let currentWeekStart = null;

const weekdays = ['Понедельник', 'Вторник', 'Среда', 'Четверг', 'Пятница', 'Суббота', 'Воскресенье'];
const weekdaysShort = ['Пн', 'Вт', 'Ср', 'Чт', 'Пт', 'Сб', 'Вс'];

function getTodayInLondon() {
    // Получаем текущую дату в таймзоне London
    const now = new Date();
    const formatter = new Intl.DateTimeFormat('en-CA', {
        timeZone: 'Europe/London',
        year: 'numeric',
        month: '2-digit',
        day: '2-digit'
    });
    return formatter.format(now);
}

function getWeekStart(dateStr = null) {
    if (!dateStr) {
        dateStr = getTodayInLondon();
    }
    const date = new Date(dateStr + 'T00:00:00');
    const day = date.getDay();
    const diff = date.getDate() - day + (day === 0 ? -6 : 1); // Понедельник = 1
    const monday = new Date(date.setDate(diff));
    return monday.toISOString().split('T')[0];
}

function formatDate(dateStr) {
    const date = new Date(dateStr + 'T00:00:00');
    return `${weekdaysShort[date.getDay()]}, ${date.getDate()}`;
}

function formatDateFull(dateStr) {
    const date = new Date(dateStr + 'T00:00:00');
    const months = ['января', 'февраля', 'марта', 'апреля', 'мая', 'июня', 
                    'июля', 'августа', 'сентября', 'октября', 'ноября', 'декабря'];
    return `${weekdays[date.getDay()]}, ${date.getDate()} ${months[date.getMonth()]}`;
}

function getWeekDates(startDate) {
    const dates = [];
    const start = new Date(startDate + 'T00:00:00');
    for (let i = 0; i < 7; i++) {
        const date = new Date(start);
        date.setDate(start.getDate() + i);
        dates.push(date.toISOString().split('T')[0]);
    }
    return dates;
}

async function loadSchedule() {
    const weekDates = getWeekDates(currentWeekStart);
    const fromDate = weekDates[0];
    const toDate = weekDates[6];
    
    console.log('Loading schedule from', fromDate, 'to', toDate);
    
    try {
        const response = await fetch(`/api/schedule?from_date=${fromDate}&to_date=${toDate}`);
        const data = await response.json();
        
        console.log('Received items:', data.items);
        
        renderSchedule(weekDates, data.items);
        
        // Обновляем заголовок недели
        const startDate = new Date(weekDates[0] + 'T00:00:00');
        const endDate = new Date(weekDates[6] + 'T00:00:00');
        document.getElementById('week-range').textContent = 
            `${formatDateFull(weekDates[0])} - ${formatDateFull(weekDates[6])}`;
    } catch (error) {
        console.error('Error loading schedule:', error);
    }
}

function renderSchedule(weekDates, items) {
    const grid = document.getElementById('schedule-grid');
    grid.innerHTML = '';
    
    console.log('Rendering schedule for dates:', weekDates);
    console.log('All items:', items);
    
    weekDates.forEach(dateStr => {
        const dayItems = items.filter(item => {
            const match = item.date === dateStr;
            if (!match && items.length > 0) {
                console.log(`Item date ${item.date} !== ${dateStr}`);
            }
            return match;
        });
        console.log(`Date ${dateStr}: ${dayItems.length} items`);
        const date = new Date(dateStr + 'T00:00:00');
        
        const column = document.createElement('div');
        column.className = 'day-column';
        
        column.innerHTML = `
            <div class="day-header">${formatDateFull(dateStr)}</div>
            <div class="day-items" data-date="${dateStr}">
                ${renderDayItems(dayItems)}
            </div>
        `;
        
        grid.appendChild(column);
    });
}

function renderDayItems(items) {
    console.log('Rendering items for day:', items);
    if (items.length === 0) {
        return '<div style="color: #999; font-style: italic; padding: 10px;">Нет записей</div>';
    }
    
    const tasks = items.filter(item => item.kind === 'task');
    const events = items.filter(item => item.kind === 'event');
    console.log('Tasks:', tasks, 'Events:', events);
    
    let html = '';
    
    // Tasks
    tasks.forEach(task => {
        html += `
            <div class="item task" data-id="${task.id}" data-kind="task">
                <div class="item-title">${task.title}</div>
                ${task.repeat_weekly ? '<div style="font-size: 11px; color: #FF9800;">Повторяется</div>' : ''}
                <div class="item-actions">
                    <button class="btn-edit" onclick="editItem(${task.id}, 'task')">Изменить</button>
                    <button class="btn-delete" onclick="deleteItem(${task.id}, 'task')">Удалить</button>
                </div>
            </div>
        `;
    });
    
