/**
 * @license
 * Copyright Endlessjs. All Rights Reserved.
 * Licensed under the MIT License. See License.txt in the project root for license information.
 */

@mixin el-scrollbars($fg, $bg, $size, $border-radius: $size / 2) {
  &::-webkit-scrollbar {
    width: $size;
    height: $size;
  }

  &::-webkit-scrollbar-thumb {
    background: $fg;
    cursor: pointer;
    border-radius: $border-radius;
  }

  &::-webkit-scrollbar-track {
    background: $bg;
  }

  // TODO: remove
  // For Internet Explorer
  scrollbar-face-color: $fg;
  scrollbar-track-color: $bg;
}

@mixin el-headings($from: 1, $to: 6) {
  @for $i from $from through $to {
    h#{$i} {
      margin: 0;
    }
  }
}

@mixin hover-focus-active {
  &:focus,
  &:active,
  &:hover {
    @content;
  }
}

@mixin center-horizontal-absolute {
  position: absolute;
  transform: translate(-50%, 0);
  left: 50%;
}

@mixin install-thumb() {
  $thumb-selectors: (
    '::-webkit-slider-thumb'
    '::-moz-range-thumb'
    '::-ms-thumb'
  );

  @each $selector in $thumb-selectors {
    &#{$selector} {
      -webkit-appearance: none;
      -moz-appearance: none;
      @content;
    }
  }
}

@mixin install-track() {
  $thumb-selectors: (
    '::-webkit-slider-runnable-track'
    '::-moz-range-track'
    '::-ms-track'
  );

  @each $selector in $thumb-selectors {
    &#{$selector} {
      -webkit-appearance: none;
      -moz-appearance: none;
      @content;
    }
  }
}

@mixin install-placeholder($color, $font-size, $opacity: 1) {
  $placeholder-selectors: (
    '::-webkit-input-placeholder'
    '::-moz-placeholder'
    ':-moz-placeholder'
    ':-ms-input-placeholder'
  );

  &::placeholder {
    @include placeholder($color, $font-size, $opacity);
  }

  @each $selector in $placeholder-selectors {
    &#{$selector} {
      @include placeholder($color, $font-size, $opacity);
    }

    &:focus#{$selector} {
      @include placeholder-focus();
    }
  }
}

@mixin placeholder($color, $font-size, $opacity) {
  color: $color;
  font-size: $font-size;
  opacity: $opacity;
  transition: opacity 0.3s ease;
  text-overflow: ellipsis;
}

@mixin placeholder-focus() {
  opacity: 0;
  transition: opacity 0.3s ease;
}

@mixin el-component-animation($properties...) {
  transition-duration: 0.15s;
  transition-property: $properties;
  transition-timing-function: ease-in;
}

@mixin animation($animate...) {
  $max: length($animate);
  $animations: '';

  @for $i from 1 through $max {
    $animations: #{$animations + nth($animate, $i)};

    @if $i < $max {
      $animations: #{$animations + ', '};
    }
  }
  -webkit-animation: $animations;
  -moz-animation:    $animations;
  -o-animation:      $animations;
  animation:         $animations;
}

@mixin keyframes($animationName) {
  @-webkit-keyframes #{$animationName} {
    @content;
  }
  @-moz-keyframes #{$animationName} {
    @content;
  }
  @-o-keyframes #{$animationName} {
    @content;
  }
  @keyframes #{$animationName} {
    @content;
  }
}

/**
 * This mixin generates keyfames.
 * Because of all keyframes can't be scoped,
 * we need to puts unique name in each btn-pulse call.
 */
@mixin btn-pulse($name, $color) {
  &.btn-pulse {
    @include animation(btn-#{$name}-pulse 1.5s infinite);
  }

  @include keyframes(btn-#{$name}-pulse) {
    0% {
      box-shadow: none;
      opacity: el-theme(btn-disabled-opacity);
    }
    50% {
      box-shadow: 0 0 1rem 0 $color;
      opacity: 0.8;
    }
    100% {
      box-shadow: none;
      opacity: el-theme(btn-disabled-opacity);
    }
  }
}

/*

According to the specification (https://www.w3.org/TR/css-scoping-1/#host-selector)
:host and :host-context are pseudo-classes. So we assume they could be combined,
like other pseudo-classes, even same ones.
For example: ':nth-of-type(2n):nth-of-type(even)'.

