engine/src/renderer/postprocessing.rs

use crate::error::Result;
use image::DynamicImage;

#[derive(Debug, Clone, Copy)]
pub enum ColorGrade {
    CinematicDark,
    CoolTones,
    WarmTones,
    Desaturated,
    HighContrast,
    None,
}

pub struct PostProcessor {
    pub color_grade: ColorGrade,
    pub contrast: f32,
    pub brightness: f32,
    pub saturation: f32,
}

impl Default for PostProcessor {
    fn default() -> Self {
        Self {
            color_grade: ColorGrade::CinematicDark,
            contrast: 1.1,
            brightness: 0.95,
            saturation: 1.1,
        }
    }
}

impl PostProcessor {
    pub fn new(color_grade: ColorGrade) -> Self {
        Self {
            color_grade,
            ..Default::default()
        }
    }

    /// Appliquer tous les traitements de post-processing
    pub fn process(&self, img: DynamicImage) -> Result<DynamicImage> {
        let mut result = img;

        // 1. Appliquer le grade de couleur
        result = self.apply_color_grade(result)?;

        // 2. Ajuster contraste/luminosité
        result = self.adjust_contrast_brightness(result)?;

        // 3. Ajuster saturation
        result = self.adjust_saturation(result)?;

        Ok(result)
    }

    fn apply_color_grade(&self, img: DynamicImage) -> Result<DynamicImage> {
        match self.color_grade {
            ColorGrade::CinematicDark => self.apply_cinematic_dark(img),
            ColorGrade::CoolTones => self.apply_cool_tones(img),
            ColorGrade::WarmTones => self.apply_warm_tones(img),
            ColorGrade::Desaturated => self.apply_desaturated(img),
            ColorGrade::HighContrast => self.apply_high_contrast(img),
            ColorGrade::None => Ok(img),
        }
    }

    fn apply_cinematic_dark(&self, img: DynamicImage) -> Result<DynamicImage> {
        let rgba = img.to_rgba8();
        let mut output = rgba.clone();

        for pixel in output.pixels_mut() {
            let [r, g, b, a] = pixel.0;
            // Ajouter une teinte bleuée et assombrir
            pixel.0 = [
                (r as f32 * 0.95) as u8,
                (g as f32 * 0.98) as u8,
                (b as f32 * 1.05).min(255.0) as u8,
                a,
            ];
        }

        Ok(DynamicImage::ImageRgba8(output))
    }

    fn apply_cool_tones(&self, img: DynamicImage) -> Result<DynamicImage> {
        let rgba = img.to_rgba8();
        let mut output = rgba.clone();

        for pixel in output.pixels_mut() {
            let [r, g, b, a] = pixel.0;
            pixel.0 = [
                (r as f32 * 0.9) as u8,
                (g as f32 * 0.98) as u8,
                (b as f32 * 1.1).min(255.0) as u8,
                a,
            ];
        }

        Ok(DynamicImage::ImageRgba8(output))
    }

    fn apply_warm_tones(&self, img: DynamicImage) -> Result<DynamicImage> {
        let rgba = img.to_rgba8();
        let mut output = rgba.clone();

        for pixel in output.pixels_mut() {
            let [r, g, b, a] = pixel.0;
            pixel.0 = [
                (r as f32 * 1.1).min(255.0) as u8,
                (g as f32 * 1.05).min(255.0) as u8,
                (b as f32 * 0.9) as u8,
                a,
            ];
        }

        Ok(DynamicImage::ImageRgba8(output))
    }

    fn apply_desaturated(&self, img: DynamicImage) -> Result<DynamicImage> {
        let rgba = img.to_rgba8();
        let mut output = rgba.clone();

        for pixel in output.pixels_mut() {
            let [r, g, b, a] = pixel.0;
            let gray = ((r as f32 + g as f32 + b as f32) / 3.0) as u8;
            // 70% saturé = 30% gris
            let sat = 0.7;
            pixel.0 = [
                ((r as f32 * sat + gray as f32 * (1.0 - sat)) as u8),
                ((g as f32 * sat + gray as f32 * (1.0 - sat)) as u8),
                ((b as f32 * sat + gray as f32 * (1.0 - sat)) as u8),
                a,
            ];
        }

        Ok(DynamicImage::ImageRgba8(output))
    }

    fn apply_high_contrast(&self, img: DynamicImage) -> Result<DynamicImage> {
        let rgba = img.to_rgba8();
        let mut output = rgba.clone();

        for pixel in output.pixels_mut() {
            let [r, g, b, a] = pixel.0;
            // Formule: (val - 128) * 1.5 + 128
            let contrast = 1.5;
            let offset = 128.0;
            pixel.0 = [
                ((r as f32 - offset) * contrast + offset).clamp(0.0, 255.0) as u8,
                ((g as f32 - offset) * contrast + offset).clamp(0.0, 255.0) as u8,
                ((b as f32 - offset) * contrast + offset).clamp(0.0, 255.0) as u8,
                a,
            ];
        }

        Ok(DynamicImage::ImageRgba8(output))
    }

    fn adjust_contrast_brightness(&self, img: DynamicImage) -> Result<DynamicImage> {
        let rgba = img.to_rgba8();
        let mut output = rgba.clone();

        for pixel in output.pixels_mut() {
            let [r, g, b, a] = pixel.0;
            pixel.0 = [
                ((r as f32 - 128.0) * self.contrast + 128.0 + self.brightness * 255.0)
                    .clamp(0.0, 255.0) as u8,
                ((g as f32 - 128.0) * self.contrast + 128.0 + self.brightness * 255.0)
                    .clamp(0.0, 255.0) as u8,
                ((b as f32 - 128.0) * self.contrast + 128.0 + self.brightness * 255.0)
                    .clamp(0.0, 255.0) as u8,
                a,
            ];
        }

        Ok(DynamicImage::ImageRgba8(output))
    }

    fn adjust_saturation(&self, img: DynamicImage) -> Result<DynamicImage> {
        let rgba = img.to_rgba8();
        let mut output = rgba.clone();

        for pixel in output.pixels_mut() {
            let [r, g, b, a] = pixel.0;
            let gray = (r as f32 + g as f32 + b as f32) / 3.0;
            pixel.0 = [
                (r as f32 + (gray - r as f32) * (1.0 - self.saturation)).clamp(0.0, 255.0) as u8,
                (g as f32 + (gray - g as f32) * (1.0 - self.saturation)).clamp(0.0, 255.0) as u8,
                (b as f32 + (gray - b as f32) * (1.0 - self.saturation)).clamp(0.0, 255.0) as u8,
                a,
            ];
        }

        Ok(DynamicImage::ImageRgba8(output))
    }
}