/// Grid-search Bevel & Emboss MAE tuning against Krita ground-truth PNGs.
///
/// Expects `_tmp/bevel_emboss_png_kra_set/` with transparent PNGs exported
/// from `_tmp/bevel_emboss_kra_set/`.

use std::io::Write;

const GT_DIR: &str = "_tmp/bevel_emboss_png_kra_set";
static mut CANVAS: u32 = 800;
const RESULTS_FILE: &str = "bevel_emboss_kra_grid_results.txt";

struct Sample {
    _name: String,
    depth: f32,
    size: f32,
    soften: f32,
    angle: f32,
    direction: String,
    ref_pixels: Vec<u8>,
    content_mask: Vec<bool>,
}

fn main() {
    let entries: Vec<_> = std::fs::read_dir(GT_DIR)
        .unwrap_or_else(|e| panic!("cannot read {}: {}", GT_DIR, e))
        .filter_map(|e| e.ok())
        .filter(|e| {
            let s = e.file_name();
            let s = s.to_string_lossy();
            s.starts_with("be_") && s.ends_with(".png")
        })
        .collect();

    println!("Found {} PNGs in {}", entries.len(), GT_DIR);

    let mut samples: Vec<Sample> = Vec::new();

    for entry in &entries {
        let path = entry.path();
        let stem = path.file_stem().unwrap().to_string_lossy().to_string();

        let params = match parse_filename(&stem) {
            Some(p) => p,
            None => { eprintln!("  SKIP: {}", stem); continue; }
        };

        let (size, soften, depth, angle, direction) = params;

        let img = match image::open(&path) {
            Ok(i) => i,
            Err(e) => { eprintln!("  SKIP {}: {}", stem, e); continue; }
        };

        let rgba = img.to_rgba8();
        let (src_w, src_h) = rgba.dimensions();
        if src_w != src_h {
            eprintln!("  SKIP {}: non-square dimensions {}x{}", stem, src_w, src_h);
            continue;
        }
        unsafe {
            CANVAS = src_w;
        }
        let src_raw = rgba.as_raw();
        let mut cropped_raw = vec![0u8; unsafe { (CANVAS * CANVAS * 4) as usize }];
        cropped_raw.copy_from_slice(src_raw);

        let npix = unsafe { (CANVAS * CANVAS) as usize };
        let mut content_mask = vec![false; npix];
        for i in 0..npix {
            content_mask[i] = cropped_raw[i * 4 + 3] > 0;
        }

        samples.push(Sample {
            _name: stem,
            depth, size, soften, angle, direction,
            ref_pixels: cropped_raw,
            content_mask,
        });
    }

    println!("Loaded {} samples", samples.len());
    if samples.is_empty() {
        eprintln!("No valid samples found.");
        std::process::exit(1);
    }

    let content_count = samples[0].content_mask.iter().filter(|&&b| b).count();
    println!("Content pixels per image: {} / {} ({:.1}%)",
        content_count, npix(), content_count as f64 / npix() as f64 * 100.0);

    let rect_alpha: Vec<u8> = {
        let n = npix();
        let mut a = vec![0u8; n];
        for i in 0..n {
            a[i] = samples[0].ref_pixels[i * 4 + 3];
        }
        a
    };

    let lighting_blurs: &[i32] = &[0, 1, 2, 3, 5];
    let hl_scales: &[f32] = &[0.3, 0.5, 0.75, 1.0, 1.5, 2.0];
    let sh_scales: &[f32] = &[0.3, 0.5, 0.75, 1.0, 1.5, 2.0];
    let profile_exponents: &[f32] = &[0.3, 0.5, 0.7, 1.0, 1.5, 2.0, 3.0];

    let total_combos = profile_exponents.len() * lighting_blurs.len() * hl_scales.len() * sh_scales.len();
    println!("Grid: {} combos x {} samples = {} evals", total_combos, samples.len(), total_combos * samples.len());
    std::io::stdout().flush().ok();

    let mut best_avg_mae = f64::MAX;
    let mut best_params = (0i32, 0.0f32, 0.0f32, 1.0f32);
    let mut eval_count = 0usize;

    for &profile_exp in profile_exponents {
    for &lighting_blur in lighting_blurs {
        for &hl_scale in hl_scales {
            for &sh_scale in sh_scales {
                let mut total_mae = 0.0f64;

                for s in &samples {
                    let style_enum = hcie_fx::types::BevelStyle::InnerBevel;
                    let dir_enum = match s.direction.as_str() {
                        "down" => hcie_fx::types::Direction::Down,
                        _ => hcie_fx::types::Direction::Up,
                    };

                    let (highlight, shadow) = hcie_fx::tuned::generate_bevel_tuned(
                        &rect_alpha, unsafe { CANVAS }, unsafe { CANVAS },
                        s.depth, s.size, s.soften, s.angle, 30.0,
                        &dir_enum, &hcie_fx::types::Technique::Smooth, &style_enum,
                        lighting_blur, hl_scale, sh_scale, profile_exp, 1.0,
                    );

                    let px = npix();
                    let mut out = vec![0u8; px * 4];

