/**
 * TPU Survey - Standalone Editor Logic
 * รองรับ Section -> Heading -> Question
 */

let currentSurvey = null;
let isDirty = false;

async function initEditor() {
    const urlParams = new URLSearchParams(window.location.search);
    const id = urlParams.get('id');
    
    if (!id) {
        alert('ไม่ระบุ ID แบบสอบถาม');
        window.close();
        return;
    }

    try {
        const data = await API.get(`surveys.php?action=get&id=${id}`);
        currentSurvey = data.survey;
        renderEditor();
    } catch (err) {
        Toast.error(err.message);
        document.getElementById('editorContent').innerHTML = `
            <div class="empty-state">
                <div class="empty-icon">❌</div>
                <h3>เกิดข้อผิดพลาด</h3>
                <p>${err.message}</p>
                <button class="btn btn-primary" onclick="window.close()">ปิดหน้านี้</button>
            </div>
        `;
    }
}

function renderEditor() {
    if (!currentSurvey) return;
    
    document.title = `แก้ไข: ${currentSurvey.title} - TPU Survey`;
    document.getElementById('surveyTitleDisplay').textContent = currentSurvey.title;
    
    let html = `
        <div class="card mb-32" style="border:none; box-shadow:var(--shadow-md); background:var(--bg-card); border-radius:var(--radius-xl);">
            <div class="card-body" style="padding:40px;">
                <div class="form-group mb-24">
                    <label class="form-label label-lg" style="font-size:1.2rem; font-weight:800;">ชื่อแบบสอบถาม</label>
                    <input type="text" id="edit-survey-title" class="form-input" style="font-size:1.6rem; font-weight:800; height:70px;" 
                           value="${escapeHtml(currentSurvey.title)}" oninput="markDirty()">
                </div>
                <div class="form-group mb-24">
                    <label class="form-label">รายละเอียด / คำชี้แจง</label>
                    <textarea id="edit-survey-desc" class="form-input" rows="3" oninput="markDirty()">${escapeHtml(currentSurvey.description || '')}</textarea>
                </div>
                <div class="form-group mt-16" style="display:flex; align-items:center; gap:10px;">
                    <input type="checkbox" id="edit-survey-cert" style="width:22px; height:22px; cursor:pointer;" 
                           ${currentSurvey.has_certificate == 1 ? 'checked' : ''} onchange="toggleCertPanel(); markDirty();">
                    <label for="edit-survey-cert" style="font-weight:700; cursor:pointer; user-select:none; font-size:0.95rem; color:var(--primary-dark);">🎓 เปิดใช้งานและจัดส่งเกียรติบัตรทางอีเมลอัตโนมัติสำหรับแบบสอบถามนี้</label>
                </div>
                
                <!-- พาเนลตั้งค่าเกียรติบัตร -->
                <div id="cert-config-panel" style="margin-top:20px; padding:24px; border:1px dashed var(--primary-color, #2563eb); border-radius:12px; background:rgba(37,99,235,0.02); display:${currentSurvey.has_certificate == 1 ? 'block' : 'none'};">
                    <h4 style="font-weight:700; color:var(--primary-dark); margin-bottom:16px; font-size:1.05rem;">⚙️ ตั้งค่าเกียรติบัตรเฉพาะแบบประเมิน</h4>
                    
