/**
 * @module Lightbox
 * @description Accessible lightbox for images, videos, and elements
 */

/**
 * LESS Variables
 * @type {number}
 * @default 739px
 * @description Maximum viewport width considered mobile (affects button positioning)
 */
@fs-lightbox-mobile-max-width: 739px;

/**
 * @type {number}
 * @default 0.25s
 * @description Lightbox open/close transition duration
 */
@fs-lightbox-duration: 0.25s;

/**
 * @type {string}
 * @default linear
 * @description Lightbox open/close transition timing function
 */
@fs-lightbox-timing: linear;

/**
 * @type {color}
 * @default rgba(0, 0, 0, 0.9)
 * @description Dialog backdrop overlay color
 */
@fs-lightbox-overlay-bg: fade(#000, 90);

/**
 * @type {color}
 * @default #fff
 * @description Loading spinner color
 */
@fs-lightbox-loading-color: #fff;

/**
 * @type {number}
 * @default 40px
 * @description Loading spinner diameter
 */
@fs-lightbox-loading-size: 40px;

/**
 * @type {number}
 * @default 5px
 * @description Loading spinner border thickness
 */
@fs-lightbox-loading-spread: 5px;

/**
 * @type {number}
 * @default 0.75s
 * @description Loading spinner rotation animation duration
 */
@fs-lightbox-loading-duration: 0.75s;

/**
 * @type {number}
 * @default 0.25s
 * @description Item transition duration when switching between gallery items
 */
@fs-lightbox-item-duration: 0.25s;

/**
 * @type {string}
 * @default ease
 * @description Item transition timing function
 */
@fs-lightbox-item-timing: ease;

/**
 * @type {color}
 * @default rgba(0, 0, 0, 0.6)
 * @description Details area (caption/ordinal) background color
 */
@fs-lightbox-details-bg: fade(#000, 60);

/**
 * @type {color}
 * @default #fff
 * @description Details area text color
 */
@fs-lightbox-details-color: #fff;

/**
 * @type {string}
 * @default 16px / 1.4 sans-serif
 * @description Details area font stack (size, line-height, family)
 */
@fs-lightbox-details-font: 16px / 1.4 sans-serif;

/**
 * @type {string}
 * @default ...
 * @description Details area padding with safe area insets for notched devices
 */
@fs-lightbox-details-padding: calc(env(safe-area-inset-top, 0px) + 40px) calc(env(safe-area-inset-right, 0px) + 60px) calc(env(safe-area-inset-bottom, 0px) + 40px) calc(env(safe-area-inset-left, 0px) + 60px);

/**
 * @type {number}
 * @default 10px
 * @description Gap between caption and ordinal in details area
 */
@fs-lightbox-details-gap: 10px;

/**
 * @type {color}
 * @default rgba(0, 0, 0, 0.8)
 * @description Control button (close, next, previous) background color
 */
@fs-lightbox-button-background: fade(#000, 80);

/**
 * @type {color}
 * @default #fff
 * @description Control button icon/text color
 */
@fs-lightbox-button-color: #fff;

/**
 * @selector .fs-lightbox
 * @description Main lightbox dialog element. Uses native HTML dialog with custom properties
 * for theming. Supports @starting-style for entry animations and respects prefers-reduced-motion.
 */
.fs-lightbox {
  /**
   * CSS Custom Properties - Timing
   * Override these properties to customize lightbox animation timing
   */

  /** @property {time} --fs-lightbox-duration - Lightbox open/close transition duration */
  --fs-lightbox-duration: @fs-lightbox-duration;

  /** @property {keyword} --fs-lightbox-timing - Lightbox open/close transition timing function */
  --fs-lightbox-timing: @fs-lightbox-timing;

  /**
   * CSS Custom Properties - Overlay
   */

  /** @property {color} --fs-lightbox-overlay-bg - Dialog backdrop overlay color */
  --fs-lightbox-overlay-bg: @fs-lightbox-overlay-bg;

  /**
   * CSS Custom Properties - Loading Spinner
   */

  /** @property {color} --fs-lightbox-loading-color - Loading spinner color */
  --fs-lightbox-loading-color: @fs-lightbox-loading-color;

  /** @property {length} --fs-lightbox-loading-size - Loading spinner diameter */
  --fs-lightbox-loading-size: @fs-lightbox-loading-size;

  /** @property {length} --fs-lightbox-loading-spread - Loading spinner border thickness */
  --fs-lightbox-loading-spread: @fs-lightbox-loading-spread;

