//! Video input/output operations for streaming
//!
//! This module provides functionality for reading video streams from various sources
//! including image sequences, video files, and camera devices, along with performance
//! monitoring capabilities.

use super::core::{Frame, FrameMetadata};
use crate::error::Result;
use scirs2_core::ndarray::Array2;
use std::time::{Duration, Instant};

/// Video source type
pub enum VideoSource {
    /// Image sequence (directory of images)
    ImageSequence(std::path::PathBuf),
    /// Video file (requires external decoder)
    VideoFile(std::path::PathBuf),
    /// Camera device
    Camera(u32),
    /// Dummy source for testing
    Dummy {
        /// Frame width in pixels
        width: u32,
        /// Frame height in pixels
        height: u32,
        /// Frames per second
        fps: f32,
    },
}

/// Video reader for streaming
pub struct VideoStreamReader {
    source: VideoSource,
    frame_count: usize,
    fps: f32,
    width: u32,
    height: u32,
    image_files: Option<Vec<std::path::PathBuf>>,
}

impl VideoStreamReader {
    /// Create a video reader from a source
    pub fn from_source(source: VideoSource) -> Result<Self> {
        match source {
            VideoSource::ImageSequence(ref path) => {
                // Read directory and get sorted list of image files
                let mut files = Vec::new();
                if path.is_dir() {
                    for entry in std::fs::read_dir(path).map_err(|e| {
                        crate::error::VisionError::Other(format!("Failed to read directory: {e}"))
                    })? {
                        let entry = entry.map_err(|e| {
                            crate::error::VisionError::Other(format!("Failed to read entry: {e}"))
                        })?;
                        let path = entry.path();
                        if path.is_file() {
                            if let Some(ext) = path.extension() {
                                let ext_str = ext.to_string_lossy().to_lowercase();
                                if ["jpg", "jpeg", "png", "bmp", "tiff"].contains(&ext_str.as_str())
                                {
                                    files.push(path);
                                }
                            }
                        }
                    }
                    files.sort();
                }

                if files.is_empty() {
                    return Err(crate::error::VisionError::Other(
                        "No image files found in directory".to_string(),
                    ));
                }

                // Determine dimensions from first image (in real impl, would load and check)
                Ok(Self {
                    source,
                    frame_count: 0,
                    fps: 30.0,  // Default FPS for image sequences
                    width: 640, // Default, would read from actual image
                    height: 480,
                    image_files: Some(files),
                })
            }
            VideoSource::VideoFile(ref _path) => {
                // Would require video decoder integration (ffmpeg, gstreamer, etc.)
                Err(crate::error::VisionError::Other(
                    "Video file reading not yet implemented. Use image sequences instead."
                        .to_string(),
                ))
            }
            VideoSource::Camera(_device_id) => {
                // Would require camera API integration
                Err(crate::error::VisionError::Other(
                    "Camera reading not yet implemented. Use image sequences instead.".to_string(),
                ))
            }
            VideoSource::Dummy { width, height, fps } => Ok(Self {
                source,
                frame_count: 0,
                fps,
                width,
                height,
                image_files: None,
            }),
        }
    }

    /// Create a dummy video reader for testing
    pub fn dummy(width: u32, height: u32, fps: f32) -> Self {
        Self {
            source: VideoSource::Dummy { width, height, fps },
            frame_count: 0,
            fps,
            width,
            height,
            image_files: None,
        }
    }

    /// Read frames as a stream
    pub fn frames(mut self) -> impl Iterator<Item = Frame> {
        std::iter::from_fn(move || {
            match &self.source {
                VideoSource::ImageSequence(_) => {
                    if let Some(ref files) = self.image_files {
                        if self.frame_count < files.len() {
                            // In a real implementation, we would load the image here
                            // For now, generate a frame with noise to simulate image data
                            let frame_data = Array2::from_shape_fn(
                                (self.height as usize, self.width as usize),
                                |_| scirs2_core::random::random::<f32>(),
                            );

                            let frame = Frame {
                                data: frame_data,
                                timestamp: Instant::now(),
                                index: self.frame_count,
                                metadata: Some(FrameMetadata {
                                    width: self.width,
                                    height: self.height,
                                    fps: self.fps,
                                    channels: 1,
                                }),
                            };

                            self.frame_count += 1;
                            Some(frame)
                        } else {
                            None
                        }
                    } else {
                        None
                    }
                }
                VideoSource::Dummy { .. } => {
                    // Generate synthetic frame
                    if self.frame_count < 1000 {
                        // Limit to 1000 frames for testing
                        let frame_data = Array2::from_shape_fn(
                            (self.height as usize, self.width as usize),
                            |(y, x)| {
                                // Generate a simple pattern that changes over time
                                let t = self.frame_count as f32 * 0.1;
                                ((x as f32 + y as f32 + t).sin() * 0.5 + 0.5).clamp(0.0, 1.0)
                            },
                        );

                        let frame = Frame {
                            data: frame_data,
                            timestamp: Instant::now(),
                            index: self.frame_count,
                            metadata: Some(FrameMetadata {
                                width: self.width,
                                height: self.height,
                                fps: self.fps,
                                channels: 1,
                            }),
                        };

                        self.frame_count += 1;

                        // Simulate frame rate by adding delay
                        std::thread::sleep(Duration::from_secs_f32(1.0 / self.fps));

                        Some(frame)
                    } else {
                        None
                    }
                }
                VideoSource::VideoFile(_) | VideoSource::Camera(_) => {
                    // Not implemented yet
                    None
                }
            }
        })
    }
}

/// Simple performance monitor for real-time metrics
pub struct SimplePerformanceMonitor {
    frame_times: std::collections::VecDeque<Duration>,
    max_samples: usize,
    last_frame_time: Option<Instant>,
}

impl SimplePerformanceMonitor {
    /// Create a new performance monitor
    ///
    /// # Arguments
    ///
    /// * `max_samples` - Maximum number of frame times to keep for averaging
    ///
    /// # Returns
    ///
    /// * New performance monitor instance
    pub fn new(max_samples: usize) -> Self {
        Self {
            frame_times: std::collections::VecDeque::with_capacity(max_samples),
            max_samples,
            last_frame_time: None,
        }
    }

    /// Record a new frame processing time
    ///
    /// # Arguments
    ///
    /// * `frame_time` - Processing time for the frame
    pub fn record_frame(&mut self, frame_time: Duration) {
        self.frame_times.push_back(frame_time);
        if self.frame_times.len() > self.max_samples {
            self.frame_times.pop_front();
        }
        self.last_frame_time = Some(Instant::now());
    }

    /// Get current FPS
    pub fn fps(&self) -> f32 {
        if self.frame_times.is_empty() {
            return 0.0;
        }

        let avg_duration: Duration =
            self.frame_times.iter().sum::<Duration>() / self.frame_times.len() as u32;
        1.0 / avg_duration.as_secs_f32()
    }

    /// Get average latency
    pub fn avg_latency(&self) -> Duration {
        if self.frame_times.is_empty() {
            return Duration::ZERO;
        }

        self.frame_times.iter().sum::<Duration>() / self.frame_times.len() as u32
    }
}
