alsa mixer: add helpful suggestions for mixer and control values

Author: eladyn

src/alsa_mixer.rs

@@ -1,8 +1,16 @@
-use color_eyre::eyre::{self, Context, eyre};
+use alsa::device_name::HintIter;
+use color_eyre::{
+    Section,
+    eyre::{self, Context, eyre},
+};
 use librespot_playback::mixer::{Mixer, MixerConfig};
 use log::error;
 use std::sync::{Arc, Mutex, MutexGuard};
 
+pub fn get_available_controls() -> alsa::Result<HintIter> {
+    alsa::device_name::HintIter::new_str(None, "ctl")
+}
+
 pub struct AlsaMixer {
     pub mixer: Arc<Mutex<alsa::Mixer>>,
     pub config: MixerConfig,
@@ -20,6 +28,25 @@ impl AlsaMixer {
                 self.config.control,
                 self.config.device,
             )
+            .with_suggestion(|| {
+                format!(
+                    "maybe try one of the following for 'control':{}",
+                    lock.iter()
+                        .filter_map(|elem| {
+                            let selem = alsa::mixer::Selem::new(elem)?;
+                            if selem.has_playback_volume() {
+                                selem
+                                    .get_id()
+                                    .get_name()
+                                    .ok()
+                                    .map(|name| format!("\n- {name}"))
+                            } else {
+                                None
+                            }
+                        })
+                        .collect::<String>()
+                )
+            })
         })?;
         Ok(selem)
     }

src/setup.rs

@@ -53,6 +53,13 @@ pub(crate) fn initial_state(
                     control,
                     index: 0,
                     volume_ctrl,
+                }).with_suggestion(|| {
+                    match alsa_mixer::get_available_controls() {
+                        Err(err) => format!("there are no controls available, maybe check that alsa is available: {err}"),
+                        Ok(controls) => {
+                            format!("maybe try one of the following as 'mixer':{}", controls.filter_map(|hint| hint.name.map(|name| format!("\n- {name}"))).collect::<String>())
+                        }
+                    }
                 })?)
             }
             _ => {