// @deno-types="https://cdn.sheetjs.com/xlsx-0.20.3/package/types/index.d.ts"
import * as XLSX from "https://cdn.sheetjs.com/xlsx-0.20.3/package/xlsx.mjs";

export type ParsedUE = {
  code: string | null;
  name: string;
  ects: number | null;
  modules: ParsedModule[];
};

export type ParsedModule = {
  code: string;
  name: string;
  coeff: number;
};

export type ParsedYear = {
  label: string;
  ues: ParsedUE[];
};

/**
 * Analyse un classeur Excel pour en extraire la maquette pédagogique.
 */
export function parseMaquette(workbook: XLSX.WorkBook): ParsedYear[] {
  const sheet = workbook.Sheets[workbook.SheetNames[0]];
  const rows = XLSX.utils.sheet_to_json<(string | number | null)[]>(sheet, {
    header: 1,
  });

  const years: ParsedYear[] = [];
  let currentYear: ParsedYear | null = null;
  let currentUE: ParsedUE | null = null;
  let moduleIndex = 0;

  for (const row of rows) {
    if (!row || row.length === 0) continue;

    const col0 = row[0] != null ? String(row[0]).trim() : "";

    // Detect year row: INFO3A, INFO4A, INFO5A, INFOAPP3A, INFOAPP4A, etc.
    if (/^(INFO|INFOAPP)\s*\d+A$/i.test(col0)) {
      currentYear = { label: col0, ues: [] };
      years.push(currentYear);
      currentUE = null;
      continue;
    }

    // Detect UE row: col[0] === "UE" or starts with "UE" (e.g., "UE51")
    if (col0 === "UE" || (col0.startsWith("UE") && /^UE\d/.test(col0))) {
      const ueCode = row[1] != null ? String(row[1]).trim() : null;
      const ueName = row[2] != null ? String(row[2]).trim() : "UE sans nom";
      const ects = typeof row[4] === "number" ? row[4] : null;

      currentUE = { code: ueCode, name: ueName, ects, modules: [] };
      if (currentYear) {
        currentYear.ues.push(currentUE);
      } else {
        // No year detected yet — create a default one
        currentYear = { label: "Maquette", ues: [currentUE] };
        years.push(currentYear);
      }
      moduleIndex = 0;
      continue;
    }

    // Detect semester header rows — just skip, don't reset UE
    if (/^SEM\s*\d/i.test(col0)) {
      currentUE = null;
      continue;
    }

    // Detect module row: inside a UE, col[3] has a name, col[5] is a number (coeff)
    if (currentUE && row[3] != null && typeof row[5] === "number") {
      const modName = String(row[3]).trim();
      if (!modName) continue;

      let modCode = row[1] != null ? String(row[1]).trim() : "";
      if (!modCode) {
        const uePrefix = (currentUE.code || "MOD").replace(/[^A-Z0-9]/gi, "");
        modCode = `${uePrefix}_${String(moduleIndex).padStart(2, "0")}`;
      }

      currentUE.modules.push({ code: modCode, name: modName, coeff: row[5] });
      moduleIndex++;
    }
  }

  return years;
}