feat: Create GPIO monitor and basic callback functionality to print

src/gpio.rs

@@ -0,0 +1,49 @@
+use std::time::Duration;
+
+use anyhow::Result;
+use rppal::gpio::{Gpio, InputPin, Level};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum CircuitEvent {
+    Open,
+    Closed,
+}
+
+pub struct GpioMonitor {
+    pin: InputPin,
+    poll_interval: Duration,
+}
+
+impl GpioMonitor {
+    pub fn new(pin_number: u8, poll_interval: Duration) -> Result<Self> {
+        let gpio = Gpio::new()?;
+        let pin = gpio.get(pin_number)?.into_input_pullup();
+
+        Ok(Self { pin, poll_interval })
+    }
+
+    pub async fn monitor<F>(&mut self, mut callback: F) -> Result<()>
+    where
+        F: FnMut(CircuitEvent) + Send + 'static,
+    {
+        let mut previous_state = self.get_current_state();
+
+        loop {
+            let current_state = self.get_current_state();
+
+            if current_state != previous_state {
+                callback(current_state);
+                previous_state = current_state;
+            }
+
+            tokio::time::sleep(self.poll_interval).await;
+        }
+    }
+
+    pub fn get_current_state(&self) -> CircuitEvent {
+        match self.pin.read() {
+            Level::High => CircuitEvent::Open,
+            Level::Low => CircuitEvent::Closed,
+        }
+    }
+}

src/main.rs

@@ -0,0 +1,33 @@
+mod gpio;
+
+use std::time::Duration;
+
+use anyhow::Result;
+use tracing::{error, info};
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    // Initialize logging
+    tracing_subscriber::fmt::init();
+
+    // Initialize GPIO monitor
+    const DEFAULT_GPIO_PIN: u8 = 17;
+    let gpio_pin = std::env::var("GPIO_PIN")
+        .ok()
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(DEFAULT_GPIO_PIN);
+
+    let mut gpio_monitor = gpio::GpioMonitor::new(gpio_pin, Duration::from_millis(100))?;
+
+    // Simple callback function that just logs the event
+    let callback = |event: gpio::CircuitEvent| {
+        info!("Circuit state changed: {:?}", event);
+    };
+
+    // Start GPIO monitoring
+    if let Err(e) = gpio_monitor.monitor(callback).await {
+        error!("GPIO monitoring error: {}", e);
+    }
+
+    Ok(())
+}