import { api } from '../api.js';
import { escapeHtml, showAlert, hideAlert } from '../utils.js';

const DAY_OPTIONS = [
    { value: 1, label: 'Понедельник' },
    { value: 2, label: 'Вторник' },
    { value: 3, label: 'Среда' },
    { value: 4, label: 'Четверг' },
    { value: 5, label: 'Пятница' },
    { value: 6, label: 'Суббота' },
    { value: 7, label: 'Воскресенье' }
];

const PARITY_LABELS = {
    BOTH: 'каждую неделю',
    ODD: 'нечётная',
    EVEN: 'чётная'
};

const SEMESTER_LABELS = {
    autumn: 'осенний',
    spring: 'весенний'
};

const ACTIVITY_LABELS = {
    THEORY: 'Теория',
    EXAM: 'Экзамены',
    VACATION: 'Каникулы',
    PRACTICE: 'Практика'
};

export async function initSchedule() {
    const ruleForm = document.getElementById('schedule-rule-form');
    const ruleFormTitle = document.getElementById('schedule-rule-form-title');
    const ruleIdInput = document.getElementById('schedule-rule-id');
    const ruleSubjectSelect = document.getElementById('schedule-rule-subject');
    const ruleSemesterSelect = document.getElementById('schedule-rule-semester');
    const ruleActiveFromInput = document.getElementById('schedule-rule-active-from');
    const ruleHoursInput = document.getElementById('schedule-rule-hours');
    const ruleGroupsContainer = document.getElementById('schedule-rule-groups');
    const ruleSlotsContainer = document.getElementById('schedule-rule-slots');
    const ruleResetButton = document.getElementById('schedule-rule-reset');
    const slotAddButton = document.getElementById('schedule-slot-add');
    const rulesTbody = document.getElementById('schedule-tbody');
    const refreshRulesButton = document.getElementById('schedule-refresh');

    const timeSlotForm = document.getElementById('time-slot-form');
    const timeSlotFormTitle = document.getElementById('time-slot-form-title');
    const timeSlotIdInput = document.getElementById('time-slot-id');
    const timeSlotOrderInput = document.getElementById('time-slot-order');
    const timeSlotStartInput = document.getElementById('time-slot-start');
    const timeSlotEndInput = document.getElementById('time-slot-end');
    const timeSlotDurationInput = document.getElementById('time-slot-duration');
    const timeSlotResetButton = document.getElementById('time-slot-reset');
    const timeSlotsTbody = document.getElementById('time-slots-tbody');
    const refreshSlotsButton = document.getElementById('time-slots-refresh');

    const academicYearForm = document.getElementById('academic-year-form');
    const academicYearFormTitle = document.getElementById('academic-year-form-title');
    const academicYearIdInput = document.getElementById('academic-year-id');
    const academicYearTitleInput = document.getElementById('academic-year-title');
    const academicYearStartInput = document.getElementById('academic-year-start');
    const academicYearEndInput = document.getElementById('academic-year-end');
    const academicYearResetButton = document.getElementById('academic-year-reset');
    const academicYearsTbody = document.getElementById('academic-years-tbody');
    const academicYearsRefreshButton = document.getElementById('academic-years-refresh');

    const semesterForm = document.getElementById('semester-form');
    const semesterFormTitle = document.getElementById('semester-form-title');
    const semesterIdInput = document.getElementById('semester-id');
    const semesterYearSelect = document.getElementById('semester-year');
    const semesterTypeSelect = document.getElementById('semester-type');
    const semesterStartInput = document.getElementById('semester-start');
    const semesterEndInput = document.getElementById('semester-end');
    const semesterResetButton = document.getElementById('semester-reset');

    const holidayForm = document.getElementById('holiday-form');
    const holidayIdInput = document.getElementById('holiday-id');
    const holidayYearSelect = document.getElementById('holiday-year');
    const holidayDateInput = document.getElementById('holiday-date');
    const holidayDescriptionInput = document.getElementById('holiday-description');
    const holidayResetButton = document.getElementById('holiday-reset');
    const holidaysTbody = document.getElementById('holidays-tbody');

    const matrixSemesterSelect = document.getElementById('matrix-semester');
    const matrixCourseInput = document.getElementById('matrix-course');
    const matrixSpecialtySelect = document.getElementById('matrix-specialty');
    const matrixLoadButton = document.getElementById('matrix-load');
    const matrixSaveButton = document.getElementById('matrix-save');
    const matrixGrid = document.getElementById('matrix-grid');

    let rules = [];
    let subjects = [];
    let groups = [];
    let teachers = [];
    let classrooms = [];
    let lessonTypes = [];
    let timeSlots = [];
    let academicYears = [];
    let semesters = [];
    let specialties = [];
    let holidays = [];

