//! Video backend module for the Geek szitman supercamera

mod pipewire;
mod v4l2;
mod stdout;

pub use pipewire::{PipeWireBackend, PipeWireConfig};
pub use v4l2::V4L2Backend;
pub use stdout::{StdoutBackend, StdoutConfig, HeaderFormat};

use crate::error::{Result, VideoError};
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use std::sync::Mutex;
use tracing::{info};

/// Video backend trait for different video output methods
pub trait VideoBackendTrait: Send + Sync {
    /// Initialize the video backend
    fn initialize(&mut self) -> Result<()>;
    
    /// Push a frame to the video backend
    fn push_frame(&self, frame_data: &[u8]) -> Result<()>;
    
    /// Get backend statistics
    fn get_stats(&self) -> VideoStats;
    
    /// Check if backend is ready
    fn is_ready(&self) -> bool;
    
    /// Shutdown the backend
    fn shutdown(&mut self) -> Result<()>;
}

/// Video backend types
#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
pub enum VideoBackendType {
    /// PipeWire backend
    PipeWire,
    /// V4L2 backend (for future use)
    V4L2,
    /// Stdout backend for piping to other tools
    Stdout,
}

/// Video backend configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VideoConfig {
    pub backend_type: VideoBackendType,
    pub width: u32,
    pub height: u32,
    pub fps: u32,
    pub format: VideoFormat,
    pub device_path: Option<String>,
}

impl Default for VideoConfig {
    fn default() -> Self {
        Self {
            backend_type: VideoBackendType::PipeWire,
            width: 640,
            height: 480,
            fps: 30,
            format: VideoFormat::MJPEG,
            device_path: None,
        }
    }
}

/// Video format types
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum VideoFormat {
    /// Motion JPEG
    MJPEG,
    /// YUV420
    YUV420,
    /// RGB24
    RGB24,
}

impl VideoFormat {
    /// Get the format name as a string
    pub fn as_str(&self) -> &'static str {
        match self {
            VideoFormat::MJPEG => "MJPEG",
            VideoFormat::YUV420 => "YUV420",
            VideoFormat::RGB24 => "RGB24",
        }
    }

    /// Get the bytes per pixel
    pub fn bytes_per_pixel(&self) -> usize {
        match self {
            VideoFormat::MJPEG => 0, // Variable for MJPEG
            VideoFormat::YUV420 => 1,
            VideoFormat::RGB24 => 3,
        }
    }
}

/// Video statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VideoStats {
    pub frames_pushed: u64,
    pub frames_dropped: u64,
    pub total_bytes: u64,
    pub fps: f64,
    pub backend_type: VideoBackendType,
    pub is_ready: bool,
}

impl Default for VideoStats {
    fn default() -> Self {
        Self {
            frames_pushed: 0,
            frames_dropped: 0,
            total_bytes: 0,
            fps: 0.0,
            backend_type: VideoBackendType::PipeWire,
            is_ready: false,
        }
    }
}

/// Video backend factory
pub struct VideoBackend;

impl VideoBackend {
    /// Create a new PipeWire backend
    pub fn new_pipewire() -> Result<Box<dyn VideoBackendTrait>> {
        Ok(Box::new(PipeWireBackend::new(PipeWireConfig::default())))
    }

    /// Create a new V4L2 backend (for future use)
    pub fn new_v4l2() -> Result<Box<dyn VideoBackendTrait>> {
        Ok(Box::new(V4L2Backend::new()?))
    }

    /// Create a new stdout backend
    pub fn new_stdout() -> Result<Box<dyn VideoBackendTrait>> {
        Ok(Box::new(StdoutBackend::new()))
    }

    /// Create a backend based on configuration
    pub fn from_config(config: &VideoConfig) -> Result<Box<dyn VideoBackendTrait>> {
        match config.backend_type {
            VideoBackendType::PipeWire => Self::new_pipewire(),
            VideoBackendType::V4L2 => Self::new_v4l2(),
            VideoBackendType::Stdout => Self::new_stdout(),
        }
    }

    /// Create a backend from type
    pub fn from_type(backend_type: VideoBackendType) -> Result<Box<dyn VideoBackendTrait>> {
        match backend_type {
            VideoBackendType::PipeWire => Self::new_pipewire(),
            VideoBackendType::V4L2 => Self::new_v4l2(),
            VideoBackendType::Stdout => Self::new_stdout(),
        }
    }
}