Ideal solution would be to prepend any selector with :host-context([dir=rtl]).
Then endlessjs components will behave as an html element and respond to [dir] attribute on any level,
so direction could be overridden on any component level.

Implementation code:

@mixin el-rtl() {
  // add # to scss interpolation statement.
  // it works in comments and we can't use it here
  @at-root {selector-append(':host-context([dir=rtl])', &)} {
    @content;
  }
}

And when we call it somewhere:

:host {
  .some-class {
    @include el-rtl() {
      ...
    }
  }
}
:host-context(...) {
  .some-class {
    @include el-rtl() {
      ...
    }
  }
}

Result will look like:

:host-context([dir=rtl]):host .some-class {
  ...
}
:host-context([dir=rtl]):host-context(...) .some-class {
  ...
}

*
  Side note:
  :host-context():host selector are valid. https://lists.w3.org/Archives/Public/www-style/2015Feb/0305.html

  :host-context([dir=rtl]):host-context(...) should match any permutation,
  so order is not important.
*


Currently, there're two problems with this approach:

First, is that we can't combine :host, :host-context. Angular bugs #14349, #19199.
For the moment of writing, the only possible way is:
:host {
  :host-context(...) {
    ...
  }
}
It doesn't work for us because mixin could be called somewhere deeper, like:
:host {
  p {
    @include el-rtl() { ... }
  }
}
We are not able to go up to :host level to place content passed to mixin.

The second problem is that we only can be sure that we appending :host-context([dir=rtl]) to another
:host/:host-context pseudo-class when called in theme files (*.theme.scss).
  *
    Side note:
    Currently, el-install-component uses another approach where :host prepended with the theme name
    (https://github.com/angular/angular/blob/5b96078624b0a4760f2dbcf6fdf0bd62791be5bb/packages/compiler/src/shadow_css.ts#L441),
    but it was made to be able to use current realization of rtl and it can be rewritten back to
    :host-context($theme) once we will be able to use multiple shadow selectors.
  *
But when it's called in *.component.scss we can't be sure, that selector starts with :host/:host-context,
because angular allows omitting pseudo-classes if we don't need to style :host component itself.
We can break such selectors, by just appending :host-context([dir=rtl]) to them.
  ***
    Possible solution
    check if we in theme by some theme variables and if so append, otherwise nest like
    @at-root :host-context([dir=rtl]) {
      // add # to scss interpolation statement.
      // it works in comments and we can't use it here
      {&} {
        @content;
      }
    }
    What if :host specified? Can we add space in :host-context(...) :host?
    Or maybe add :host selector anyway? If multiple :host selectors are allowed
  ***


Problems with the current approach.

1. Direction can be applied only on document level, because mixin prepends theme class,
which placed on the body.
2. *.component.scss styles should be in :host selector. Otherwise angular will add host
attribute to [dir=rtl] attribute as well.


General problems.

Ltr is default document direction, but for proper work of el-ltr (means ltr only),
[dir=ltr] should be specified at least somewhere. ':not([dir=rtl]' not applicable here,
because it's satisfy any parent, that don't have [dir=rtl] attribute.
Previous approach was to use single rtl mixin and reset ltr properties to initial value.
But sometimes it's hard to find, what the previous value should be. And such mixin call looks too verbose.
*/

@mixin _prepend-with-selector($selector, $prop: null, $value: null) {
  #{$selector} & {
    @if $prop != null {
      #{$prop}: $value;
    }

    @content;
  }
}

@mixin el-ltr($prop: null, $value: null) {
  @include _prepend-with-selector('[dir=ltr]', $prop, $value) {
    @content;
  }
}

@mixin el-rtl($prop: null, $value: null) {
  @include _prepend-with-selector('[dir=rtl]', $prop, $value) {
    @content;
  };
}
