#![allow(dead_code, unused_imports, unused_variables, unused_macros, unreachable_patterns)]
/// Grid-search inner-shadow MAE tuning against Photoshop ground-truth PNGs.
///
/// Handles both RGBA (transparent bg) and RGB (white bg from flatten) reference PNGs.
/// Only pixels that differ from the background are compared.

use std::io::Write;

const GT_DIR: &str = "_tmp/inner_shadow_png_set";
const CANVAS: u32 = 256;
const MARGIN: u32 = 64;
const RESULTS_FILE: &str = "inner_shadow_grid_results.txt";

struct Sample {
    name: String,
    angle: f32,
    distance: f32,
    size: f32,
    choke: f32,
    opacity: f32,
    noise: f32,
    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("is_a") && s.ends_with(".png")
        })
        .collect();

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

    let mut samples: Vec<Sample> = Vec::new();
    let mut skipped_noise = 0;

    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 (angle, distance, size, choke, opacity, noise, _blend) = params;

        if noise > 0.0 {
            skipped_noise += 1;
            continue;
        }

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

        let rgba = img.to_rgba8();
        let raw = rgba.into_raw();
        let npix = (CANVAS * CANVAS) as usize;
        let mut content_mask = vec![false; npix];
        for i in 0..npix {
            let r = raw[i * 4];
            let g = raw[i * 4 + 1];
            let b = raw[i * 4 + 2];
            let a = raw[i * 4 + 3];
            content_mask[i] = a > 0 || !(r == 255 && g == 255 && b == 255);
        }

        samples.push(Sample {
            name: stem,
            angle, distance, size, choke, opacity, noise,
            ref_pixels: raw,
            content_mask,
        });
    }

    println!("Loaded {} samples (skipped {} with noise>0)", samples.len(), skipped_noise);
    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 y in 0..CANVAS {
            for x in 0..CANVAS {
                if x >= MARGIN && x < CANVAS - MARGIN && y >= MARGIN && y < CANVAS - MARGIN {
                    a[(y * CANVAS + x) as usize] = 255;
                }
            }
        }
        a
    };

    let shadow_color: [u8; 4] = [220, 30, 30, 255];

    let blur_factors: &[f32] = &[1.0, 1.5, 2.0, 3.0, 4.0, 6.0];
    let passes_list: &[i32] = &[1, 2, 3, 5];
    let choke_scales: &[f32] = &[0.0, 0.5, 1.0, 1.5];
    let mask_strengths: &[f32] = &[0.75, 1.0, 1.25, 1.5];

    let total_combos = blur_factors.len() * passes_list.len() * choke_scales.len() * mask_strengths.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 = (0.0f32, 0i32, 0.0f32, 0.0f32);
    let mut eval_count = 0usize;

    for &blur_factor in blur_factors {
        for &passes in passes_list {
            for &choke_scale in choke_scales {
                for &mask_strength in mask_strengths {
                    let mut total_mae = 0.0f64;

                    for s in &samples {
                        let shadow = hcie_fx::tuned::generate_inner_shadow_tuned(
                            &rect_alpha, CANVAS, CANVAS,
                            s.angle, s.distance, s.choke, s.size,
                            shadow_color,
                            blur_factor, passes, choke_scale, mask_strength,
                        );

                        let px = npix();
                        let mut out = vec![0u8; px * 4];
                        for i in 0..px {
                            if rect_alpha[i] > 0 {
                                out[i * 4] = 0;
                                out[i * 4 + 1] = 0;
                                out[i * 4 + 2] = 0;
                                out[i * 4 + 3] = 255;
                            }
                        }
                        for i in 0..px {
                            let sa = shadow[i * 4 + 3];
                            if sa == 0 { continue; }
                            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::Normal, s.opacity);
                            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 = (blur_factor, passes, choke_scale, mask_strength);
                        println!("*** [{}/{}] NEW BEST avg MAE = {:.4} (bf={:.1}, p={}, cs={:.2}, ms={:.2})",
                            eval_count, total_combos, best_avg_mae, blur_factor, passes, choke_scale, mask_strength);
                        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 (bbf, bp, bcs, bms) = best_params;
    println!("\n=== RESULT ===");
    println!("Best avg MAE = {:.4}", best_avg_mae);
    println!("  blur_factor    = {:.1}", bbf);
    println!("  passes         = {}", bp);
    println!("  choke_scale    = {:.2}", bcs);
    println!("  mask_strength  = {:.2}", bms);

    if let Ok(mut file) = std::fs::OpenOptions::new()
        .create(true).write(true).truncate(true).open(RESULTS_FILE)
    {
        let _ = writeln!(file,
            "blur_factor={:.1}  passes={}  choke_scale={:.2}  mask_strength={:.2}\n\
             avg_mae={:.4}  samples={}  combos={}",
            bbf, bp, bcs, bms, best_avg_mae, samples.len(), total_combos);
    }
}

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

fn parse_filename(name: &str) -> Option<(f32, f32, f32, f32, f32, f32, String)> {
    let parts: Vec<&str> = name.split('_').collect();
    if parts.len() < 8 || parts[0] != "is" { return None; }
    let angle    = parts[1].strip_prefix('a')?.parse::<f32>().ok()?;
    let distance = parts[2].strip_prefix('d')?.parse::<f32>().ok()?;
    let size     = parts[3].strip_prefix('s')?.parse::<f32>().ok()?;
    let choke    = parts[4].strip_prefix('c')?.parse::<f32>().ok()?;
    let opacity  = parts[5].strip_prefix("op")?.parse::<f32>().ok()? / 100.0;
    let noise    = parts[6].strip_prefix('n')?.parse::<f32>().ok()?;
    let blend    = parts[7].to_string();
    Some((angle, distance, size, choke, opacity, noise, blend))
}