    bindEvents();

    try {
        await Promise.all([loadBaseLists(), loadTimeSlots(), loadYears()]);
        renderRuleGroups([]);
        renderRuleSlots([{}]);
        await Promise.all([loadRules(), loadHolidays()]);
    } catch (error) {
        showAlert('schedule-rule-alert', error.message || 'Ошибка загрузки данных расписания', 'error');
    }

    function bindEvents() {
        refreshRulesButton?.addEventListener('click', loadRules);
        refreshSlotsButton?.addEventListener('click', loadTimeSlots);
        academicYearsRefreshButton?.addEventListener('click', loadYears);
        ruleResetButton?.addEventListener('click', resetRuleForm);
        slotAddButton?.addEventListener('click', () => renderRuleSlots([...readRuleSlots(false), {}]));
        timeSlotResetButton?.addEventListener('click', resetTimeSlotForm);
        academicYearResetButton?.addEventListener('click', resetAcademicYearForm);
        semesterResetButton?.addEventListener('click', resetSemesterForm);
        holidayResetButton?.addEventListener('click', resetHolidayForm);
        holidayYearSelect?.addEventListener('change', loadHolidays);
        matrixLoadButton?.addEventListener('click', loadMatrix);
        matrixSaveButton?.addEventListener('click', saveMatrix);

        ruleSlotsContainer.addEventListener('click', (event) => {
            const removeButton = event.target.closest('.schedule-slot-remove');
            if (!removeButton) return;
            const slots = readRuleSlots(false);
            slots.splice(Number(removeButton.dataset.index), 1);
            renderRuleSlots(slots.length ? slots : [{}]);
        });

        ruleForm.addEventListener('submit', saveRule);
        timeSlotForm.addEventListener('submit', saveTimeSlot);
        academicYearForm.addEventListener('submit', saveAcademicYear);
        semesterForm.addEventListener('submit', saveSemester);
        holidayForm.addEventListener('submit', saveHoliday);

        rulesTbody.addEventListener('click', handleRuleTableClick);
        timeSlotsTbody.addEventListener('click', handleTimeSlotTableClick);
        academicYearsTbody.addEventListener('click', handleAcademicYearTableClick);
        holidaysTbody.addEventListener('click', handleHolidayTableClick);
    }

    async function loadBaseLists() {
        [subjects, groups, teachers, classrooms, lessonTypes, specialties] = await Promise.all([
            api.get('/api/subjects'),
            api.get('/api/groups'),
            api.get('/api/users/teachers'),
            api.get('/api/classrooms'),
            api.get('/api/lesson-types'),
            api.get('/api/specialties')
        ]);

        populateSubjectSelects();
        populateSpecialtySelects();
    }

    async function loadRules() {
        rulesTbody.innerHTML = '<tr><td colspan="8" class="loading-row">Загрузка...</td></tr>';
        try {
            rules = await api.get('/api/admin/schedule-rules');
            renderRules();
        } catch (error) {
            rulesTbody.innerHTML = `<tr><td colspan="8" class="loading-row">Ошибка загрузки: ${escapeHtml(error.message)}</td></tr>`;
        }
    }

    function renderRules() {
        if (!rules || !rules.length) {
            rulesTbody.innerHTML = '<tr><td colspan="8" class="loading-row">Правила расписания не созданы</td></tr>';
            return;
        }

        rulesTbody.innerHTML = rules.map(rule => `
            <tr>
                <td>${rule.id}</td>
                <td>${escapeHtml(rule.subjectName || '-')}</td>
                <td>${escapeHtml(formatSemester(rule))}</td>
                <td>${escapeHtml((rule.groupNames || []).join(', ') || '-')}</td>
                <td>${escapeHtml(rule.activeFromDate || '-')}</td>
                <td>${escapeHtml(String(rule.totalAcademicHours ?? '-'))}</td>
                <td>${renderRuleSlotsSummary(rule.slots)}</td>
                <td>
                    <button class="btn-edit-classroom btn-edit-rule" data-id="${rule.id}">Изменить</button>
                    <button class="btn-delete btn-delete-rule" data-id="${rule.id}">Удалить</button>
                </td>
            </tr>
        `).join('');
    }

    function renderRuleSlotsSummary(slots) {
        if (!slots || !slots.length) return '<span class="muted">Нет слотов</span>';

