(function (root, factory) {
  if (typeof module === 'object' && module.exports) {
    module.exports = factory();
  } else {
    root.ISMIStools = Object.assign(root.ISMIStools || {}, factory());
  }
})(typeof self !== 'undefined' ? self : this, function () {
  'use strict';

  function cleanText(s) {
    return String(s == null ? '' : s)
      .replace(/<[^>]+>/g, ' ')
      .replace(/&nbsp;/gi, ' ')
      .replace(/\s+/g, ' ')
      .trim();
  }

  function extractRows(html) {
    const rows = [];
    const trRe = /<tr[^>]*>([\s\S]*?)<\/tr>/gi;
    let trMatch;
    while ((trMatch = trRe.exec(html)) !== null) {
      const rowHtml = trMatch[1];
      if (/<th/i.test(rowHtml)) continue;
      const tds = [];
      const tdRe = /<td[^>]*>([\s\S]*?)<\/td>/gi;
      let tdMatch;
      while ((tdMatch = tdRe.exec(rowHtml)) !== null) {
        tds.push(cleanText(tdMatch[1]));
      }
      rows.push(tds);
    }
    return rows;
  }

  function parseStudyLoadTable(html) {
    return extractRows(html)
      .filter((tds) => tds.length >= 6)
      .map((tds) => ({
        group: tds[0],
        courseCode: tds[1],
        schedule: tds[2],
        faculty: tds[3],
        units: tds[4],
        status: tds[5]
      }));
  }

  function parseProfilePage(html) {
    const result = {};
    const h3Match = /<h3[^>]*>([\s\S]*?)<\/h3>/i.exec(html);
    const bMatch = (h3Match && /<b>([\s\S]*?)<\/b>/i.exec(h3Match[1])) ||
      /<b>([\s\S]*?)<\/b>/i.exec(html);
    if (bMatch) result.program = cleanText(bMatch[1]);

    const smallMatch = /<small>([\s\S]*?)<\/small>/i.exec(html);
    if (smallMatch) {
      const lines = smallMatch[1].split(/<br\s*\/?>/i).map(cleanText).filter(Boolean);
      result.semester = lines[lines.length - 1] || '';
    }

    const kvRe = /<td[^>]*>([\s\S]*?)<\/td>\s*<td[^>]*class=["'][^"']*\bbold\b[^"']*["'][^>]*>([\s\S]*?)<\/td>/gi;
    let m;
    while ((m = kvRe.exec(html)) !== null) {
      const key = cleanText(m[1]);
      const val = cleanText(m[2]);
      if (/full name/i.test(key)) result.fullName = val;
      else if (/student id/i.test(key)) result.studentId = val;
      else if (/year level/i.test(key)) result.yearLevel = val;
      else if (/student type/i.test(key)) result.studentType = val;
    }
    return result;
  }

  function parseOfferedCourses(html) {
    return extractRows(html)
      .filter((tds) => tds.length >= 2)
      .map((tds) => ({
        courseCode: tds[0].replace(/\s*-\s*Group\s*\d+$/i, '').trim(),
        description: tds[1]
      }));
  }

  // ---- Year standing helpers ----

  // Parse the View Grades page into an ordered list of academic terms:
  //   [{ semester: 'FIRST'|'SECOND'|'SUMMER', year: 2024 }, ...]
  // Terms appear in chronological order in the page. Regular semesters appear
  // as "FIRST SEMESTER - YYYY"; summer appears as "SUMMER - YYYY".
  function parseGradeHistory(html) {
    const history = [];
    const re = /\b(FIRST|SECOND)\s+SEMESTER\s*-\s*(\d{4})\b|\bSUMMER\s*-\s*(\d{4})\b/gi;
    let m;
    while ((m = re.exec(html)) !== null) {
      if (m[1]) {
        history.push({ semester: m[1].toUpperCase(), year: parseInt(m[2], 10) });
      } else {
        history.push({ semester: 'SUMMER', year: parseInt(m[3], 10) });
      }
    }
    return history;
  }

