// public/admin.js – панель администратора

let currentUser = null;
let currentPreviewLessons = [];
let allLessonsForFilters = []; // храним все уроки для построения зависимых фильтров

document.addEventListener('DOMContentLoaded', async () => {
    await checkAuth();
    await loadFilterOptions();
    loadLessons();
    setupEventListeners();
});

async function checkAuth() {
    try {
        const res = await fetch('/api/me');
        const data = await res.json();
        if (!data.authenticated || data.user.role !== 'admin') {
            window.location.href = '/login.html';
            return;
        }
        currentUser = data.user;
        document.getElementById('userInfo').innerHTML = `👋 ${currentUser.full_name} (${currentUser.role})`;
    } catch (err) {
        window.location.href = '/login.html';
    }
}

// Загрузка опций для выпадающих списков фильтров (начальные)
async function loadFilterOptions() {
    try {
        const [classes, teachers, topics] = await Promise.all([
            fetch('/api/filter-options/class-names').then(r => r.json()),
            fetch('/api/filter-options/teachers').then(r => r.json()),
            fetch('/api/filter-options/topics').then(r => r.json())
        ]);
        window.allClassNames = classes;
        window.allTeachers = teachers;
        window.allTopics = topics;
        
        populateSelect('filterClass', window.allClassNames, 'Все классы');
        populateSelect('filterTeacher', window.allTeachers, 'Все учителя');
        populateSelect('filterTopic', window.allTopics, 'Все темы');
    } catch (err) {
        console.error('Ошибка загрузки опций фильтров', err);
    }
}

function populateSelect(selectId, options, defaultLabel) {
    const select = document.getElementById(selectId);
    if (!select) return;
    const currentValue = select.value;
    select.innerHTML = `<option value="">${defaultLabel}</option>`;
    options.forEach(opt => {
        const option = document.createElement('option');
        option.value = opt;
        option.textContent = opt;
        select.appendChild(option);
    });
    if (currentValue && options.includes(currentValue)) {
        select.value = currentValue;
    } else {
        select.value = '';
    }
}

// Обновление зависимых фильтров на основе текущих значений и allLessonsForFilters
function updateDependentFilters() {
    const selectedClass = document.getElementById('filterClass').value;
    const selectedTeacher = document.getElementById('filterTeacher').value;
    const selectedTopic = document.getElementById('filterTopic').value;
    
    let filteredLessons = allLessonsForFilters;
    if (selectedClass) {
        filteredLessons = filteredLessons.filter(l => l.class_name === selectedClass);
    }
    if (selectedTeacher) {
        filteredLessons = filteredLessons.filter(l => l.teacher === selectedTeacher);
    }
    if (selectedTopic) {
        filteredLessons = filteredLessons.filter(l => l.topic === selectedTopic);
    }
    
    const availableClasses = [...new Set(filteredLessons.map(l => l.class_name))].sort();
    const availableTeachers = [...new Set(filteredLessons.map(l => l.teacher))].sort();
    const availableTopics = [...new Set(filteredLessons.map(l => l.topic).filter(t => t))].sort();
    
    const oldClass = document.getElementById('filterClass').value;
    const oldTeacher = document.getElementById('filterTeacher').value;
    const oldTopic = document.getElementById('filterTopic').value;
    
    populateSelect('filterClass', availableClasses, 'Все классы');
    populateSelect('filterTeacher', availableTeachers, 'Все учителя');
    populateSelect('filterTopic', availableTopics, 'Все темы');
    
    if (oldClass && availableClasses.includes(oldClass)) document.getElementById('filterClass').value = oldClass;
    else document.getElementById('filterClass').value = '';
    if (oldTeacher && availableTeachers.includes(oldTeacher)) document.getElementById('filterTeacher').value = oldTeacher;
    else document.getElementById('filterTeacher').value = '';
    if (oldTopic && availableTopics.includes(oldTopic)) document.getElementById('filterTopic').value = oldTopic;
    else document.getElementById('filterTopic').value = '';
}

async function loadLessons(filters = {}) {
    const params = new URLSearchParams(filters);
    const res = await fetch(`/api/admin/lessons?${params}`);
    const lessons = await res.json();
    // Сохраняем полный список для фильтрации (без учёта фильтров)
    allLessonsForFilters = lessons;
    updateDependentFilters(); // обновить списки в select на основе всех уроков
    
