(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 getPDFLib() {
    return (typeof self !== 'undefined' && self.PDFLib) ||
           (typeof globalThis !== 'undefined' && globalThis.PDFLib);
  }

  function wrapText(text, font, size, maxWidth) {
    const words = String(text).split(/\s+/).filter(Boolean);
    const lines = [];
    let line = '';
    for (const word of words) {
      const candidate = line ? line + ' ' + word : word;
      if (font.widthOfTextAtSize(candidate, size) <= maxWidth) {
        line = candidate;
      } else {
        if (line) lines.push(line);
        line = word;
      }
    }
    if (line) lines.push(line);
    return lines.length ? lines : [''];
  }

  // Wraps multi-line text (segments split on \n) into wrapped lines.
  function wrapLines(text, font, size, maxWidth) {
    const out = [];
    String(text == null ? '' : text).split(/\n/).forEach((seg) => {
      out.push(...wrapText(seg, font, size, maxWidth));
    });
    return out.length ? out : [''];
  }

  // Builds a Letter-size PDF replicating the official ISMIS Study Load layout:
  // title block (STUDENT'S STUDY LOAD, semester, date range, date enrolled),
  // a student info row (ID, name, program, Year Level), the course table
  // (GROUP, COURSE, COURSE DESCRIPTION, TEACHER, UNITS, NOTE), and a footer
  // (total units, printed-by). NOTE is the status; UNITS/NOTE are right-aligned;
  // schedule is stacked under the course description.
  async function buildStudyLoadPdf(data) {
    const PDFLib = getPDFLib();
    const { PDFDocument, StandardFonts, rgb } = PDFLib;
    const header = data.header || {};
    const courses = data.courses || [];

    const doc = await PDFDocument.create();
    let page = doc.addPage([612, 792]); // Letter
    const font = doc.embedStandardFont(StandardFonts.Helvetica);
    const bold = doc.embedStandardFont(StandardFonts.HelveticaBold);
    const italic = doc.embedStandardFont(StandardFonts.HelveticaOblique);
    const margin = 50;
    const contentWidth = 612 - margin * 2;
    let y = 792 - 50;

    const black = rgb(0, 0, 0);
    const gray = rgb(0.3, 0.3, 0.3);

    function center(text, size, f, dy) {
      const w = f.widthOfTextAtSize(text, size);
      page.drawText(text, { x: (612 - w) / 2, y, size, font: f, color: black });
      y -= dy;
    }
    function left(text, size, f, x, dy) {
      page.drawText(text, { x, y, size, font: f, color: black });
      y -= dy;
    }
    function hline(x1, x2, atY) {
      page.drawRectangle({ x: x1, y: atY, width: x2 - x1, height: 0.75, color: black });
    }

    // ---- Header ----
    center("STUDENT'S STUDY LOAD", 9.5, bold, 18);
    if (header.semester) center(header.semester, 9, font, 15);
    if (header.dateRange) center(header.dateRange, 9, font, 15);
    if (header.dateEnrolled) left('Date Enrolled: ' + header.dateEnrolled, 8, italic, margin, 13);

    // Student info row: ID (bold), name, program, "Year Level: N"
    const studentParts = [];
    if (header.studentId) studentParts.push({ text: header.studentId, f: bold });
    if (header.fullName) studentParts.push({ text: header.fullName, f: font });
    if (header.program) studentParts.push({ text: header.program, f: font });
    if (header.yearLevel) studentParts.push({ text: 'Year Level: ' + header.yearLevel, f: font });
    if (studentParts.length) {
      let sx = margin;
      for (const part of studentParts) {
        const w = part.f.widthOfTextAtSize(part.text, 9);
        page.drawText(part.text, { x: sx, y, size: 9, font: part.f, color: black });
        sx += w + 18;
      }
      y -= 16;
    }

    // ---- Table: GROUP, COURSE, COURSE DESCRIPTION, TEACHER, UNITS, NOTE ----
    const cols = [
      { key: 'group', label: 'GROUP', x: margin, w: 26, align: 'left' },
      { key: 'courseCode', label: 'COURSE', x: margin + 26, w: 46, align: 'left' },
      { key: 'description', label: 'COURSE DESCRIPTION', x: margin + 72, w: 189, align: 'left' },
      { key: 'teacher', label: 'TEACHER', x: margin + 261, w: 123, align: 'left' },
      { key: 'units', label: 'UNITS', x: margin + 384, w: 31, align: 'right' },
      { key: 'status', label: 'NOTE', x: margin + 415, w: 97, align: 'right' }
    ];
    const cellSize = 8;
    const headerSize = 8;
    const lineH = 10;

    function rowLines(cells) {
      return cols.map((c) => {
        let lines;
        if (c.key === 'description') {
          lines = wrapLines(cells.description, font, cellSize, c.w - 6);
          const sched = String(cells.schedule || '');
          if (sched) lines.push(...wrapText(sched, font, cellSize, c.w - 6));
        } else {
          lines = wrapLines(cells[c.key], font, cellSize, c.w - 6);
        }
        return lines;
      });
    }

    function drawRow(cells, isHeader) {
      const f = isHeader ? bold : font;
      const size = isHeader ? headerSize : cellSize;
      const linesPerCol = rowLines(cells);
      const rowHeight = Math.max(...linesPerCol.map((l) => l.length)) * lineH + 8;

      if (y - rowHeight < 50) {
        page = doc.addPage([612, 792]);
        y = 792 - 50;
        drawHeaderRow();
      }

      if (isHeader) {
        // top line above the header row
        hline(margin, margin + contentWidth, y);
      }

      for (let i = 0; i < cols.length; i++) {
        const c = cols[i];
        const lines = linesPerCol[i];
        let ty = y - 9;
        for (const line of lines) {
          if (c.align === 'right') {
            const w = f.widthOfTextAtSize(line, size);
            page.drawText(line, { x: c.x + c.w - 3 - w, y: ty, size, font: f, color: black });
          } else {
            page.drawText(line, { x: c.x + 3, y: ty, size, font: f, color: black });
          }
          ty -= lineH;
        }
      }

      y -= rowHeight;

      if (isHeader) {
        // line below the header row
        hline(margin, margin + contentWidth, y);
      }
      return true;
    }

    function drawHeaderRow() {
      const cells = {};
      cols.forEach((c) => { cells[c.key] = c.label; });
      drawRow(cells, true);
    }

    drawHeaderRow();

    for (const course of courses) {
      const cells = {
        group: course.group,
        courseCode: course.courseCode,
        description: course.description,
        schedule: course.schedule,
        teacher: course.teacher,
        units: course.units,
        status: course.status
      };
      drawRow(cells, false);
    }

    // ---- Footer ----
    if (y < 90) {
      page = doc.addPage([612, 792]);
      y = 792 - 50;
    }
    y -= 8;
    if (data.totalUnits) {
      const w = bold.widthOfTextAtSize(data.totalUnits, 9);
      page.drawText(data.totalUnits, { x: margin + contentWidth - w, y, size: 9, font: bold, color: black });
      y -= 14;
    }
    hline(margin, margin + contentWidth, y);
    y -= 12;
    const printedBy = 'Printed by: ' + (header.studentId || '') + ' on ' + new Date().toLocaleDateString();
    const pw = font.widthOfTextAtSize(printedBy, 8);
    page.drawText(printedBy, { x: margin + contentWidth - pw, y, size: 8, font, color: gray });

    return doc.save(); // returns Promise<Uint8Array>
  }

  return { buildStudyLoadPdf };
});