  /** @property {time} --fs-lightbox-loading-duration - Loading spinner rotation animation duration */
  --fs-lightbox-loading-duration: @fs-lightbox-loading-duration;

  /**
   * CSS Custom Properties - Gallery Items
   */

  /** @property {time} --fs-lightbox-item-duration - Item transition duration when switching between gallery items */
  --fs-lightbox-item-duration: @fs-lightbox-item-duration;

  /** @property {keyword} --fs-lightbox-item-timing - Item transition timing function */
  --fs-lightbox-item-timing: @fs-lightbox-item-timing;

  /**
   * CSS Custom Properties - Details Area (Caption/Ordinal)
   */

  /** @property {color} --fs-lightbox-details-bg - Details area background color (gradient start) */
  --fs-lightbox-details-bg: @fs-lightbox-details-bg;

  /** @property {color} --fs-lightbox-details-color - Details area text color */
  --fs-lightbox-details-color: @fs-lightbox-details-color;

  /** @property {font} --fs-lightbox-details-font - Details area font stack (size, line-height, family) */
  --fs-lightbox-details-font: @fs-lightbox-details-font;

  /** @property {length} --fs-lightbox-details-padding - Details area padding with safe area insets */
  --fs-lightbox-details-padding: @fs-lightbox-details-padding;

  /** @property {length} --fs-lightbox-details-gap - Gap between caption and ordinal in details area */
  --fs-lightbox-details-gap: @fs-lightbox-details-gap;

  /**
   * CSS Custom Properties - Control Buttons (Close, Previous, Next)
   */

  /** @property {color} --fs-lightbox-button-background - Control button background color */
  --fs-lightbox-button-background: @fs-lightbox-button-background;

  /** @property {color} --fs-lightbox-button-color - Control button icon/text color */
  --fs-lightbox-button-color: @fs-lightbox-button-color;

  /**
   * Accessibility - Reduced Motion
   * Disables all animations when user prefers reduced motion
   */
  @media (prefers-reduced-motion) {

    & {
      --fs-lightbox-duration: 0s;
      --fs-lightbox-loading-duration: 0s;
      --fs-lightbox-item-duration: 0s;
    }
  }

  //

  height: 100vh;
  width: 100vw;
  max-height: 100vh;
  max-width: 100vw;

  position: fixed;
  inset: 0;

  background: transparent;
  border: none;
  margin: 0;

  opacity: 0;
  overflow: hidden;
  padding: 0;
  transition: display var(--fs-lightbox-duration) var(--fs-lightbox-timing) allow-discrete,
  opacity var(--fs-lightbox-duration) var(--fs-lightbox-timing),
  overlay var(--fs-lightbox-duration) var(--fs-lightbox-timing) allow-discrete;

  @starting-style {
    opacity: 0;
  }

  &[open] {
    display: flex;
  }

  //

  &,
  & * {
    box-sizing: border-box;
  }

  &::backdrop {
    background: var(--fs-lightbox-overlay-bg);
    opacity: 0;
    transition:
      display var(--fs-lightbox-duration) var(--fs-lightbox-timing) allow-discrete,
      opacity var(--fs-lightbox-duration) var(--fs-lightbox-timing),
      overlay var(--fs-lightbox-duration) var(--fs-lightbox-timing) allow-discrete;
  }

  //

  /**
   * @modifier .fs-lightbox-open
   * @description Open state modifier. Applied after modal is shown to trigger transition.
   * Dialog and backdrop fade to full opacity.
   */
  &-open {
    opacity: 1;

    &::backdrop {
      opacity: 1;

      @starting-style {
        opacity: 0;
      }
    }
  }

  //

  /**
   * @selector .fs-lightbox-sr
   * @description Screen reader only content. Visually hidden but accessible to assistive tech.
   * Used for accessible button labels and status announcements.
   */
  &-sr {
    width: 1px !important;
    height: 1px !important;

    position: absolute !important;

    border-width: 0 !important;
    clip-path: rect(0 0 0 0) !important;
    margin: -1px !important;
    overflow: hidden !important;
    padding: 0 !important;
    white-space: nowrap !important;
  }

  //

  /**
   * @selector .fs-lightbox-container
   * @description Main content container that holds all gallery items. Positioned absolutely
   * to fill dialog and handle pointer events for swipe navigation.
   */
  &-container {
    position: absolute;
    inset: 0;
    z-index: 1;

    user-select: none;
  }

  /**
   * @modifier .fs-lightbox-touching
   * @description Applied to container during active touch/pointer drag. Changes cursor to
   * grabbing state.
   */
  &-container&-touching {
    cursor: grabbing;
  }

