//! Simple DataShader implementation without parallel features
//! This will be used to make tests pass initially, then enhanced

use crate::core::error::{PlottingError, Result};
use crate::core::types::{BoundingBox, Point2f};
use std::sync::atomic::{AtomicU32, Ordering};

/// Simple DataShader canvas for aggregation
pub struct DataShaderCanvas {
    width: usize,
    height: usize,
    canvas: Vec<AtomicU32>,
    bounds: BoundingBox,
    total_points: u64,
}

impl DataShaderCanvas {
    /// Create new DataShader canvas
    pub fn new(width: usize, height: usize) -> Self {
        let canvas_size = width * height;
        let canvas = (0..canvas_size).map(|_| AtomicU32::new(0)).collect();

        Self {
            width,
            height,
            canvas,
            bounds: BoundingBox::new(0.0, 1.0, 0.0, 1.0),
            total_points: 0,
        }
    }

    /// Calculate bounds from a set of points
    pub fn calculate_bounds(points: &[(f64, f64)]) -> Result<BoundingBox> {
        if points.is_empty() {
            return Err(PlottingError::EmptyDataSet);
        }

        let mut min_x = f64::INFINITY;
        let mut max_x = f64::NEG_INFINITY;
        let mut min_y = f64::INFINITY;
        let mut max_y = f64::NEG_INFINITY;

        for &(x, y) in points {
            min_x = min_x.min(x);
            max_x = max_x.max(x);
            min_y = min_y.min(y);
            max_y = max_y.max(y);
        }

        Ok(BoundingBox::new(
            min_x as f32,
            max_x as f32,
            min_y as f32,
            max_y as f32,
        ))
    }

    /// Create a DataShaderCanvas with specific bounds
    pub fn with_bounds(width: usize, height: usize, bounds: BoundingBox) -> Self {
        let canvas_size = width * height;
        let canvas = (0..canvas_size).map(|_| AtomicU32::new(0)).collect();

        Self {
            width,
            height,
            canvas,
            bounds,
            total_points: 0,
        }
    }

    /// Set the world coordinate bounds
    pub fn set_bounds(&mut self, bounds: BoundingBox) {
        self.bounds = bounds;
    }

    /// Get the bounds
    pub fn bounds(&self) -> BoundingBox {
        self.bounds
    }

    /// Get canvas width
    pub fn width(&self) -> usize {
        self.width
    }

    /// Get canvas height  
    pub fn height(&self) -> usize {
        self.height
    }

    /// Clear the canvas
    pub fn clear(&self) {
        for cell in &self.canvas {
            cell.store(0, Ordering::Relaxed);
        }
    }

    /// Convert world coordinates to grid coordinates
    fn world_to_grid(&self, point: &Point2f) -> Option<(usize, usize)> {
        // Check if point is within bounds
        if point.x < self.bounds.min_x
            || point.x > self.bounds.max_x
            || point.y < self.bounds.min_y
            || point.y > self.bounds.max_y
        {
            return None;
        }

        // Convert to grid coordinates
        let x_norm = (point.x - self.bounds.min_x) / (self.bounds.max_x - self.bounds.min_x);
        let y_norm = (point.y - self.bounds.min_y) / (self.bounds.max_y - self.bounds.min_y);

        let grid_x = (x_norm * (self.width - 1) as f32) as usize;
        let grid_y = (y_norm * (self.height - 1) as f32) as usize;

        Some((grid_x, grid_y))
    }

    /// Aggregate points from (x, y) tuples
    pub fn aggregate(&mut self, points: &[(f64, f64)]) {
        // Convert to Point2f first
        let point2f_vec: Vec<Point2f> = points
            .iter()
            .map(|&(x, y)| Point2f::new(x as f32, y as f32))
            .collect();

        self.aggregate_points(&point2f_vec);
    }

    /// Aggregate points
    pub fn aggregate_points(&mut self, points: &[Point2f]) {
        for point in points {
            if let Some((grid_x, grid_y)) = self.world_to_grid(point) {
                let idx = grid_y * self.width + grid_x;
                if idx < self.canvas.len() {
                    self.canvas[idx].fetch_add(1, Ordering::Relaxed);
                }
            }
        }

        self.total_points += points.len() as u64;
    }

    /// Get aggregated count at grid position
    pub fn get_count(&self, grid_x: usize, grid_y: usize) -> Option<u32> {
        if grid_x >= self.width || grid_y >= self.height {
            return None;
        }

        let idx = grid_y * self.width + grid_x;
        Some(self.canvas[idx].load(Ordering::Relaxed))
    }

