(function () {
  'use strict';

  // Cross-browser API namespace (see background.js). No-op in Firefox.
  if (typeof browser === 'undefined' || browser == null) {
    var browser = (typeof chrome !== 'undefined' ? chrome : {});
  }

  const MASTER_KEY = 'enabled';

  async function isEnabled() {
    const { enabled } = await browser.storage.local.get(MASTER_KEY);
    return enabled !== false;
  }

  function autoAcceptPrivacy() {
    const modal = document.getElementById('myModal');
    if (!modal) return;
    const checkbox = document.getElementById('Confirmation');
    const submit = document.getElementById('Submit');
    if (checkbox && !checkbox.checked) checkbox.click();
    if (submit) submit.click();
  }

  function watchPrivacyModal() {
    autoAcceptPrivacy();
    const observer = new MutationObserver(() => autoAcceptPrivacy());
    observer.observe(document.body, { childList: true, subtree: true });
    setTimeout(() => observer.disconnect(), 30000);
  }

  async function autoLogin() {
    const { profiles } = await browser.storage.local.get('profiles');
    const active = (profiles || []).find((p) => p.enabled);
    if (!active) return;
    const userField = document.querySelector(
      'input[name="Username"], input[id="Username"], input[name="UserName"], input[name="username"], input[id="UserName"], input[id="username"]'
    );
    const passField = document.querySelector('input[type="password"]');
    if (!userField || !passField) return;
    userField.value = active.username;
    passField.value = active.password;
    userField.dispatchEvent(new Event('input', { bubbles: true }));
    passField.dispatchEvent(new Event('input', { bubbles: true }));
    const form = userField.closest('form') || passField.closest('form');
    if (!form) return;
    setTimeout(() => {
      const submitBtn = form.querySelector('input[type="submit"], button[type="submit"]');
      if (submitBtn) submitBtn.click();
      else form.submit();
    }, 300);
  }

  async function fetchCourseDescription(courseCode, academicPeriod, academicYear, token) {
    const body = new URLSearchParams();
    body.set('Courses', courseCode);
    body.set('AcademicPeriod', academicPeriod);
    body.set('AcademicYear', academicYear);
    body.set('AjaxFormVM.Controller', 'CourseSchedule');
    body.set('AjaxFormVM.Action', 'CourseScheduleOffered');
    body.set('AjaxFormVM.ResultTargetId', 'CourseScheduleOfferedList');
    body.set('AjaxFormVM.LinkToReturn', '');
    body.set('AjaxFormVM.LinkToReturnTargetId', '');
    body.set('AjaxFormVM.FormHeader', 'Choose term to view courses offered');
    body.set('AjaxFormVM.FormHeaderIcon', '');
    body.set('AjaxFormVM.FormId', 'CourseScheduleCourseScheduleOffered');
    body.set('AjaxFormVM.ShowCloseButton', 'True');
    body.set('AjaxFormVM.PreventAutoUpdateTarget', 'True');
    body.set('AjaxFormVM.CloseModalAfterSubmit', 'False');
    body.set('AjaxFormVM.AjaxFormType', 'Search');
    body.set('AjaxFormVM.FormNoteLocation', '');
    body.set('AjaxFormVM.SubmitButton.FaIcon', '');
    body.set('AjaxFormVM.SubmitButton.ButtonText', '');
    body.set('AjaxFormVM.SubmitButton.ButtonSize', '');
    body.set('__RequestVerificationToken', token);
    const resp = await fetch('/CourseSchedule/CourseScheduleOffered?Length=14', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8',
        'X-Requested-With': 'XMLHttpRequest'
      },
      body: body.toString(),
      credentials: 'same-origin'
    });
    if (!resp.ok) throw new Error('Offered courses request failed: ' + resp.status);
    const html = await resp.text();
    const courses = ISMIStools.parseOfferedCourses(html);
    const match = courses.find((c) => c.courseCode === courseCode);
    return match ? match.description : '';
  }

  function extractTotalUnits(text) {
    const m = /Total Units:\s*([\d.]+)/i.exec(text);
    return m ? m[1] : '';
  }

  async function scrapeStudyLoad() {
    const table = document.querySelector('table.table-forum');
    if (!table) throw new Error('No study load table found on this page.');
    const courses = ISMIStools.parseStudyLoadTable(table.outerHTML);
    if (!courses.length) throw new Error('No courses found in study load table.');

    const periodEl = document.getElementById('AcademicPeriod');
    const yearEl = document.getElementById('AcademicYear');
    const tokenEl = document.querySelector('input[name="__RequestVerificationToken"]');
    const academicPeriod = periodEl ? periodEl.value : '';
    const academicYear = yearEl ? yearEl.value : '';
    const token = tokenEl ? tokenEl.value : '';

