// Auteur : Simon-Pierre Boucher — contact@spboucher.ai
/**
 * Moteur de conversion d'unités de la base de coûts. Module PUR.
 * Règle : on conserve TOUJOURS l'unité d'origine (source_unit), l'unité
 * canonique (canonical_unit) et le facteur de conversion appliqué.
 */
import type { CanonicalUnit } from "./types";

export const SQFT_PER_M2 = 10.7639;
export const M2_PER_SQFT = 0.092903;
export const FT_PER_M = 3.28084;
export const M3_PER_FT3 = 0.0283168;
export const LB_PER_KG = 2.20462;
export const L_PER_GAL_US = 3.78541;
export const L_PER_GAL_IMP = 4.54609;

/** Libellés FR/EN des unités canoniques. */
export const UNIT_LABELS: Record<CanonicalUnit, { fr: string; en: string }> = {
  unit: { fr: "unité", en: "each" },
  pi2: { fr: "pi²", en: "sq ft" },
  pi_lin: { fr: "pi lin.", en: "lin ft" },
  pi3: { fr: "pi³", en: "cu ft" },
  m2: { fr: "m²", en: "m²" },
  m3: { fr: "m³", en: "m³" },
  kg: { fr: "kg", en: "kg" },
  lb: { fr: "lb", en: "lb" },
  L: { fr: "L", en: "L" },
  gal: { fr: "gal", en: "gal" },
  h: { fr: "heure", en: "hour" },
  day: { fr: "jour", en: "day" },
  lump: { fr: "forfait", en: "lump sum" },
};

/** Unités source reconnues (normalisées en minuscules, sans accents). */
export type SourceUnit =
  | CanonicalUnit
  | "chaque"
  | "each"
  | "ea"
  | "paquet"
  | "pack"
  | "boite"
  | "box"
  | "sac"
  | "bag"
  | "rouleau"
  | "roll"
  | "feuille"
  | "sheet"
  | "seau"
  | "pail"
  | "planche"
  | "board"
  | "longueur"
  | "length"
  | "ballot"
  | "bundle"
  | "verge3"
  | "cu_yd"
  | "tonne"
  | "kit";

export interface UnitConversion {
  sourceUnit: string;
  canonicalUnit: CanonicalUnit;
  /** prix canonique = prix source × factor (ex. feuille 32 pi² → factor 1/32) */
  factor: number;
  method: string;
}

export function normalizeUnitToken(raw: string): string {
  return raw
    .normalize("NFD")
    .replace(/[̀-ͯ]/g, "")
    .toLowerCase()
    .replace(/[^a-z0-9/]/g, "")
    .trim();
}

/** Unités « emballage » qui nécessitent une quantité par emballage propre à l'article. */
const PACK_UNITS = new Set(["paquet", "pack", "boite", "box", "sac", "bag", "rouleau", "roll", "feuille", "sheet", "seau", "pail", "planche", "board", "longueur", "length", "ballot", "bundle", "kit", "pqt", "bte"]);

const DIRECT: Record<string, CanonicalUnit> = {
  unit: "unit", chaque: "unit", each: "unit", ea: "unit", ch: "unit", un: "unit", unite: "unit",
  pi2: "pi2", pi: "pi_lin", sqft: "pi2", "pi²": "pi2", pieds2: "pi2", piedcarre: "pi2", ft2: "pi2",
  pilin: "pi_lin", lf: "pi_lin", linft: "pi_lin", pl: "pi_lin", ft: "pi_lin",
  pi3: "pi3", ft3: "pi3", m2: "m2", m3: "m3", kg: "kg", lb: "lb", lbs: "lb", l: "L", litre: "L", liter: "L",
  gal: "gal", gallon: "gal", h: "h", heure: "h", hour: "h", hr: "h", day: "day", jour: "day", lump: "lump", forfait: "lump",
};

/**
 * Convertit un prix exprimé dans une unité source vers l'unité canonique de
 * l'article. `packQty` = contenu d'un emballage exprimé dans l'unité canonique
 * (ex. feuille de gypse 4×8 → 32 pi² ; paquet d'isolant R24 → 78,3 pi²).
 */
export function convertPrice(
  price: number,
  sourceUnitRaw: string,
  canonical: CanonicalUnit,
  packQty?: number | null
): { price: number; conversion: UnitConversion } {
  const tok = normalizeUnitToken(sourceUnitRaw);
  const direct = DIRECT[tok];
  if (direct === canonical) {
    return { price, conversion: { sourceUnit: sourceUnitRaw, canonicalUnit: canonical, factor: 1, method: "identité" } };
  }
  // conversions métriques ↔ impériales simples
  const pair = `${direct ?? tok}->${canonical}`;
  const SIMPLE: Record<string, [number, string]> = {
    "m2->pi2": [1 / SQFT_PER_M2, "1 m² = 10,764 pi²"],
    "pi2->m2": [SQFT_PER_M2, "1 m² = 10,764 pi²"],
    "m3->pi3": [M3_PER_FT3, "1 pi³ = 0,0283 m³"],
    "pi3->m3": [1 / M3_PER_FT3, "1 pi³ = 0,0283 m³"],
    "verge3->m3": [1 / 0.764555, "1 vg³ = 0,7646 m³"],
    "cu_yd->m3": [1 / 0.764555, "1 vg³ = 0,7646 m³"],
    "kg->lb": [1 / LB_PER_KG, "1 kg = 2,2046 lb"],
    "lb->kg": [LB_PER_KG, "1 kg = 2,2046 lb"],
    "gal->L": [1 / L_PER_GAL_US, "1 gal US = 3,785 L"],
    "L->gal": [L_PER_GAL_US, "1 gal US = 3,785 L"],
    "m->pi_lin": [1 / FT_PER_M, "1 m = 3,2808 pi"],
    "pi_lin->m": [FT_PER_M, "1 m = 3,2808 pi"],
  };
  const s = SIMPLE[pair];
  if (s) return { price: price * s[0], conversion: { sourceUnit: sourceUnitRaw, canonicalUnit: canonical, factor: s[0], method: s[1] } };
  // emballages : besoin de la quantité par emballage
  if ((PACK_UNITS.has(tok) || direct === "unit" || tok === "") && packQty && packQty > 0) {
    const f = 1 / packQty;
    return {
      price: price * f,
      conversion: { sourceUnit: sourceUnitRaw, canonicalUnit: canonical, factor: f, method: `1 ${sourceUnitRaw || "emballage"} = ${packQty} ${UNIT_LABELS[canonical].fr}` },
    };
  }
  throw new Error(`Conversion impossible : « ${sourceUnitRaw} » → ${canonical}${packQty ? "" : " (quantité par emballage inconnue)"}`);
}

/** Vrai si l'unité source est reconnue (canonique, métrique/impériale ou emballage). */
export function isKnownUnit(raw: string): boolean {
  const tok = normalizeUnitToken(raw);
  return tok in DIRECT || PACK_UNITS.has(tok) || ["m", "verge3", "cu_yd", "tonne"].includes(tok);
}

export const sqftFromM2 = (m2: number): number => m2 * SQFT_PER_M2;
export const m2FromSqft = (sqft: number): number => sqft * M2_PER_SQFT;