foundryvtt-reve-de-dragon/module/tirage/raretes.js

const RARETE_COMMUNE = { code: 'Commune', label: 'Commune', frequence: 54, min: 27, max: 108 };
const RARETE_FREQUENTE = { code: 'Frequente', label: 'Fréquente', frequence: 18, min: 9, max: 36 };
const RARETE_RARE = { code: 'Rare', label: 'Rare', frequence: 6, min: 3, max: 12 };
const RARETE_RARISSIME = { code: 'Rarissime', label: 'Rarissime', frequence: 2, min: 1, max: 4 };
const RARETE_INEXISTANT = { code: 'Inexistant', label: 'Inexistant', frequence: 0, min: 0, max: 0 };

const RARETES = [
  RARETE_COMMUNE,
  RARETE_FREQUENTE,
  RARETE_RARE,
  RARETE_RARISSIME,
  RARETE_INEXISTANT,
]

export class RdDRaretes {

  static getRarete(code = undefined) {
    return RARETES.find(it => it.code == code) ?? RARETE_FREQUENTE;
  }

  static getChamp(rarete, field = undefined) {
    const selected = this.getRarete(rarete);
    return field ? selected[field] : selected[frequence];
  }

  static rareteFrequente() {
    return RARETE_FREQUENTE;
  }

  static raretes() {
    return RARETES;
  }

  static frequenceEquipement(item) {
    return RdDRaretes.rareteEquipement(item).frequence
  }


  static rareteEnvironnement(item, milieux = undefined) {
    const list = item.getEnvironnements(milieux);
    const freqMax = Math.max(0, ...list.map(env => env.frequence));
    const env = list.find(env => env.frequence == freqMax);
    return env ? RdDRaretes.getRarete(env.rarete) : RARETE_INEXISTANT;

  }
  static rareteEquipement(item) {
    const qualite = item.system.qualite ?? 0;
    if (qualite <= 0) {
      return RARETE_COMMUNE
    }
    if (qualite <= 3) {
      return RARETE_FREQUENTE
    }
    if (qualite <= 6) {
      return RARETE_RARE
    }
    if (qualite <= 9) {
      return RARETE_RARISSIME
    }
    return RARETE_INEXISTANT
  }
}