        return slots.map(slot => {
            const parity = PARITY_LABELS[slot.parity] || slot.parity || '-';
            const parts = [
                slot.dayName,
                slot.timeSlotLabel,
                parity,
                slot.teacherName,
                slot.classroomName,
                slot.lessonTypeName,
                slot.lessonFormat
            ].filter(Boolean);
            return `<div class="schedule-slot-summary">${escapeHtml(parts.join(' · '))}</div>`;
        }).join('');
    }

    async function handleRuleTableClick(event) {
        const editButton = event.target.closest('.btn-edit-rule');
        const deleteButton = event.target.closest('.btn-delete-rule');

        if (editButton) {
            const rule = rules.find(item => item.id == editButton.dataset.id)
                || await api.get('/api/admin/schedule-rules/' + editButton.dataset.id);
            fillRuleForm(rule);
            return;
        }

        if (deleteButton) {
            if (!confirm('Удалить правило расписания?')) return;
            try {
                await api.delete('/api/admin/schedule-rules/' + deleteButton.dataset.id);
                showAlert('schedule-rule-alert', 'Правило расписания удалено', 'success');
                await loadRules();
            } catch (error) {
                showAlert('schedule-rule-alert', error.message || 'Ошибка удаления правила', 'error');
            }
        }
    }

    async function saveRule(event) {
        event.preventDefault();
        hideAlert('schedule-rule-alert');

        try {
            const payload = buildRulePayload();
            const id = ruleIdInput.value;
            const saved = id
                ? await api.put('/api/admin/schedule-rules/' + id, payload)
                : await api.post('/api/admin/schedule-rules', payload);
            showAlert('schedule-rule-alert', `Правило "${saved.subjectName || 'расписания'}" сохранено`, 'success');
            resetRuleForm();
            await loadRules();
        } catch (error) {
            showAlert('schedule-rule-alert', error.message || 'Ошибка сохранения правила', 'error');
        }
    }

    function buildRulePayload() {
        const groupIds = Array.from(ruleGroupsContainer.querySelectorAll('input[type="checkbox"]:checked'))
            .map(input => Number(input.value));
        const slots = readRuleSlots(true);

        if (!ruleSubjectSelect.value) {
            throw new Error('Выберите дисциплину');
        }
        if (!ruleSemesterSelect.value) {
            throw new Error('Выберите семестр');
        }
        if (!ruleActiveFromInput.value) {
            throw new Error('Укажите дату начала правила');
        }
        if (!ruleHoursInput.value || Number(ruleHoursInput.value) <= 0) {
            throw new Error('Укажите количество академических часов');
        }
        if (!groupIds.length) {
            throw new Error('Выберите хотя бы одну группу');
        }
        if (!slots.length) {
            throw new Error('Добавьте хотя бы один слот занятия');
        }

        return {
            id: ruleIdInput.value ? Number(ruleIdInput.value) : null,
            subjectId: Number(ruleSubjectSelect.value),
            semesterId: Number(ruleSemesterSelect.value),
            activeFromDate: ruleActiveFromInput.value,
            totalAcademicHours: Number(ruleHoursInput.value),
            groupIds,
            slots
        };
    }

    function fillRuleForm(rule) {
        ruleFormTitle.textContent = 'Редактирование правила расписания';
        ruleIdInput.value = rule.id;
        ruleSubjectSelect.value = rule.subjectId || '';
        ruleSemesterSelect.value = rule.semesterId || '';
        ruleActiveFromInput.value = rule.activeFromDate || '';
        ruleHoursInput.value = rule.totalAcademicHours || '';
        syncSelects(ruleSubjectSelect, ruleSemesterSelect);
        renderRuleGroups(rule.groupIds || []);
        renderRuleSlots(rule.slots && rule.slots.length ? rule.slots : [{}]);
        hideAlert('schedule-rule-alert');
        ruleForm.scrollIntoView({ behavior: 'smooth', block: 'start' });
    }

    function resetRuleForm() {
        ruleForm.reset();
        ruleFormTitle.textContent = 'Новое правило расписания';
        ruleIdInput.value = '';
        renderRuleGroups([]);
        renderRuleSlots([{}]);
        syncSelects(ruleSubjectSelect, ruleSemesterSelect);
        hideAlert('schedule-rule-alert');
    }

    function renderRuleGroups(selectedIds) {
        if (!groups.length) {
            ruleGroupsContainer.innerHTML = '<div class="loading-row">Нет групп</div>';
            return;
        }

        const selected = new Set((selectedIds || []).map(String));
        ruleGroupsContainer.innerHTML = groups.map(group => `
            <label class="checkbox-item">
                <input type="checkbox" value="${group.id}" ${selected.has(String(group.id)) ? 'checked' : ''}>
                <span class="checkmark"></span>
                <span>${escapeHtml(group.name)}</span>
            </label>
        `).join('');
    }