                    <div class="form-group mb-20">
                        <label class="form-label" style="font-weight:700;">รูปภาพเทมเพลตเกียรติบัตร (กระดาษ A4 แนวนอน แนะนำไฟล์ PNG ขนาดประมาณ 2970x2100px)</label>
                        <div style="display:flex; gap:16px; align-items:center; margin-top:8px;">
                            <input type="file" id="edit-survey-cert-file" accept="image/png, image/jpeg" style="display:none;" onchange="uploadCertTemplate(this)">
                            <button type="button" class="btn btn-secondary btn-sm" onclick="document.getElementById('edit-survey-cert-file').click()">
                                📤 อัปโหลดรูปภาพเทมเพลต
                            </button>
                            <span id="cert-upload-status" style="font-size:0.85rem; color:#6b7280;">
                                ${currentSurvey.certificate_template ? 'ใช้รูปภาพเทมเพลตที่อัปโหลดไว้แล้ว' : 'ใช้เทมเพลตเริ่มต้นของระบบ'}
                            </span>
                            ${currentSurvey.certificate_template ? `<button type="button" id="cert-delete-btn" class="btn btn-ghost btn-sm text-red-500" onclick="resetCertTemplate()" style="color:#ef4444; border:1px solid #ef4444; padding:2px 8px; margin-left:10px;">ลบรูปภาพ</button>` : ''}
                        </div>
                        <input type="hidden" id="edit-survey-cert-template-path" value="${escapeHtml(currentSurvey.certificate_template || '')}">
                        
                        <div id="cert-preview-wrapper" style="margin-top:12px; display:${currentSurvey.certificate_template ? 'block' : 'none'};">
                            <img id="cert-template-preview" src="${currentSurvey.certificate_template ? (window.location.pathname.includes('/survey') ? '/survey/' : '/') + currentSurvey.certificate_template : ''}" style="max-height:140px; width:auto; border-radius:8px; border:1px solid var(--border-color); box-shadow:var(--shadow-sm);">
                        </div>
                    </div>
                    
                    <div style="display:flex; gap:24px; flex-wrap:wrap; margin-top:16px;">
                        <div class="form-group" style="flex:1; min-width:200px;">
                            <label class="form-label" style="font-weight:700;">ตำแหน่งชื่อแนวตั้ง (Name Y-Position)</label>
                            <div style="display:flex; align-items:center; gap:8px; margin-top:8px;">
                                <input type="number" step="0.1" id="edit-survey-cert-name-y" class="form-input" style="width:110px;" value="${currentSurvey.cert_name_y || 82.5}" oninput="markDirty()">
                                <span style="font-size:0.9rem; color:#4b5563;">มิลลิเมตร (mm)</span>
                            </div>
                            <small style="color:#6b7280; display:block; margin-top:4px;">(ค่าปกติคือ 82.5 มม.) วัดจากขอบบนสุดของกระดาษ</small>
                        </div>
                        
                        <div class="form-group" style="flex:1; min-width:200px;">
                            <label class="form-label" style="font-weight:700;">ตำแหน่งรหัสตรวจสอบแนวตั้ง (Code Y-Position)</label>
                            <div style="display:flex; align-items:center; gap:8px; margin-top:8px;">
                                <input type="number" step="0.1" id="edit-survey-cert-code-y" class="form-input" style="width:110px;" value="${currentSurvey.cert_code_y || 190.5}" oninput="markDirty()">
                                <span style="font-size:0.9rem; color:#4b5563;">มิลลิเมตร (mm)</span>
                            </div>
                            <small style="color:#6b7280; display:block; margin-top:4px;">(ค่าปกติคือ 190.5 มม.) วัดจากขอบบนสุดของกระดาษ</small>
                        </div>
                    </div>
                </div>
            </div>
        </div>
        <div id="sectionsContainer"></div>
    `;
    
    document.getElementById('editorContent').innerHTML = html;
    
    const container = document.getElementById('sectionsContainer');
    (currentSurvey.sections || []).forEach((section, si) => {
        container.insertAdjacentHTML('beforeend', buildSectionUI(si, section));
    });
}

/* ============================================================
   SECTION
   ============================================================ */
function buildSectionUI(si, section) {
    // Build headings HTML
    let headingsHTML = '';
    (section.headings || []).forEach((heading, hi) => {
        headingsHTML += buildHeadingUI(si, hi, heading);
    });

