document.addEventListener('DOMContentLoaded', () => {
    const ifsScrollable = document.getElementById('ifsList');
    const brcScrollable = document.getElementById('brcList');
    const searchInput   = document.getElementById('searchInput');

    let appData        = null;
    let currentLang    = 'fr';
    let comparisonMode = false;
    let selectedIfsIds = new Set();

    // ─── Translations ────────────────────────────────────────────────────────────
    const translations = {
        fr: {
            mainTitle:      'Correspondance IFS v8 ↔ BRC v9',
            subTitle:       "Outil d'analyse comparative des référentiels de sécurité des aliments",
            searchPh:       'Rechercher...',
            guideBtn:       '? Guide',
            guideBtnClose:  '✕ Guide',
            help1Title: 'Cliquez sur une exigence',
            help1Text:  'pour voir sa correspondance',
            help2Title: 'Correspondance approximative',
            help2Text:  'pas de correspondance directe',
            help3Title: 'Pas de correspondance',
            help3Text:  'exigence non cartographiée',
            help4Text:  'Exigence éliminatoire',
            help5Title: 'Mode comparaison',
            help5Text:  'multi-sélection IFS',
            ifsTitle:   'IFS Food v8',
            brcTitle:   'BRCGS Food v9',
            expandTip:  'Tout déplier',
            collapseTip:'Tout réduire',
            compareModeOn:  'Mode comparaison multi-sélection',
            compareModeOff: 'Quitter le mode comparaison',
            selected:       'sélectionné(s)',
            clearSel:       'Effacer la sélection',
            noMatchTitle:   'Aucune correspondance dans la norme liée',
            approxTitle:    'Correspondance approximative – pas de correspondance directe',
        },
        en: {
            mainTitle:      'IFS v8 ↔ BRC v9 Mapping',
            subTitle:       'Comparative analysis tool for food safety standards',
            searchPh:       'Search...',
            guideBtn:       '? Guide',
            guideBtnClose:  '✕ Guide',
            help1Title: 'Click on a requirement',
            help1Text:  'to see its correspondence',
            help2Title: 'Approximate correspondence',
            help2Text:  'no direct correspondence',
            help3Title: 'No correspondence',
            help3Text:  'unmapped requirement',
            help4Text:  'Knock-out requirement',
            help5Title: 'Comparison mode',
            help5Text:  'multi-select IFS items',
            ifsTitle:   'IFS Food v8',
            brcTitle:   'BRCGS Food v9',
            expandTip:  'Expand all',
            collapseTip:'Collapse all',
            compareModeOn:  'Multi-select comparison mode',
            compareModeOff: 'Exit comparison mode',
            selected:       'selected',
            clearSel:       'Clear selection',
            noMatchTitle:   'No correspondence in the linked standard',
            approxTitle:    'Approximate correspondence – no direct match in the linked standard',
        }
    };

    // ─── Helper: safely set text / title on an element ───────────────────────────
    function setText(id, value) {
        const el = document.getElementById(id);
        if (el) el.textContent = value;
    }
    function setTitle(id, value) {
        const el = document.getElementById(id);
        if (el) el.title = value;
    }
    function setPlaceholder(id, value) {
        const el = document.getElementById(id);
        if (el) el.placeholder = value;
    }
    function qs(sel) { return document.querySelector(sel); }

    // ─── Language toggle ─────────────────────────────────────────────────────────
    document.getElementById('langToggle')?.addEventListener('click', () => {
        currentLang = currentLang === 'fr' ? 'en' : 'fr';
        updateLanguage();
    });

    function updateLanguage() {
        const t = translations[currentLang];

        // Header
        setText('mainTitle', t.mainTitle);
        setText('subTitle',  t.subTitle);
        setPlaceholder('searchInput', t.searchPh);

        // Guide panel content
        setText('help1Title', t.help1Title);
        setText('help1Text',  t.help1Text);
        setText('help2Title', t.help2Title);
        setText('help2Text',  t.help2Text);
        setText('help3Title', t.help3Title);
        setText('help3Text',  t.help3Text);
        setText('help4Text',  t.help4Text);
        setText('help5Title', t.help5Title);
        setText('help5Text',  t.help5Text);