    function renderRuleSlots(slots) {
        ruleSlotsContainer.innerHTML = (slots || [{}]).map((slot, index) => `
            <div class="schedule-slot-row" data-index="${index}">
                <div class="form-group">
                    <label>День</label>
                    <select class="slot-day" required>${options(DAY_OPTIONS, slot.dayOfWeek)}</select>
                </div>
                <div class="form-group">
                    <label>Чётность</label>
                    <select class="slot-parity" required>
                        ${options(Object.entries(PARITY_LABELS).map(([value, label]) => ({ value, label })), slot.parity || 'BOTH')}
                    </select>
                </div>
                <div class="form-group">
                    <label>Пара</label>
                    <select class="slot-time" required>${options(timeSlots.map(toTimeSlotOption), slot.timeSlotId)}</select>
                </div>
                <div class="form-group">
                    <label>Преподаватель</label>
                    <select class="slot-teacher" required>${options(teachers.map(toTeacherOption), slot.teacherId)}</select>
                </div>
                <div class="form-group">
                    <label>Аудитория</label>
                    <select class="slot-classroom" required>${options(classrooms.map(toClassroomOption), slot.classroomId)}</select>
                </div>
                <div class="form-group">
                    <label>Тип</label>
                    <select class="slot-lesson-type" required>${options(lessonTypes.map(toLessonTypeOption), slot.lessonTypeId)}</select>
                </div>
                <div class="form-group">
                    <label>Формат</label>
                    <select class="slot-format" required>
                        ${options([{ value: 'Очно', label: 'Очно' }, { value: 'Онлайн', label: 'Онлайн' }], slot.lessonFormat || 'Очно')}
                    </select>
                </div>
                <button type="button" class="btn-delete schedule-slot-remove" data-index="${index}">Удалить</button>
            </div>
        `).join('');
    }

    function readRuleSlots(validate) {
        const rows = Array.from(ruleSlotsContainer.querySelectorAll('.schedule-slot-row'));
        return rows.map((row, index) => {
            const slot = {
                id: null,
                dayOfWeek: Number(row.querySelector('.slot-day').value),
                parity: row.querySelector('.slot-parity').value,
                timeSlotId: Number(row.querySelector('.slot-time').value),
                subgroupId: null,
                teacherId: Number(row.querySelector('.slot-teacher').value),
                classroomId: Number(row.querySelector('.slot-classroom').value),
                lessonTypeId: Number(row.querySelector('.slot-lesson-type').value),
                lessonFormat: row.querySelector('.slot-format').value
            };

            if (validate && (!slot.dayOfWeek || !slot.parity || !slot.timeSlotId
                || !slot.teacherId || !slot.classroomId || !slot.lessonTypeId || !slot.lessonFormat)) {
                throw new Error(`Заполните слот ${index + 1}`);
            }
            return slot;
        });
    }

    async function loadTimeSlots() {
        timeSlotsTbody.innerHTML = '<tr><td colspan="5" class="loading-row">Загрузка...</td></tr>';
        try {
            timeSlots = await api.get('/api/admin/time-slots');
            renderTimeSlots();
        } catch (error) {
            timeSlotsTbody.innerHTML = `<tr><td colspan="5" class="loading-row">Ошибка загрузки: ${escapeHtml(error.message)}</td></tr>`;
        }
    }

    function renderTimeSlots() {
        if (!timeSlots || !timeSlots.length) {
            timeSlotsTbody.innerHTML = '<tr><td colspan="5" class="loading-row">Сетка пар не настроена</td></tr>';
            return;
        }

        timeSlotsTbody.innerHTML = timeSlots.map(slot => `
            <tr>
                <td>${slot.orderNumber}</td>
                <td>${escapeHtml(trimTime(slot.startTime))}</td>
                <td>${escapeHtml(trimTime(slot.endTime))}</td>
                <td>${escapeHtml(String(slot.durationMinutes ?? '-'))}</td>
                <td>
                    <button class="btn-edit-classroom btn-edit-time-slot" data-id="${slot.id}">Изменить</button>
                    <button class="btn-delete btn-delete-time-slot" data-id="${slot.id}">Удалить</button>
                </td>
            </tr>
        `).join('');
    }

    async function saveTimeSlot(event) {
        event.preventDefault();
        hideAlert('time-slot-alert');

        const payload = {
            id: timeSlotIdInput.value ? Number(timeSlotIdInput.value) : null,
            orderNumber: Number(timeSlotOrderInput.value),
            startTime: timeSlotStartInput.value,
            endTime: timeSlotEndInput.value,
            durationMinutes: timeSlotDurationInput.value ? Number(timeSlotDurationInput.value) : null
        };