    // Build loose questions (not in any heading) HTML
    let looseQuestionsHTML = '';
    (section.questions || []).forEach((q, qi) => {
        looseQuestionsHTML += buildQuestionUI(si, null, qi, q);
    });

    return `
        <div class="card mb-40" data-section="${si}" style="border:none; box-shadow:var(--shadow-md); overflow:visible;">
            <div class="card-header" style="background:var(--bg-secondary); border-radius:var(--radius-xl) var(--radius-xl) 0 0; padding:24px 32px;">
                <div class="d-flex items-center gap-16 flex-1">
                    <div style="flex:1;">
                        <input type="text" class="form-input section-title-input" style="font-weight:800;font-size:24px;border:none;padding:4px 0;background:transparent; color:var(--primary-dark);" 
                               value="${escapeHtml(section.title)}" oninput="markDirty()">
                    </div>
                    <select class="form-input section-category-select" style="width:auto;font-size:14px;padding:6px 12px;border:1px solid var(--border-color); border-radius:var(--radius-md); background:var(--bg-card);" 
                            onchange="markDirty()">
                        <option value="general" ${section.category==='general'?'selected':''}>📊 ข้อมูลทั่วไป (General)</option>
                        <option value="rating" ${section.category==='rating'?'selected':''}>⭐ การประเมิน (Rating)</option>
                        <option value="suggestions" ${section.category==='suggestions'?'selected':''}>📝 ข้อเสนอแนะ (Suggestions)</option>
                    </select>
                </div>
                <button type="button" class="btn btn-ghost btn-sm text-danger" onclick="removeSection(this)" style="margin-left:16px;">🗑️ ลบส่วนนี้</button>
            </div>
            <div class="card-body" style="padding:32px;">
                <!-- Headings Container -->
                <div class="headings-container" data-section-headings="${si}">${headingsHTML}</div>

                <!-- Loose Questions Container (questions not in any heading) -->
                <div class="loose-questions-container" data-section-loose="${si}">
                    ${looseQuestionsHTML ? `<div class="loose-questions-label" style="font-size:13px;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:0.5px;margin:16px 0 12px;padding-bottom:8px;border-bottom:1px dashed var(--border-color);">📋 คำถามทั่วไป (ไม่อยู่ในหัวข้อย่อย)</div>` : ''}
                    ${looseQuestionsHTML}
                </div>

                <div class="section-actions-bar" style="display:flex;gap:12px;margin-top:24px;">
                    <button type="button" class="btn btn-ghost" style="border:2px dashed var(--primary-color); flex:1; border-radius:var(--radius-lg); color:var(--primary-color); font-weight:700;" 
                            onclick="addHeading(this)">📑 เพิ่มหัวข้อย่อย</button>
                    <button type="button" class="btn btn-ghost" style="border:2px dashed var(--border-color); flex:1; border-radius:var(--radius-lg);" 
                            onclick="addLooseQuestion(this)">+ เพิ่มคำถามทั่วไป</button>
                </div>
            </div>
        </div>
    `;
}

function addSection() {
    const si = document.querySelectorAll('[data-section]').length;
    const html = buildSectionUI(si, { title: `ส่วนที่ ${si+1}`, category: 'rating', headings: [], questions: [] });
    document.getElementById('sectionsContainer').insertAdjacentHTML('beforeend', html);
    markDirty();
}

function removeSection(btn) {
    if (!confirm('ยืนยันลบส่วนนี้พร้อมหัวข้อย่อยและคำถามทั้งหมด?')) return;
    btn.closest('.card').remove();
    markDirty();
}

/* ============================================================
   HEADING (หัวข้อย่อย)
   ============================================================ */
function buildHeadingUI(si, hi, heading = {}) {
    let questionsHTML = '';
    (heading.questions || []).forEach((q, qi) => {
        questionsHTML += buildQuestionUI(si, hi, qi, q);
    });