        // Guide button label (changes based on panel state)
        const isOpen = qs('#guidePanel')?.classList.contains('open');
        setText('guideBtnLabel', isOpen ? t.guideBtnClose : t.guideBtn);

        // Column headers
        const ifsH2 = qs('.ifs-column .column-header h2');
        const brcH2 = qs('.brc-column .column-header h2');
        if (ifsH2) ifsH2.textContent = t.ifsTitle;
        if (brcH2) brcH2.textContent = t.brcTitle;

        // Buttons
        setTitle('expandIfs',   t.expandTip);
        setTitle('collapseIfs', t.collapseTip);
        setTitle('expandBrc',   t.expandTip);
        setTitle('collapseBrc', t.collapseTip);
        setTitle('compareMode', comparisonMode ? t.compareModeOff : t.compareModeOn);

        setText('clearCompare', '✕ ' + t.clearSel);

        // Visual indicator on FR|EN button
        const frEl = qs('.lang-fr');
        const enEl = qs('.lang-en');
        if (frEl) frEl.style.opacity = currentLang === 'fr' ? '1' : '0.4';
        if (enEl) enEl.style.opacity = currentLang === 'en' ? '1' : '0.4';

        updateComparisonUI();
    }

    // ─── Guide panel ─────────────────────────────────────────────────────────────
    const guideToggleBtn = document.getElementById('guideToggle');
    const guidePanel     = document.getElementById('guidePanel');

    guideToggleBtn?.addEventListener('click', (e) => {
        e.stopPropagation();
        const isOpen = guidePanel.classList.toggle('open');
        guidePanel.setAttribute('aria-hidden', String(!isOpen));
        const t = translations[currentLang];
        setText('guideBtnLabel', isOpen ? t.guideBtnClose : t.guideBtn);
        guideToggleBtn.classList.toggle('active-mode', isOpen);
    });

    // Close guide panel when clicking outside
    document.addEventListener('click', (e) => {
        if (!e.target.closest('.guide-wrapper')) {
            guidePanel?.classList.remove('open');
            guidePanel?.setAttribute('aria-hidden', 'true');
            setText('guideBtnLabel', translations[currentLang].guideBtn);
            guideToggleBtn?.classList.remove('active-mode');
        }
    });

    // ─── Data loading ────────────────────────────────────────────────────────────
    if (window.APP_DATA) {
        appData = window.APP_DATA;
        renderLists(appData);
    } else {
        console.error('APP_DATA not found. Ensure data.js is loaded.');
    }

    // ─── Render ──────────────────────────────────────────────────────────────────
    function renderLists(data) {
        renderGroupedList(ifsScrollable, groupData(data.ifs_standards, 'chapter', 'section'),    'ifs');
        renderGroupedList(brcScrollable, groupData(data.brc_standards,  'chapter', 'subsection'), 'brc');
    }

    function groupData(items, key1, key2) {
        const groups = {};
        items.forEach(item => {
            const k1 = (item[key1] && item[key1] !== 'undefined') ? item[key1] : 'Général';
            const k2 = (item[key2] && item[key2] !== 'undefined') ? item[key2] : 'Section Générale';
            if (!groups[k1])     groups[k1]     = {};
            if (!groups[k1][k2]) groups[k1][k2] = [];
            groups[k1][k2].push(item);
        });
        return groups;
    }

    function renderGroupedList(container, groups, type) {
        container.innerHTML = '';

        // Build chapter-number map
        const chNumMap = {};
        [...(appData?.ifs_standards || []), ...(appData?.brc_standards || [])].forEach(item => {
            if (item.chapter && item.chapter_num) chNumMap[item.chapter] = item.chapter_num;
        });

