// SNOWARE — Dynamic Nature Background (Stars + Mountains + Meteors)
(function(){
  var canvas = document.createElement('canvas');
  canvas.id = 'nature-bg';
  canvas.style.cssText = 'position:fixed;top:0;left:0;width:100%;height:100%;z-index:-1;pointer-events:none;';
  document.body.prepend(canvas);
  var ctx = canvas.getContext('2d');
  var stars = [], shootingStars = [];
  var W, H;
  var lastShooting = 0;

  function resize(){
    W = canvas.width = window.innerWidth;
    H = canvas.height = window.innerHeight;
    initStars();
  }

  function initStars(){
    stars = [];
    var count = Math.floor(W * H / 2800);
    for(var i = 0; i < count; i++){
      stars.push({
        x: Math.random() * W,
        y: Math.random() * H * 0.55,
        r: Math.random() * 1.5 + 0.3,
        a: Math.random() * 0.6 + 0.2,
        speed: Math.random() * 0.008 + 0.002,
        phase: Math.random() * Math.PI * 2
      });
    }
  }

  function addShootingStar(){
    shootingStars.push({
      x: Math.random() * W * 0.6 + W * 0.1,
      y: Math.random() * H * 0.25,
      len: Math.random() * 120 + 60,
      speed: Math.random() * 6 + 4,
      angle: Math.random() * 0.25 + 0.15,
      a: 1,
      life: 0,
      sparks: []
    });
  }

  function getTheme(){
    return document.documentElement.getAttribute('data-theme') || 'warm';
  }

  function getColors(){
    var t = getTheme();
    if(t === 'cyan'){
      return {
        sky1: '#0a1525', sky2: '#101828', sky3: '#182436',
        star: '#c8dff0', starBright: '#81d4fa',
        mtn1: '#0e1826', mtn2: '#162230', mtn3: '#1e2e40',
        mtnLine: 'rgba(92,184,228,0.12)', mtnSnow: 'rgba(200,220,240,0.08)',
        shoot: '#81d4fa', shootGlow: 'rgba(129,212,250,0.2)'
      };
    }
    return {
      sky1: '#0a0c08', sky2: '#141210', sky3: '#1a1710',
      star: '#d4c0a0', starBright: '#e8c9a0',
      mtn1: '#0e0c08', mtn2: '#181610', mtn3: '#242014',
      mtnLine: 'rgba(200,168,122,0.08)', mtnSnow: 'rgba(232,201,160,0.06)',
      shoot: '#e8c9a0', shootGlow: 'rgba(232,201,160,0.15)'
    };
  }

  function drawSky(c){
    var g = ctx.createLinearGradient(0, 0, 0, H);
    g.addColorStop(0, c.sky1);
    g.addColorStop(0.35, c.sky2);
    g.addColorStop(1, c.sky3);
    ctx.fillStyle = g;
    ctx.fillRect(0, 0, W, H);
  }

  function drawStars(c, t){
    for(var i = 0; i < stars.length; i++){
      var s = stars[i];
      var twinkle = Math.sin(t * s.speed + s.phase) * 0.3 + 0.7;
      var alpha = s.a * twinkle;
      ctx.beginPath();
      ctx.arc(s.x, s.y, s.r, 0, Math.PI * 2);
      ctx.fillStyle = s.r > 1.2 ? c.starBright : c.star;
      ctx.globalAlpha = alpha;
      ctx.fill();
    }
    ctx.globalAlpha = 1;
  }

  function drawShootingStars(c, t){
    // More frequent meteors: every 3-7 seconds
    if(t - lastShooting > 3000 + Math.random() * 4000){
      addShootingStar();
      lastShooting = t;
    }
    for(var i = shootingStars.length - 1; i >= 0; i--){
      var s = shootingStars[i];
      s.life += 1;
      s.x += s.speed;
      s.y += s.speed * s.angle;
      s.a -= 0.008;
      if(s.a <= 0){ shootingStars.splice(i, 1); continue; }