        try {
            if (!payload.orderNumber || !payload.startTime || !payload.endTime) {
                throw new Error('Заполните номер пары, начало и окончание');
            }
            const id = timeSlotIdInput.value;
            await (id
                ? api.put('/api/admin/time-slots/' + id, payload)
                : api.post('/api/admin/time-slots', payload));
            showAlert('time-slot-alert', 'Временной слот сохранён', 'success');
            resetTimeSlotForm();
            await loadTimeSlots();
            renderRuleSlots(readRuleSlots(false));
        } catch (error) {
            showAlert('time-slot-alert', error.message || 'Ошибка сохранения временного слота', 'error');
        }
    }

    async function handleTimeSlotTableClick(event) {
        const editButton = event.target.closest('.btn-edit-time-slot');
        const deleteButton = event.target.closest('.btn-delete-time-slot');

        if (editButton) {
            const slot = timeSlots.find(item => item.id == editButton.dataset.id);
            if (!slot) return;
            timeSlotFormTitle.textContent = 'Редактирование временного слота';
            timeSlotIdInput.value = slot.id;
            timeSlotOrderInput.value = slot.orderNumber || '';
            timeSlotStartInput.value = trimTime(slot.startTime);
            timeSlotEndInput.value = trimTime(slot.endTime);
            timeSlotDurationInput.value = slot.durationMinutes || '';
            hideAlert('time-slot-alert');
            timeSlotForm.scrollIntoView({ behavior: 'smooth', block: 'start' });
            return;
        }

        if (deleteButton) {
            if (!confirm('Удалить временной слот?')) return;
            try {
                await api.delete('/api/admin/time-slots/' + deleteButton.dataset.id);
                showAlert('time-slot-alert', 'Временной слот удалён', 'success');
                await loadTimeSlots();
            } catch (error) {
                showAlert('time-slot-alert', error.message || 'Ошибка удаления временного слота', 'error');
            }
        }
    }

    function resetTimeSlotForm() {
        timeSlotForm.reset();
        timeSlotFormTitle.textContent = 'Новый временной слот';
        timeSlotIdInput.value = '';
        hideAlert('time-slot-alert');
    }

    async function loadYears() {
        academicYearsTbody.innerHTML = '<tr><td colspan="4" class="loading-row">Загрузка...</td></tr>';
        try {
            academicYears = await api.get('/api/admin/calendar/years');
            semesters = academicYears.flatMap(year => year.semesters || []);
            renderAcademicYears();
            populateYearSelects();
            populateSemesterSelects();
        } catch (error) {
            academicYearsTbody.innerHTML = `<tr><td colspan="4" class="loading-row">Ошибка загрузки: ${escapeHtml(error.message)}</td></tr>`;
        }
    }

    function renderAcademicYears() {
        if (!academicYears || !academicYears.length) {
            academicYearsTbody.innerHTML = '<tr><td colspan="4" class="loading-row">Учебные годы не созданы</td></tr>';
            return;
        }

        academicYearsTbody.innerHTML = academicYears.map(year => `
            <tr>
                <td>${escapeHtml(year.title)}</td>
                <td>${escapeHtml(year.startDate)} — ${escapeHtml(year.endDate)}</td>
                <td>${renderSemesterList(year.semesters || [])}</td>
                <td>
                    <button class="btn-edit-classroom btn-edit-year" data-id="${year.id}">Изменить</button>
                    <button class="btn-delete btn-delete-year" data-id="${year.id}">Удалить</button>
                </td>
            </tr>
        `).join('');
    }

    function renderSemesterList(items) {
        if (!items.length) return '<span class="muted">Нет семестров</span>';
        return items.map(semester => `
            <div class="schedule-semester-line">
                ${escapeHtml(semesterLabel(semester))}
                <button class="btn-edit-classroom btn-edit-semester" data-id="${semester.id}">Изменить</button>
            </div>
        `).join('');
    }

    async function saveAcademicYear(event) {
        event.preventDefault();
        hideAlert('academic-year-alert');

        const payload = {
            title: academicYearTitleInput.value.trim(),
            startDate: academicYearStartInput.value,
            endDate: academicYearEndInput.value
        };

        try {
            if (!payload.title || !payload.startDate || !payload.endDate) {
                throw new Error('Заполните название и даты учебного года');
            }
            const id = academicYearIdInput.value;
            await (id
                ? api.put('/api/admin/calendar/years/' + id, payload)
                : api.post('/api/admin/calendar/years', payload));
            showAlert('academic-year-alert', 'Учебный год сохранён', 'success');
            resetAcademicYearForm();
            await loadYears();
        } catch (error) {
            showAlert('academic-year-alert', error.message || 'Ошибка сохранения учебного года', 'error');
        }
    }

