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'
};

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');

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

    bindEvents();

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

    function bindEvents() {
        refreshRulesButton?.addEventListener('click', loadRules);
        ruleResetButton?.addEventListener('click', resetRuleForm);
        slotAddButton?.addEventListener('click', () => renderRuleSlots([...readRuleSlots(false), {}]));

        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);
        rulesTbody.addEventListener('click', handleRuleTableClick);
    }

    async function loadBaseLists() {
        [subjects, groups, teachers, classrooms, lessonTypes] = 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')
        ]);
        populateSubjectSelects();
    }

    async function loadYears() {
        const academicYears = await api.get('/api/admin/calendar/years');
        semesters = academicYears.flatMap(year => year.semesters || []);
        populateSemesterSelects();
    }

    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.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() {
        const slots = await api.get('/api/admin/time-slots');
        timeSlots = slots
            .filter(slot => slot.scopeApplyMode === 'DEFAULT')
            .sort((a, b) => (a.orderNumber || 0) - (b.orderNumber || 0));
    }

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

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

    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 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 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 }));
        });
    }
}