1 files changed, 321 insertions, 0 deletions
diff --git a/src/video/v4l2.rs b/src/video/v4l2.rs
new file mode 100644
index 0000000..792ff51
--- /dev/null
+++ b/src/video/v4l2.rs
@@ -0,0 +1,321 @@
+//! V4L2 backend for video streaming (placeholder for future implementation)
+
+use super::{VideoBackendTrait, VideoStats, VideoFormat};
+use crate::error::{Result, VideoError};
+use std::sync::Arc;
+use std::sync::Mutex;
+use tracing::{debug, info, trace, warn};
+
+/// V4L2 backend implementation (placeholder)
+pub struct V4L2Backend {
+    device_path: String,
+    is_initialized: bool,
+    stats: Arc<Mutex<VideoStats>>,
+    config: V4L2Config,
+}
+
+/// V4L2 configuration
+#[derive(Debug, Clone)]
+pub struct V4L2Config {
+    pub device_path: String,
+    pub width: u32,
+    pub height: u32,
+    pub fps: u32,
+    pub format: VideoFormat,
+    pub buffer_size: usize,
+}
+
+impl Default for V4L2Config {
+    fn default() -> Self {
+        Self {
+            device_path: "/dev/video10".to_string(),
+            width: 640,
+            height: 480,
+            fps: 30,
+            format: VideoFormat::MJPEG,
+            buffer_size: 0x10000, // 64KB
+        }
+    }
+}
+
+impl V4L2Backend {
+    /// Create a new V4L2 backend
+    pub fn new() -> Result<Self> {
+        let stats = VideoStats {
+            backend_type: super::VideoBackendType::V4L2,
+            ..Default::default()
+        };
+        
+        Ok(Self {
+            device_path: "/dev/video10".to_string(),
+            is_initialized: false,
+            stats: Arc::new(Mutex::new(stats)),
+            config: V4L2Config::default(),
+        })
+    }
+
+    /// Create a new V4L2 backend with custom configuration
+    pub fn with_config(config: V4L2Config) -> Result<Self> {
+        let stats = VideoStats {
+            backend_type: super::VideoBackendType::V4L2,
+            ..Default::default()
+        };
+        
+        Ok(Self {
+            device_path: config.device_path.clone(),
+            is_initialized: false,
+            stats: Arc::new(Mutex::new(stats)),
+            config,
+        })
+    }
+
+    /// Check if V4L2 device exists and is accessible
+    fn check_device(&self) -> Result<()> {
+        use std::path::Path;
+        
+        if !Path::new(&self.device_path).exists() {
+            return Err(VideoError::V4L2(format!("Device not found: {}", self.device_path)).into());
+        }
+
+        // TODO: Check device permissions and capabilities
+        debug!("V4L2 device found: {}", self.device_path);
+        Ok(())
+    }
+
+    /// Update statistics
+    fn update_stats(&self, frame_size: usize) {
+        let mut stats = self.stats.lock().unwrap();
+        stats.frames_pushed += 1;
+        stats.total_bytes += frame_size as u64;
+        stats.backend_type = super::VideoBackendType::V4L2;
+        stats.is_ready = self.is_initialized;
+        
+        // Calculate FPS (simple rolling average)
+        // TODO: Implement proper FPS calculation
+        stats.fps = 30.0; // Placeholder
+    }
+}
+
+impl VideoBackendTrait for V4L2Backend {
+    fn initialize(&mut self) -> Result<()> {
+        if self.is_initialized {
+            warn!("V4L2 backend already initialized");
+            return Ok(());
+        }
+
+        info!("Initializing V4L2 backend...");
+        
+        // Check if device exists and is accessible
+        if let Err(e) = self.check_device() {
+            warn!("V4L2 device check failed: {}", e);
+            return Err(e);
+        }
+
+        // TODO: Implement actual V4L2 device initialization
+        // For now, this is a placeholder that simulates success
+        debug!("V4L2 initialization (placeholder) - would open device: {}", self.device_path);
+        debug!("Format: {}x{} @ {}fps ({})", 
+               self.config.width, 
+               self.config.height, 
+               self.config.fps, 
+               self.config.format.as_str());
+
+        self.is_initialized = true;
+        info!("V4L2 backend initialized successfully (placeholder)");
+        
+        Ok(())
+    }
+
+    fn push_frame(&self, frame_data: &[u8]) -> Result<()> {
+        if !self.is_initialized {
+            return Err(VideoError::DeviceNotReady.into());
+        }
+
+        trace!("Pushing frame to V4L2 (placeholder): {} bytes", frame_data.len());
+
+        // TODO: Implement actual frame pushing to V4L2
+        // For now, this is a placeholder that simulates success
+        debug!("Would push frame of {} bytes to V4L2 device: {}", frame_data.len(), self.device_path);
+
+        // Update statistics
+        self.update_stats(frame_data.len());
+
+        trace!("Frame processed successfully (placeholder)");
+        Ok(())
+    }
+
+    fn get_stats(&self) -> VideoStats {