    return `
        <div class="heading-block" data-heading="${hi}" style="margin-bottom:28px; border:2px solid var(--primary-color); border-radius:var(--radius-lg); background:linear-gradient(135deg, rgba(37,99,235,0.03), rgba(37,99,235,0.06)); overflow:visible;">
            <div class="heading-header" style="padding:16px 20px; background:linear-gradient(135deg, rgba(37,99,235,0.08), rgba(37,99,235,0.12)); border-bottom:1px solid rgba(37,99,235,0.15); display:flex; align-items:center; gap:12px;">
                <span style="font-size:20px;">📑</span>
                <div style="flex:1;">
                    <input type="text" class="form-input heading-title-input" style="font-weight:700;font-size:18px;border:none;padding:4px 0;background:transparent; color:var(--primary-dark);" 
                           value="${escapeHtml(heading.title || '')}" placeholder="ชื่อหัวข้อย่อย..." oninput="markDirty()">
                    <input type="text" class="form-input heading-desc-input" style="font-size:13px;border:none;padding:2px 0;background:transparent; color:var(--text-muted);" 
                           value="${escapeHtml(heading.description || '')}" placeholder="คำอธิบายหัวข้อ (ไม่บังคับ)" oninput="markDirty()">
                </div>
                <button type="button" class="btn btn-ghost btn-sm text-danger" onclick="removeHeading(this)" title="ลบหัวข้อย่อย">🗑️</button>
            </div>
            <div class="heading-questions" style="padding:16px 20px;">
                <div class="heading-questions-list">${questionsHTML}</div>
                <button type="button" class="btn btn-ghost btn-sm" style="border:1px dashed var(--border-color); width:100%; border-radius:var(--radius-md); margin-top:12px;" 
                        onclick="addQuestionToHeading(this)">+ เพิ่มคำถามในหัวข้อนี้</button>
            </div>
        </div>
    `;
}

function addHeading(btn) {
    const sectionEl = btn.closest('[data-section]');
    const headingsContainer = sectionEl.querySelector('.headings-container');
    const hi = headingsContainer.querySelectorAll('.heading-block').length;
    const si = parseInt(sectionEl.dataset.section);
    
    const html = buildHeadingUI(si, hi, { title: '', description: '', questions: [] });
    headingsContainer.insertAdjacentHTML('beforeend', html);
    
    // Focus on the title input
    const newHeading = headingsContainer.lastElementChild;
    const titleInput = newHeading.querySelector('.heading-title-input');
    if (titleInput) titleInput.focus();
    
    markDirty();
}

function removeHeading(btn) {
    if (!confirm('ยืนยันลบหัวข้อย่อยนี้พร้อมคำถามทั้งหมด?')) return;
    btn.closest('.heading-block').remove();
    markDirty();
}

/* ============================================================
   QUESTION
   ============================================================ */
function buildQuestionUI(si, hi, qi, q = {}) {
    const qType = q.question_type || 'radio';
    const qText = q.question_text || '';
    const qDescription = q.description || '';
    const qOptions = Array.isArray(q.options) ? q.options.join('\n') : '';
    const showOptions = ['radio', 'checkbox', 'dropdown'].includes(qType);
    
    // Context label: which heading or "ทั่วไป"
    const contextLabel = hi !== null ? `หัวข้อ ${hi+1}` : '';
    
