document.addEventListener('DOMContentLoaded', fetchHabits);

const habitListDiv = document.getElementById('habitList');
const dateModal = document.getElementById('dateModal');
const modalHabitName = document.getElementById('modalHabitName');
const modalDateGrid = document.getElementById('modalDateGrid');
const modalCompleteTodayBtn = document.getElementById('modalCompleteTodayBtn');
const modalEditBtn = document.getElementById('modalEditBtn'); // Neu hinzugefügt
const modalDeleteBtn = document.getElementById('modalDeleteBtn'); // Neu hinzugefügt


let currentHabitId = null; // Stellt sicher, dass diese globale Variable korrekt ist
let currentModalDate = new Date(); // Aktueller Monat im Modal
let currentHabitCompletedDates = {}; // Completed dates für das aktuelle Habit (now object with counts)
let currentHabitColor = '#4CAF50'; // Current habit color
let currentHabitDailyTarget = 1; // Current habit daily target

function getCurrentDate() {
    const today = new Date();
    const year = today.getFullYear();
    const month = String(today.getMonth() + 1).padStart(2, '0');
    const day = String(today.getDate()).padStart(2, '0');
    return `${year}-${month}-${day}`;
}

function getPastDates(days) {
    const dates = [];
    for (let i = days - 1; i >= 0; i--) {
        const d = new Date();
        d.setDate(d.getDate() - i);
        const year = d.getFullYear();
        const month = String(d.getMonth() + 1).padStart(2, '0');
        const day = String(d.getDate()).padStart(2, '0');
        dates.push(`${year}-${month}-${day}`);
    }
    return dates;
}

function calculateStreak(completedDates, dailyTarget) {
    if (!completedDates || Object.keys(completedDates).length === 0) {
        return 0;
    }

    const today = getCurrentDate();
    let streak = 0;
    let currentDate = new Date();

    // Check if today is completed, if not, start from yesterday
    const todayCount = completedDates[today] || 0;
    if (todayCount < dailyTarget) {
        currentDate.setDate(currentDate.getDate() - 1);
    }

    // Count consecutive days backwards from today (or yesterday)
    while (true) {
        const dateStr = `${currentDate.getFullYear()}-${String(currentDate.getMonth() + 1).padStart(2, '0')}-${String(currentDate.getDate()).padStart(2, '0')}`;
        const count = completedDates[dateStr] || 0;

        if (count >= dailyTarget) {
            streak++;
            currentDate.setDate(currentDate.getDate() - 1);
        } else {
            break;
        }
    }

    return streak;
}

async function fetchHabits() {
    try {
        const response = await fetch('/habits');
        const habits = await response.json();
        renderHabits(habits);
    } catch (error) {
        console.error('Error fetching habits:', error);
    }
}

function renderHabits(habits) {
    habitListDiv.innerHTML = ''; // Clear previous habits
    const last30Days = getPastDates(30);

    habits.forEach(habit => {
        const habitItem = document.createElement('div');
        habitItem.className = 'habit-item';
        habitItem.dataset.id = habit.id; // Store habit ID

        // Apply custom color to the habit item
        const habitColor = habit.color || '#4CAF50';
        habitItem.style.setProperty('--habit-color', habitColor);

        const habitHeader = document.createElement('div');
        habitHeader.className = 'habit-header';

        const habitName = document.createElement('div');
        habitName.className = 'habit-name';
        habitName.textContent = habit.name;
        habitHeader.appendChild(habitName);

        const habitActions = document.createElement('div');
        habitActions.className = 'habit-actions';

        // Haken-Button für heute abhaken/rückgängig machen mit Zähler
        const todayToggleButton = document.createElement('button');
        const today = getCurrentDate();
        const todayCount = habit.completed_dates[today] || 0;
        const dailyTarget = habit.daily_target || 1;
        const isCompletedToday = todayCount >= dailyTarget;