                    // Detect actual shape color from ground truth center pixel
                    let c = unsafe { CANVAS };
                    let center = ((c / 2) * c + (c / 2)) as usize;
                    let shape_r = s.ref_pixels[center * 4];
                    let shape_g = s.ref_pixels[center * 4 + 1];
                    let shape_b = s.ref_pixels[center * 4 + 2];

                    for i in 0..px {
                        if rect_alpha[i] > 0 {
                            out[i * 4] = shape_r;
                            out[i * 4 + 1] = shape_g;
                            out[i * 4 + 2] = shape_b;
                            out[i * 4 + 3] = 255;
                        }
                    }

                    // 2. Composite highlight (screen) and shadow (multiply) over the shape
                    for i in 0..px {
                        let sa = highlight[i * 4 + 3];
                        if sa > 0 {
                            let dst = [out[i * 4], out[i * 4 + 1], out[i * 4 + 2], out[i * 4 + 3]];
                            let src = [highlight[i * 4], highlight[i * 4 + 1], highlight[i * 4 + 2], sa];
                            let blended = hcie_blend::blend_pixels(dst, src, hcie_blend::BlendMode::Screen, 1.0);
                            out[i * 4..i * 4 + 4].copy_from_slice(&blended);
                        }
                    }
                    for i in 0..px {
                        let sa = shadow[i * 4 + 3];
                        if sa > 0 {
                            let dst = [out[i * 4], out[i * 4 + 1], out[i * 4 + 2], out[i * 4 + 3]];
                            let src = [shadow[i * 4], shadow[i * 4 + 1], shadow[i * 4 + 2], sa];
                            let blended = hcie_blend::blend_pixels(dst, src, hcie_blend::BlendMode::Multiply, 1.0);
                            out[i * 4..i * 4 + 4].copy_from_slice(&blended);
                        }
                    }

                    let mut diff_sum = 0.0f64;
                    let mut content_pixels = 0u64;
                    for i in 0..px {
                        if !s.content_mask[i] { continue; }
                        content_pixels += 1;
                        for c in 0..4 {
                            diff_sum += (out[i * 4 + c] as i32 - s.ref_pixels[i * 4 + c] as i32).abs() as f64;
                        }
                    }
                    if content_pixels > 0 {
                        total_mae += diff_sum / content_pixels as f64 / 4.0;
                    }
                }

                eval_count += 1;
                let avg_mae = total_mae / samples.len() as f64;

                if avg_mae < best_avg_mae {
                    best_avg_mae = avg_mae;
                    best_params = (lighting_blur, hl_scale, sh_scale, profile_exp);
                    println!("*** [{}/{}] NEW BEST avg MAE = {:.4} (lb={}, hl={:.2}, sh={:.2}, pe={:.2})",
                        eval_count, total_combos, best_avg_mae, lighting_blur, hl_scale, sh_scale, profile_exp);
                    std::io::stdout().flush().ok();
                } else if eval_count % 100 == 0 {
                    println!("  [{}/{}] avg={:.4}  best={:.4}", eval_count, total_combos, avg_mae, best_avg_mae);
                    std::io::stdout().flush().ok();
                }
            }
        }
    }
    }

    let (lb, hl, sh, pe) = best_params;
    println!("\n=== RESULT ===");
    println!("Best avg MAE = {:.4}", best_avg_mae);
    println!("  lighting_blur = {}", lb);
    println!("  hl_scale      = {:.2}", hl);
    println!("  sh_scale      = {:.2}", sh);
    println!("  profile_exp   = {:.2}", pe);

    if let Ok(mut file) = std::fs::OpenOptions::new()
        .create(true).write(true).truncate(true).open(RESULTS_FILE)
    {
        let _ = writeln!(file,
            "lighting_blur={}  hl_scale={:.2}  sh_scale={:.2}  profile_exp={:.2}\n\
             avg_mae={:.4}  samples={}  combos={}",
            lb, hl, sh, pe, best_avg_mae, samples.len(), total_combos);
    }
}

fn npix() -> usize { unsafe { (CANVAS * CANVAS) as usize } }

fn parse_filename(name: &str) -> Option<(f32, f32, f32, f32, String)> {
    // be_s{size}_sf{soften}_d{depth}_a{angle}_{dir_name}
    let parts: Vec<&str> = name.split('_').collect();
    if parts.len() < 6 || parts[0] != "be" { return None; }
    let size = parts[1].strip_prefix('s')?.parse::<f32>().ok()?;
    let soften = parts[2].strip_prefix("sf")?.parse::<f32>().ok()?;
    let depth = parts[3].strip_prefix('d')?.parse::<f32>().ok()?;
    let angle = parts[4].strip_prefix('a')?.parse::<f32>().ok()?;
    let direction = parts[5].to_string();
    Some((size, soften, depth, angle, direction))
}