import type { MasseSalarialeImportRemuneration, MasseSalarialeImportSalarie } from "./db";
import XLSX from "xlsx";

type SpreadsheetValue = string | number | Date | null | undefined;

function cents(value: SpreadsheetValue): number {
  if (typeof value === "number") return Math.round(value * 100);
  if (typeof value !== "string") return 0;
  const normalized = value.replace(/[\s\u00a0]/g, "").replace(",", ".");
  const parsed = Number(normalized);
  return Number.isFinite(parsed) ? Math.round(parsed * 100) : 0;
}

function bps(value: SpreadsheetValue): number | null {
  if (value === null || value === undefined || value === "") return null;
  const numeric = typeof value === "number" ? value : Number(String(value).replace(",", "."));
  return Number.isFinite(numeric) ? Math.round(numeric * 10_000) : null;
}

function isoDate(value: SpreadsheetValue): string | null {
  if (value instanceof Date && !Number.isNaN(value.valueOf())) return value.toISOString().slice(0, 10);
  if (typeof value === "number" && Number.isFinite(value)) {
    const excelDate = new Date(Date.UTC(1899, 11, 30) + Math.round(value * 86_400_000));
    return Number.isNaN(excelDate.valueOf()) ? null : excelDate.toISOString().slice(0, 10);
  }
  if (typeof value === "string" && /^\d{4}-\d{2}-\d{2}$/.test(value)) return value;
  if (typeof value === "string" && /^\d{2}\/\d{2}\/\d{4}$/.test(value)) {
    const [day, month, year] = value.split("/");
    return `${year}-${month}-${day}`;
  }
  return null;
}

function text(value: SpreadsheetValue): string {
  return typeof value === "string" || typeof value === "number" ? String(value).trim() : "";
}

export type MasseSalarialeWorkbookImport = {
  salaries: MasseSalarialeImportSalarie[];
  remunerations: MasseSalarialeImportRemuneration[];
};

/**
 * Convertit les lignes de la feuille modèle (index Excel 1, en-tête sur la
 * ligne 5) sans évaluer de formules côté application : les valeurs calculées
 * et sauvegardées par le fichier fourni servent de référence importée.
 */
export function parseMasseSalarialeWorkbookRows(rows: SpreadsheetValue[][]): MasseSalarialeWorkbookImport {
  const salaries: MasseSalarialeImportSalarie[] = [];
  const remunerations: MasseSalarialeImportRemuneration[] = [];

  for (const row of rows.slice(5)) {
    // SheetJS supprime la cellule A vide de certaines lignes. On repère donc
    // la présence effective de cette cellule plutôt que de supposer un index.
    const originalColumn = (excelColumn: number) => row[excelColumn + (row[0] === null || row[0] === undefined ? 0 : -1)];
    const matricule = text(originalColumn(1));
    const nom = text(originalColumn(2));
    const prenom = text(originalColumn(3));
    const poste = text(originalColumn(4));
    const dateEmbauche = isoDate(originalColumn(5));
    if (!matricule || !nom || !prenom || !poste || !dateEmbauche) continue;

    salaries.push({ matricule, nom, prenom, poste, dateEmbauche });
    const addForecast = (annee: number, startIndex: number, tauxChargeBps: number | null, periodeReference: string) => {
      const brutHorsAstreinte = cents(originalColumn(startIndex));
      const brutAvecPrimes = cents(originalColumn(startIndex + 1));
      const primeAstreinte = cents(originalColumn(startIndex + 2));
      const brutMensuel = cents(originalColumn(startIndex + 3));
      const evolution = cents(originalColumn(startIndex + 5));
      const prime = annee === 2027 ? cents(originalColumn(startIndex + 6)) : 0;
      if (brutHorsAstreinte === 0 && brutAvecPrimes === 0 && brutMensuel === 0) return;

      remunerations.push({
        matricule,
        annee,
        nature: "previsionnel",
        salaireAnnuelBrutHorsPrimesCents: brutHorsAstreinte,
        salaireAnnuelBrutAvecPrimesCents: brutAvecPrimes,
        salaireMensuelBrutHorsPrimesCents: brutMensuel,
        tauxChargeBps,
        primeAstreinteCents: primeAstreinte,
        primeCents: prime,
        evolutionCents: evolution,
        primeReferenceCents: prime,
        evolutionReferenceCents: evolution,
        periodeReference,
        statut: annee === 2025 ? "annuel" : "previsionnel",
        source: "fichier_modele_2026-08-28",
      });
    };

    addForecast(2025, 6, bps(originalColumn(10)), "2025-12");
    addForecast(2026, 12, bps(originalColumn(16)), "2026-08");
    addForecast(2027, 18, null, "2027-01");
  }

  return { salaries, remunerations };
}

/**
 * Lit le fichier exclusivement côté serveur, afin que les données de masse
 * salariale ne soient ni transformées ni renvoyées par le navigateur.
 */
export function parseMasseSalarialeWorkbookBuffer(buffer: Buffer): MasseSalarialeWorkbookImport {
  const workbook = XLSX.read(buffer, { type: "buffer", cellDates: true });
  const sheet = workbook.Sheets["Masse salariale"];
  if (!sheet) throw new Error("Feuille Masse salariale introuvable");
  const rows = XLSX.utils.sheet_to_json<SpreadsheetValue[]>(sheet, {
    header: 1,
    raw: true,
    defval: null,
  });
  const parsed = parseMasseSalarialeWorkbookRows(rows);
  if (parsed.salaries.length === 0 || parsed.remunerations.length === 0) {
    throw new Error("Le fichier ne contient aucune prévision exploitable");
  }
  return parsed;
}