    async function handleAcademicYearTableClick(event) {
        const editYearButton = event.target.closest('.btn-edit-year');
        const deleteYearButton = event.target.closest('.btn-delete-year');
        const editSemesterButton = event.target.closest('.btn-edit-semester');

        if (editYearButton) {
            const year = academicYears.find(item => item.id == editYearButton.dataset.id);
            if (!year) return;
            academicYearFormTitle.textContent = 'Редактирование учебного года';
            academicYearIdInput.value = year.id;
            academicYearTitleInput.value = year.title || '';
            academicYearStartInput.value = year.startDate || '';
            academicYearEndInput.value = year.endDate || '';
            hideAlert('academic-year-alert');
            academicYearForm.scrollIntoView({ behavior: 'smooth', block: 'start' });
            return;
        }

        if (editSemesterButton) {
            const semester = semesters.find(item => item.id == editSemesterButton.dataset.id);
            if (!semester) return;
            semesterFormTitle.textContent = 'Редактирование семестра';
            semesterIdInput.value = semester.id;
            semesterYearSelect.value = semester.academicYearId || '';
            semesterTypeSelect.value = normalizeSemesterType(semester.semesterType);
            semesterStartInput.value = semester.startDate || '';
            semesterEndInput.value = semester.endDate || '';
            syncSelects(semesterYearSelect, semesterTypeSelect);
            hideAlert('semester-alert');
            semesterForm.scrollIntoView({ behavior: 'smooth', block: 'start' });
            return;
        }

        if (deleteYearButton) {
            if (!confirm('Удалить учебный год вместе с семестрами?')) return;
            try {
                await api.delete('/api/admin/calendar/years/' + deleteYearButton.dataset.id);
                showAlert('academic-year-alert', 'Учебный год удалён', 'success');
                await loadYears();
            } catch (error) {
                showAlert('academic-year-alert', error.message || 'Ошибка удаления учебного года', 'error');
            }
        }
    }

    function resetAcademicYearForm() {
        academicYearForm.reset();
        academicYearFormTitle.textContent = 'Учебный год';
        academicYearIdInput.value = '';
        hideAlert('academic-year-alert');
    }

    async function saveSemester(event) {
        event.preventDefault();
        hideAlert('semester-alert');

        const yearId = semesterYearSelect.value;
        const payload = {
            semesterType: semesterTypeSelect.value,
            startDate: semesterStartInput.value,
            endDate: semesterEndInput.value
        };

        try {
            if (!yearId || !payload.semesterType || !payload.startDate || !payload.endDate) {
                throw new Error('Заполните учебный год, тип и даты семестра');
            }
            const id = semesterIdInput.value;
            await (id
                ? api.put('/api/admin/calendar/semesters/' + id, payload)
                : api.post(`/api/admin/calendar/years/${yearId}/semesters`, payload));
            showAlert('semester-alert', 'Семестр сохранён', 'success');
            resetSemesterForm();
            await loadYears();
        } catch (error) {
            showAlert('semester-alert', error.message || 'Ошибка сохранения семестра', 'error');
        }
    }

    function resetSemesterForm() {
        semesterForm.reset();
        semesterFormTitle.textContent = 'Семестр';
        semesterIdInput.value = '';
        syncSelects(semesterYearSelect, semesterTypeSelect);
        hideAlert('semester-alert');
    }

    async function saveHoliday(event) {
        event.preventDefault();
        hideAlert('holiday-alert');

        const payload = {
            id: holidayIdInput.value ? Number(holidayIdInput.value) : null,
            academicYearId: Number(holidayYearSelect.value),
            date: holidayDateInput.value,
            description: holidayDescriptionInput.value.trim()
        };

        try {
            if (!payload.academicYearId || !payload.date) {
                throw new Error('Выберите учебный год и дату');
            }
            const id = holidayIdInput.value;
            await (id
                ? api.put('/api/admin/calendar/holidays/' + id, payload)
                : api.post('/api/admin/calendar/holidays', payload));
            showAlert('holiday-alert', 'Дата сохранена', 'success');
            resetHolidayForm(false);
            await loadHolidays();
        } catch (error) {
            showAlert('holiday-alert', error.message || 'Ошибка сохранения даты', 'error');
        }
    }

    async function loadHolidays() {
        const yearId = holidayYearSelect.value;
        if (!yearId) {
            holidaysTbody.innerHTML = '<tr><td colspan="3" class="loading-row">Выберите учебный год</td></tr>';
            return;
        }

