Add ASR loader module

src/overlay/asr.rs

@@ -0,0 +1,59 @@
+//! ASR subtitle loader and manager
+
+use anyhow::{Context, Result};
+use serde::Deserialize;
+use std::path::Path;
+
+#[derive(Debug, Clone, Deserialize)]
+pub struct AsrSegment {
+    pub start: f64,
+    pub end: f64,
+    pub text: String,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+pub struct AsrData {
+    pub language: Option<String>,
+    pub language_probability: Option<f64>,
+    pub segments: Vec<AsrSegment>,
+}
+
+#[derive(Debug, Clone)]
+pub struct AsrLoader {
+    data: AsrData,
+}
+
+impl AsrLoader {
+    pub fn load(path: &Path) -> Result<Self> {
+        let content = std::fs::read_to_string(path)
+            .with_context(|| format!("Failed to read ASR file: {:?}", path))?;
+        
+        let data: AsrData = serde_json::from_str(&content)
+            .with_context(|| "Failed to parse ASR JSON")?;
+        
+        Ok(Self { data })
+    }
+
+    pub fn get_segment_at(&self, time_ms: f64) -> Option<&AsrSegment> {
+        let time_sec = time_ms / 1000.0;
+        self.data.segments.iter().find(|seg| {
+            time_sec >= seg.start && time_sec < seg.end
+        })
+    }
+
+    pub fn get_text_at(&self, time_ms: f64) -> Option<String> {
+        self.get_segment_at(time_ms).map(|seg| seg.text.clone())
+    }
+
+    pub fn get_all_segments(&self) -> &[AsrSegment] {
+        &self.data.segments
+    }
+
+    pub fn segment_count(&self) -> usize {
+        self.data.segments.len()
+    }
+
+    pub fn duration(&self) -> f64 {
+        self.data.segments.last().map(|s| s.end).unwrap_or(0.0)
+    }
+}