    /// Get maximum count in the canvas
    pub fn max_count(&self) -> u32 {
        self.canvas
            .iter()
            .map(|cell| cell.load(Ordering::Relaxed))
            .max()
            .unwrap_or(0)
    }

    /// Get statistics about the aggregated data
    pub fn statistics(&self) -> DataShaderStats {
        let counts: Vec<u32> = self
            .canvas
            .iter()
            .map(|cell| cell.load(Ordering::Relaxed))
            .collect();

        let non_zero_counts: Vec<u32> = counts.iter().filter(|&&c| c > 0).cloned().collect();
        let max_count = *non_zero_counts.iter().max().unwrap_or(&0);
        let min_count = *non_zero_counts.iter().min().unwrap_or(&0);
        let total_count: u64 = counts.iter().map(|&c| c as u64).sum();
        let filled_pixels = non_zero_counts.len();

        DataShaderStats {
            total_points: self.total_points,
            filled_pixels,
            total_pixels: self.width * self.height,
            max_count,
            min_count,
            total_count,
            canvas_utilization: filled_pixels as f64 / (self.width * self.height) as f64,
        }
    }

    /// Create image data as simple grayscale
    pub fn to_image_data(&self) -> Vec<u8> {
        let max_count = self.max_count();
        let mut pixels = Vec::with_capacity(self.width * self.height * 4);

        for y in 0..self.height {
            for x in 0..self.width {
                let idx = y * self.width + x;
                let count = self.canvas[idx].load(Ordering::Relaxed);

                // Normalize to grayscale
                let intensity = if max_count > 0 {
                    ((count as f64 / max_count as f64) * 255.0) as u8
                } else {
                    0
                };

                // RGBA
                pixels.push(intensity); // R
                pixels.push(intensity); // G  
                pixels.push(intensity); // B
                pixels.push(255); // A
            }
        }

        pixels
    }
}

/// Statistics about aggregated data
#[derive(Debug, Clone)]
pub struct DataShaderStats {
    pub total_points: u64,
    pub filled_pixels: usize,
    pub total_pixels: usize,
    pub max_count: u32,
    pub min_count: u32,
    pub total_count: u64,
    pub canvas_utilization: f64,
}

/// Simple image representation
pub struct DataShaderImage {
    pub width: usize,
    pub height: usize,
    pub pixels: Vec<u8>,
}

impl DataShaderImage {
    pub fn new(width: usize, height: usize, pixels: Vec<u8>) -> Self {
        Self {
            width,
            height,
            pixels,
        }
    }
}

/// DataShader facade - simple aggregation for massive datasets
pub struct DataShader {
    canvas: DataShaderCanvas,
}

impl Default for DataShader {
    fn default() -> Self {
        Self::new()
    }
}

impl DataShader {
    /// Create new DataShader with default canvas size
    pub fn new() -> Self {
        Self::with_canvas_size(512, 512)
    }

    /// Create DataShader with specific canvas size
    pub fn with_canvas_size(width: usize, height: usize) -> Self {
        Self {
            canvas: DataShaderCanvas::new(width, height),
        }
    }

    /// Check if DataShader should be activated for the given point count
    pub fn should_activate(point_count: usize) -> bool {
        point_count >= 100_000
    }

    /// Create canvas size recommendation based on data points and dimensions
    pub fn create_canvas(point_count: usize, width: usize, height: usize) -> (usize, usize) {
        // For simplicity, just return the given dimensions
        // In a more sophisticated implementation, this could adjust canvas size based on point density
        (width, height)
    }

    fn validate_explicit_bounds(x_min: f64, x_max: f64, y_min: f64, y_max: f64) -> Result<()> {
        if !x_min.is_finite() || !x_max.is_finite() || !y_min.is_finite() || !y_max.is_finite() {
            return Err(PlottingError::InvalidInput(format!(
                "DataShader bounds must be finite, got x=({x_min}, {x_max}), y=({y_min}, {y_max})"
            )));
        }

        if x_min >= x_max || y_min >= y_max {
            return Err(PlottingError::InvalidInput(format!(
                "DataShader bounds must satisfy x_min < x_max and y_min < y_max, got x=({x_min}, {x_max}), y=({y_min}, {y_max})"
            )));
        }