        holidaysTbody.innerHTML = '<tr><td colspan="3" class="loading-row">Загрузка...</td></tr>';
        try {
            holidays = await api.get('/api/admin/calendar/holidays?academicYearId=' + encodeURIComponent(yearId));
            renderHolidays();
        } catch (error) {
            holidaysTbody.innerHTML = `<tr><td colspan="3" class="loading-row">Ошибка загрузки: ${escapeHtml(error.message)}</td></tr>`;
        }
    }

    function renderHolidays() {
        if (!holidays || !holidays.length) {
            holidaysTbody.innerHTML = '<tr><td colspan="3" class="loading-row">Исключения не добавлены</td></tr>';
            return;
        }

        holidaysTbody.innerHTML = holidays.map(holiday => `
            <tr>
                <td>${escapeHtml(holiday.date)}</td>
                <td>${escapeHtml(holiday.description || '-')}</td>
                <td>
                    <button class="btn-edit-classroom btn-edit-holiday" data-id="${holiday.id}">Изменить</button>
                    <button class="btn-delete btn-delete-holiday" data-id="${holiday.id}">Удалить</button>
                </td>
            </tr>
        `).join('');
    }

    async function handleHolidayTableClick(event) {
        const editButton = event.target.closest('.btn-edit-holiday');
        const deleteButton = event.target.closest('.btn-delete-holiday');

        if (editButton) {
            const holiday = holidays.find(item => item.id == editButton.dataset.id);
            if (!holiday) return;
            holidayIdInput.value = holiday.id;
            holidayYearSelect.value = holiday.academicYearId || holidayYearSelect.value;
            holidayDateInput.value = holiday.date || '';
            holidayDescriptionInput.value = holiday.description || '';
            syncSelects(holidayYearSelect);
            hideAlert('holiday-alert');
            holidayForm.scrollIntoView({ behavior: 'smooth', block: 'start' });
            return;
        }

        if (deleteButton) {
            if (!confirm('Удалить дату-исключение?')) return;
            try {
                await api.delete('/api/admin/calendar/holidays/' + deleteButton.dataset.id);
                showAlert('holiday-alert', 'Дата удалена', 'success');
                await loadHolidays();
            } catch (error) {
                showAlert('holiday-alert', error.message || 'Ошибка удаления даты', 'error');
            }
        }
    }

    function resetHolidayForm(clearYear = true) {
        const yearId = holidayYearSelect.value;
        holidayForm.reset();
        if (!clearYear) holidayYearSelect.value = yearId;
        holidayIdInput.value = '';
        syncSelects(holidayYearSelect);
        hideAlert('holiday-alert');
    }

    async function loadMatrix() {
        hideAlert('matrix-alert');
        const semesterId = matrixSemesterSelect.value;
        const courseNumber = Number(matrixCourseInput.value);
        const specialtyId = matrixSpecialtySelect.value;

        if (!semesterId || !courseNumber || !specialtyId) {
            showAlert('matrix-alert', 'Выберите семестр, курс и специальность', 'error');
            return;
        }

        try {
            const params = new URLSearchParams({ semesterId, courseNumber: String(courseNumber), specialtyId });
            const rows = await api.get('/api/admin/calendar/matrix?' + params.toString());
            renderMatrix(rows && rows.length ? rows : buildDefaultMatrixRows(semesterId, courseNumber, specialtyId));
            showAlert('matrix-alert', rows && rows.length ? 'Матрица загружена' : 'Матрица не найдена, подготовлена новая сетка', 'success');
        } catch (error) {
            showAlert('matrix-alert', error.message || 'Ошибка загрузки матрицы', 'error');
        }
    }

    async function saveMatrix() {
        hideAlert('matrix-alert');
        const rows = Array.from(matrixGrid.querySelectorAll('.matrix-week')).map(item => ({
            id: item.dataset.id ? Number(item.dataset.id) : null,
            semesterId: Number(item.dataset.semesterId),
            courseNumber: Number(item.dataset.courseNumber),
            specialtyId: Number(item.dataset.specialtyId),
            weekNumber: Number(item.dataset.weekNumber),
            activityType: item.querySelector('select').value
        }));

        if (!rows.length) {
            showAlert('matrix-alert', 'Сначала загрузите матрицу', 'error');
            return;
        }

        try {
            await api.put('/api/admin/calendar/matrix', rows);
            showAlert('matrix-alert', 'Матрица учебного графика сохранена', 'success');
            await loadMatrix();
        } catch (error) {
            showAlert('matrix-alert', error.message || 'Ошибка сохранения матрицы', 'error');
        }
    }