    // Semester/year come from the search dropdowns the user picked.
    // AcademicPeriod's selected option label (e.g. "1ST Semester") + year.
    const periodLabel = (periodEl && periodEl.selectedOptions && periodEl.selectedOptions[0])
      ? periodEl.selectedOptions[0].textContent.trim()
      : '';
    const selectedPeriod = periodLabel || academicPeriod;
    const selectedYear = academicYear;

    const uniqueCodes = [...new Set(courses.map((c) => c.courseCode))];
    const descMap = {};
    for (const code of uniqueCodes) {
      try {
        descMap[code] = await fetchCourseDescription(code, academicPeriod, academicYear, token);
      } catch (e) {
        descMap[code] = '';
      }
    }
    courses.forEach((c) => { c.description = descMap[c.courseCode] || ''; });

    let header = {};
    try {
      const resp = await fetch('/Manage/Student', { credentials: 'same-origin' });
      if (!resp.ok) throw new Error('Profile request failed: ' + resp.status);
      const html = await resp.text();
      header = ISMIStools.parseProfilePage(html);
    } catch (e) {
      header = {};
    }

    // Semester goes into the header so the PDF shows the dropdown's term/year.
    header.semester = (selectedPeriod && selectedYear)
      ? selectedPeriod + ' ' + selectedYear
      : (header.semester || '');

    // Resolve the Year Level for the PRINTED semester (hybrid, see design
    // spec): custom setting wins; else View Grades history matching; else the
    // units math; else the profile-scraped value.
    header.yearLevel = await resolveYearLevel(header, selectedPeriod, selectedYear);

    return { header, courses, period: selectedPeriod, year: selectedYear };
  }

  // Fetch a same-origin page and return its text, or null on failure.
  async function fetchText(path) {
    try {
      const resp = await fetch(path, { credentials: 'same-origin' });
      if (!resp.ok) return null;
      return await resp.text();
    } catch (e) {
      return null;
    }
  }

  // Hybrid year-level resolution. Returns null only if every source failed.
  // mode: 'auto' (default) runs the full hybrid; 'custom' uses only the custom
  // value; 'off' uses only the profile-scraped value.
  async function resolveYearLevel(header, period, year) {
    const settings = await browser.storage.local.get(['yearMode', 'customYearLevel']);
    const mode = settings.yearMode || 'auto';
    const custom = String(settings.customYearLevel || '').trim();

    if (mode === 'off') {
      return header.yearLevel ? String(header.yearLevel) : null;
    }
    if (mode === 'custom') {
      return custom ? custom : null;
    }
    // auto: custom value wins, then the hybrid sources.
    if (custom) return custom;

    const yearNum = parseInt(year, 10);

    // 1. UNITS MATH — primary. Standing from units actually passed:
    //    total prospectus units minus still-lacking units. This reflects real
    //    earned units and is correct even for students who repeated or failed
    //    a year (the naive grade-history count would over-advance them).
    const [prospectusHtml, lackingHtml] = await Promise.all([
      fetchText('/prospectus/StudentProspectus'),
      fetchText('/Extras/ViewLackingSubjectsStudent1')
    ]);
    if (prospectusHtml) {
      const yearUnits = ISMIStools.parseProspectusYearUnits(prospectusHtml);
      const lacking = lackingHtml ? ISMIStools.parseLackingSubjectsUnits(lackingHtml) : 0;
      const level = ISMIStools.computeYearStandingFromUnits(yearUnits, lacking);
      if (level != null) return String(level);
    }

    // 2. GRADE HISTORY — fallback only when the units path is unavailable.
    //    It counts distinct academic years, so it is only an approximation for
    //    the printed semester and is not used when units data is present.
    const gradesHtml = await fetchText('/ViewGrades');
    if (gradesHtml) {
      const history = ISMIStools.parseGradeHistory(gradesHtml);
      const level = ISMIStools.yearLevelForSemester(history, yearNum);
      if (level != null) return String(level);
    }

    // 3. Profile-scraped value as a last resort.
    if (header.yearLevel) return String(header.yearLevel);
    return null;
  }