    // Events
    events.sort((a, b) => a.start_time.localeCompare(b.start_time)).forEach(event => {
        const endTime = calculateEndTime(event.start_time, event.duration_min);
        html += `
            <div class="item event" data-id="${event.id}" data-kind="event">
                <div class="item-time">${event.start_time}-${endTime}</div>
                <div class="item-title">${event.title}</div>
                <div class="item-actions">
                    <button class="btn-edit" onclick="editItem(${event.id}, 'event')">Изменить</button>
                    <button class="btn-delete" onclick="deleteItem(${event.id}, 'event')">Удалить</button>
                </div>
            </div>
        `;
    });
    
    return html;
}

function calculateEndTime(startTime, durationMin) {
    const [hour, minute] = startTime.split(':').map(Number);
    const totalMinutes = hour * 60 + minute + durationMin;
    const endHour = Math.floor(totalMinutes / 60);
    const endMinute = totalMinutes % 60;
    return `${String(endHour).padStart(2, '0')}:${String(endMinute).padStart(2, '0')}`;
}

function showModal(content) {
    document.getElementById('modal-body').innerHTML = content;
    document.getElementById('modal').style.display = 'block';
}

function closeModal() {
    document.getElementById('modal').style.display = 'none';
}

function showAddTaskModal(selectedDate = null) {
    const weekDates = getWeekDates(currentWeekStart);
    const today = getTodayInLondon();
    const todayDate = new Date(today + 'T00:00:00');
    const selectedDateObj = selectedDate ? new Date(selectedDate + 'T00:00:00') : todayDate;
    // getDay() возвращает 0=воскресенье, 1=понедельник, ..., 6=суббота
    // Конвертируем в формат 0=понедельник, 6=воскресенье
    const jsWeekday = selectedDateObj.getDay();
    const selectedWeekday = jsWeekday === 0 ? 6 : jsWeekday - 1; // 0=пн, 6=вс
    const remainingWeekdays = [];
    
    // Оставшиеся дни недели после выбранного (среда=2, четверг=3, пятница=4, суббота=5, воскресенье=6)
    for (let i = selectedWeekday + 1; i <= 6; i++) {
        remainingWeekdays.push(i);
    }
    
    const content = `
        <h2>Добавить задачу</h2>
        <form id="add-task-form">
            <div class="form-group">
                <label>Дата:</label>
                <input type="date" id="task-date" value="${selectedDate || today}" required>
            </div>
            <div class="form-group">
                <label>Название:</label>
                <textarea id="task-title" required></textarea>
            </div>
            <div class="form-group">
                <div class="checkbox-group">
                    <input type="checkbox" id="task-repeat-weekly">
                    <label for="task-repeat-weekly">Повторять каждую неделю</label>
                </div>
            </div>
            <div class="form-group" id="copy-weekdays-group" style="display: none;">
                <label>Добавить на другие дни недели:</label>
                <div class="weekdays-select">
                    ${remainingWeekdays.map(day => {
                        // day в формате 0=пн, 6=вс, но weekdaysShort использует JS формат (0=вс)
                        const jsDay = day === 6 ? 0 : day + 1;
                        return `
                        <label>
                            <input type="checkbox" name="copy-weekday" value="${day}">
                            ${weekdaysShort[jsDay]}
                        </label>
                    `;
                    }).join('')}
                </div>
            </div>
            <div style="margin-top: 20px;">
                <button type="submit" class="btn btn-primary">Добавить</button>
                <button type="button" class="btn" onclick="closeModal()">Отмена</button>
            </div>
        </form>
    `;
    
    showModal(content);
    
    document.getElementById('task-repeat-weekly').addEventListener('change', function() {
        document.getElementById('copy-weekdays-group').style.display = 
            this.checked ? 'none' : 'block';
    });
    
    document.getElementById('add-task-form').addEventListener('submit', async (e) => {
        e.preventDefault();
        const date = document.getElementById('task-date').value;
        const title = document.getElementById('task-title').value;
        const repeatWeekly = document.getElementById('task-repeat-weekly').checked;
        const copyWeekdays = Array.from(document.querySelectorAll('input[name="copy-weekday"]:checked'))
            .map(cb => parseInt(cb.value));
        
        try {
            const response = await fetch('/api/events?kind=task', {
                method: 'POST',
                headers: {'Content-Type': 'application/json'},
                body: JSON.stringify({
                    date,
                    title,
                    repeat_weekly: repeatWeekly,
                    copy_to_weekdays: copyWeekdays.length > 0 ? copyWeekdays : null
                })
            });
            
            if (response.ok) {
                const result = await response.json();
                console.log('Task created:', result);
                closeModal();
                await loadSchedule();
            } else {
                const error = await response.json();
                console.error('Error creating task:', error);
                alert('Ошибка: ' + (error.detail || 'Неизвестная ошибка'));
            }
        } catch (error) {
            console.error('Exception creating task:', error);
            alert('Ошибка при добавлении задачи: ' + error.message);
        }
    });
}