        // Show count if target > 1, otherwise just checkmark
        if (dailyTarget > 1) {
            todayToggleButton.innerHTML = `${todayCount}/${dailyTarget}`;
        } else {
            todayToggleButton.innerHTML = '&#x2713;'; // Checkmark symbol
        }

        todayToggleButton.className = isCompletedToday ? 'completed-today' : 'not-completed-today';
        todayToggleButton.onclick = () => toggleTodayCompletion(habit.id, today, todayToggleButton, habit.daily_target);
        habitActions.appendChild(todayToggleButton);

        // Drei-Punkte-Menü für erweiterte Optionen
        const menuButton = document.createElement('button');
        menuButton.innerHTML = '&#x22EE;'; // Vertical ellipsis (drei Punkte)
        menuButton.onclick = () => openHabitModal(habit.id, habit.name, habit.completed_dates, habitColor, habit.daily_target);
        habitActions.appendChild(menuButton);
        habitHeader.appendChild(habitActions);
        habitItem.appendChild(habitHeader);

        const dateGrid = document.createElement('div');
        dateGrid.className = 'date-grid';

        last30Days.forEach(date => {
            const dateSquare = document.createElement('div');
            dateSquare.className = 'date-square';
            const dateCount = habit.completed_dates[date] || 0;
            const isCompleted = dateCount >= dailyTarget;

            // Apply gradient styling based on completion percentage
            applyCompletionStyling(dateSquare, dateCount, dailyTarget, habitColor);

            // Show count in tooltip if target > 1
            if (dailyTarget > 1) {
                dateSquare.title = `${date}: ${dateCount}/${dailyTarget}`;
            } else {
                dateSquare.title = date;
            }
            dateGrid.appendChild(dateSquare);
        });
        habitItem.appendChild(dateGrid);

        // Streak Counter hinzufügen
        const streakContainer = document.createElement('div');
        streakContainer.className = 'streak-container';

        const flameIcon = document.createElement('span');
        flameIcon.className = 'flame-icon';
        flameIcon.innerHTML = '🔥'; // Flammen-Emoji

        const streakCount = document.createElement('span');
        streakCount.className = 'streak-count';
        const currentStreak = calculateStreak(habit.completed_dates, dailyTarget);
        streakCount.textContent = `${currentStreak} Tag${currentStreak !== 1 ? 'e' : ''}`;

        streakContainer.appendChild(flameIcon);
        streakContainer.appendChild(streakCount);
        habitItem.appendChild(streakContainer);

        habitListDiv.appendChild(habitItem);
    });
}

async function addHabit() {
    const newHabitNameInput = document.getElementById('newHabitName');
    const name = newHabitNameInput.value.trim();

    if (name) {
        try {
            const response = await fetch('/habits', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ name: name })
            });
            const newHabit = await response.json();
            if (response.ok) {
                newHabitNameInput.value = '';
                fetchHabits(); // Re-fetch and re-render all habits
            } else {
                console.error('Failed to add habit:', newHabit.error);
            }
        } catch (error) {
            console.error('Error adding habit:', error);
        }
    }
}

async function openHabitModal(habitId, habitName, completedDates, habitColor = '#4CAF50', dailyTarget = 1) {
    currentHabitId = habitId;
    currentHabitCompletedDates = completedDates;
    currentHabitColor = habitColor;
    currentHabitDailyTarget = dailyTarget;
    currentModalDate = new Date(); // Reset to current month
    modalHabitName.textContent = habitName;

    // Setzen der habitId auf den Buttons im Modal
    modalCompleteTodayBtn.dataset.habitId = habitId;
    modalEditBtn.dataset.habitId = habitId;
    modalDeleteBtn.dataset.habitId = habitId;

    // Set color picker to current habit color
    document.getElementById('habitColorPicker').value = habitColor;

    // Set daily target input to current value
    document.getElementById('habitDailyTarget').value = dailyTarget;

    // Set CSS variable for modal elements
    dateModal.style.setProperty('--current-habit-color', habitColor);