        Object.keys(groups).forEach(l1Key => {
            const detailsL1  = document.createElement('details');
            detailsL1.className = 'acc-l1';

            const summaryL1  = document.createElement('summary');
            summaryL1.className = 'acc-summary-l1';
            let title = l1Key;
            if (chNumMap[l1Key]) {
                title = `${type === 'ifs' ? 'Chapitre' : 'Section'} ${chNumMap[l1Key]}: ${l1Key}`;
            }
            summaryL1.innerHTML = `<span>${title}</span>`;
            detailsL1.appendChild(summaryL1);

            const contentL1  = document.createElement('div');
            contentL1.className = 'acc-content-l1';

            Object.keys(groups[l1Key]).forEach(l2Key => {
                const detailsL2  = document.createElement('details');
                detailsL2.className = 'acc-l2';

                const summaryL2  = document.createElement('summary');
                summaryL2.className = 'acc-summary-l2';
                summaryL2.innerHTML = `<span>${l2Key}</span>`;
                detailsL2.appendChild(summaryL2);

                const contentL2  = document.createElement('div');
                contentL2.className = 'acc-content-l2';

                groups[l1Key][l2Key].forEach(item => contentL2.appendChild(createCard(item, type)));

                detailsL2.appendChild(contentL2);
                contentL1.appendChild(detailsL2);
            });

            detailsL1.appendChild(contentL1);
            container.appendChild(detailsL1);
        });
    }

    function createCard(item, type) {
        const div = document.createElement('div');
        div.className  = `item-card ${type}-card`;
        div.dataset.id   = cleanId(item.id);
        div.dataset.type = type;

        const isKO   = item.ko === true;
        const koBadge = isKO ? '<span class="ko-tag">KO</span>' : '';

        div.innerHTML = `
            <div class="meta-info">
                <span class="ref-id">${item.id}</span>
                ${koBadge}
            </div>
            <div class="item-text">${truncateText(item.text, 300)}</div>
        `;

        // Pre-build search index so innerText (which ignores collapsed <details>) is never used
        div.dataset.search = (item.id + ' ' + (item.text || '')).toLowerCase();

        div.addEventListener('click', () => handleCardClick(div, item.id, type));
        return div;
    }

    // ─── Click handling ──────────────────────────────────────────────────────────
    function handleCardClick(element, id, type) {
        if (comparisonMode && type === 'ifs') {
            handleComparisonClick(element, id);
            return;
        }

        const cleanID = cleanId(id);

        // Reset
        document.querySelectorAll('.item-card.active').forEach(el => el.classList.remove('active'));
        document.querySelectorAll('.approximate-indicator, .no-match-indicator').forEach(el => el.remove());
        document.querySelectorAll('.approximate-active, .no-match-active').forEach(el => {
            el.classList.remove('approximate-active', 'no-match-active');
        });

        element.classList.add('active');
        openParents(element);
        scrollToInContainer(element, type === 'ifs' ? ifsScrollable : brcScrollable);

        // Resolve mapping
        let targetIds    = [];
        let isApproximate = false;
        let hasNoMatch   = false;

        if (type === 'ifs') {
            const mapping = appData.mappings.find(m => cleanId(m.source_id) === cleanID);
            if (mapping && mapping.target_ids && mapping.target_ids.length > 0) {
                targetIds     = mapping.target_ids;
                isApproximate = mapping.approximate === true;
            } else if (mapping && mapping.approximate) {
                isApproximate = true;
            } else {
                hasNoMatch = true;
            }
        } else {
            const related = appData.mappings.filter(m =>
                m.target_ids && m.target_ids.some(tid => cleanId(tid) === cleanID)
            );
            targetIds     = related.map(m => m.source_id);
            hasNoMatch    = related.length === 0;
            isApproximate = related.some(m => m.approximate === true);
        }

        const targetContainer = type === 'ifs' ? brcScrollable : ifsScrollable;
        highlightTargets(targetIds, type === 'ifs' ? 'brc' : 'ifs', isApproximate, hasNoMatch, targetContainer);