      // Head glow
      ctx.save();
      ctx.globalAlpha = s.a * 0.6;
      var headGlow = ctx.createRadialGradient(s.x, s.y, 0, s.x, s.y, 8);
      headGlow.addColorStop(0, c.shoot);
      headGlow.addColorStop(1, 'transparent');
      ctx.fillStyle = headGlow;
      ctx.beginPath();
      ctx.arc(s.x, s.y, 8, 0, Math.PI * 2);
      ctx.fill();

      // Main trail
      ctx.globalAlpha = s.a;
      ctx.strokeStyle = c.shoot;
      ctx.lineWidth = 1.8;
      ctx.lineCap = 'round';
      ctx.beginPath();
      ctx.moveTo(s.x, s.y);
      var tailX = s.x - s.len * Math.cos(s.angle);
      var tailY = s.y - s.len * Math.sin(s.angle);
      ctx.lineTo(tailX, tailY);
      ctx.stroke();

      // Wide glow trail
      ctx.globalAlpha = s.a * 0.25;
      ctx.lineWidth = 6;
      ctx.strokeStyle = c.shoot;
      ctx.beginPath();
      ctx.moveTo(s.x, s.y);
      ctx.lineTo(s.x - s.len * 0.5 * Math.cos(s.angle), s.y - s.len * 0.5 * Math.sin(s.angle));
      ctx.stroke();

      // Secondary thin glow trail
      ctx.globalAlpha = s.a * 0.12;
      ctx.lineWidth = 12;
      ctx.strokeStyle = c.shootGlow;
      ctx.beginPath();
      ctx.moveTo(s.x, s.y);
      ctx.lineTo(s.x - s.len * 0.3 * Math.cos(s.angle), s.y - s.len * 0.3 * Math.sin(s.angle));
      ctx.stroke();

      ctx.restore();
    }
  }

  function drawMountainLayer(yBase, height, color, lineColor, snowPatches, seed){
    ctx.beginPath();
    ctx.moveTo(0, yBase);
    var step = 3;
    for(var x = 0; x <= W; x += step){
      var h = 0;
      h += Math.sin(x * 0.003 + seed) * height * 0.5;
      h += Math.sin(x * 0.007 + seed * 2) * height * 0.3;
      h += Math.sin(x * 0.015 + seed * 3) * height * 0.15;
      ctx.lineTo(x, yBase - Math.abs(h));
    }
    ctx.lineTo(W, H);
    ctx.lineTo(0, H);
    ctx.closePath();
    ctx.fillStyle = color;
    ctx.fill();
    // subtle outline
    ctx.strokeStyle = lineColor;
    ctx.lineWidth = 1;
    ctx.stroke();
    // snow patches on peaks
    if(snowPatches > 0){
      ctx.globalAlpha = snowPatches;
      ctx.fillStyle = lineColor;
      for(var x = 0; x <= W; x += step){
        var h = 0;
        h += Math.sin(x * 0.003 + seed) * height * 0.5;
        h += Math.sin(x * 0.007 + seed * 2) * height * 0.3;
        h += Math.sin(x * 0.015 + seed * 3) * height * 0.15;
        var peakY = yBase - Math.abs(h);
        if(Math.abs(h) > height * 0.6){
          ctx.beginPath();
          ctx.arc(x, peakY + 2, 2 + Math.random(), 0, Math.PI * 2);
          ctx.fill();
        }
      }
      ctx.globalAlpha = 1;
    }
  }

  function drawMountains(c){
    // far layer
    drawMountainLayer(H * 0.65, H * 0.18, c.mtn1, c.mtnLine, c.mtnSnow, 1.2);
    // mid layer
    drawMountainLayer(H * 0.72, H * 0.14, c.mtn2, c.mtnLine, 0, 3.7);
    // near layer
    drawMountainLayer(H * 0.82, H * 0.10, c.mtn3, c.mtnLine, 0, 7.1);
  }

  var startTime = performance.now();
  function render(){
    var t = (performance.now() - startTime) / 1000;
    var c = getColors();
    ctx.clearRect(0, 0, W, H);
    drawSky(c);
    drawStars(c, t);
    drawShootingStars(c, performance.now());
    drawMountains(c);
    requestAnimationFrame(render);
  }

  resize();
  window.addEventListener('resize', resize);
  render();
})();