import { initializeApp } from "https://www.gstatic.com/firebasejs/10.8.0/firebase-app.js";
import { getAuth, createUserWithEmailAndPassword, signInWithEmailAndPassword, signOut, onAuthStateChanged } from "https://www.gstatic.com/firebasejs/10.8.0/firebase-auth.js";
import { getFirestore, collection, addDoc, deleteDoc, doc, onSnapshot, query, orderBy, where, setDoc, getDoc, limit } from "https://www.gstatic.com/firebasejs/10.8.0/firebase-firestore.js";

// --- CONFIGURATION ---
const firebaseConfig = {
    apiKey: "AIzaSyACa6exkcvxegYEsudPpw9puJt7NcZQYrY",
    authDomain: "calories-75d65.firebaseapp.com",
    projectId: "calories-75d65",
    storageBucket: "calories-75d65.firebasestorage.app",
    messagingSenderId: "875037676758",
    appId: "1:875037676758:web:3db8c1bf501f08d740e577",
    measurementId: "G-G9H9Q84MEG"
};

const app = initializeApp(firebaseConfig);
const auth = getAuth(app);
const db = getFirestore(app);
const MEALS_COL = "meals";
const PREFS_COL = "user_settings";

// State
let currentUser = null;
let unsubscribeMeals = null;
let PROFILE = { 
    calories: 2500, protein: 180, carbs: 250, fat: 80,
    weight: 180, tdee: 2500 
};

// UI Refs
const authView = document.getElementById('auth-view');
const appView = document.getElementById('app-view');
const errorMsg = document.getElementById('auth-error');
const modal = document.getElementById('settings-modal');

// Display & Bar Refs
const displays = {
    cals: document.getElementById('total-cals'),
    prot: document.getElementById('total-prot'),
    carb: document.getElementById('total-carb'),
    fat: document.getElementById('total-fat'),
    predWeight: document.getElementById('pred-weight'),
    predDiff: document.getElementById('pred-diff'),
    calPercent: document.getElementById('cal-percent'),
    calBarFill: document.getElementById('cal-bar-fill'),
    protBar: document.getElementById('prot-bar'),
    carbBar: document.getElementById('carb-bar'),
    fatBar: document.getElementById('fat-bar')
};

const ring = document.getElementById('ring-cals');
const circumference = 2 * Math.PI * 42;

// Initialize ring
ring.style.strokeDasharray = `${circumference} ${circumference}`;
ring.style.strokeDashoffset = circumference;

// Set greeting based on time
function setGreeting() {
    const hour = new Date().getHours();
    const greeting = document.getElementById('greeting');
    if (hour < 12) greeting.textContent = 'Good morning';
    else if (hour < 18) greeting.textContent = 'Good afternoon';
    else greeting.textContent = 'Good evening';
}

// --- AUTH HANDLERS ---
document.getElementById('login-btn').addEventListener('click', () => {
    const e = document.getElementById('email').value;
    const p = document.getElementById('password').value;
    errorMsg.innerText = "Signing in...";
    signInWithEmailAndPassword(auth, e, p).catch(err => showError(err));
});

document.getElementById('signup-btn').addEventListener('click', () => {
    const e = document.getElementById('email').value;
    const p = document.getElementById('password').value;
    errorMsg.innerText = "Creating account...";
    createUserWithEmailAndPassword(auth, e, p).catch(err => showError(err));
});

document.getElementById('logout-btn').addEventListener('click', () => signOut(auth));

onAuthStateChanged(auth, (user) => {
    if (user) {
        currentUser = user;
        authView.classList.add('hidden');
        appView.classList.remove('hidden');
        setGreeting();
        loadSettings();
        loadMeals();
    } else {
        currentUser = null;
        authView.classList.remove('hidden');
        appView.classList.add('hidden');
        if(unsubscribeMeals) unsubscribeMeals();
        errorMsg.innerText = "";
    }
});

function showError(error) {
    let msg = error.code.replace("auth/", "").replace(/-/g, " ");
    errorMsg.innerText = "Error: " + msg;
}