        Ok(())
    }

    /// Set data bounds
    pub fn set_bounds(&mut self, min_x: f64, min_y: f64, max_x: f64, max_y: f64) {
        let bounds = BoundingBox::new(min_x as f32, max_x as f32, min_y as f32, max_y as f32);
        self.canvas.set_bounds(bounds);
    }

    /// Aggregate data points
    pub fn aggregate(&mut self, x_data: &[f64], y_data: &[f64]) -> Result<()> {
        if x_data.len() != y_data.len() {
            return Err(PlottingError::DataLengthMismatch {
                x_len: x_data.len(),
                y_len: y_data.len(),
                series_index: None,
            });
        }

        if x_data.is_empty() {
            return Err(PlottingError::EmptyDataSet);
        }

        // Auto-calculate bounds if not set
        let x_min = x_data.iter().fold(f64::INFINITY, |a, &b| a.min(b));
        let x_max = x_data.iter().fold(f64::NEG_INFINITY, |a, &b| a.max(b));
        let y_min = y_data.iter().fold(f64::INFINITY, |a, &b| a.min(b));
        let y_max = y_data.iter().fold(f64::NEG_INFINITY, |a, &b| a.max(b));

        self.set_bounds(x_min, y_min, x_max, y_max);

        self.aggregate_with_current_bounds(x_data, y_data)
    }

    /// Aggregate data points using explicit `x_min/x_max/y_min/y_max` bounds
    /// instead of auto-fitting to the data.
    pub fn aggregate_with_bounds(
        &mut self,
        x_data: &[f64],
        y_data: &[f64],
        x_min: f64,
        x_max: f64,
        y_min: f64,
        y_max: f64,
    ) -> Result<()> {
        if x_data.len() != y_data.len() {
            return Err(PlottingError::DataLengthMismatch {
                x_len: x_data.len(),
                y_len: y_data.len(),
                series_index: None,
            });
        }

        if x_data.is_empty() {
            return Err(PlottingError::EmptyDataSet);
        }

        Self::validate_explicit_bounds(x_min, x_max, y_min, y_max)?;
        self.set_bounds(x_min, y_min, x_max, y_max);
        self.aggregate_with_current_bounds(x_data, y_data)
    }

    fn aggregate_with_current_bounds(&mut self, x_data: &[f64], y_data: &[f64]) -> Result<()> {
        self.canvas.clear();

        // Create point tuples and aggregate
        let points: Vec<(f64, f64)> = x_data
            .iter()
            .zip(y_data.iter())
            .map(|(&x, &y)| (x, y))
            .collect();
        self.canvas.aggregate(&points);

        Ok(())
    }

    /// Get statistics
    pub fn statistics(&self) -> DataShaderStats {
        self.canvas.statistics()
    }

    /// Render to image data
    pub fn render(&self) -> DataShaderImage {
        let pixels = self.canvas.to_image_data();
        DataShaderImage::new(self.canvas.width(), self.canvas.height(), pixels)
    }
}

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

    #[test]
    fn test_datashader_canvas_creation() {
        let canvas = DataShaderCanvas::new(800, 600);
        assert_eq!(canvas.width(), 800);
        assert_eq!(canvas.height(), 600);
    }

    #[test]
    fn test_point_aggregation() {
        let mut canvas = DataShaderCanvas::new(10, 10);
        canvas.set_bounds(BoundingBox::new(0.0, 1.0, 0.0, 1.0));

        // Add points to the canvas
        let points = vec![
            Point2f::new(0.1, 0.1),
            Point2f::new(0.12, 0.12),
            Point2f::new(0.08, 0.08),
        ];

        canvas.aggregate_points(&points);

        // Check that points were aggregated
        assert!(canvas.max_count() > 0);
    }