    return `
        <div class="question-builder mb-24" style="border-left:4px solid var(--primary-color);">
            <div class="qb-header">
                <span class="qb-handle">⋮⋮</span>
                <span class="text-md fw-800 q-number-label" style="color:var(--primary-dark); font-size:1.1rem;">คำถาม</span>
                ${contextLabel ? `<span style="font-size:11px;color:var(--text-muted);margin-left:8px;">(${contextLabel})</span>` : ''}
                <div class="qb-actions">
                    <button type="button" class="btn btn-ghost btn-sm text-danger" onclick="removeQuestion(this)" title="ลบคำถาม">🗑️ ลบ</button>
                </div>
            </div>
            <div class="form-group mb-16">
                <label class="form-label">คำถาม / หัวข้อ</label>
                <input type="text" class="form-input q-text-input" value="${escapeHtml(qText)}" placeholder="พิมพ์คำถามที่นี่..." oninput="markDirty()">
            </div>
            <div class="form-group mb-16">
                <label class="form-label">รายละเอียดเพิ่มเติม (คำชี้แจง/คำใบ้ - ไม่บังคับ)</label>
                <input type="text" class="form-input q-desc-input" value="${escapeHtml(qDescription)}" placeholder="เช่น กรุณาระบุรหัสนักศึกษา..." oninput="markDirty()">
            </div>
            <div class="grid grid-2 gap-24 items-end">
                <div class="form-group">
                    <label class="form-label">ประเภทการตอบ</label>
                    <select class="form-input q-type-select" onchange="toggleOptions(this);markDirty();">
                        <option value="radio" ${qType==='radio'?'selected':''}>📊 ระดับ 1-5 (Radio)</option>
                        <option value="text" ${qType==='text'?'selected':''}>📝 พิมพ์ตอบ (Short Text)</option>
                        <option value="dropdown" ${qType==='dropdown'?'selected':''}>📋 รายการเลือก (Dropdown)</option>
                        <option value="checkbox" ${qType==='checkbox'?'selected':''}>☑️ เลือกได้หลายข้อ (Checkbox)</option>
                    </select>
                </div>
                <div class="form-group q-options-group" style="${showOptions ? '' : 'display:none;'}">
                    <label class="form-label">ตัวเลือก (1 บรรทัดต่อ 1 ข้อ)</label>
                    <textarea class="form-input q-options-input" placeholder="ตัวเลือก 1\nตัวเลือก 2" rows="2" oninput="markDirty()">${escapeHtml(qOptions)}</textarea>
                </div>
            </div>
        </div>
    `;
}

function addQuestionToHeading(btn) {
    const headingEl = btn.closest('.heading-block');
    const listEl = headingEl.querySelector('.heading-questions-list');
    const qi = listEl.querySelectorAll('.question-builder').length;
    const si = parseInt(headingEl.closest('[data-section]').dataset.section);
    const hi = parseInt(headingEl.dataset.heading);
    
    const html = buildQuestionUI(si, hi, qi);
    listEl.insertAdjacentHTML('beforeend', html);
    reindexQuestions(listEl);
    markDirty();
}

function addLooseQuestion(btn) {
    const sectionEl = btn.closest('[data-section]');
    const looseContainer = sectionEl.querySelector('.loose-questions-container');
    const si = parseInt(sectionEl.dataset.section);
    const qi = looseContainer.querySelectorAll('.question-builder').length;
    
    // Add label if first loose question
    if (qi === 0) {
        looseContainer.insertAdjacentHTML('afterbegin', 
            `<div class="loose-questions-label" style="font-size:13px;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:0.5px;margin:16px 0 12px;padding-bottom:8px;border-bottom:1px dashed var(--border-color);">📋 คำถามทั่วไป (ไม่อยู่ในหัวข้อย่อย)</div>`
        );
    }
    
    const html = buildQuestionUI(si, null, qi);
    looseContainer.insertAdjacentHTML('beforeend', html);
    reindexQuestions(looseContainer);
    markDirty();
}

function removeQuestion(btn) {
    if (!confirm('ยืนยันลบคำถามนี้?')) return;
    const container = btn.closest('.heading-questions-list') || btn.closest('.loose-questions-container');
    btn.closest('.question-builder').remove();
    if (container) reindexQuestions(container);
    markDirty();
}

function reindexQuestions(container) {
    if (!container) return;
    container.querySelectorAll('.question-builder').forEach((qEl, idx) => {
        const label = qEl.querySelector('.q-number-label');
        if (label) label.textContent = `คำถาม`;
    });
}

function toggleOptions(select) {
    const group = select.closest('.question-builder').querySelector('.q-options-group');
    if (['radio', 'checkbox', 'dropdown'].includes(select.value)) {
        group.style.display = 'block';
    } else {
        group.style.display = 'none';
    }
}