  //

  /**
   * @selector .fs-lightbox-item
   * @description Individual gallery item element. Contains wrap, media, and details.
   * Positioned absolutely and uses transforms for slide transitions between items.
   */
  &-item {
    position: absolute;
    top: env(safe-area-inset-top, 0px);
    right: env(safe-area-inset-right, 0px);
    bottom: env(safe-area-inset-bottom, 0px);
    left: env(safe-area-inset-left, 0px);

    display: flex;
    flex-direction: column;
    justify-content: center;

    opacity: 0;
    transition:
      opacity var(--fs-lightbox-item-duration) var(--fs-lightbox-item-timing),
      transform var(--fs-lightbox-item-duration) var(--fs-lightbox-item-timing);
    transform: none;

    /**
     * @modifier .fs-lightbox-item_previous
     * @description Previous item modifier. Item is translated -100% to the left (or right in RTL).
     */
    &_previous {
      transform: translate(-100%, 0);
    }

    /**
     * @modifier .fs-lightbox-item_next
     * @description Next item modifier. Item is translated 100% to the right (or left in RTL).
     */
    &_next {
      transform: translate(100%, 0);
    }
  }

  /**
   * @modifier .fs-lightbox-active.fs-lightbox-loaded
   * @description Combined state for active item that has finished loading. Fades to full opacity.
   */
  &-item&-active&-loaded {
    opacity: 1;
  }

  //

  /**
   * @selector .fs-lightbox-rtl .fs-lightbox-item
   * @description RTL direction overrides. Reverses previous/next transform directions.
   */
  &-rtl &-item {

    &_previous {
      transform: translate(100%, 0);
    }

    &_next {
      transform: translate(-100%, 0);
    }
  }

  //

  // &-item&-zoomed img {
  //   max-height: none;
  //   max-width: none;
  // }

  /**
   * @selector .fs-lightbox-container.fs-lightbox-touching .fs-lightbox-item
   * @description Disables transitions during touch drag for immediate transform feedback.
   */
  &-container&-touching &-item {
    transition: none;
  }

  /**
   * @selector .fs-lightbox-wrap
   * @description Inner wrapper for media content. Provides flexbox centering within item bounds.
   */
  &-wrap {
    max-height: 100%;
    max-width: 100%;

    display: flex;
    justify-content: center;

    position: relative;
  }

  //

  /**
   * @selector .fs-lightbox-media
   * @description Media container. Holds the actual content (image, video iframe, etc.).
   * Constrains to viewport dimensions.
   */
  &-media {
    height: auto;
    width: auto;
    max-height: 100%;
    max-width: 100%;

    display: flex;
    align-items: center;
    justify-content: center;
  }

  /**
   * @modifier .fs-lightbox-media_video
   * @description Video media type modifier. Sets max-width and allows growth for responsive embed.
   */
  &-media_video {
    max-width: 1200px;

    flex-grow: 1;
  }

  /**
   * @modifier .fs-lightbox-media_image
   * @description Image media type modifier. Constrains image dimensions and prevents user interaction.
   */
  &-media_image {

    img {
      height: auto;
      width: auto;

      min-width: 200px;

      max-height: 100%;
      max-width: 100%;

      border: none;
      display: block;
      margin: auto;

      user-select: none;
      touch-action: none;
    }
  }

  /**
   * @selector .fs-lightbox-video
   * @description Video iframe container. Maintains 16:9 aspect ratio via aspect-ratio property.
   */
  &-video {
    position: relative;

    width: 100%;

    iframe {
      aspect-ratio: 16 / 9;

      width: 100%;

      background: #000;
    }
  }

  /**
   * @selector .fs-lightbox-iframe
   * @description Generic iframe container. Sets iframe to full viewport dimensions minus safe areas.
   */
  &-iframe {

    iframe {
      height: calc(100vh - env(safe-area-inset-top, 0px) - env(safe-area-inset-bottom, 0px));
      width: calc(100vw - env(safe-area-inset-left, 0px) - env(safe-area-inset-right, 0px));

      background: #000;
    }
  }

  &-iframe &-close {
    // background: var(--fs-lightbox-button-background);
    // color: var(--fs-lightbox-button-color);
  }