    // Set contrast color for text on colored backgrounds
    const contrastColor = getContrastColor(habitColor);
    dateModal.style.setProperty('--current-habit-text-color', contrastColor);

    renderModalCalendar();
    dateModal.style.display = 'flex';
}

function renderModalCalendar() {
    modalDateGrid.innerHTML = '';

    // Update month/year display
    const monthNames = ['Januar', 'Februar', 'März', 'April', 'Mai', 'Juni',
        'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'];
    document.getElementById('currentMonthYear').textContent =
        `${monthNames[currentModalDate.getMonth()]} ${currentModalDate.getFullYear()}`;

    const today = getCurrentDate();
    const year = currentModalDate.getFullYear();
    const month = currentModalDate.getMonth();

    // Get first day of month and calculate starting position
    const firstDay = new Date(year, month, 1);
    const lastDay = new Date(year, month + 1, 0);
    const startingDayOfWeek = (firstDay.getDay() + 6) % 7; // Monday = 0

    // Add empty cells for days before month starts
    for (let i = 0; i < startingDayOfWeek; i++) {
        const emptyCell = document.createElement('div');
        emptyCell.className = 'date-cell empty';
        modalDateGrid.appendChild(emptyCell);
    }

    // Add days of the month
    for (let day = 1; day <= lastDay.getDate(); day++) {
        const dateStr = `${year}-${String(month + 1).padStart(2, '0')}-${String(day).padStart(2, '0')}`;

        const dateCell = document.createElement('div');
        dateCell.className = 'date-cell';
        dateCell.textContent = day;

        const dateCount = currentHabitCompletedDates[dateStr] || 0;
        const isCompleted = dateCount >= currentHabitDailyTarget;

        if (isCompleted) {
            dateCell.classList.add('completed');
        }

        // Use the new display function for consistent formatting
        updateDateCellDisplay(dateCell, dateStr, dateCount);
        if (dateStr === today) {
            dateCell.classList.add('today');
        }

        dateCell.dataset.date = dateStr;
        dateCell.onclick = (event) => toggleCompletionForDate(event, currentHabitId, dateStr);
        modalDateGrid.appendChild(dateCell);
    }
}

function changeMonth(direction) {
    currentModalDate.setMonth(currentModalDate.getMonth() + direction);
    renderModalCalendar();
}

function closeModal() {
    dateModal.style.display = 'none';
    currentHabitId = null; // Zurücksetzen, wenn das Modal geschlossen wird
    fetchHabits(); // Refresh habits after closing modal
}

async function toggleCompletionForDate(event, habitId, date) {
    // Find the actual date cell, even if clicked on child elements
    let cell = event.target;
    if (!cell.classList.contains('date-cell')) {
        cell = cell.closest('.date-cell');
    }

    if (!cell) return; // Safety check

    let response;
    let data;

    const currentCount = currentHabitCompletedDates[date] || 0;
    const shouldDecrement = event.shiftKey || event.ctrlKey || currentCount >= currentHabitDailyTarget;

    if (shouldDecrement && currentCount > 0) {
        // Decrement completion count
        response = await fetch(`/habits/${habitId}/uncomplete`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ date: date })
        });
    } else {
        // Increment completion count
        response = await fetch(`/habits/${habitId}/complete`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ date: date })
        });
    }

    data = await response.json();

    if (response.ok) {
        // Update local completed dates object
        currentHabitCompletedDates[date] = data.current_count;

        // Update cell appearance
        const newCount = data.current_count;
        const isCompleted = newCount >= currentHabitDailyTarget;

        if (isCompleted) {
            cell.classList.add('completed');
        } else {
            cell.classList.remove('completed');
        }