        // Mobile: auto-switch column
        if (window.innerWidth <= 768 && targetIds.length > 0) {
            switchMobileTab(type === 'ifs' ? 'brc' : 'ifs');
        }
    }

    function highlightTargets(ids, targetType, isApproximate, hasNoMatch, container) {
        if (!ids || ids.length === 0) {
            const activeEl = qs('.item-card.active');
            if (activeEl) {
                if (hasNoMatch)         addNoMatchIndicator(activeEl);
                else if (isApproximate) addApproximateIndicator(activeEl);
            }
            return;
        }

        let firstFound = null;
        const foundTargets = [];
        ids.forEach(id => {
            const el = qs(`.${targetType}-card[data-id="${cleanId(id)}"]`);
            if (el) {
                el.classList.add('active');
                openParents(el);
                foundTargets.push(el);
                if (!firstFound) firstFound = el;
            }
        });

        if (isApproximate) {
            // Mark the source card (already .active)
            const sourceEl = qs('.item-card.active:not(.' + targetType + '-card)');
            if (sourceEl) addApproximateIndicator(sourceEl);
            // Mark each target card with the same ⚠ indicator
            foundTargets.forEach(el => addApproximateIndicator(el));
        }

        if (firstFound && container) {
            setTimeout(() => scrollToInContainer(firstFound, container), 120);
        }
    }

    // ─── Scroll sync ─────────────────────────────────────────────────────────────
    function scrollToInContainer(element, container) {
        const cRect  = container.getBoundingClientRect();
        const eRect  = element.getBoundingClientRect();
        const target = container.scrollTop + (eRect.top - cRect.top) - (cRect.height / 2) + (eRect.height / 2);
        container.scrollTo({ top: Math.max(0, target), behavior: 'smooth' });
    }

    // ─── Comparison mode ─────────────────────────────────────────────────────────
    document.getElementById('compareMode')?.addEventListener('click', () => {
        comparisonMode = !comparisonMode;
        if (!comparisonMode) clearComparison();
        updateComparisonUI();
    });

    document.getElementById('clearCompare')?.addEventListener('click', clearComparison);

    function clearComparison() {
        selectedIfsIds.clear();
        document.querySelectorAll('.ifs-card.selected').forEach(el => el.classList.remove('selected'));
        document.querySelectorAll('.item-card.active').forEach(el => el.classList.remove('active'));
        document.querySelectorAll('.approximate-indicator, .no-match-indicator').forEach(el => el.remove());
        document.querySelectorAll('.approximate-active, .no-match-active').forEach(el => {
            el.classList.remove('approximate-active', 'no-match-active');
        });
        updateComparisonUI();
    }

    function updateComparisonUI() {
        const t   = translations[currentLang];
        const btn = document.getElementById('compareMode');
        const bar = document.getElementById('compareBar');
        const cnt = document.getElementById('compareCount');
        if (btn) {
            btn.classList.toggle('active-mode', comparisonMode);
            btn.title = comparisonMode ? t.compareModeOff : t.compareModeOn;
        }
        if (bar) bar.classList.toggle('visible', comparisonMode);
        if (cnt) cnt.textContent = selectedIfsIds.size + ' ' + t.selected;
    }

    function handleComparisonClick(element, id) {
        const cleanID = cleanId(id);
        if (selectedIfsIds.has(cleanID)) {
            selectedIfsIds.delete(cleanID);
            element.classList.remove('selected');
        } else {
            selectedIfsIds.add(cleanID);
            element.classList.add('selected');
        }
        updateComparisonUI();
        recomputeComparisonHighlights();
    }

    function recomputeComparisonHighlights() {
        document.querySelectorAll('.brc-card.active').forEach(el => el.classList.remove('active'));
        document.querySelectorAll('.approximate-indicator, .no-match-indicator').forEach(el => el.remove());

        if (selectedIfsIds.size === 0) return;

        const union = new Set();
        selectedIfsIds.forEach(ifsId => {
            const m = appData.mappings.find(m => cleanId(m.source_id) === ifsId);
            if (m && m.target_ids) m.target_ids.forEach(tid => union.add(cleanId(tid)));
        });

        let first = null;
        union.forEach(brcId => {
            const el = qs(`.brc-card[data-id="${brcId}"]`);
            if (el) {
                el.classList.add('active');
                openParents(el);
                if (!first) first = el;
            }
        });

        if (first) setTimeout(() => scrollToInContainer(first, brcScrollable), 120);
    }