+        self.stats.lock().unwrap().clone()
+    }
+
+    fn is_ready(&self) -> bool {
+        self.is_initialized
+    }
+
+    fn shutdown(&mut self) -> Result<()> {
+        if !self.is_initialized {
+            return Ok(());
+        }
+
+        info!("Shutting down V4L2 backend (placeholder)...");
+
+        // TODO: Implement actual V4L2 device cleanup
+        // For now, this is a placeholder that simulates success
+
+        self.is_initialized = false;
+        info!("V4L2 backend shut down successfully (placeholder)");
+
+        Ok(())
+    }
+}
+
+impl Drop for V4L2Backend {
+    fn drop(&mut self) {
+        if self.is_initialized {
+            // Try to shutdown gracefully (synchronous)
+            let _ = self.shutdown();
+        }
+    }
+}
+
+/// V4L2 device information (placeholder)
+#[derive(Debug, Clone)]
+pub struct V4L2DeviceInfo {
+    pub device_path: String,
+    pub driver_name: String,
+    pub card_name: String,
+    pub bus_info: String,
+    pub capabilities: u32,
+}
+
+impl V4L2DeviceInfo {
+    /// Create new device info
+    pub fn new(device_path: String) -> Self {
+        Self {
+            device_path,
+            driver_name: "Unknown".to_string(),
+            card_name: "Unknown".to_string(),
+            bus_info: "Unknown".to_string(),
+            capabilities: 0,
+        }
+    }
+
+    /// Check if device supports video output
+    pub fn supports_video_output(&self) -> bool {
+        // TODO: Implement capability checking
+        true
+    }
+
+    /// Check if device supports MJPEG format
+    pub fn supports_mjpeg(&self) -> bool {
+        // TODO: Implement format checking
+        true
+    }
+}
+
+/// V4L2 format information (placeholder)
+#[derive(Debug, Clone)]
+pub struct V4L2Format {
+    pub width: u32,
+    pub height: u32,
+    pub pixel_format: u32,
+    pub field: u32,
+    pub bytes_per_line: u32,
+    pub size_image: u32,
+    pub colorspace: u32,
+}
+
+impl V4L2Format {
+    /// Create new format
+    pub fn new(width: u32, height: u32, pixel_format: u32) -> Self {
+        Self {
+            width,
+            height,
+            pixel_format,
+            field: 1, // V4L2_FIELD_NONE
+            bytes_per_line: 0,
+            size_image: width * height * 2, // Estimate for MJPEG
+            colorspace: 1, // V4L2_COLORSPACE_SMPTE170M
+        }
+    }
+
+    /// Get format description
+    pub fn description(&self) -> String {
+        format!("{}x{} @ {} bytes", self.width, self.height, self.size_image)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_v4l2_config_default() {
+        let config = V4L2Config::default();
+        assert_eq!(config.device_path, "/dev/video10");
+        assert_eq!(config.width, 640);
+        assert_eq!(config.height, 480);
+        assert_eq!(config.fps, 30);
+        assert!(matches!(config.format, VideoFormat::MJPEG));
+        assert_eq!(config.buffer_size, 0x10000);
+    }
+
+    #[test]
+    fn test_v4l2_backend_creation() {
+        let backend = V4L2Backend::new();
+        assert!(backend.is_ok());
+        
+        let backend = backend.unwrap();
+        assert!(!backend.is_initialized);
+        assert_eq!(backend.device_path, "/dev/video10");
+    }
+
+    #[test]
+    fn test_v4l2_backend_with_config() {
+        let config = V4L2Config {
+            device_path: "/dev/video20".to_string(),
+            width: 1280,
+            height: 720,
+            fps: 60,
+            ..Default::default()
+        };
+        
+        let backend = V4L2Backend::with_config(config);
+        assert!(backend.is_ok());
+    }
+
+    #[test]
+    fn test_v4l2_device_info() {
+        let device_info = V4L2DeviceInfo::new("/dev/video10".to_string());
+        assert_eq!(device_info.device_path, "/dev/video10");
+        assert_eq!(device_info.driver_name, "Unknown");
+        assert!(device_info.supports_video_output());
+        assert!(device_info.supports_mjpeg());
+    }
+
+    #[test]
+    fn test_v4l2_format() {
+        let format = V4L2Format::new(640, 480, 0x47504A4D); // MJPEG
+        assert_eq!(format.width, 640);
+        assert_eq!(format.height, 480);
+        assert_eq!(format.pixel_format, 0x47504A4D);
+        assert_eq!(format.description(), "640x480 @ 614400 bytes");
+    }
+
+    #[test]
+    fn test_v4l2_backend_stats() {
+        let backend = V4L2Backend::new().unwrap();
+        let stats = backend.get_stats();
+        
+        assert_eq!(stats.frames_pushed, 0);
+        assert_eq!(stats.total_bytes, 0);
+        assert!(!stats.is_ready);
+        assert!(matches!(stats.backend_type, super::super::VideoBackendType::V4L2));
+    }
+
+    #[test]
+    fn test_v4l2_backend_ready_state() {
+        let backend = V4L2Backend::new().unwrap();
+        assert!(!backend.is_ready());
+    }
+}