        // Update cell text display
        updateDateCellDisplay(cell, date, newCount);
    }
}


async function completeHabitForDate(event, habitId, date) {
    // Der habitId kommt jetzt direkt vom dataset des Buttons oder der Funktion, die ihn aufruft
    // Sicherstellen, dass habitId gültig ist
    if (!habitId) {
        console.error('Habit ID is undefined for completion.');
        return;
    }
    try {
        const response = await fetch(`/habits/${habitId}/complete`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ date: date })
        });
        const data = await response.json();
        if (response.ok) {
            // Update the modal's date grid immediately
            const dateCells = modalDateGrid.querySelectorAll('.date-cell');
            dateCells.forEach(cell => {
                if (cell.dataset.date === date) {
                    cell.classList.add('completed');
                }
            });
        } else {
            console.error('Failed to complete habit:', data.error);
        }
    } catch (error) {
        console.error('Error completing habit:', error);
    }
}

async function editHabitName() {
    // Sicherstellen, dass currentHabitId gesetzt ist
    if (!currentHabitId) {
        console.error('No habit selected for editing.');
        return;
    }
    const newName = prompt("Neuen Namen für die Gewohnheit eingeben:", modalHabitName.textContent);
    if (newName && newName.trim() !== "") {
        try {
            const response = await fetch(`/habits/${currentHabitId}`, { // Verwendet currentHabitId
                method: 'PUT',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ name: newName.trim() })
            });
            const data = await response.json();
            if (response.ok) {
                modalHabitName.textContent = newName.trim();
                fetchHabits(); // Re-fetch and re-render all habits to update the main view
            } else {
                console.error('Failed to update habit:', data.error);
            }
        } catch (error) {
            console.error('Error updating habit:', error);
        }
    }
}

async function deleteHabitFromModal() {
    // Sicherstellen, dass currentHabitId gesetzt ist
    if (!currentHabitId) {
        console.error('No habit selected for deletion.');
        return;
    }
    if (confirm("Bist du sicher, dass du diese Gewohnheit löschen möchtest?")) {
        try {
            const response = await fetch(`/habits/${currentHabitId}`, { // Verwendet currentHabitId
                method: 'DELETE'
            });
            const data = await response.json();
            if (response.ok) {
                closeModal();
                fetchHabits(); // Re-fetch and re-render all habits
            } else {
                console.error('Failed to delete habit:', data.error);
            }
        } catch (error) {
            console.error('Error deleting habit:', error);
        }
    }
}

async function toggleTodayCompletion(habitId, date, buttonElement, dailyTarget = 1) {
    try {
        // Always increment completion count
        const response = await fetch(`/habits/${habitId}/complete`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ date: date })
        });

        const data = await response.json();
        if (response.ok) {
            const newCount = data.current_count;
            const isCompleted = newCount >= dailyTarget;

            // Update button appearance and text
            if (dailyTarget > 1) {
                buttonElement.innerHTML = `${newCount}/${dailyTarget}`;
            }

            buttonElement.className = isCompleted ? 'completed-today' : 'not-completed-today';

            // Refresh the date grid to show updated completion status
            fetchHabits();
        } else {
            console.error('Failed to toggle habit completion:', data.error);
        }
    } catch (error) {
        console.error('Error toggling habit completion:', error);
    }
}

async function updateHabitColor() {
    if (!currentHabitId) {
        console.error('No habit selected for color update.');
        return;
    }

    const newColor = document.getElementById('habitColorPicker').value;
    currentHabitColor = newColor;

    try {
        const response = await fetch(`/habits/${currentHabitId}`, {
            method: 'PUT',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ color: newColor })
        });
        const data = await response.json();
        if (response.ok) {
            // Update CSS variable for modal elements
            dateModal.style.setProperty('--current-habit-color', newColor);

            // Update contrast color for text on colored backgrounds
            const contrastColor = getContrastColor(newColor);
            dateModal.style.setProperty('--current-habit-text-color', contrastColor);

            // Update modal calendar colors immediately
            updateModalColors(newColor);
            // Refresh habits list to show new color
            fetchHabits();
        } else {
            console.error('Failed to update habit color:', data.error);
        }
    } catch (error) {
        console.error('Error updating habit color:', error);
    }
}

function updateModalColors(color) {
    // Update all date cells in modal to use new color
    const allCells = modalDateGrid.querySelectorAll('.date-cell');
    allCells.forEach(cell => {
        const dateStr = cell.dataset.date;
        if (dateStr) {
            const dateCount = currentHabitCompletedDates[dateStr] || 0;
            // Re-apply styling with new color
            applyModalCompletionStyling(cell, dateCount, currentHabitDailyTarget, color);
        }
    });
}

function getContrastColor(hexColor) {
    // Convert hex to RGB
    const r = parseInt(hexColor.slice(1, 3), 16);
    const g = parseInt(hexColor.slice(3, 5), 16);
    const b = parseInt(hexColor.slice(5, 7), 16);

