document.addEventListener('DOMContentLoaded', () => {

    // =============================================
    // 🧠 NEURAL PARTICLE NETWORK — Living Background
    // =============================================
    const canvas = document.getElementById('particle-canvas');
    const ctx = canvas.getContext('2d');
    let particles = [];
    const PARTICLE_COUNT = window.innerWidth < 768 ? 40 : 75;
    const CONNECTION_DIST = 150;
    let mouseX = window.innerWidth / 2;
    let mouseY = window.innerHeight / 2;

    function resizeCanvas() {
        canvas.width = window.innerWidth;
        canvas.height = window.innerHeight;
    }
    resizeCanvas();
    window.addEventListener('resize', resizeCanvas);

    class Particle {
        constructor() {
            this.reset();
        }
        reset() {
            this.x = Math.random() * canvas.width;
            this.y = Math.random() * canvas.height;
            this.vx = (Math.random() - 0.5) * 0.6;
            this.vy = (Math.random() - 0.5) * 0.6;
            this.size = Math.random() * 2.5 + 1;
            this.opacity = Math.random() * 0.6 + 0.2;
        }
        update() {
            // Gentle mouse repulsion
            const dx = this.x - mouseX;
            const dy = this.y - mouseY;
            const dist = Math.sqrt(dx * dx + dy * dy);
            if (dist < 180) {
                const force = (180 - dist) / 180 * 0.3;
                this.vx += (dx / dist) * force * 0.1;
                this.vy += (dy / dist) * force * 0.1;
            }
            // Damping
            this.vx *= 0.998;
            this.vy *= 0.998;
            this.x += this.vx;
            this.y += this.vy;
            // Wrap edges
            if (this.x < -20) this.x = canvas.width + 20;
            if (this.x > canvas.width + 20) this.x = -20;
            if (this.y < -20) this.y = canvas.height + 20;
            if (this.y > canvas.height + 20) this.y = -20;
        }
        draw() {
            ctx.beginPath();
            ctx.arc(this.x, this.y, this.size, 0, Math.PI * 2);
            ctx.fillStyle = `rgba(0, 242, 254, ${this.opacity})`;
            ctx.fill();
        }
    }

    // Initialize particles
    for (let i = 0; i < PARTICLE_COUNT; i++) {
        particles.push(new Particle());
    }

    function animateParticles() {
        ctx.clearRect(0, 0, canvas.width, canvas.height);
        // Update & draw particles
        particles.forEach(p => { p.update(); p.draw(); });
        // Draw connections
        for (let i = 0; i < particles.length; i++) {
            for (let j = i + 1; j < particles.length; j++) {
                const dx = particles[i].x - particles[j].x;
                const dy = particles[i].y - particles[j].y;
                const dist = Math.sqrt(dx * dx + dy * dy);
                if (dist < CONNECTION_DIST) {
                    const alpha = (1 - dist / CONNECTION_DIST) * 0.2;
                    ctx.beginPath();
                    ctx.moveTo(particles[i].x, particles[i].y);
                    ctx.lineTo(particles[j].x, particles[j].y);
                    ctx.strokeStyle = `rgba(0, 220, 255, ${alpha})`;
                    ctx.lineWidth = 0.5;
                    ctx.stroke();
                }
            }
        }
        requestAnimationFrame(animateParticles);
    }
    animateParticles();

    // --- Update mouse for particles ---
    document.addEventListener('mousemove', (e) => {
        mouseX = e.clientX;
        mouseY = e.clientY;
        document.documentElement.style.setProperty('--cursor-x', e.clientX / window.innerWidth);
        document.documentElement.style.setProperty('--cursor-y', e.clientY / window.innerHeight);
    });

    // =============================================
    // 📜 SCROLL PROGRESS BAR
    // =============================================
    const scrollProgress = document.getElementById('scroll-progress');
    window.addEventListener('scroll', () => {
        const scrollTop = window.scrollY;
        const docHeight = document.documentElement.scrollHeight - window.innerHeight;
        const progress = docHeight > 0 ? (scrollTop / docHeight) * 100 : 0;
        scrollProgress.style.width = progress + '%';
    });

