@charset "UTF-8";

$breakpoints: (
  'phone': 320px,
  'tablet': 768px,
  'desktop': 1024px
) !default;

$media-expressions: (
  'screen': 'screen',
  'print': 'print',
  'handheld': 'handheld',
  'landscape': '(orientation: landscape)',
  'portrait': '(orientation: portrait)',
  'retina2x': '(-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi), (min-resolution: 2dppx)',
  'retina3x': '(-webkit-min-device-pixel-ratio: 3), (min-resolution: 350dpi), (min-resolution: 3dppx)'
) !default;

$unit-intervals: (
  'px': 1,
  'em': 0.01,
  'rem': 0.1,
  '': 0
) !default;

$im-media-support: true !default;

$im-no-media-breakpoint: 'desktop' !default;

$im-no-media-expressions: ('screen', 'portrait', 'landscape') !default;

@function im-log($message) {
  @if feature-exists('at-error') {
    @error $message;
  } @else {
    @warn $message;
    $_: noop();
  }

  @return $message;
}

@mixin log($message) {
  @if im-log($message) {}
}

@function noop() {}

@function im-intercepts-static-breakpoint($conditions...) {
  $no-media-breakpoint-value: map-get($breakpoints, $im-no-media-breakpoint);

  @if not $no-media-breakpoint-value {
    @if im-log('`#{$im-no-media-breakpoint}` is not a valid breakpoint.') {}
  }

  @each $condition in $conditions {
    @if not map-has-key($media-expressions, $condition) {
      $operator: get-expression-operator($condition);
      $prefix: get-expression-prefix($operator);
      $value: get-expression-value($condition, $operator);

      @if ($prefix == 'max' and $value <= $no-media-breakpoint-value) or
          ($prefix == 'min' and $value > $no-media-breakpoint-value) {
        @return false;
      }
    } @else if not index($im-no-media-expressions, $condition) {
      @return false;
    }
  }

  @return true;
}

@function get-expression-operator($expression) {
  @each $operator in ('>=', '>', '<=', '<', '≥', '≤') {
    @if str-index($expression, $operator) {
      @return $operator;
    }
  }

  $_: im-log('No operator found in `#{$expression}`.');
}

@function get-expression-dimension($expression, $operator) {
  $operator-index: str-index($expression, $operator);
  $parsed-dimension: str-slice($expression, 0, $operator-index - 1);
  $dimension: 'width';

  @if str-length($parsed-dimension) > 0 {
    $dimension: $parsed-dimension;
  }

  @return $dimension;
}

@function get-expression-prefix($operator) {
  @return if(index(('<', '<=', '≤'), $operator), 'max', 'min');
}

@function get-expression-value($expression, $operator) {
  $operator-index: str-index($expression, $operator);
  $value: str-slice($expression, $operator-index + str-length($operator));

  @if map-has-key($breakpoints, $value) {
    $value: map-get($breakpoints, $value);
  } @else {
    $value: to-number($value);
  }

  $interval: map-get($unit-intervals, unit($value));

  @if not $interval {
    $_: im-log('Unknown unit `#{unit($value)}`.');
  }

  @if $operator == '>' {
    $value: $value + $interval;
  } @else if $operator == '<' {
    $value: $value - $interval;
  }

  @return $value;
}

@function parse-expression($expression) {
  @if map-has-key($media-expressions, $expression) {
    @return map-get($media-expressions, $expression);
  }

  $operator: get-expression-operator($expression);
  $dimension: get-expression-dimension($expression, $operator);
  $prefix: get-expression-prefix($operator);
  $value: get-expression-value($expression, $operator);

  @return '(#{$prefix}-#{$dimension}: #{$value})';
}

@function slice($list, $start: 1, $end: length($list)) {
  @if length($list) < 1 or $start > $end {
    @return ();
  }

  $result: ();

  @for $i from $start through $end {
    $result: append($result, nth($list, $i));
  }

  @return $result;
}

@function to-number($value) {
  @if type-of($value) == 'number' {
    @return $value;
  } @else if type-of($value) != 'string' {
    $_: im-log('Value for `to-number` should be a number or a string.');
  }

  $first-character: str-slice($value, 1, 1);
  $result: 0;
  $digits: 0;
  $minus: ($first-character == '-');
  $numbers: ('0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9);

  @if ($first-character == '+' or $first-character == '-') {
    $value: str-slice($value, 2);
  }

  @for $i from 1 through str-length($value) {
    $character: str-slice($value, $i, $i);

    @if not (index(map-keys($numbers), $character) or $character == '.') {
      @return to-length(if($minus, -$result, $result), str-slice($value, $i))
    }

    @if $character == '.' {
      $digits: 1;
    } @else if $digits == 0 {
      $result: $result * 10 + map-get($numbers, $character);
    } @else {
      $digits: $digits * 10;
      $result: $result + map-get($numbers, $character) / $digits;
    }
  }

  @return if($minus, -$result, $result);
}

@function to-length($value, $unit) {
  $units: ('px': 1px, 'cm': 1cm, 'mm': 1mm, '%': 1%, 'ch': 1ch, 'pc': 1pc, 'in': 1in, 'em': 1em, 'rem': 1rem, 'pt': 1pt, 'ex': 1ex, 'vw': 1vw, 'vh': 1vh, 'vmin': 1vmin, 'vmax': 1vmax);

  @if not index(map-keys($units), $unit) {
    $_: im-log('Invalid unit `#{$unit}`.');
  }

  @return $value * map-get($units, $unit);
}


@mixin media-context($tweakpoints: (), $tweak-media-expressions: ()) {
  $global-breakpoints: $breakpoints;
  $global-media-expressions: $media-expressions;

  $breakpoints: map-merge($breakpoints, $tweakpoints) !global;
  $media-expressions: map-merge($media-expressions, $tweak-media-expressions) !global;

  @content;

  $breakpoints: $global-breakpoints !global;
  $media-expressions: $global-media-expressions !global;
}

@mixin media($conditions...) {
  @if ($im-media-support and length($conditions) == 0) or
      (not $im-media-support and im-intercepts-static-breakpoint($conditions...)) {
    @content;
  } @else if ($im-media-support and length($conditions) > 0) {
    @media #{unquote(parse-expression(nth($conditions, 1)))} {
      @include media(slice($conditions, 2)...) {
        @content;
      }
    }
  }
}