first commit

src/app/config.rs

@@ -0,0 +1,60 @@
+pub struct Config {
+    pub token: String,
+    pub device_id: String,
+    pub base_url: String,
+    pub max_output_bytes: u64,
+    pub writer_channel_capacity: usize,
+}
+
+impl Config {
+    const DEFAULT_BASE_URL: &str = "ws://127.0.0.1:8000";
+    const DEFAULT_DEVICE_ID: &str = "device";
+    const DEFAULT_MAX_OUTPUT_BYTES: u64 = 10 * 1024 * 1024;
+    const DEFAULT_WRITER_CHANNEL_CAPACITY: usize = 32;
+
+    pub fn from_env() -> Result<Self, String> {
+        let token = std::env::var("TOKEN")
+            .map_err(|_| "TOKEN environment variable is required".to_string())?;
+
+        let device_id =
+            std::env::var("DEVICE_ID").unwrap_or_else(|_| Self::DEFAULT_DEVICE_ID.to_string());
+        validate_device_id(&device_id).map_err(|e| format!("Invalid DEVICE_ID: {e}"))?;
+
+        let base_url =
+            std::env::var("BASE_URL").unwrap_or_else(|_| Self::DEFAULT_BASE_URL.to_string());
+
+        Ok(Self {
+            token,
+            device_id,
+            base_url,
+            max_output_bytes: parse_env("MAX_OUTPUT_BYTES", Self::DEFAULT_MAX_OUTPUT_BYTES),
+            writer_channel_capacity: parse_env(
+                "WRITER_CHANNEL_CAPACITY",
+                Self::DEFAULT_WRITER_CHANNEL_CAPACITY,
+            ),
+        })
+    }
+}
+
+fn parse_env<T: std::str::FromStr>(key: &str, default: T) -> T {
+    std::env::var(key)
+        .ok()
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(default)
+}
+
+fn validate_device_id(id: &str) -> Result<(), String> {
+    if id.is_empty() {
+        return Err("cannot be empty".into());
+    }
+    if id.len() > 64 {
+        return Err("too long (max 64 characters)".into());
+    }
+    if !id
+        .chars()
+        .all(|c| c.is_alphanumeric() || c == '-' || c == '_')
+    {
+        return Err("contains invalid characters (allowed: a-z A-Z 0-9 - _)".into());
+    }
+    Ok(())
+}