-
-        display.printf("%2s %-11.11s %6s\n",
-          departure["symbol"].as<const char*>(),
-          dirStart,
-          departure["leaving"].as<const char*>()
-        );
-      }
-      display.display();
-      
-      frame++;
-      delay(500);
-      return;
   }
 }
+
+/*
+Maps german umlauts and sharp s from utf8 to cp437 encoding.
+Other utf8 characters and malformed utf8 are replaced by '?'.
+The resulting string is truncated to cp437StrSize.
+*/
+void utf8ToCP437German(const char *utf8Str, char *cp437Str, size_t cp437StrSize) {
+  size_t utf8StrLength = strlen(utf8Str);
+  size_t utf8StrIndex = 0;
+  size_t cp437StrIndex = 0;
+
+  char c;
+
+  // One char at the end of the cp437Str is reserved to the terminating null
+  while (utf8StrIndex < utf8StrLength && cp437StrIndex + 1 < cp437StrSize) {
+    uint8_t cu0 = utf8Str[utf8StrIndex];
+
+    if (cu0 < 0x80) {
+      // ASCII maps to ASCII
+      c = cu0;
+      utf8StrIndex++;
+    } else if ((cu0 & 0b11100000) == 0b11000000) {
+      // codepoints encoded as two code units may contain german special characters
+      if (utf8StrIndex + 1 >= utf8StrLength) {
+        // if there's no 10xxxxxxx byte after this one, we've reached the end (malformed)
+        c = '?';
+        break;
+      } else {
+        // otherwise decode the codepoint and map it to cp437
+        uint8_t cu1 = utf8Str[utf8StrIndex + 1];
+        uint32_t cp = (cu0 & 0x1f << 6) | cu1 & 0x3f;
+        c = mapUtf8CodepointToCP437German(cp);
+        utf8StrIndex += 2;
+      }
+    // for 3 and 4-code unit codepoints just put a ? and skip all their code units
+    // here we dont care whether the string is malformed
+    } else if ((cu0 & 0b11110000) == 0b11100000) {
+      c = '?';
+      utf8StrIndex += 3;
+    } else if ((cu0 & 0b11111000) == 0b11110000) {
+      c = '?';
+      utf8StrIndex += 4;
+    } else {
+      // catch all for malformed utf8
+      c = '?';
+      utf8StrIndex++;
+    }
+
+    cp437Str[cp437StrIndex] = c;
+    cp437StrIndex++;
+  }
+
+  cp437Str[cp437StrIndex] = '\0';
+}

client/scripts/extract_bitmaps.py

@@ -43,3 +43,4 @@ def generate_bitmap_from_gif(file: Path, fd):
 
 if __name__ == "__main__":
     generate_bitmap_from_gif(Path("./animations/spinny.gif"), sys.stdout)
+    generate_bitmap_from_gif(Path("./animations/tiny_train.gif"), sys.stdout)

