feat: add cpal-based auto device detection and configuration

1 files changed, 78 insertions, 0 deletions

diff --git a/src/device_selector.rs b/src/device_selector.rs
new file mode 100644
index 0000000..12f8a79
--- /dev/null
+++ b/src/device_selector.rs
@@ -0,0 +1,78 @@
+use cpal::traits::{DeviceTrait, HostTrait};
+
+/// Pick the best input device from the available list.
+///
+/// - `"auto"` → query OS default input device via cpal, match against list
+/// - `"<name>"` → match by device ID or name; exits if not found
+/// - `None` → exits with error
+pub fn pick_device<'a>(
+    name: &Option<String>,
+    devices: &'a [vtx_engine::AudioDevice],
+) -> Option<&'a vtx_engine::AudioDevice> {
+    let name = match name {
+        Some(n) if n == "auto" || n.is_empty() => return pick_auto(devices),
+        Some(n) => n.as_str(),
+        None => {
+            eprintln!(
+                "[dmvop] No device specified. Use --device=<name> or --list-devices to see available devices."
+            );
+            std::process::exit(1);
+        }
+    };
+
+    // Try exact match by id or name
+    if let Some(d) = devices.iter().find(|d| d.id == name || d.name == name) {
+        return Some(d);
+    }
+
+    eprintln!(
+        "[dmvop] Device '{}' not found. Use --list-devices to see available devices.",
+        name
+    );
+    std::process::exit(1);
+}
+
+/// Use cpal to find the system's default input device, then match it
+/// against the vtx-engine device list by WASAPI ID.
+fn pick_auto<'a>(devices: &'a [vtx_engine::AudioDevice]) -> Option<&'a vtx_engine::AudioDevice> {
+    let host = cpal::default_host();
+    let device = match host.default_input_device() {
+        Some(d) => d,
+        None => {
+            eprintln!("[dmvop] No default input device found.");
+            return devices.first();
+        }
+    };
+
+    // Get the WASAPI device ID from cpal
+    let cpal_device_id = match device.id() {
+        Ok(id) => id,
+        Err(_) => return devices.first(),
+    };
+    let cpal_raw_id = cpal_device_id.id().to_string();
+
+    // Match against vtx-engine devices by ID (substring — cpal might omit braces)
+    for dev in devices {
+        let dev_id_clean = dev.id.trim_matches('{').trim_matches('}');
+        let cpal_id_clean = cpal_raw_id.trim_matches('{').trim_matches('}');
+        if dev_id_clean.contains(cpal_id_clean) || cpal_id_clean.contains(dev_id_clean) {
+            return Some(dev);
+        }
+    }
+
+    // Fallback: match by name (cpal DeviceId Display includes host:raw_id)
+    let cpal_display = cpal_device_id.to_string().to_lowercase();
+    for dev in devices {
+        if cpal_display.contains(&dev.name.to_lowercase())
+            || dev.name.to_lowercase().contains(&cpal_display)
+        {
+            return Some(dev);
+        }
+    }
+
+    eprintln!(
+        "[dmvop] Default device ({}) not matched, using first available.",
+        cpal_raw_id
+    );
+    devices.first()
+}