    // =============================================
    // 🎯 3D TILT EFFECT FOR CARDS
    // =============================================
    const tiltCards = document.querySelectorAll('.tilt-card');
    tiltCards.forEach(card => {
        card.addEventListener('mousemove', (e) => {
            const rect = card.getBoundingClientRect();
            const x = e.clientX - rect.left;
            const y = e.clientY - rect.top;
            const centerX = rect.width / 2;
            const centerY = rect.height / 2;
            const rotateX = ((y - centerY) / centerY) * -6;
            const rotateY = ((x - centerX) / centerX) * 6;
            const glareX = (x / rect.width) * 100;
            const glareY = (y / rect.height) * 100;
            card.style.transform = `perspective(1000px) rotateX(${rotateX}deg) rotateY(${rotateY}deg) scale3d(1.02, 1.02, 1.02)`;
            card.style.setProperty('--glare-x', glareX + '%');
            card.style.setProperty('--glare-y', glareY + '%');
        });
        card.addEventListener('mouseleave', () => {
            card.style.transform = 'perspective(1000px) rotateX(0deg) rotateY(0deg) scale3d(1, 1, 1)';
            card.style.setProperty('--glare-x', '50%');
            card.style.setProperty('--glare-y', '50%');
        });
    });

    // =============================================
    // 🧲 MAGNETIC BUTTONS
    // =============================================
    const magneticBtns = document.querySelectorAll('.magnetic-btn');
    magneticBtns.forEach(btn => {
        btn.addEventListener('mousemove', (e) => {
            const rect = btn.getBoundingClientRect();
            const x = e.clientX - rect.left - rect.width / 2;
            const y = e.clientY - rect.top - rect.height / 2;
            const dist = Math.sqrt(x * x + y * y);
            const maxDist = 120;
            if (dist < maxDist) {
                const strength = (1 - dist / maxDist) * 10;
                btn.style.transform = `translate(${x * strength * 0.06}px, ${y * strength * 0.06}px) scale(1.05)`;
            }
        });
        btn.addEventListener('mouseleave', () => {
            btn.style.transform = 'translate(0px, 0px) scale(1)';
        });
    });

    // =============================================
    // 🌈 SCROLL-DRIVEN COLOR MORPHING
    // =============================================
    window.addEventListener('scroll', () => {
        const scrollTop = window.scrollY;
        const maxScroll = document.documentElement.scrollHeight - window.innerHeight;
        const scrollFraction = maxScroll > 0 ? scrollTop / maxScroll : 0;
        // Hue shifts from 188 (cyan) → 200 (blue) → 270 (violet)
        const hue = 188 + scrollFraction * 82;
        document.documentElement.style.setProperty('--accent-hue', hue);
    });

    // =============================================
    // 👁️ FADE-IN OBSERVER FOR TIMELINE
    // =============================================
    const timelineItems = document.querySelectorAll('.timeline-item');
    const observer = new IntersectionObserver((entries) => {
        entries.forEach(entry => {
            if (entry.isIntersecting) {
                entry.target.classList.add('revealed');
            }
        });
    }, { threshold: 0.2 });
    timelineItems.forEach(item => observer.observe(item));

    // =============================================
    // 🔄 MODE TOGGLE: Bento Grid <-> Terminal
    // =============================================
    const toggleBtn = document.getElementById('mode-toggle');
    const mainContent = document.getElementById('main-content');
    const terminalMode = document.getElementById('terminal-mode');
    const terminalOutput = document.getElementById('terminal-output');
    const terminalInput = document.getElementById('terminal-input');
    const toggleText = document.getElementById('toggle-text');
    let isTerminal = false;

    toggleBtn.addEventListener('click', () => {
        if (!isTerminal) {
            if (document.startViewTransition) {
                document.startViewTransition(() => {
                    mainContent.classList.add('hidden');
                    terminalMode.classList.remove('hidden');
                });
            } else {
                mainContent.classList.add('hidden');
                terminalMode.classList.remove('hidden');
            }
            toggleText.textContent = '🏠 GUI';
            printTerminal("SYSTEM > Terminal Mode Activated.", 'cyan');
            printTerminal("Type 'help' for a list of commands.", 'dim');
            isTerminal = true;
            terminalInput.focus();
        } else {
            if (document.startViewTransition) {
                document.startViewTransition(() => {
                    terminalMode.classList.add('hidden');
                    mainContent.classList.remove('hidden');
                });
            } else {
                terminalMode.classList.add('hidden');
                mainContent.classList.remove('hidden');
            }
            toggleText.textContent = '>_ TERMINAL';
            isTerminal = false;
        }
    });