/* ============================================================
   SAVE — อ่าน DOM แปลงเป็น JSON แล้วส่ง API
   ============================================================ */
async function saveSurvey() {
    if (!currentSurvey) return;
    
    const titleEl = document.getElementById('edit-survey-title');
    const title = titleEl ? titleEl.value.trim() : currentSurvey.title;
    if (!title) {
        Toast.error('กรุณาระบุชื่อแบบสอบถาม');
        return;
    }
    
    const description = document.getElementById('edit-survey-desc')?.value || '';
    const hasCertificate = document.getElementById('edit-survey-cert')?.checked ? 1 : 0;
    
    const sections = [];
    document.querySelectorAll('[data-section]').forEach((sectionEl, si) => {
        const sTitle = sectionEl.querySelector('.section-title-input')?.value?.trim() || `ส่วนที่ ${si+1}`;
        const sCategory = sectionEl.querySelector('.section-category-select')?.value || 'rating';
        
        // Collect headings and their questions
        const headings = [];
        sectionEl.querySelectorAll('.heading-block').forEach((headingEl, hi) => {
            const hTitle = headingEl.querySelector('.heading-title-input')?.value?.trim() || '';
            const hDesc = headingEl.querySelector('.heading-desc-input')?.value?.trim() || '';
            const hQuestions = collectQuestions(headingEl.querySelector('.heading-questions-list'));
            
            if (hTitle) {
                headings.push({
                    title: hTitle,
                    description: hDesc || null,
                    order_num: hi,
                    questions: hQuestions
                });
            }
        });

        // Collect loose questions (not in any heading)
        const looseQuestions = collectQuestions(sectionEl.querySelector('.loose-questions-container'));

        sections.push({
            section_number: si + 1,
            title: sTitle,
            category: sCategory,
            headings: headings,
            questions: looseQuestions
        });
    });

    const setSaveButtonsLoading = (loading) => {
        const btns = [document.getElementById('saveSurveyBtnTop'), document.getElementById('saveSurveyBtnBottom')];
        btns.forEach(btn => {
            if (btn) {
                btn.disabled = loading;
                btn.innerHTML = loading ? '<i class="fas fa-spinner fa-spin"></i> กำลังบันทึก...' : '💾 บันทึกการเปลี่ยนแปลง';
            }
        });
    };

    try {
        setSaveButtonsLoading(true);
        
        const certificateTemplate = document.getElementById('edit-survey-cert-template-path')?.value || null;
        const certNameY = parseFloat(document.getElementById('edit-survey-cert-name-y')?.value || 82.5);
        const certCodeY = parseFloat(document.getElementById('edit-survey-cert-code-y')?.value || 190.5);

        await API.post('surveys.php?action=update', { 
            id: currentSurvey.id, 
            title, 
            description, 
            has_certificate: hasCertificate,
            certificate_template: certificateTemplate,
            cert_name_y: certNameY,
            cert_code_y: certCodeY,
            sections 
        });
        
        Toast.success('บันทึกการแก้ไขเรียบร้อยแล้ว');
        isDirty = false;
        const dirtyIndicator = document.getElementById('saveStatusIndicator');
        if (dirtyIndicator) dirtyIndicator.style.display = 'none';
        
        // Update survey title display in header
        const headerTitleEl = document.getElementById('surveyTitleDisplay');
        if (headerTitleEl) headerTitleEl.textContent = title;
    } catch (err) {
        Toast.error(err.message || 'บันทึกล้มเหลว');
    } finally {
        setSaveButtonsLoading(false);
    }
}

function collectQuestions(container) {
    if (!container) return [];
    const questions = [];
    container.querySelectorAll('.question-builder').forEach((qEl, qi) => {
        const qText = qEl.querySelector('.q-text-input')?.value || '';
        const qDescription = qEl.querySelector('.q-desc-input')?.value || '';
        const qType = qEl.querySelector('.q-type-select')?.value || 'radio';
        const qOptionsRaw = qEl.querySelector('.q-options-input')?.value || '';
        const options = qOptionsRaw.split('\n').map(o => o.trim()).filter(o => o !== '');

        if (qText.trim()) {
            questions.push({
                question_text: qText.trim(),
                description: qDescription.trim() || null,
                question_type: qType,
                order_num: qi,
                is_required: 1,
                options: options.length > 0 ? options : null
            });
        }
    });
    return questions;
}

