[refactor] simplify backend initialization and transcription logic using macro and trait improvements

src/backend.rs

@@ -87,63 +87,22 @@ fn vulkan_available() -> bool {
 }
 
 /// CPU-based transcription backend using whisper-rs.
+#[derive(Default)]
 pub struct CpuBackend;
 /// CUDA-accelerated transcription backend for NVIDIA GPUs.
+#[derive(Default)]
 pub struct CudaBackend;
 /// ROCm/HIP-accelerated transcription backend for AMD GPUs.
+#[derive(Default)]
 pub struct HipBackend;
 /// Vulkan-based transcription backend (experimental/incomplete).
+#[derive(Default)]
 pub struct VulkanBackend;
 
-impl CpuBackend {
+macro_rules! impl_whisper_backend {
-    /// Create a new CPU backend instance.
+    ($ty:ty, $kind:expr) => {
-    pub fn new() -> Self {
+        impl TranscribeBackend for $ty {
-        CpuBackend
+            fn kind(&self) -> BackendKind { $kind }
-    }
-}
-impl Default for CpuBackend {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-impl CudaBackend {
-    /// Create a new CUDA backend instance.
-    pub fn new() -> Self {
-        CudaBackend
-    }
-}
-impl Default for CudaBackend {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-impl HipBackend {
-    /// Create a new HIP backend instance.
-    pub fn new() -> Self {
-        HipBackend
-    }
-}
-impl Default for HipBackend {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-impl VulkanBackend {
-    /// Create a new Vulkan backend instance.
-    pub fn new() -> Self {
-        VulkanBackend
-    }
-}
-impl Default for VulkanBackend {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-impl TranscribeBackend for CpuBackend {
-    fn kind(&self) -> BackendKind {
-        BackendKind::Cpu
-    }
             fn transcribe(
                 &self,
                 audio_path: &Path,
@@ -154,40 +113,13 @@ impl TranscribeBackend for CpuBackend {
             ) -> Result<Vec<OutputEntry>> {
                 transcribe_with_whisper_rs(audio_path, speaker, lang_opt, progress_cb)
             }
+        }
+    };
 }
 
-impl TranscribeBackend for CudaBackend {
+impl_whisper_backend!(CpuBackend, BackendKind::Cpu);
-    fn kind(&self) -> BackendKind {
+impl_whisper_backend!(CudaBackend, BackendKind::Cuda);
-        BackendKind::Cuda
+impl_whisper_backend!(HipBackend, BackendKind::Hip);
-    }
-    fn transcribe(
-        &self,
-        audio_path: &Path,
-        speaker: &str,
-        lang_opt: Option<&str>,
-        _gpu_layers: Option<u32>,
-        progress_cb: Option<&(dyn Fn(i32) + Send + Sync)>,
-    ) -> Result<Vec<OutputEntry>> {
-        // whisper-rs uses enabled CUDA feature at build time; call same code path
-        transcribe_with_whisper_rs(audio_path, speaker, lang_opt, progress_cb)
-    }
-}
-
-impl TranscribeBackend for HipBackend {
-    fn kind(&self) -> BackendKind {
-        BackendKind::Hip
-    }
-    fn transcribe(
-        &self,
-        audio_path: &Path,
-        speaker: &str,
-        lang_opt: Option<&str>,
-        _gpu_layers: Option<u32>,
-        progress_cb: Option<&(dyn Fn(i32) + Send + Sync)>,
-    ) -> Result<Vec<OutputEntry>> {
-        transcribe_with_whisper_rs(audio_path, speaker, lang_opt, progress_cb)
-    }
-}
 
 impl TranscribeBackend for VulkanBackend {
     fn kind(&self) -> BackendKind {
@@ -239,11 +171,11 @@ pub fn select_backend(requested: BackendKind, verbose: bool) -> Result<Selection
 
     let mk = |k: BackendKind| -> Box<dyn TranscribeBackend + Send + Sync> {
         match k {
-            BackendKind::Cpu => Box::new(CpuBackend::new()),
+            BackendKind::Cpu => Box::new(CpuBackend::default()),
-            BackendKind::Cuda => Box::new(CudaBackend::new()),
+            BackendKind::Cuda => Box::new(CudaBackend::default()),
-            BackendKind::Hip => Box::new(HipBackend::new()),
+            BackendKind::Hip => Box::new(HipBackend::default()),
-            BackendKind::Vulkan => Box::new(VulkanBackend::new()),
+            BackendKind::Vulkan => Box::new(VulkanBackend::default()),
-            BackendKind::Auto => Box::new(CpuBackend::new()), // will be replaced
+            BackendKind::Auto => Box::new(CpuBackend::default()), // will be replaced
         }
     };
 

src/models.rs

@@ -15,23 +15,13 @@ use std::path::{Path, PathBuf};
 ///
 /// Heuristic: choose the largest .bin file by size. Returns None if none found.
 pub fn pick_best_local_model(dir: &Path) -> Option<PathBuf> {
-    let mut best: Option<(u64, PathBuf)> = None;
     let rd = fs::read_dir(dir).ok()?;
-    for e in rd.flatten() {
+    rd.flatten()
-        let p = e.path();
+        .map(|e| e.path())
-        if p.is_file() {
+        .filter(|p| p.is_file() && p.extension().and_then(|s| s.to_str()).is_some_and(|s| s.eq_ignore_ascii_case("bin")))
-            if p.extension().and_then(|s| s.to_str()).map(|s| s.eq_ignore_ascii_case("bin")).unwrap_or(false) {
+        .filter_map(|p| fs::metadata(&p).ok().map(|md| (md.len(), p)))
-                if let Ok(md) = fs::metadata(&p) {
+        .max_by_key(|(sz, _)| *sz)
-                    let sz = md.len();
+        .map(|(_, p)| p)
-                    match &best {
-                        Some((b_sz, _)) if *b_sz >= sz => {}
-                        _ => best = Some((sz, p.clone())),
-                    }
-                }
-            }
-        }
-    }
-    best.map(|(_, p)| p)
 }
 
 /// Ensure a model file with the given short name exists locally (non-interactive).
@@ -105,22 +95,19 @@ pub fn run_interactive_model_downloader() -> Result<()> {
     let selection = if selection_raw.is_empty() { "1" } else { &selection_raw };
 
     // Parse indices
-    let mut picked_indices: Vec<usize> = Vec::new();
+    use std::collections::BTreeSet;
-    for part in selection.split(|c| c == ',' || c == ' ' || c == ';') {
+    let mut picked_set: BTreeSet<usize> = BTreeSet::new();
+    for part in selection.split([',', ' ', ';']) {
         let t = part.trim();
         if t.is_empty() { continue; }
         match t.parse::<usize>() {
-            Ok(n) if n >= 1 && n <= available.len() => {
+            Ok(n) if (1..=available.len()).contains(&n) => {
-                let idx = n - 1;
+                picked_set.insert(n - 1);
-                if !picked_indices.contains(&idx) {
+            }
-                    picked_indices.push(idx);
+            _ => ui::warn(format!("Ignoring invalid selection: '{}'", t)),
-                }
-            }
-            _ => {
-                ui::warn(format!("Ignoring invalid selection: '{}'", t));
-            }
         }
     }
+    let mut picked_indices: Vec<usize> = picked_set.into_iter().collect();
     if picked_indices.is_empty() {
         // Fallback to default first item
         picked_indices.push(0);