// Name:            Dropdown
//
// Description:     Define style for dropdown
//
// Component:       `.am-dropdown`
//
// Sub-objects:     `.am-dropdown-toggle`
//                  `.am-dropdown-content`
//                  `.am-dropdown-header`
//
// Modifiers:       `.am-dropdown-flip`
//                  `.am-dropdown-center`
//                  `.am-dropdown-justify`
//                  `.am-dropdown-up`
//                  `.am-dropdown-stack`
//                  `.am-dropdown-navbar`
//
// States:          `.am-active`
//                  `.am-disabled`
//
// Uses:             Animation
//
// =============================================================================


// Variables
// =============================================================================

@dropdown-bg:                    #fff;
@dropdown-border-color:          #ddd;
@dropdown-divider-bg:            #e5e5e5;

@dropdown-link-color:            @gray-dark;
@dropdown-link-hover-color:      darken(@gray-dark, 5%);
@dropdown-link-hover-bg:         #f5f5f5;
@dropdown-link-active-color:     @component-active-color;
@dropdown-link-active-bg:        @component-active-bg;
@dropdown-link-disabled-color:   @gray-light;

@dropdown-header-color:          @gray-light;
@dropdown-caret-color:           darken(@dropdown-border-color, 5%);

@caret-width-base:               6px;
@dropdown-animation:             am-slide-top-fixed;


// Dropdown mixin
// =============================================================================
// Dividers (basically an hr) within dropdowns and nav lists
.nav-divider(@color: #e5e5e5) {
  height: 1px;
  margin: ((@line-height-computed / 2) - 1) 0;
  overflow: hidden;
  background-color: @color;
}


.@{ns}dropdown {
  position: relative;
  display: inline-block;
  .hook-dropdown;
}

.@{ns}dropdown-toggle:focus {
  outline: 0;
}

.@{ns}dropdown-content {
  position: absolute;
  top: 100%;
  left: 0;
  z-index: @z-index-dropdown;
  display: none;
  float: left;
  min-width: 160px;
  padding: 15px;
  margin: 9px 0 0;
  text-align: left;
  line-height: @global-line-height;
  background-color: @dropdown-bg;
  border: 1px solid @dropdown-border-color;
  border-radius: @global-radius;
  background-clip: padding-box;
  animation-duration: .15s;

  .hook-dropdown-content;
  .angle-base;
  .angle-up-variant(@dropdown-border-color, @dropdown-bg, 8px);

  &:before,
  &:after {
    left: 10px;
    top: -8px;
    pointer-events: none;
  }

  &:after {
    top: -7px;
  }

  .@{ns}active > & {
    display: block;
    // .animation(@dropdown-animation 0.3s ease-in-out);
  }

  :first-child {
    margin-top: 0;
  }
}


// Dropdown Up
// =============================================================================

.@{ns}dropdown-up .@{ns}dropdown-content {
  top: auto;
  bottom: 100%;
  margin: 0 0 9px;
  .hook-dropdown-up;

  &:before,
  &:after {
    border-bottom: none;
    border-top: 8px solid @dropdown-border-color;
    top: auto;
    bottom: -8px;
  }

  &:after {
    bottom: -7px;
    border-top-color: @dropdown-bg;
  }
}

.@{ns}dropdown-flip .@{ns}dropdown-content {
  left: auto;
  right: 0;

  &:before,
  &:after {
    left: auto;
    right: 10px;
  }
}


// dropdown menu (ul)
// =============================================================================

ul.@{ns}dropdown-content {
  list-style: none;
  padding: 5px 0;
  .hook-dropdown-ul-content;

  // Aligns the dropdown menu to right
  &.@{ns}fr {
    right: 0;
    left: auto;
  }

  // Dividers (basically an hr) within the dropdown
  .@{ns}divider {
    .nav-divider(@dropdown-divider-bg);
    .hook-dropdown-ul-content-divdier;
  }

  // Links within the dropdown menu
  > li > a {
    display: block;
    padding: 6px 20px;
    clear: both;
    font-weight: normal;
    color: @dropdown-link-color;
    white-space: nowrap;

    &:hover,
    &:focus {
      text-decoration: none;
      color: @dropdown-link-hover-color;
      background-color: @dropdown-link-hover-bg;
      .hook-dropdown-ul-content-hover;
    }
  }

  // Active state
  > .@{ns}active > a {
    &,
    &:hover,
    &:focus {
      color: @dropdown-link-active-color;
      text-decoration: none;
      outline: 0;
      background-color: @dropdown-link-active-bg;
      .hook-dropdown-ul-content-active;
    }
  }

  // Disabled state
  > .@{ns}disabled > a {
    &,
    &:hover,
    &:focus {
      color: @dropdown-link-disabled-color;
      .hook-dropdown-ul-content-disabled;
    }
  }

  > .@{ns}disabled > a {
    &:hover,
    &:focus {
      text-decoration: none;
      background-color: transparent;
      background-image: none; // Remove CSS gradient
      .reset-filter();
      cursor: not-allowed;
      .hook-dropdown-ul-content-disabled;
    }
  }
}

// Dropdown section headers
.@{ns}dropdown-header {
  display: block;
  padding: 6px 20px;
  font-size: @font-size-xs;
  color: @dropdown-header-color;
  .hook-dropdown-header;
}


// Right aligned dropdown
// =============================================================================

.@{ns}fr > .@{ns}dropdown-content {
  right: 0;
  left: auto;

  &:before {
    right: 10px;
    left: auto;
  }
}


// Dropdown out animation
.@{ns}dropdown-animation {
  animation: am-dropdown-animation .15s ease-out;
}

@keyframes am-dropdown-animation {
  0% {
    opacity: 1;
    transform: translateY(0);
  }

  100% {
    opacity: 0;
    transform: translateY(-10px);
  }
}

// Hooks
// =============================================================================
.hook-dropdown() {}
.hook-dropdown-content() {}
.hook-dropdown-ul-content() {}
.hook-dropdown-ul-content-active() {}
.hook-dropdown-ul-content-hover() {}
.hook-dropdown-ul-content-disabled() {}
.hook-dropdown-ul-content-divdier() {}
.hook-dropdown-up() {}
.hook-dropdown-header() {}

// TODO: 1. 分隔线上下间距调整