/* ============================================================
   UTILITY FUNCTIONS & SHORTCUTS
   ============================================================ */
function markDirty() {
    isDirty = true;
    const dirtyIndicator = document.getElementById('saveStatusIndicator');
    if (dirtyIndicator) dirtyIndicator.style.display = 'inline-flex';
}

function closeEditor() {
    if (isDirty) {
        if (!confirm('มีการเปลี่ยนแปลงที่ยังไม่ได้บันทึก ยืนยันปิดหรือไม่?')) return;
    }
    if (window.history.length > 1) {
        window.history.back();
    } else {
        window.close();
    }
}

function previewSurvey() {
    if (!currentSurvey) return;
    const basePath = window.location.pathname.includes('/survey') ? '/survey' : '';
    window.open(`${basePath}/respond.php?link=${currentSurvey.unique_link}`, '_blank');
}

// Keyboard shortcut: Ctrl+S / Cmd+S to save
document.addEventListener('keydown', (e) => {
    if ((e.ctrlKey || e.metaKey) && e.key === 's') {
        e.preventDefault();
        saveSurvey();
    }
});

// Warn before leave if dirty
window.addEventListener('beforeunload', (e) => {
    if (isDirty) {
        e.preventDefault();
        e.returnValue = '';
    }
});

function toggleCertPanel() {
    const isChecked = document.getElementById('edit-survey-cert').checked;
    const panel = document.getElementById('cert-config-panel');
    if (panel) {
        panel.style.display = isChecked ? 'block' : 'none';
    }
}

async function uploadCertTemplate(input) {
    if (!input.files || input.files.length === 0) return;
    const file = input.files[0];
    
    const statusEl = document.getElementById('cert-upload-status');
    statusEl.textContent = '⌛ กำลังอัปโหลดไฟล์...';
    statusEl.style.color = '#2563eb';
    
    const formData = new FormData();
    formData.append('template_image', file);
    
    try {
        const basePath = window.location.pathname.includes('/survey') ? '/survey' : '';
        const res = await fetch(`${basePath}/api/surveys.php?action=uploadTemplate`, {
            method: 'POST',
            body: formData
        });
        const data = await res.json();
        
        if (!res.ok) throw new Error(data.error || 'การอัปโหลดล้มเหลว');
        
        document.getElementById('edit-survey-cert-template-path').value = data.template_path;
        statusEl.textContent = '✅ อัปโหลดเทมเพลตสำเร็จ';
        statusEl.style.color = '#16a34a';
        
        // Update preview
        const previewImg = document.getElementById('cert-template-preview');
        const previewWrapper = document.getElementById('cert-preview-wrapper');
        previewImg.src = (basePath ? `${basePath}/` : '/') + data.template_path;
        previewWrapper.style.display = 'block';
        
        // Add dynamic delete button if it doesn't exist
        if (!document.getElementById('cert-delete-btn')) {
            const btnHTML = `<button type="button" id="cert-delete-btn" class="btn btn-ghost btn-sm text-red-500" onclick="resetCertTemplate()" style="color:#ef4444; border:1px solid #ef4444; padding:2px 8px; margin-left:10px;">ลบรูปภาพ</button>`;
            input.parentElement.insertAdjacentHTML('beforeend', btnHTML);
        }
        
        markDirty();
    } catch (err) {
        statusEl.textContent = '❌ ' + err.message;
        statusEl.style.color = '#dc2626';
    }
}

function resetCertTemplate() {
    document.getElementById('edit-survey-cert-template-path').value = '';
    document.getElementById('cert-upload-status').textContent = 'ใช้เทมเพลตเริ่มต้นของระบบ';
    document.getElementById('cert-upload-status').style.color = '#6b7280';
    document.getElementById('cert-preview-wrapper').style.display = 'none';
    document.getElementById('cert-template-preview').src = '';
    document.getElementById('edit-survey-cert-file').value = '';
    
    const deleteBtn = document.getElementById('cert-delete-btn');
    if (deleteBtn) deleteBtn.remove();
    
    markDirty();
}

document.addEventListener('DOMContentLoaded', initEditor);