    // ─── Mobile tabs ──────────────────────────────────────────────────────────────
    document.getElementById('tabIfs')?.addEventListener('click', () => switchMobileTab('ifs'));
    document.getElementById('tabBrc')?.addEventListener('click', () => switchMobileTab('brc'));

    function switchMobileTab(tab) {
        const ifsCol = document.getElementById('ifsColumn');
        const brcCol = document.getElementById('brcColumn');
        const tabIfs = document.getElementById('tabIfs');
        const tabBrc = document.getElementById('tabBrc');
        ifsCol?.classList.toggle('mobile-hidden', tab !== 'ifs');
        brcCol?.classList.toggle('mobile-hidden', tab !== 'brc');
        tabIfs?.classList.toggle('active', tab === 'ifs');
        tabBrc?.classList.toggle('active', tab === 'brc');
    }

    // ─── Search ──────────────────────────────────────────────────────────────────
    searchInput.addEventListener('input', (e) => {
        const term = e.target.value.toLowerCase().trim();

        // 1. Show/hide individual cards using the pre-built index (works on closed accordions too)
        document.querySelectorAll('.item-card').forEach(card => {
            const match = !term || card.dataset.search.includes(term);
            card.style.display = match ? '' : 'none';
            if (match && term.length > 1) openParents(card);
        });

        // 2. Hide L2 accordions whose every card is hidden
        document.querySelectorAll('details.acc-l2').forEach(l2 => {
            const hasVisible = [...l2.querySelectorAll('.item-card')]
                .some(c => c.style.display !== 'none');
            l2.style.display = hasVisible ? '' : 'none';
        });

        // 3. Hide L1 accordions whose every L2 is hidden
        document.querySelectorAll('details.acc-l1').forEach(l1 => {
            const hasVisible = [...l1.querySelectorAll('details.acc-l2')]
                .some(l2 => l2.style.display !== 'none');
            l1.style.display = hasVisible ? '' : 'none';
        });
    });

    // ─── Expand / Collapse ───────────────────────────────────────────────────────
    document.getElementById('expandIfs')?.addEventListener('click',   () => toggleAll('ifsList', true));
    document.getElementById('collapseIfs')?.addEventListener('click', () => toggleAll('ifsList', false));
    document.getElementById('expandBrc')?.addEventListener('click',   () => toggleAll('brcList', true));
    document.getElementById('collapseBrc')?.addEventListener('click', () => toggleAll('brcList', false));

    function toggleAll(containerId, expand) {
        document.getElementById(containerId)?.querySelectorAll('details').forEach(d => { d.open = expand; });
    }

    // ─── Utilities ───────────────────────────────────────────────────────────────
    function cleanId(id) {
        return id ? id.replace(/\*$/, '').trim() : '';
    }

    function openParents(el) {
        let p = el.parentElement;
        while (p) {
            if (p.tagName === 'DETAILS') p.open = true;
            p = p.parentElement;
        }
    }

    function truncateText(text, len) {
        if (!text) return '';
        return text.length <= len ? text : text.substring(0, len) + '...';
    }

    function addNoMatchIndicator(el) {
        if (el.querySelector('.no-match-indicator')) return;
        const span = document.createElement('span');
        span.className = 'no-match-indicator';
        span.innerHTML = '⛔';
        span.title = translations[currentLang].noMatchTitle;
        const ref = el.querySelector('.ref-id');
        ref ? ref.parentNode.insertBefore(span, ref.nextSibling) : el.appendChild(span);
        el.classList.add('no-match-active');
    }

    function addApproximateIndicator(el) {
        if (el.querySelector('.approximate-indicator')) return;
        const span = document.createElement('span');
        span.className = 'approximate-indicator';
        span.innerHTML = '⚠';
        span.title = translations[currentLang].approxTitle;
        const ref = el.querySelector('.ref-id');
        ref ? ref.parentNode.insertBefore(span, ref.nextSibling) : el.appendChild(span);
        el.classList.add('approximate-active');
    }

});