    // =============================================
    // 💻 ENHANCED TERMINAL LOGIC
    // =============================================
    const commands = {
        help: {
            desc: "Shows this help message",
            action: () => {
                let output = "Available Commands:\n";
                for (let cmd in commands) {
                    output += `  ${cmd.padEnd(14)} - ${commands[cmd].desc}\n`;
                }
                return output;
            }
        },
        whoami: {
            desc: "Display current user",
            action: () => "🛡️  Sebastian F. Nestler | TryHackMe Top 7% | Annaberg-Buchholz, DE"
        },
        skills: {
            desc: "List core competencies",
            action: () => "⚡ Python | JavaScript | C | SQL | Logfile Analysis | Incident Response | Applied AI & Automation"
        },
        contact: {
            desc: "Show contact info",
            action: () => "📧 snestler110@gmail.com  |  🌐 nestler.dev  |  🏅 credly.com/users/sebastian-nestler"
        },
        experience: {
            desc: "Show career timeline",
            action: () => {
                return `📋 CAREER TIMELINE:
  [2022-2023] 3rd Level Support Engineer @ GK Software SE
  [2022]      Ethical Hacking Trainee @ T-Systems
  [2016]      Dispatcher & Medical Assistant @ KV Brandenburg
  [2010-2014]  Independent Entrepreneur @ Rio de Janeiro
  [2001-2015]  Paramedic / Medical Assistant @ Multiple Orgs`;
            }
        },
        education: {
            desc: "Show educational background",
            action: () => {
                return `🎓 EDUCATION:
  • Medical Studies (1st State Exam) — Friedrich Schiller Univ. Jena
  • Certified Pharmaceutical Consultant (IHK) — Pharmaakademie Leipzig
  • Paramedic Training — Landesschule Sachsen Rotes Kreuz`;
            }
        },
        languages: {
            desc: "Show spoken languages",
            action: () => "🗣️ German (Native) | English (Fluent) | Portuguese (Fluent - Brazilian)"
        },
        clear: {
            desc: "Clear the terminal",
            action: () => {
                terminalOutput.innerHTML = '';
                return '';
            }
        },
        matrix: {
            desc: "Fun easter egg",
            action: () => {
                let rain = '';
                const chars = '01アイウエオカキクケコサシスセソタチツテト';
                for (let i = 0; i < 15; i++) {
                    let line = '';
                    for (let j = 0; j < 50; j++) {
                        line += chars[Math.floor(Math.random() * chars.length)];
                    }
                    rain += line + '\n';
                }
                return rain;
            }
        }
    };

    function printTerminal(text, color = 'green') {
        const span = document.createElement('span');
        span.textContent = text + '\n';
        if (color === 'dim') span.style.opacity = '0.5';
        if (color === 'cyan') span.style.color = '#00F2FE';
        if (color === 'red') span.style.color = '#ff4444';
        if (color === 'white') span.style.color = '#e0ffe0';
        terminalOutput.appendChild(span);
        terminalOutput.scrollTop = terminalOutput.scrollHeight;
    }

    terminalInput.addEventListener('keydown', (e) => {
        if (e.key === 'Enter') {
            const input = terminalInput.value.trim().toLowerCase();
            terminalInput.value = '';
            if (commands[input]) {
                const result = commands[input].action();
                printTerminal(`❯ ${input}`, 'white');
                if (result) printTerminal(result, 'white');
            } else if (input !== '') {
                printTerminal(`❯ ${input}`, 'white');
                printTerminal(`Command not found: ${input}. Type 'help' for options.`, 'red');
            }
        }
    });

    function initTerminal() {
        const welcomeMsg = `
 ██████╗██╗   ██╗██████╗ ███████╗██████╗     ███╗   ███╗███████╗██████╗ 
██╔════╝╚██╗ ██╔╝██╔══██╗██╔════╝██╔══██╗    ████╗ ████║██╔════╝██╔══██╗
██║      ╚████╔╝ ██████╔╝█████╗  ██████╔╝    ██╔████╔██║█████╗  ██║  ██║
██║       ╚██╔╝  ██╔══██╗██╔══╝  ██╔══██╗    ██║╚██╔╝██║██╔══╝  ██║  ██║
╚██████╗   ██║   ██████╔╝███████╗██║  ██║    ██║ ╚═╝ ██║███████╗██████╔╝
 ╚═════╝   ╚═╝   ╚═════╝ ╚══════╝╚═╝  ╚═╝    ╚═╝     ╚═╝╚══════╝╚═════╝ 
`;
        printTerminal(welcomeMsg, 'cyan');
        printTerminal('⚡ CYBER-MEDICAL TERMINAL v2.0 — Sebastian F. Nestler', 'white');
        printTerminal('🛡️ Cybersecurity | 🤖 AI Applications | 🏥 Emergency Operations', 'dim');
        printTerminal('\nType "help" to explore available commands.', 'dim');
    }
    initTerminal();

});