use serde_json::{json, Value};

pub fn generate_preset_options(preset: &str, epsg: i64, has_gcp: bool, nb_images: usize) -> Value {
    let srs = format!("EPSG:{}", epsg);

    // Détection internationale pieds US vs mètres
    let is_feet = (3400..=3460).contains(&epsg) || (2225..=2285).contains(&epsg);
    let resolution_value: f64 = if is_feet { 0.065 } else { 2.0 };

    // Split-merge si > 80 images → RAM divisée par 3
    let use_split = nb_images > 80;

    let (mut fq, pq, min_feat) = match preset {
        "PRECISION" => ("ultra", "low", 10000),
        "RAPIDE"    => ("medium", "low", 6000),
        _           => ("medium", "low", 8000), // STANDARD — medium = 2x plus rapide
    };

    // GCP présent → feature ultra obligatoire, jamais dégradé
    if has_gcp { fq = "ultra"; }

    let mut opts = vec![
        json!({"name":"feature-quality",                     "value":fq}),
        json!({"name":"pc-quality",                          "value":pq}),
        json!({"name":"min-num-features",                    "value":min_feat}),
        json!({"name":"matcher-type",                        "value":"flann"}),
        json!({"name":"out-crs",                             "value":&srs}),
        json!({"name":"dsm-out-srs",                         "value":&srs}),
        json!({"name":"orthophoto-resolution",               "value":resolution_value}),
        json!({"name":"dsm",                                 "value":true}),
        json!({"name":"dtm",                                 "value":true}),
        json!({"name":"smrf-threshold",                      "value":0.5}),
        json!({"name":"smrf-scalar",                         "value":1.2}),
        json!({"name":"pc-copc",                             "value":true}),
        json!({"name":"pc-filter",                           "value":2.0}),
        json!({"name":"pc-sample",                           "value":0.05}),
        json!({"name":"max-concurrency",                     "value":4}),
        json!({"name":"fast-orthophoto",                     "value": preset == "RAPIDE" && !has_gcp}), // Skip maillage 3D pour RAPIDE sans GCP seulement
        json!({"name":"texturing-skip-global-seam-leveling", "value":true}),
        json!({"name":"mesh-size",                            "value":200000}),
    ];

    // Split-merge anti-OOM pour gros projets
    if use_split {
        opts.extend(vec![
            json!({"name":"split",         "value":75}),
            json!({"name":"split-overlap", "value":15}),
        ]);
    }

    // Paramètres GCP avancés
    if has_gcp {
        opts.extend(vec![
            json!({"name":"gcp-error-threshold",         "value":0.01}),
            json!({"name":"optimize-camera-intrinsics",  "value":"all"}),
            json!({"name":"primary-ranking",             "value":"none"}),
        ]);
    }

    Value::Array(opts)
}

pub fn calculate_preset_hash(options: &Value) -> String {
    use sha2::{Sha256, Digest};
    let mut h = Sha256::new();
    h.update(options.to_string().as_bytes());
    format!("{:x}", h.finalize())
}