    function renderMatrix(rows) {
        matrixGrid.innerHTML = rows.map(row => `
            <div class="matrix-week"
                 data-id="${row.id || ''}"
                 data-semester-id="${row.semesterId}"
                 data-course-number="${row.courseNumber}"
                 data-specialty-id="${row.specialtyId}"
                 data-week-number="${row.weekNumber}">
                <span>${row.weekNumber}</span>
                <select>${options(activityOptions(), row.activityType || 'THEORY')}</select>
            </div>
        `).join('');
    }

    function buildDefaultMatrixRows(semesterId, courseNumber, specialtyId) {
        return Array.from({ length: 22 }, (_, index) => ({
            id: null,
            semesterId: Number(semesterId),
            courseNumber,
            specialtyId: Number(specialtyId),
            weekNumber: index + 1,
            activityType: 'THEORY'
        }));
    }

    function populateSubjectSelects() {
        ruleSubjectSelect.innerHTML = '<option value="">Выберите дисциплину</option>' +
            subjects.map(subject => `<option value="${subject.id}">${escapeHtml(subject.name)}</option>`).join('');
    }

    function populateYearSelects() {
        const yearOptions = '<option value="">Выберите учебный год</option>' +
            academicYears.map(year => `<option value="${year.id}">${escapeHtml(year.title)}</option>`).join('');
        semesterYearSelect.innerHTML = yearOptions;
        holidayYearSelect.innerHTML = yearOptions;

        if (!holidayYearSelect.value && academicYears.length) {
            holidayYearSelect.value = String(academicYears[0].id);
        }
        syncSelects(semesterYearSelect, holidayYearSelect);
    }

    function populateSemesterSelects() {
        const semesterOptions = '<option value="">Выберите семестр</option>' +
            semesters.map(semester => `<option value="${semester.id}">${escapeHtml(semesterLabel(semester))}</option>`).join('');
        ruleSemesterSelect.innerHTML = semesterOptions;
        matrixSemesterSelect.innerHTML = semesterOptions;
        syncSelects(ruleSemesterSelect, matrixSemesterSelect);
    }

    function populateSpecialtySelects() {
        matrixSpecialtySelect.innerHTML = '<option value="">Выберите специальность</option>' +
            specialties.map(speciality => `<option value="${speciality.id}">${escapeHtml(specialityLabel(speciality))}</option>`).join('');
        syncSelects(matrixSpecialtySelect);
    }

    function options(items, selectedValue) {
        const selected = selectedValue == null ? '' : String(selectedValue);
        return '<option value="">Выберите</option>' + items.map(item => {
            const value = String(item.value);
            return `<option value="${escapeHtml(value)}" ${value === selected ? 'selected' : ''}>${escapeHtml(item.label)}</option>`;
        }).join('');
    }

    function activityOptions() {
        return Object.entries(ACTIVITY_LABELS).map(([value, label]) => ({ value, label }));
    }

    function toTimeSlotOption(slot) {
        return { value: slot.id, label: `${slot.orderNumber} пара, ${trimTime(slot.startTime)} - ${trimTime(slot.endTime)}` };
    }

    function toTeacherOption(teacher) {
        return { value: teacher.id, label: teacher.fullName || teacher.username || `ID ${teacher.id}` };
    }

    function toClassroomOption(classroom) {
        const capacity = classroom.capacity ? `, ${classroom.capacity} чел.` : '';
        return { value: classroom.id, label: `${classroom.name}${capacity}` };
    }

    function toLessonTypeOption(lessonType) {
        return { value: lessonType.id, label: lessonType.name || lessonType.lessonType || `ID ${lessonType.id}` };
    }

    function semesterLabel(semester) {
        const type = normalizeSemesterType(semester.semesterType);
        return `${semester.academicYearTitle || '-'}, ${SEMESTER_LABELS[type] || type} (${semester.startDate} — ${semester.endDate})`;
    }

    function formatSemester(rule) {
        const type = normalizeSemesterType(rule.semesterType);
        return `${rule.academicYearTitle || '-'}, ${SEMESTER_LABELS[type] || type || '-'}`;
    }

    function normalizeSemesterType(type) {
        return String(type || '').toLowerCase();
    }

    function specialityLabel(speciality) {
        const code = speciality.specialityCode || speciality.specialtyCode || speciality.specialty_code || speciality.id;
        const name = speciality.specialityName || speciality.name || '';
        return name ? `${code} — ${name}` : String(code);
    }

    function trimTime(value) {
        if (!value) return '';
        return String(value).slice(0, 5);
    }

    function syncSelects(...selects) {
        selects.filter(Boolean).forEach(select => {
            select.dispatchEvent(new Event('change', { bubbles: true }));
        });
    }
}