efa_client.go

@@ -0,0 +1,143 @@
+package main
+
+import "net/http"
+import "net/url"
+import "strings"
+
+type EFAClient interface {
+	GetName() string
+	BuildRequest(string) (*http.Request, error)
+}
+
+var allEfaClients []EFAClient = []EFAClient{
+	BwegtEFAClient{},
+	VRNEFAClient{},
+	KVVEFAClient{},
+	VAGEFAClient{},
+}
+
+type VRNEFAClient struct {
+}
+
+func (c VRNEFAClient) GetName() string {
+	return "VRN"
+}
+
+func (c VRNEFAClient) BuildRequest(stopId string) (*http.Request, error) {
+	// Create request object
+	req, err := http.NewRequest("GET", "https://www.vrn.de/mngvrn/XML_DM_REQUEST", nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Configure our request
+	query := url.Values{}
+	query.Set("coordOutputFormat", "EPSG:4326")
+	query.Set("depType", "stopEvents")
+	query.Set("includeCompleteStopSeq", "0")
+	query.Set("limit", "10")
+	query.Set("locationServerActive", "0")
+	query.Set("mode", "direct")
+	query.Set("name_dm", stopId)
+	query.Set("outputFormat", "json")
+	query.Set("type_dm", "stop")
+	query.Set("useOnlyStops", "1")
+	query.Set("useRealtime", "1")
+	req.URL.RawQuery = query.Encode()
+
+	return req, nil
+}
+
+type KVVEFAClient struct {
+}
+
+func (c KVVEFAClient) GetName() string {
+	return "KVV"
+}
+
+func (c KVVEFAClient) BuildRequest(stopId string) (*http.Request, error) {
+	form := url.Values{}
+	form.Set("action", "XSLT_DM_REQUEST")
+	form.Set("name_dm", stopId)
+	form.Set("type_dm", "stop")
+	form.Set("useRealtime", "1")
+	form.Set("limit", "10")
+	form.Set("mode", "direct")
+	form.Set("useRealtime", "1")
+	form.Set("outputFormat", "json")
+	body := strings.NewReader(form.Encode())
+
+	req, err := http.NewRequest("POST", "https://www.kvv.de/tunnelEfaDirect.php", body)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("User-Agent", "coolio/1.0")
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	return req, nil
+}
+
+type BwegtEFAClient struct {
+}
+
+func (c BwegtEFAClient) GetName() string {
+	return "bwegt"
+}
+
+func (c BwegtEFAClient) BuildRequest(stopId string) (*http.Request, error) {
+	// Create request object
+	req, err := http.NewRequest("GET", "https://www.bwegt.de/bwegt-efa/XML_DM_REQUEST", nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Configure our request
+	query := url.Values{}
+	query.Set("coordOutputFormat", "EPSG:4326")
+	query.Set("depType", "stopEvents")
+	query.Set("includeCompleteStopSeq", "0")
+	query.Set("limit", "10")
+	query.Set("locationServerActive", "0")
+	query.Set("mode", "direct")
+	query.Set("name_dm", stopId)
+	query.Set("outputFormat", "json")
+	query.Set("type_dm", "stop")
+	query.Set("useOnlyStops", "1")
+	query.Set("useRealtime", "1")
+	req.URL.RawQuery = query.Encode()
+
+	return req, nil
+}
+
+type VAGEFAClient struct {
+}
+
+func (c VAGEFAClient) GetName() string {
+	return "VAG"
+}
+
+func (c VAGEFAClient) BuildRequest(stopId string) (*http.Request, error) {
+	// Create request object
+	req, err := http.NewRequest("GET", "https://efa.vagfr.de/vagfr3/XSLT_DM_REQUEST", nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Configure our request
+	query := url.Values{}
+	query.Set("coordOutputFormat", "EPSG:4326")
+	query.Set("depType", "stopEvents")
+	query.Set("includeCompleteStopSeq", "0")
+	query.Set("limit", "10")
+	query.Set("locationServerActive", "0")
+	query.Set("mode", "direct")
+	query.Set("name_dm", stopId)
+	query.Set("outputFormat", "json")
+	query.Set("type_dm", "stop")
+	query.Set("useOnlyStops", "1")
+	query.Set("useRealtime", "1")
+	req.URL.RawQuery = query.Encode()
+
+	return req, nil
+}

flake.lock

@@ -1,5 +1,23 @@
 {
   "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "gitignore": {
       "inputs": {
         "nixpkgs": [
@@ -38,9 +56,25 @@
     },
     "root": {
       "inputs": {
+        "flake-utils": "flake-utils",
         "gitignore": "gitignore",
         "nixpkgs": "nixpkgs"
       }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -3,57 +3,58 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
     gitignore = {
       url = "github:hercules-ci/gitignore.nix";
       inputs.nixpkgs.follows = "nixpkgs";
     };
   };
 
-  outputs = { self, nixpkgs, gitignore }:
+  outputs = { self, nixpkgs, flake-utils, gitignore }: flake-utils.lib.eachDefaultSystem (system:
-  let
+    let
-    system = "x86_64-linux";
+      pkgs = import nixpkgs { inherit system; };
-    pkgs = nixpkgs.legacyPackages.${system};
 