  // ---- On-page Download PDF button ----
  const BTN_ID = 'ismisHelperDownloadBtn';

  function showToast(msg, isError) {
    if (window.toastr) {
      if (isError) window.toastr.error(msg);
      else window.toastr.success(msg);
    } else if (isError) {
      alert(msg);
    }
  }

  function findTotalUnitsP() {
    const ps = document.querySelectorAll('#StudyLoad p');
    for (const p of ps) {
      if (/Total Units/i.test(p.textContent || '')) return p;
    }
    return null;
  }

  async function onDownloadPdf() {
    const btn = document.getElementById(BTN_ID);
    try {
      btn.disabled = true;
      btn.innerHTML = '<i class="fa fa-spinner fa-spin"></i> Downloading...';
      const { header, courses } = await scrapeStudyLoad();
      const included = ISMIStools.filterStudyLoadCourses(courses);
      if (!included.length) throw new Error('No enrolled courses found.');
      const totalUnits = ISMIStools.sumUnits(included);
      const settings = await browser.storage.local.get(['truncateDescription', 'showYearLevel']);
      header.showYearLevel = settings.showYearLevel !== false;
      const res = await browser.runtime.sendMessage({
        type: 'generate-pdf',
        data: { header, courses: included, totalUnits, truncateDescription: settings.truncateDescription !== false }
      });
      if (!res || !res.ok) throw new Error((res && res.error) || 'PDF generation failed');
      showToast('PDF downloaded.');
    } catch (err) {
      showToast('Error: ' + ((err && err.message) || err), true);
    } finally {
      btn.disabled = false;
      btn.innerHTML = '<i class="fa fa-download"></i> Download PDF';
    }
  }

  // Export another format (csv/json/xlsx/nextup). Reuses scrapeStudyLoad so
  // every format gets the same header/courses/totalUnits payload and the same
  // hybrid year-level resolution.
  async function onExport(format) {
    try {
      const { header, courses, period, year } = await scrapeStudyLoad();
      const included = ISMIStools.filterStudyLoadCourses(courses);
      if (!included.length) throw new Error('No enrolled courses found.');
      const totalUnits = ISMIStools.sumUnits(included);
      const res = await browser.runtime.sendMessage({
        type: 'export',
        format,
        data: { header, courses: included, totalUnits, period, year }
      });
      if (!res || !res.ok) throw new Error((res && res.error) || 'Export failed');
      showToast('Exported ' + format.toUpperCase() + '.');
    } catch (err) {
      showToast('Error: ' + ((err && err.message) || err), true);
    }
  }

  function makeExportButton(id, label, icon, format) {
    const b = document.createElement('button');
    b.id = id;
    b.type = 'button';
    b.className = 'btn green';
    b.style.marginLeft = '6px';
    b.innerHTML = '<i class="' + icon + '"></i> ' + label;
    b.addEventListener('click', () => onExport(format));
    return b;
  }

  function injectDownloadButton() {
    if (document.getElementById(BTN_ID)) return;
    const unitsP = findTotalUnitsP();
    if (!unitsP) return;

    const wrapper = document.createElement('div');
    wrapper.style.display = 'flex';
    wrapper.style.alignItems = 'center';
    wrapper.style.justifyContent = 'space-between';
    wrapper.style.margin = '10px 0';
    wrapper.style.flexWrap = 'wrap';

    const btn = document.createElement('button');
    btn.id = BTN_ID;
    btn.type = 'button';
    btn.className = 'btn green';
    btn.innerHTML = '<i class="fa fa-download"></i> Download PDF';
    btn.addEventListener('click', onDownloadPdf);

    const btnCsv = makeExportButton('ismisHelperExportCsvBtn', 'CSV', 'fa fa-file-text-o', 'csv');
    const btnXlsx = makeExportButton('ismisHelperExportXlsxBtn', 'Excel', 'fa fa-file-o', 'xlsx');
    const btnJson = makeExportButton('ismisHelperExportJsonBtn', 'JSON', 'fa fa-file-code-o', 'json');
    const btnNextUp = makeExportButton('ismisHelperExportNextUpBtn', 'Next Up', 'fa fa-calendar', 'nextup');

    const btnGroup = document.createElement('div');
    btnGroup.style.display = 'flex';
    btnGroup.appendChild(btn);
    btnGroup.appendChild(btnCsv);
    btnGroup.appendChild(btnXlsx);
    btnGroup.appendChild(btnJson);
    btnGroup.appendChild(btnNextUp);

    unitsP.parentNode.insertBefore(wrapper, unitsP);
    wrapper.appendChild(btnGroup);
    wrapper.appendChild(unitsP);
  }

  function tryInjectButton() {
    if (document.getElementById(BTN_ID)) return;
    if (document.querySelector('#StudyLoad table.table-forum')) injectDownloadButton();
  }

  function watchStudyLoad() {
    tryInjectButton();
    const observer = new MutationObserver((mutations) => {
      const inStudyLoad = mutations.some(
        (m) => m.target && m.target.closest && m.target.closest('#StudyLoad')
      );
      if (inStudyLoad) tryInjectButton();
    });
    observer.observe(document.body, { childList: true, subtree: true });
  }

  (async function init() {
    if (!(await isEnabled())) return;
    watchPrivacyModal();
    if (/\/Account\/Login/i.test(location.href)) autoLogin();
    if (document.getElementById('StudyLoad')) watchStudyLoad();
  })();
})();