const themeToggleBtn = document.getElementById('theme-toggle');
const roomConfigForm = document.getElementById('room-config-form');
const statusLine = document.getElementById('config-status');
const scaleSelect = document.getElementById('estimation-scale');
const maxPeopleInput = document.getElementById('max-people');
const previewScale = document.getElementById('preview-scale');
const previewMaxPeople = document.getElementById('preview-max-people');
const previewCards = document.getElementById('preview-cards');
const customCardInput = document.getElementById('custom-card');
const addCardButton = document.getElementById('add-card');

const SCALE_PRESETS = {
    fibonacci: ['0', '1', '2', '3', '5', '8', '13', '21', '?'],
    tshirt: ['XS', 'S', 'M', 'L', 'XL', '?'],
    'powers-of-two': ['1', '2', '4', '8', '16', '32', '?'],
};

let isDarkMode = false;
let nextCardID = 1;
let currentCards = [];

themeToggleBtn.addEventListener('click', () => {
    isDarkMode = !isDarkMode;
    if (isDarkMode) {
        document.documentElement.setAttribute('data-theme', 'dark');
        themeToggleBtn.textContent = 'Light Mode';
        return;
    }

    document.documentElement.removeAttribute('data-theme');
    themeToggleBtn.textContent = 'Dark Mode';
});

function createCard(value) {
    return { id: nextCardID++, value: value.toString() };
}

function getCardsForScale(scale) {
    return (SCALE_PRESETS[scale] || SCALE_PRESETS.fibonacci).map(createCard);
}

function captureCardPositions() {
    const positions = new Map();
    previewCards.querySelectorAll('.preview-card').forEach((el) => {
        positions.set(el.dataset.cardId, el.getBoundingClientRect());
    });
    return positions;
}

function animateCardReflow(previousPositions) {
    previewCards.querySelectorAll('.preview-card').forEach((el) => {
        const oldRect = previousPositions.get(el.dataset.cardId);
        if (!oldRect) {
            el.style.opacity = '0';
            el.style.transform = 'scale(0.85)';
            requestAnimationFrame(() => {
                el.style.opacity = '1';
                el.style.transform = 'translate(0, 0) scale(1)';
            });
            return;
        }

        const newRect = el.getBoundingClientRect();
        const deltaX = oldRect.left - newRect.left;
        const deltaY = oldRect.top - newRect.top;

        if (deltaX === 0 && deltaY === 0) {
            return;
        }

        el.style.transform = `translate(${deltaX}px, ${deltaY}px)`;
        requestAnimationFrame(() => {
            el.style.transform = 'translate(0, 0)';
        });
    });
}

function renderCards(previousPositions = new Map()) {
    previewCards.innerHTML = '';

    currentCards.forEach((card) => {
        const cardEl = document.createElement('div');
        cardEl.className = 'preview-card';
        cardEl.dataset.cardId = String(card.id);
        cardEl.textContent = card.value;

        const removeBtn = document.createElement('button');
        removeBtn.type = 'button';
        removeBtn.className = 'preview-card-remove';
        removeBtn.textContent = 'X';
        removeBtn.setAttribute('aria-label', `Remove card ${card.value}`);
        removeBtn.addEventListener('click', (event) => {
            event.stopPropagation();
            removeCard(card.id);
        });

        cardEl.appendChild(removeBtn);
        previewCards.appendChild(cardEl);
    });

    animateCardReflow(previousPositions);
}

function removeCard(cardID) {
    const cardEl = previewCards.querySelector(`[data-card-id="${cardID}"]`);
    if (!cardEl) {
        return;
    }

    cardEl.classList.add('is-removing');

    window.setTimeout(() => {
        const previousPositions = captureCardPositions();
        currentCards = currentCards.filter((card) => card.id !== cardID);
        renderCards(previousPositions);
    }, 160);
}

function resetCardsForCurrentScale() {
    const previousPositions = captureCardPositions();
    currentCards = getCardsForScale(scaleSelect.value);
    renderCards(previousPositions);
}

function updatePreviewMeta() {
    previewScale.textContent = `Scale: ${scaleSelect.value}`;
    previewMaxPeople.textContent = `Max: ${maxPeopleInput.value || 0}`;
}

addCardButton.addEventListener('click', () => {
    const value = customCardInput.value.trim();
    if (!value) {
        return;
    }

    const previousPositions = captureCardPositions();
    currentCards.push(createCard(value.slice(0, 8)));
    renderCards(previousPositions);
    customCardInput.value = '';
    customCardInput.focus();
});

customCardInput.addEventListener('keydown', (event) => {
    if (event.key === 'Enter') {
        event.preventDefault();
        addCardButton.click();
    }
});

scaleSelect.addEventListener('change', () => {
    resetCardsForCurrentScale();
    updatePreviewMeta();
    statusLine.textContent = 'Card deck reset to selected estimation scale.';
});

maxPeopleInput.addEventListener('input', () => {
    updatePreviewMeta();
});

roomConfigForm.addEventListener('submit', (event) => {
    event.preventDefault();

    const formData = new FormData(roomConfigForm);
    const roomName = (formData.get('roomName') || '').toString().trim();
    const username = (formData.get('username') || '').toString().trim();

    if (!roomName || !username) {
        statusLine.textContent = 'Please fill in both room name and username.';
        return;
    }

    statusLine.textContent = `Room "${roomName}" prepared by ${username} with ${currentCards.length} cards.`;
});

roomConfigForm.addEventListener('reset', () => {
    window.setTimeout(() => {
        updatePreviewMeta();
        resetCardsForCurrentScale();
        statusLine.textContent = 'Room settings reset to defaults.';
    }, 0);
});

updatePreviewMeta();
resetCardsForCurrentScale();