-    vrnp-static = pkgs.buildGoModule {
+      vrnp-static = pkgs.buildGoModule {
-      pname = "vrnp";
+        pname = "vrnp";
-      version = "0.0.4";
+        version = "0.0.10";
-      vendorHash = null;
+        vendorHash = null;
 
-      # For building the package, we use only the files not ignored by Git as inputs.
+        # For building the package, we use only the files not ignored by Git as inputs.
-      # Also, flake.nix and flake.lock are not included to avoid annoying rebuilds when
+        # Also, flake.nix and flake.lock are not included to avoid annoying rebuilds when
-      # working on them.
+        # working on them.
-      src = pkgs.lib.cleanSourceWith {
+        src = pkgs.lib.cleanSourceWith {
-        src = gitignore.lib.gitignoreSource ./.;
+          src = gitignore.lib.gitignoreSource ./.;
-        filter = path: type: builtins.baseNameOf path != "flake.nix" && builtins.baseNameOf path != "flake.lock";
+          filter = path: type: builtins.baseNameOf path != "flake.nix" && builtins.baseNameOf path != "flake.lock";
-      };
-
-      # Avoid linking against libc
-      CGO_ENABLED = 0;
-    };
-  in {
-    devShell.${system} = pkgs.mkShellNoCC {
-      packages = [
-        pkgs.go
-        (pkgs.python3.withPackages (ps: with ps; [ pillow ]))
-      ];
-    };
-    packages.${system} = {
-      default = vrnp-static;
-      image-meta = pkgs.runCommand "vrnp-version" {} ''
-        mkdir -p $out
-        echo -n ${vrnp-static.version} > $out/version
-        echo -n git.pbrinkmeier.de/paul/vrnp:${vrnp-static.version} > $out/name
-      '';
-      image = pkgs.dockerTools.buildImage {
-        name = "git.pbrinkmeier.de/paul/vrnp";
-        tag = vrnp-static.version;
-        copyToRoot = pkgs.buildEnv {
-          name = "vrnp-root";
-          paths = [ vrnp-static pkgs.cacert ];
-          pathsToLink = [ "/bin" "/etc" ];
         };
-        config.Cmd = [ "${vrnp-static}/bin/vrnp" ];
+
+        # Avoid linking against libc
+        CGO_ENABLED = 0;
       };
-    };
+    in {
-  };
+      devShell = pkgs.mkShell {
+        packages = [
+          pkgs.go
+          (pkgs.python3.withPackages (ps: with ps; [ pillow ]))
+        ];
+      };
+      packages = {
+        default = vrnp-static;
+        image-meta = pkgs.runCommand "image-meta" {} ''
+          mkdir -p $out
+          echo -n ${vrnp-static.version} > $out/version
+          echo -n git.pbrinkmeier.de/paul/vrnp:${vrnp-static.version} > $out/name
+        '';
+        image = pkgs.dockerTools.buildImage {
+          name = "git.pbrinkmeier.de/paul/vrnp";
+          tag = vrnp-static.version;
+          copyToRoot = pkgs.buildEnv {
+            name = "vrnp-root";
+            paths = [ vrnp-static pkgs.cacert ];
+            pathsToLink = [ "/bin" "/etc" ];
+          };
+          config.Cmd = [ "${vrnp-static}/bin/vrnp" ];
+        };
+      };
+    }
+  );
 }

main.go

@@ -1,19 +1,22 @@
 package main
 
+import "cmp"
 import "encoding/json"
 import "errors"
 import "fmt"
 import "log"
 import "net/http"
-import "net/url"
 import "os"
 import "slices"
+import "strings"
 import "strconv"
+import "sync/atomic"
 import "time"
 
 // JSON unmarshaling types for departure monitor API
 
 type DMResponse struct {
+	DateTime DMDateTime `json:"dateTime"`
 	DepartureList []DMDeparture `json:"departureList"`
 }
 
@@ -43,28 +46,12 @@ type DMDateTime struct {
 	Minute string `json:"minute"`
 }
 
-func FetchDepartures(stopId string) (DMResponse, error) {
+func FetchDepartures(c EFAClient, stopId string) (DMResponse, error) {
-	// Create request object
+	req, err := c.BuildRequest(stopId)
-	req, err := http.NewRequest("GET", "https://www.vrn.de/mngvrn/XML_DM_REQUEST", nil)
 	if err != nil {
 		return DMResponse{}, err
 	}
 