/// Video frame metadata
#[derive(Debug, Clone)]
pub struct VideoFrame {
    pub data: Vec<u8>,
    pub width: u32,
    pub height: u32,
    pub format: VideoFormat,
    pub timestamp: std::time::Instant,
}

impl VideoFrame {
    /// Create a new video frame
    pub fn new(data: Vec<u8>, width: u32, height: u32, format: VideoFormat) -> Self {
        Self {
            data,
            width,
            height,
            format,
            timestamp: std::time::Instant::now(),
        }
    }

    /// Get frame size in bytes
    pub fn size(&self) -> usize {
        self.data.len()
    }

    /// Get frame dimensions
    pub fn dimensions(&self) -> (u32, u32) {
        (self.width, self.height)
    }

    /// Check if frame is valid
    pub fn is_valid(&self) -> bool {
        !self.data.is_empty() && self.width > 0 && self.height > 0
    }
}

/// Video backend manager
pub struct VideoBackendManager {
    backend: Arc<Mutex<Box<dyn VideoBackendTrait>>>,
    config: VideoConfig,
    stats: Arc<Mutex<VideoStats>>,
}

impl VideoBackendManager {
    /// Create a new video backend manager
    pub fn new(config: VideoConfig) -> Result<Self> {
        let backend = VideoBackend::from_config(&config)?;
        let stats = Arc::new(Mutex::new(VideoStats::default()));
        
        let manager = Self {
            backend: Arc::new(Mutex::new(backend)),
            config,
            stats,
        };

        // Initialize the backend
        let mut backend_guard = manager.backend.lock().unwrap();
        backend_guard.initialize()?;
        drop(backend_guard);

        Ok(manager)
    }

    /// Push a frame to the video backend
    pub fn push_frame(&self, frame_data: &[u8]) -> Result<()> {
        let backend = self.backend.lock().unwrap();
        
        if !backend.is_ready() {
            return Err(VideoError::DeviceNotReady.into());
        }

        // Update statistics
        let mut stats = self.stats.lock().unwrap();
        stats.frames_pushed += 1;
        stats.total_bytes += frame_data.len() as u64;
        drop(stats);

        // Push frame to backend
        backend.push_frame(frame_data)?;
        
        Ok(())
    }

    /// Get current statistics
    pub fn get_stats(&self) -> VideoStats {
        let stats = self.stats.lock().unwrap();
        stats.clone()
    }

    /// Switch video backend
    pub fn switch_backend(&mut self, new_type: VideoBackendType) -> Result<()> {
        // Shutdown current backend
        let mut backend = self.backend.lock().unwrap();
        backend.shutdown()?;
        drop(backend);

        // Create new backend
        let new_backend = VideoBackend::from_type(new_type)?;
        let mut backend = self.backend.lock().unwrap();
        *backend = new_backend;
        
        // Initialize new backend
        backend.initialize()?;
        
        // Update config
        self.config.backend_type = new_type;
        
        info!("Switched to {:?} backend", new_type);
        Ok(())
    }

    /// Get configuration
    pub fn config(&self) -> &VideoConfig {
        &self.config
    }

    /// Update configuration
    pub fn update_config(&mut self, config: VideoConfig) -> Result<()> {
        // Recreate backend if type changed
        if self.config.backend_type != config.backend_type {
            self.switch_backend(config.backend_type)?;
        }
        
        self.config = config;
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_video_backend_factory() {
        // Test PipeWire backend creation
        let pipewire_backend = VideoBackend::new_pipewire();
        assert!(pipewire_backend.is_ok());

        // Test V4L2 backend creation
        let v4l2_backend = VideoBackend::new_v4l2();
        assert!(v4l2_backend.is_ok());
    }

    #[test]
    fn test_video_frame_creation() {
        let frame_data = vec![0u8; 1024];
        let frame = VideoFrame::new(frame_data.clone(), 32, 32, VideoFormat::RGB24);

        assert_eq!(frame.data, frame_data);
        assert_eq!(frame.width, 32);
        assert_eq!(frame.height, 32);
        assert_eq!(frame.format, VideoFormat::RGB24);
        assert!(frame.is_valid());
    }

    #[test]
    fn test_video_format_conversions() {
        assert_eq!(VideoFormat::MJPEG.as_str(), "MJPEG");
        assert_eq!(VideoFormat::YUV420.as_str(), "YUV420");
        assert_eq!(VideoFormat::RGB24.as_str(), "RGB24");

        assert_eq!(VideoFormat::MJPEG.bytes_per_pixel(), 0);
        assert_eq!(VideoFormat::YUV420.bytes_per_pixel(), 1);
        assert_eq!(VideoFormat::RGB24.bytes_per_pixel(), 3);
    }
}