  // Standing for a study load printed in `year` from the View Grades history.
  // It is the number of distinct academic years strictly before that year + 1
  // (FIRST/SECOND/SUMMER of a year share the same standing), clamped to at most
  // the number of distinct years in history. NOTE: this is only an
  // approximation for the printed semester — it counts calendar years present,
  // not units passed — so a repeated/failed year can over-advance. It is used
  // only as a fallback when the units-based standing is unavailable.
  function yearLevelForSemester(history, year) {
    if (!history || !history.length || !Number.isFinite(year)) return null;
    const distinctYears = [...new Set(history.map((t) => t.year))].sort((a, b) => a - b);
    const yearsBefore = distinctYears.filter((y) => y < year).length;
    const level = Math.min(yearsBefore + 1, distinctYears.length);
    return Number.isFinite(level) && level >= 1 ? level : null;
  }

  // Parse the Student Prospectus into per-year unit totals. Each table is
  // preceded by a "Year Level: N" heading. Returns [{ year, units }].
  function parseProspectusYearUnits(html) {
    const segs = String(html || '').split(/(Year Level:\s*\d)/i);
    const yearUnits = {};
    let cur = null;
    for (let i = 0; i < segs.length; i++) {
      const s = segs[i];
      const ym = /Year Level:\s*(\d+)/i.exec(s);
      if (ym) { cur = parseInt(ym[1], 10); continue; }
      if (cur == null) continue;
      const tm = /<table[^>]*>([\s\S]*?)<\/table>/i.exec(s);
      if (!tm) continue;
      const rows = extractRows(tm[1]);
      let units = 0;
      for (const r of rows) {
        if (r.length >= 3 && /^[A-Z]/.test(r[0]) && /[\d.]+/.test(r[2])) {
          const u = parseFloat(String(r[2]).replace(/[^\d.]/g, ''));
          if (Number.isFinite(u)) units += u;
        }
      }
      yearUnits[cur] = (yearUnits[cur] || 0) + units;
      cur = null; // only the immediately-following table belongs to this heading
    }
    const years = Object.keys(yearUnits).map(Number).sort((a, b) => a - b);
    return years.map((y) => ({ year: y, units: yearUnits[y] }));
  }

  // Parse the Lacking Subjects page for total remaining units.
  function parseLackingSubjectsUnits(html) {
    return parseLackingSubjects(html).units;
  }
  function parseLackingSubjects(html) {
    const rows = extractRows(String(html || ''));
    let units = 0;
    const courses = [];
    for (const r of rows) {
      if (r.length >= 3 && /^[A-Z]/.test(r[0]) && /[\d.]+/.test(r[2])) {
        const u = parseFloat(String(r[2]).replace(/[^\d.]/g, ''));
        if (Number.isFinite(u)) {
          units += u;
          courses.push({ courseCode: r[0], description: r[1], units: String(u) });
        }
      }
    }
    return { units: units.toFixed(2), courses };
  }

  // Year standing from units: finished = totalProspectusUnits - lackingUnits;
  // standing = first N in [1..maxYear] where finished < cumulativeUnits(N);
  // if finished passes every threshold, standing = maxYear (program length).
  // yearUnits is the array [{year, units}] from parseProspectusYearUnits.
  function computeYearStandingFromUnits(yearUnits, lackingUnits) {
    const yrs = (yearUnits || []).slice().sort((a, b) => a.year - b.year);
    if (!yrs.length) return null;
    const total = yrs.reduce((s, y) => s + y.units, 0);
    const finished = total - (parseFloat(lackingUnits) || 0);
    if (finished < 0) return yrs[0].year;
    let cum = 0;
    for (const y of yrs) {
      cum += y.units;
      if (finished < cum) return y.year;
    }
    return yrs[yrs.length - 1].year; // passed everything -> final level
  }

  function filterStudyLoadCourses(courses) {
    return (courses || []).filter(
      (c) => String(c.status || '').trim().toUpperCase() !== 'DISSOLVED'
    );
  }

  function sumUnits(courses) {
    return (courses || [])
      .reduce((sum, c) => sum + (parseFloat(c.units) || 0), 0)
      .toFixed(2);
  }

  return {
    parseStudyLoadTable, parseProfilePage, parseOfferedCourses,
    filterStudyLoadCourses, sumUnits,
    parseGradeHistory, yearLevelForSemester,
    parseProspectusYearUnits, parseLackingSubjects, parseLackingSubjectsUnits,
    computeYearStandingFromUnits
  };
});