    const container = document.getElementById('lessonsList');
    if (!container) return;
    
    const grouped = {};
    lessons.forEach(lesson => {
        if (!grouped[lesson.class_name]) grouped[lesson.class_name] = [];
        grouped[lesson.class_name].push(lesson);
    });
    
    container.innerHTML = '';
    for (const [className, classLessons] of Object.entries(grouped)) {
        const section = document.createElement('div');
        section.className = 'class-group';
        section.innerHTML = `<h2>${className}</h2>`;
        classLessons.forEach(lesson => {
            const div = document.createElement('div');
            div.className = 'lesson-item';
            div.innerHTML = `
                <div>
                    <strong>${lesson.subject}</strong> — ${lesson.teacher}<br>
                    <em>Тема: ${lesson.topic || '—'}</em><br>
                    ${lesson.date} ${lesson.time} | Места: ${lesson.current_slots}/${lesson.max_slots}
                </div>
                <div class="lesson-actions">
                    <button class="viewRegBtn" data-id="${lesson.id}">Записи</button>
                    <button class="editBtn" data-id="${lesson.id}">✏️</button>
                    <button class="deleteBtn danger" data-id="${lesson.id}">🗑️</button>
                </div>
            `;
            section.appendChild(div);
        });
        container.appendChild(section);
    }
    
    document.querySelectorAll('.viewRegBtn').forEach(btn => btn.addEventListener('click', () => showRegistrations(btn.dataset.id)));
    document.querySelectorAll('.editBtn').forEach(btn => btn.addEventListener('click', () => openLessonModal(btn.dataset.id)));
    document.querySelectorAll('.deleteBtn').forEach(btn => btn.addEventListener('click', () => deleteLesson(btn.dataset.id)));
}

async function showRegistrations(lessonId) {
    const res = await fetch(`/api/admin/registrations?lesson_id=${lessonId}`);
    const registrations = await res.json();
    const modal = document.getElementById('registrationsModal');
    const listDiv = document.getElementById('registrationsList');
    listDiv.innerHTML = registrations.length ? '<ul>' + registrations.map(r => `<li><strong>${r.parent_name}</strong> — ${r.parent_phone} (${new Date(r.created_at).toLocaleString()})</li>`).join('') + '</ul>' : '<p>Нет записей</p>';
    modal.style.display = 'flex';
    modal.querySelector('.close').onclick = () => modal.style.display = 'none';
}

async function deleteLesson(id) {
    if (!confirm('Удалить урок? Все записи будут удалены.')) return;
    await fetch(`/api/admin/lessons/${id}`, { method: 'DELETE' });
    loadLessons(getCurrentFilters());
}

function openLessonModal(id = null) {
    const modal = document.getElementById('lessonModal');
    const form = document.getElementById('lessonForm');
    form.reset();
    document.getElementById('lessonId').value = '';
    document.getElementById('modalTitle').innerText = id ? 'Редактирование урока' : 'Новый урок';
    if (id) {
        fetch(`/api/admin/lessons`).then(res => res.json()).then(lessons => {
            const lesson = lessons.find(l => l.id == id);
            if (lesson) {
                document.getElementById('lessonId').value = lesson.id;
                document.getElementById('className').value = lesson.class_name;
                document.getElementById('parallel').value = lesson.parallel;
                document.getElementById('subject').value = lesson.subject;
                document.getElementById('teacher').value = lesson.teacher;
                document.getElementById('topic').value = lesson.topic || '';
                document.getElementById('maxSlots').value = lesson.max_slots;
                document.getElementById('date').value = lesson.date;
                document.getElementById('time').value = lesson.time;
            }
        });
    }
    modal.style.display = 'flex';
    modal.querySelector('.close').onclick = () => modal.style.display = 'none';
}

document.getElementById('lessonForm')?.addEventListener('submit', async (e) => {
    e.preventDefault();
    const id = document.getElementById('lessonId').value;
    const payload = {
        id: id || undefined,
        class_name: document.getElementById('className').value,
        parallel: parseInt(document.getElementById('parallel').value),
        subject: document.getElementById('subject').value,
        teacher: document.getElementById('teacher').value,
        topic: document.getElementById('topic').value,
        max_slots: parseInt(document.getElementById('maxSlots').value),
        date: document.getElementById('date').value,
        time: document.getElementById('time').value
    };
    await fetch('/api/admin/lessons', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(payload)
    });
    document.getElementById('lessonModal').style.display = 'none';
    loadLessons(getCurrentFilters());
});