// --- SETTINGS HANDLERS ---
document.getElementById('settings-btn').addEventListener('click', () => {
    document.getElementById('set-cals').value = PROFILE.calories;
    document.getElementById('set-prot').value = PROFILE.protein;
    document.getElementById('set-carb').value = PROFILE.carbs;
    document.getElementById('set-fat').value = PROFILE.fat;
    document.getElementById('set-weight').value = PROFILE.weight || 180;
    document.getElementById('set-tdee').value = PROFILE.tdee || 2000;
    modal.style.display = 'flex';
});

document.getElementById('close-settings').addEventListener('click', () => modal.style.display = 'none');

modal.addEventListener('click', (e) => {
    if (e.target === modal) modal.style.display = 'none';
});

document.getElementById('settings-form').addEventListener('submit', async (e) => {
    e.preventDefault();
    const newProfile = {
        calories: parseInt(document.getElementById('set-cals').value) || 2000,
        protein: parseInt(document.getElementById('set-prot').value) || 150,
        carbs: parseInt(document.getElementById('set-carb').value) || 200,
        fat: parseInt(document.getElementById('set-fat').value) || 60,
        weight: parseFloat(document.getElementById('set-weight').value) || 180,
        tdee: parseInt(document.getElementById('set-tdee').value) || 2000,
    };
    try {
        await setDoc(doc(db, PREFS_COL, currentUser.uid), newProfile);
        PROFILE = newProfile;
        updateGoalsUI();
        modal.style.display = 'none';
        location.reload();
    } catch (e) {
        alert("Error saving settings: " + e.message);
    }
});

async function loadSettings() {
    const docSnap = await getDoc(doc(db, PREFS_COL, currentUser.uid));
    if (docSnap.exists()) PROFILE = docSnap.data();
    updateGoalsUI();
}

function updateGoalsUI() {
    document.getElementById('goal-label').innerText = `of ${PROFILE.calories} kcal`;
}

// --- DATA LOGIC ---
function loadMeals() {
    const q = query(
        collection(db, MEALS_COL), 
        where("uid", "==", currentUser.uid), 
        orderBy("timestamp", "desc"),
        limit(50)
    );
    
    unsubscribeMeals = onSnapshot(q, 
        (snap) => {
            const entries = [];
            snap.forEach(doc => entries.push({ ...doc.data(), id: doc.id }));
            render(entries);
        },
        (error) => {
            console.error(error);
            if(error.message.includes("index")) {
                alert("Database Index Missing. Check console for link.");
            }
        }
    );
}

document.getElementById('tracker-form').addEventListener('submit', async (e) => {
    e.preventDefault();
    if(!currentUser) return;

    const btn = document.getElementById('submit-btn');
    const btnText = btn.querySelector('span');
    btnText.innerText = "Adding...";

    try {
        await addDoc(collection(db, MEALS_COL), {
            uid: currentUser.uid,
            name: document.getElementById('in-name').value,
            cals: parseInt(document.getElementById('in-cals').value) || 0,
            prot: parseInt(document.getElementById('in-prot').value) || 0,
            carb: parseInt(document.getElementById('in-carb').value) || 0,
            fat: parseInt(document.getElementById('in-fat').value) || 0,
            timestamp: Date.now()
        });
        e.target.reset();
        document.getElementById('in-name').focus();
    } catch (e) {
        alert("Error adding meal: " + e.message);
    }
    btnText.innerText = "Add Entry";
});

window.deleteEntry = async (id) => {
    if(confirm("Delete this entry?")) await deleteDoc(doc(db, MEALS_COL, id));
}

// --- RENDER UI & PREDICTION ---
function render(entries) {
    const todayStr = new Date().toDateString();

    const todaysEntries = entries.filter(item => {
        const itemDate = new Date(item.timestamp).toDateString();
        return itemDate === todayStr;
    });

    const totals = todaysEntries.reduce((acc, item) => {
        acc.cals += item.cals; acc.prot += item.prot; acc.carb += item.carb; acc.fat += item.fat;
        return acc;
    }, { cals: 0, prot: 0, carb: 0, fat: 0 });