function showAddEventModal(selectedDate = null) {
    const today = getTodayInLondon();
    const content = `
        <h2>Добавить занятие</h2>
        <form id="add-event-form">
            <div class="form-group">
                <label>Дата:</label>
                <input type="date" id="event-date" value="${selectedDate || today}" required>
            </div>
            <div class="form-group">
                <label>Время начала:</label>
                <div style="display: flex; gap: 10px;">
                    <select id="event-hour" required>
                        ${Array.from({length: 13}, (_, i) => i + 8).map(h => 
                            `<option value="${String(h).padStart(2, '0')}">${String(h).padStart(2, '0')}</option>`
                        ).join('')}
                    </select>
                    <select id="event-minute" required>
                        <option value="00">00</option>
                        <option value="15">15</option>
                        <option value="30">30</option>
                        <option value="45">45</option>
                    </select>
                </div>
            </div>
            <div class="form-group">
                <label>Длительность:</label>
                <div style="display: flex; gap: 10px;">
                    <select id="event-duration-hour">
                        <option value="0">0</option>
                        <option value="1">1</option>
                        <option value="2">2</option>
                        <option value="3">3</option>
                    </select>
                    <select id="event-duration-minute">
                        <option value="00">00</option>
                        <option value="15">15</option>
                        <option value="30">30</option>
                        <option value="45">45</option>
                    </select>
                </div>
            </div>
            <div class="form-group">
                <label>Название:</label>
                <textarea id="event-title" required></textarea>
            </div>
            <div style="margin-top: 20px;">
                <button type="submit" class="btn btn-primary">Добавить</button>
                <button type="button" class="btn" onclick="closeModal()">Отмена</button>
            </div>
        </form>
    `;
    
    showModal(content);
    
    document.getElementById('add-event-form').addEventListener('submit', async (e) => {
        e.preventDefault();
        const date = document.getElementById('event-date').value;
        const hour = document.getElementById('event-hour').value;
        const minute = document.getElementById('event-minute').value;
        const durHour = parseInt(document.getElementById('event-duration-hour').value);
        const durMin = parseInt(document.getElementById('event-duration-minute').value);
        const title = document.getElementById('event-title').value;
        
        const durationMin = durHour * 60 + durMin;
        if (durationMin === 0) {
            alert('Длительность должна быть минимум 15 минут');
            return;
        }
        
        try {
            const response = await fetch('/api/events?kind=event', {
                method: 'POST',
                headers: {'Content-Type': 'application/json'},
                body: JSON.stringify({
                    date,
                    start_time: `${hour}:${minute}`,
                    duration_min: durationMin,
                    title
                })
            });
            
            if (response.ok) {
                const result = await response.json();
                console.log('Event created:', result);
                closeModal();
                await loadSchedule();
            } else {
                const error = await response.json();
                console.error('Error creating event:', error);
                alert('Ошибка: ' + (error.detail || 'Неизвестная ошибка'));
            }
        } catch (error) {
            console.error('Exception creating event:', error);
            alert('Ошибка при добавлении занятия: ' + error.message);
        }
    });
}

async function editItem(id, kind) {
    // TODO: Реализовать редактирование
    alert('Редактирование будет реализовано позже');
}

async function deleteItem(id, kind) {
    if (!confirm('Удалить эту запись?')) return;
    
    try {
        const response = await fetch(`/api/events/${id}`, {
            method: 'DELETE'
        });
        
        if (response.ok) {
            loadSchedule();
        } else {
            alert('Ошибка при удалении');
        }
    } catch (error) {
        alert('Ошибка при удалении');
        console.error(error);
    }
}

// Инициализация
document.addEventListener('DOMContentLoaded', () => {
    currentWeekStart = getWeekStart();
    loadSchedule();
    
    document.getElementById('prev-week').addEventListener('click', () => {
        const date = new Date(currentWeekStart + 'T00:00:00');
        date.setDate(date.getDate() - 7);
        currentWeekStart = date.toISOString().split('T')[0];
        loadSchedule();
    });
    
    document.getElementById('next-week').addEventListener('click', () => {
        const date = new Date(currentWeekStart + 'T00:00:00');
        date.setDate(date.getDate() + 7);
        currentWeekStart = date.toISOString().split('T')[0];
        loadSchedule();
    });
    
    document.getElementById('add-task-btn').addEventListener('click', () => showAddTaskModal());
    document.getElementById('add-event-btn').addEventListener('click', () => showAddEventModal());
    
    document.querySelector('.close').addEventListener('click', closeModal);
    window.addEventListener('click', (e) => {
        const modal = document.getElementById('modal');
        if (e.target === modal) {
            closeModal();
        }
    });
    
    // Клик по дню для добавления
    document.addEventListener('click', (e) => {
        if (e.target.closest('.day-items')) {
            const date = e.target.closest('.day-items').dataset.date;
            if (e.ctrlKey || e.metaKey) {
                showAddEventModal(date);
            } else if (e.shiftKey) {
                showAddTaskModal(date);
            }
        }
    });
});