function getCurrentFilters() {
    return {
        class_name: document.getElementById('filterClass').value,
        parallel: document.getElementById('filterParallel').value,
        teacher: document.getElementById('filterTeacher').value,
        topic: document.getElementById('filterTopic').value
    };
}

function setupEventListeners() {
    const classSelect = document.getElementById('filterClass');
    const teacherSelect = document.getElementById('filterTeacher');
    const topicSelect = document.getElementById('filterTopic');
    
    function handleFilterChange() {
        // Обновить зависимые списки, затем применить фильтрацию списка уроков
        updateDependentFilters();
        loadLessons(getCurrentFilters());
    }
    
    classSelect?.addEventListener('change', handleFilterChange);
    teacherSelect?.addEventListener('change', handleFilterChange);
    topicSelect?.addEventListener('change', handleFilterChange);
    
    document.getElementById('applyFilters')?.addEventListener('click', () => {
        loadLessons(getCurrentFilters());
    });
    
    document.getElementById('resetFilters')?.addEventListener('click', () => {
        document.getElementById('filterClass').value = '';
        document.getElementById('filterParallel').value = '';
        document.getElementById('filterTeacher').value = '';
        document.getElementById('filterTopic').value = '';
        updateDependentFilters();
        loadLessons({});
    });
    
    document.getElementById('addLessonBtn')?.addEventListener('click', () => openLessonModal());
    document.getElementById('logoutBtn')?.addEventListener('click', async () => {
        await fetch('/api/logout', { method: 'POST' });
        window.location.href = '/';
    });
    
    // Импорт JSON (без изменений)
    document.getElementById('previewImportBtn')?.addEventListener('click', async () => {
        const file = document.getElementById('jsonFileInput').files[0];
        if (!file) return alert('Выберите JSON-файл');
        const importMaxSlots = document.getElementById('importMaxSlots').value;
        if (!importMaxSlots) return alert('Укажите максимальное количество мест');
        
        const text = await file.text();
        try {
            const response = await fetch('/api/admin/import/preview', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ jsonData: JSON.parse(text) })
            });
            const data = await response.json();
            if (data.success) {
                currentPreviewLessons = data.preview;
                const tbody = document.querySelector('#previewTable tbody');
                tbody.innerHTML = '';
                data.preview.slice(0,20).forEach(lesson => {
                    const row = tbody.insertRow();
                    row.insertCell(0).innerText = lesson.className;
                    row.insertCell(1).innerText = lesson.subject;
                    row.insertCell(2).innerText = lesson.teacher;
                    row.insertCell(3).innerText = lesson.topic || '';
                });
                if (data.preview.length > 20) {
                    const row = tbody.insertRow();
                    const cell = row.insertCell(0);
                    cell.colSpan = 4;
                    cell.innerText = `... и ещё ${data.preview.length - 20} записей`;
                }
                document.getElementById('importPreview').style.display = 'block';
            } else {
                alert('Ошибка предпросмотра: ' + (data.error || ''));
            }
        } catch (err) {
            alert('Ошибка при разборе JSON: ' + err.message);
        }
    });
    
    document.getElementById('confirmImportBtn')?.addEventListener('click', async () => {
        if (!confirm(`Импортировать ${currentPreviewLessons.length} уроков?`)) return;
        const importMaxSlots = document.getElementById('importMaxSlots').value;
        const response = await fetch('/api/admin/import', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({
                lessons: currentPreviewLessons,
                defaultMaxSlots: importMaxSlots
            })
        });
        const result = await response.json();
        if (result.success) {
            const created = result.results.filter(r => r.status === 'created').length;
            const skipped = result.results.filter(r => r.status === 'skipped').length;
            document.getElementById('importResult').innerHTML = `<span style="color:green">Импорт завершён: создано ${created}, пропущено (дубликаты) ${skipped}</span>`;
            loadLessons(getCurrentFilters());
            document.getElementById('importPreview').style.display = 'none';
        } else {
            alert('Ошибка импорта: ' + (result.error || ''));
        }
    });
}