    #[test]
    fn test_should_activate() {
        assert!(!DataShader::should_activate(1000));
        assert!(!DataShader::should_activate(50000));
        assert!(DataShader::should_activate(100000));
        assert!(DataShader::should_activate(150000));
        assert!(DataShader::should_activate(1000000));
    }

    #[test]
    fn test_bounds_calculation() {
        let points = vec![(1.0, 2.0), (5.0, 8.0), (3.0, 4.0)];

        let bounds = DataShaderCanvas::calculate_bounds(&points).unwrap();

        assert_eq!(bounds.min_x, 1.0);
        assert_eq!(bounds.max_x, 5.0);
        assert_eq!(bounds.min_y, 2.0);
        assert_eq!(bounds.max_y, 8.0);
    }

    #[test]
    fn test_statistics() {
        let mut canvas = DataShaderCanvas::new(10, 10);
        canvas.set_bounds(BoundingBox::new(0.0, 1.0, 0.0, 1.0));

        // Add some test points
        let points = vec![Point2f::new(0.1, 0.1), Point2f::new(0.9, 0.9)];

        canvas.aggregate_points(&points);
        let stats = canvas.statistics();

        assert_eq!(stats.total_points, 2);
        assert!(stats.filled_pixels > 0);
        assert_eq!(stats.total_pixels, 100);
        assert!(stats.canvas_utilization > 0.0);
    }

    #[test]
    fn test_datashader_aggregate() {
        let mut ds = DataShader::with_canvas_size(100, 100);
        let x_data = vec![0.1, 0.2, 0.3, 0.4, 0.5];
        let y_data = vec![0.1, 0.2, 0.3, 0.4, 0.5];

        let result = ds.aggregate(&x_data, &y_data);
        assert!(result.is_ok());

        let stats = ds.statistics();
        assert_eq!(stats.total_points, 5);
    }

    #[test]
    fn test_datashader_render() {
        let mut ds = DataShader::with_canvas_size(10, 10);
        let x_data = vec![0.5];
        let y_data = vec![0.5];

        ds.aggregate(&x_data, &y_data).unwrap();
        let image = ds.render();

        assert_eq!(image.width, 10);
        assert_eq!(image.height, 10);
        assert_eq!(image.pixels.len(), 10 * 10 * 4); // RGBA
    }

    #[test]
    fn test_datashader_aggregate_with_explicit_bounds_uses_named_order() {
        let mut ds = DataShader::with_canvas_size(16, 16);
        let x_data = vec![0.25, 0.75];
        let y_data = vec![10.5, 19.5];

        ds.aggregate_with_bounds(&x_data, &y_data, 0.0, 1.0, 10.0, 20.0)
            .unwrap();

        let bounds = ds.canvas.bounds();
        assert_eq!(bounds.min_x, 0.0);
        assert_eq!(bounds.max_x, 1.0);
        assert_eq!(bounds.min_y, 10.0);
        assert_eq!(bounds.max_y, 20.0);
    }

    #[test]
    fn test_datashader_aggregate_with_explicit_bounds_rejects_invalid_range() {
        let mut ds = DataShader::with_canvas_size(16, 16);
        let x_data = vec![0.25, 0.75];
        let y_data = vec![10.5, 19.5];

        let err = ds
            .aggregate_with_bounds(&x_data, &y_data, 1.0, 0.0, 10.0, 20.0)
            .unwrap_err();

        match err {
            PlottingError::InvalidInput(message) => {
                assert!(message.contains("x_min < x_max"));
            }
            other => panic!("expected InvalidInput, got {other:?}"),
        }
    }

    #[test]
    fn test_datashader_aggregate_with_explicit_bounds_rejects_non_finite_values() {
        let mut ds = DataShader::with_canvas_size(16, 16);
        let x_data = vec![0.25, 0.75];
        let y_data = vec![10.5, 19.5];

        let err = ds
            .aggregate_with_bounds(&x_data, &y_data, f64::NAN, 1.0, 10.0, 20.0)
            .unwrap_err();

        match err {
            PlottingError::InvalidInput(message) => {
                assert!(message.contains("must be finite"));
            }
            other => panic!("expected InvalidInput, got {other:?}"),
        }
    }
}