    // Update Main Stats
    displays.cals.innerText = totals.cals.toLocaleString();
    displays.prot.innerText = totals.prot + 'g';
    displays.carb.innerText = totals.carb + 'g';
    displays.fat.innerText = totals.fat + 'g';

    // Calculate percentages
    const calPercent = Math.min((totals.cals / PROFILE.calories) * 100, 100);
    const protPercent = Math.min((totals.prot / PROFILE.protein) * 100, 100);
    const carbPercent = Math.min((totals.carb / PROFILE.carbs) * 100, 100);
    const fatPercent = Math.min((totals.fat / PROFILE.fat) * 100, 100);

    // Update percentage display
    displays.calPercent.innerText = Math.round(calPercent) + '%';

    // Update ring
    const offset = circumference - (calPercent / 100) * circumference;
    ring.style.strokeDashoffset = offset;

    // Update bars
    displays.calBarFill.style.width = calPercent + '%';
    displays.protBar.style.width = protPercent + '%';
    displays.carbBar.style.width = carbPercent + '%';
    displays.fatBar.style.width = fatPercent + '%';

    // Over limit styling
    const goalLabel = document.getElementById('goal-label');
    const isOver = totals.cals > PROFILE.calories;
    
    displays.cals.classList.toggle('over', isOver);
    ring.classList.toggle('over', isOver);
    displays.calBarFill.classList.toggle('over', isOver);
    goalLabel.classList.toggle('over', isOver);
    
    if (isOver) {
        goalLabel.innerText = `Over by ${(totals.cals - PROFILE.calories).toLocaleString()} kcal`;
    } else {
        goalLabel.innerText = `of ${PROFILE.calories.toLocaleString()} kcal`;
    }

    // --- WEIGHT PREDICTION ---
    const dailyDeficit = totals.cals - (PROFILE.tdee || 2000); 
    const totalChangeCals = dailyDeficit * 28;
    const lbsChange = totalChangeCals / 3500;
    const futureWeight = (PROFILE.weight || 180) + lbsChange;

    displays.predWeight.innerText = futureWeight.toFixed(1) + " lbs";
    displays.predWeight.classList.toggle('gain', lbsChange > 0);
    
    const changeIndicator = document.querySelector('.change-indicator');
    const changeText = document.querySelector('.change-text');
    
    changeIndicator.classList.toggle('gain', lbsChange > 0);
    
    if (lbsChange > 0) {
        changeText.innerText = `+${lbsChange.toFixed(1)} lbs gain`;
    } else {
        changeText.innerText = `${lbsChange.toFixed(1)} lbs loss`;
    }

    // --- LIST RENDER ---
    const list = document.getElementById('log-list');
    list.innerHTML = '';
    
    entries.forEach(item => {
        const itemDateStr = new Date(item.timestamp).toDateString();
        const isToday = itemDateStr === todayStr;
        
        const timeLabel = new Date(item.timestamp).toLocaleTimeString([], {hour: '2-digit', minute:'2-digit'});
        const dateLabel = isToday ? timeLabel : new Date(item.timestamp).toLocaleDateString([], {month:'short', day:'numeric'});

        const li = document.createElement('li');
        li.className = `log-item${isToday ? '' : ' old'}`;

        li.innerHTML = `
            <div class="item-details">
                <h4>${item.name}</h4>
                <span class="item-time">${dateLabel}</span>
                <div class="item-macros">
                    <span class="p">${item.prot}p</span>
                    <span class="c">${item.carb}c</span>
                    <span class="f">${item.fat}f</span>
                </div>
            </div>
            <div class="item-cals">${item.cals}</div>
            <button class="del-btn" onclick="deleteEntry('${item.id}')">
                <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" width="18" height="18">
                    <line x1="18" y1="6" x2="6" y2="18"/>
                    <line x1="6" y1="6" x2="18" y2="18"/>
                </svg>
            </button>
        `;
        list.appendChild(li);
    });
}