@import "helpers";
@import "fonts/clear-sans.css";

$field-width: 500px;
$grid-spacing: 15px;
$grid-row-cells: 4;
$tile-size: ($field-width - $grid-spacing * ($grid-row-cells + 1)) / $grid-row-cells;
$tile-border-radius: 3px;

$text-color: #776E65;
$bright-text-color: #f9f6f2;

$tile-color: #eee4da;
$tile-gold-color: #edc22e;
$tile-gold-glow-color: lighten($tile-gold-color, 15%);

$transition-speed: 100ms;

html, body {
  margin: 0;
  padding: 0;

  background: #faf8ef;
  color: $text-color;
  font-family: "Clear Sans", "Helvetica Neue", Arial, sans-serif;
  font-size: 18px;
}

body {
  margin: 80px 0;
}

h1 {
  font-size: 80px;
  font-weight: bold;
  margin: 0;
}

p {
  margin-top: 0;
  margin-bottom: 10px;
  line-height: 1.65;
}

a {
  color: $text-color;
  font-weight: bold;
  text-decoration: underline;
}

strong {
  &.important {
    text-transform: uppercase;
  }
}

hr {
  border: none;
  border-bottom: 1px solid lighten($text-color, 40%);
  margin-top: 20px;
  margin-bottom: 30px;
}

.container {
  width: $field-width;
  margin: 0 auto;
}

.game-container {
  margin-top: 40px;
  position: relative;
  padding: $grid-spacing;

  cursor: default;
  -webkit-touch-callout: none;
  -webkit-user-select: none;
  -moz-user-select: none;

  background: #bbada0;
  border-radius: $tile-border-radius * 2;
  width: $field-width;
  height: $field-width;
  box-sizing: border-box;
}

.grid-container {
  position: absolute;
  z-index: 1;
}

.grid-row {
  margin-bottom: $grid-spacing;

  &:last-child {
    margin-bottom: 0;
  }

  &:after {
    content: "";
    display: block;
    clear: both;
  }
}

.grid-cell {
  width: $tile-size;
  height: $tile-size;
  margin-right: $grid-spacing;
  float: left;

  border-radius: $tile-border-radius;

  background: rgba($tile-color, .35);

  &:last-child {
    margin-right: 0;
  }
}

.tile-container {
  position: absolute;
  z-index: 2;
}

.tile {
  background: red;
  width: $tile-size;
  height: $tile-size;
  border-radius: $tile-border-radius;

  background: $tile-color;
  text-align: center;
  line-height: $tile-size + 10px;
  font-size: 55px;
  font-weight: bold;

  @include transition($transition-speed ease-in-out);
  @include transition-property(top, left);

  // Build position classes
  @for $x from 1 through $grid-row-cells {
    @for $y from 1 through $grid-row-cells {
      &.tile-position-#{$x}-#{$y} {
        position: absolute;
        left: ($tile-size + $grid-spacing) * ($x - 1);
        top: ($tile-size + $grid-spacing) * ($y - 1);
      }
    }
  }

  $base: 2;
  $exponent: 1;
  $limit: 11;

  // Colors for all 11 states, false = no special color
  $special-colors: false false, // 2
                   false false, // 4
                   #f78e48 true, // 8
                   #fc5e2e true, // 16
                   #ff3333 true, // 32
                   #ff0000 true, // 64
                   false true, // 128
                   false true, // 256
                   false true, // 512
                   false true, // 1024
                   false true; // 2048

  // Build tile colors
  @while $exponent <= $limit {
    $power: pow($base, $exponent);

    &.tile-#{$power} {
      // Calculate base background color
      $gold-percent: ($exponent - 1) / ($limit - 1) * 100;
      $mixed-background: mix($tile-gold-color, $tile-color, $gold-percent);

      $nth-color: nth($special-colors, $exponent);

      $special-background: nth($nth-color, 1);
      $bright-color: nth($nth-color, 2);

      @if $special-background {
        $mixed-background: mix($special-background, $mixed-background, 55%);
      }

      @if $bright-color {
        color: $bright-text-color;
      }

      // Set background
      background: $mixed-background;

      // Add glow
      $glow-opacity: max($exponent - 4, 0) / ($limit - 4);
      box-shadow: 0 0 30px 10px rgba($tile-gold-glow-color, $glow-opacity / 1.8),
                  inset 0 0 0 1px rgba(white, $glow-opacity / 3);

      // Adjust font size for bigger numbers
      @if $power >= 100 and $power < 1000 {
        font-size: 45px;
      } @else if $power >= 1000 {
        font-size: 35px;
      }
    }

    $exponent: $exponent + 1;
  }
}

@include keyframes(appear) {
  0% {
    -webkit-transform: scale(1.5);
    opacity: 0;
  }

  100% {
    -webkit-transform: scale(1);
    opacity: 1;
  }
}

.tile-new {
  @include animation(appear 200ms ease $transition-speed);
  @include animation-fill-mode(both);
}

.game-intro {
  margin-bottom: 0;
}

.game-explanation {
  margin-top: 50px;
}