-	// Configure our request
-	query := url.Values{}
-	query.Set("coordOutputFormat", "EPSG:4326")
-	query.Set("depType", "stopEvents")
-	query.Set("includeCompleteStopSeq", "0")
-	query.Set("limit", "10")
-	query.Set("locationServerActive", "0")
-	query.Set("mode", "direct")
-	query.Set("name_dm", stopId)
-	query.Set("outputFormat", "json")
-	query.Set("type_dm", "stop")
-	query.Set("useOnlyStops", "1")
-	query.Set("useRealtime", "1")
-	req.URL.RawQuery = query.Encode()
-
 	// Send the request, wait max 10 seconds
 	client := http.Client{
 		Timeout: 10 * time.Second,
@@ -88,6 +75,7 @@ func FetchDepartures(stopId string) (DMResponse, error) {
 
 type Departures struct {
 	Departures []Departure `json:"departures"`
+	ServerTime string      `json:"serverTime"`
 }
 
 type Departure struct {
@@ -95,6 +83,7 @@ type Departure struct {
 	Symbol    string `json:"symbol"`
 	Direction string `json:"direction"`
 	Leaving   string `json:"leaving"`
+	Countdown int    `json:"-"`
 }
 
 func ParseDepartures(response DMResponse, allowedPlatform *string) (Departures, error) {
@@ -117,6 +106,12 @@ func ParseDepartures(response DMResponse, allowedPlatform *string) (Departures,
 			return Departures{}, errors.New("could not parse countdown")
 		}
 
+		matchesPlatform := allowedPlatform == nil || d.Platform == *allowedPlatform
+		isInThePast := countdown < 0
+		if !matchesPlatform || isInThePast {
+			continue
+		}
+
 		if countdown == 0 {
 			leaving = "sofort"
 		}
@@ -128,25 +123,42 @@ func ParseDepartures(response DMResponse, allowedPlatform *string) (Departures,
 			leaving = fmt.Sprintf("%02s:%02s", dt.Hour, dt.Minute)
 		}
 
-		if allowedPlatform != nil && d.Platform != *allowedPlatform {
-			continue
-		}
-
 		ds = append(ds, Departure{
 			d.Platform,
 			d.ServingLine.Symbol,
 			direction,
 			leaving,
+			countdown,
 		})
 	}
 
-	return Departures{ds}, nil
+	slices.SortFunc(ds, func(a Departure, b Departure) int {
+		return cmp.Compare(a.Countdown, b.Countdown)
+	})
+
+	dt := response.DateTime
+
+	return Departures{
+		ds,
+		fmt.Sprintf("%02s:%02s", dt.Hour, dt.Minute),
+	}, nil
 }
 
 func main() {
 	password := os.Getenv("VRNP_PASSWORD")
 	if len(password) == 0 {
-		panic("Required environment variable VRNP_PASSWORD is not set")
+		log.Fatal("Required environment variable VRNP_PASSWORD is not set")
+	}
+
+	clientAllowlist := strings.Split(os.Getenv("VRNP_CLIENT_ALLOWLIST"), ",")
+
+	// Use round-robin to send incoming requests to different servers
+	var efaClient atomic.Uint64
+	var efaClients []EFAClient
+	for _, efaClient := range allEfaClients {
+		if len(clientAllowlist) != 0 && slices.Contains(clientAllowlist, efaClient.GetName()) {
+			efaClients = append(efaClients, efaClient)
+		}
 	}
 
 	http.HandleFunc("/departures", func(w http.ResponseWriter, r *http.Request) {
@@ -170,7 +182,8 @@ func main() {
 			platform = &query["platform"][0]
 		}
 
-		ds, err := FetchDepartures(stopId)
+		c := efaClients[(efaClient.Add(1) - 1) % uint64(len(efaClients))]
+		ds, err := FetchDepartures(c, stopId)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return