    // Calculate luminance
    const luminance = (0.299 * r + 0.587 * g + 0.114 * b) / 255;

    // Return dark text for light colors, light text for dark colors
    return luminance > 0.5 ? '#333333' : '#ffffff';
}

async function updateDailyTarget() {
    if (!currentHabitId) {
        console.error('No habit selected for daily target update.');
        return;
    }

    const newTarget = parseInt(document.getElementById('habitDailyTarget').value);
    if (newTarget < 1 || newTarget > 20) {
        alert('Tägliches Ziel muss zwischen 1 und 20 liegen.');
        return;
    }

    currentHabitDailyTarget = newTarget;

    try {
        const response = await fetch(`/habits/${currentHabitId}`, {
            method: 'PUT',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ daily_target: newTarget })
        });
        const data = await response.json();
        if (response.ok) {
            // Re-render modal calendar with new target
            renderModalCalendar();
            // Refresh habits list to show new target
            fetchHabits();
        } else {
            console.error('Failed to update daily target:', data.error);
        }
    } catch (error) {
        console.error('Error updating daily target:', error);
    }
}

function updateDateCellDisplay(cell, date, count) {
    const day = date.split('-')[2]; // Get day from YYYY-MM-DD format

    // Clear any existing content first
    cell.innerHTML = '';

    // Apply gradient styling for modal cells
    applyModalCompletionStyling(cell, count, currentHabitDailyTarget, currentHabitColor);

    if (currentHabitDailyTarget > 1) {
        // Create structured display with date on top, counter below
        const dayDiv = document.createElement('div');
        dayDiv.className = 'date-day';
        dayDiv.textContent = parseInt(day);

        const counterDiv = document.createElement('div');
        counterDiv.className = 'date-counter';
        counterDiv.textContent = `${count}/${currentHabitDailyTarget}`;

        cell.appendChild(dayDiv);
        cell.appendChild(counterDiv);
    } else {
        cell.textContent = parseInt(day);
    }
}

function applyCompletionStyling(element, currentCount, targetCount, color) {
    // Remove existing classes
    element.classList.remove('completed', 'partial');

    if (currentCount === 0) {
        // No completion - default background
        return;
    } else if (currentCount >= targetCount) {
        // Fully completed - solid color
        element.classList.add('completed');
    } else {
        // Partially completed - gradient
        element.classList.add('partial');
        const percentage = Math.round((currentCount / targetCount) * 100);
        element.style.setProperty('--completion-percentage', `${percentage}%`);
        element.style.setProperty('--habit-color', color);
    }
}

function applyModalCompletionStyling(element, currentCount, targetCount, color) {
    // Remove existing classes
    element.classList.remove('completed', 'partial');

    if (currentCount === 0) {
        // No completion - default background and text
        element.style.removeProperty('color');
        return;
    } else if (currentCount >= targetCount) {
        // Fully completed - solid color with contrast text
        element.classList.add('completed');
        const contrastColor = getContrastColor(color);
        element.style.setProperty('color', contrastColor);
    } else {
        // Partially completed - gradient with smart text color
        element.classList.add('partial');
        const percentage = Math.round((currentCount / targetCount) * 100);
        element.style.setProperty('--completion-percentage', `${percentage}%`);
        element.style.setProperty('--current-habit-color', color);

        // For partial completion, use contrast color if more than 50% completed
        if (percentage > 50) {
            const contrastColor = getContrastColor(color);
            element.style.setProperty('color', contrastColor);
        } else {
            // Use default text color for low completion
            element.style.setProperty('color', '#e0e0e0');
        }
    }
}