  /**
   * @selector .fs-lightbox-element
   * @description Inline element container. Allows scrolling for content that exceeds viewport.
   */
  &-element {
    max-width: 100%;
    max-height: 100%;

    overflow: auto;
  }

  //

  /**
   * @selector .fs-lightbox-details
   * @description Details section at bottom of active item. Contains caption and ordinal position.
   * Gradient background and delayed fade-in on item change.
   */
  &-details {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--fs-lightbox-details-gap);

    position: absolute;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 2;

    background: linear-gradient(to bottom, transparent, var(--fs-lightbox-details-bg));
    color: var(--fs-lightbox-details-color);
    font: var(--fs-lightbox-details-font);
    opacity: 0;
    padding: var(--fs-lightbox-details-padding);
    transition: opacity 0.001s var(--fs-lightbox-item-timing) 0s;

    pointer-events: none;

    * {
      pointer-events: all;
    }
  }

  /**
   * @selector .fs-lightbox-item.fs-lightbox-active .fs-lightbox-details
   * @description Details visible state. Fades in with delay after item transition completes.
   */
  &-item&-active &-details {
    opacity: 1;
    transition-delay: var(--fs-lightbox-item-duration);
    transition-duration: var(--fs-lightbox-item-duration);
  }

  /**
   * @selector .fs-lightbox-container.fs-lightbox-touching .fs-lightbox-item.fs-lightbox-active .fs-lightbox-details
   * @description Details hidden during touch interaction. Improves visibility of content being swiped.
   */
  &-container&-touching &-item&-active &-details {
    opacity: 0;
    transition-delay: 0.001s;
    transition-duration: 0s;
  }

  //

  /**
   * @selector .fs-lightbox-close
   * @description Close button. Fixed at top-right with safe area offset. Always visible.
   */
  &-close {
    display: flex;
    align-items: center;
    justify-content: center;

    height: 40px;
    width: 40px;

    position: absolute;
    top: env(safe-area-inset-top, 0px);
    right: env(safe-area-inset-right, 0px);
    z-index: 2;

    appearance: none;

    background: var(--fs-lightbox-button-background);
    border: none;
    color: var(--fs-lightbox-button-color);
    cursor: pointer;
    padding: 0;

    svg {
      width: 30px;
    }
  }

  //

  &:not(&-gallery) &-control {
    display: none;
  }

  /**
   * @selector .fs-lightbox-control
   * @description Previous/next navigation buttons. Hidden for single-item lightboxes.
   * Vertically centered on desktop, bottom-aligned on mobile.
   */
  &-control {
    display: flex;
    align-items: center;
    justify-content: center;

    height: 40px;
    width: 40px;

    position: absolute;
    top: env(safe-area-inset-top, 0px);
    bottom: env(safe-area-inset-bottom, 0px);
    z-index: 2;

    appearance: none;

    background: var(--fs-lightbox-button-background);
    border: none;
    color: var(--fs-lightbox-button-color);
    margin: auto;
    padding: 0;
    opacity: 0.5;
    transition: opacity var(--fs-lightbox-duration) var(--fs-lightbox-timing);

    @media screen and (max-width: @fs-lightbox-mobile-max-width) {
      top: auto;
    }

    /**
     * @modifier .fs-lightbox-control_previous
     * @description Previous button modifier. Positioned on left edge (or right in RTL).
     */
    &_previous {
      left: 0;
    }

    /**
     * @modifier .fs-lightbox-control_next
     * @description Next button modifier. Positioned on right edge (or left in RTL).
     */
    &_next {
      right: 0;
    }

    svg {
      width: 28px;
    }
  }

  //

  /**
   * @selector .fs-lightbox-rtl .fs-lightbox-control
   * @description RTL overrides for navigation buttons. Swaps left/right positioning and flips icons.
   */
  &-rtl &-control {

    svg {
      transform: scale(-1);
    }

    &_previous {
      left: unset;
      right: 0;
    }

    &_next {
      right: unset;
      left: 0;
    }
  }

  //

  /**
   * @selector .fs-lightbox-control:not([disabled])
   * @description Enabled control buttons. Full opacity and clickable cursor.
   */
  &-control:not([disabled]) {
    cursor: pointer;
    opacity: 1;
  }

  //

  // &-zoom {
  //   display: flex;
  //   align-items: center;
  //   justify-content: center;

  //   height: 40px;
  //   width: 40px;

  //   position: absolute;
  //   bottom: env(safe-area-inset-bottom, 0px);
  //   right: env(safe-area-inset-right, 0px);
  //   z-index: 2;

  //   appearance: none;

  //   background: var(--fs-lightbox-button-background);
  //   border: none;
  //   color: var(--fs-lightbox-button-color);
  //   display: none;
  //   margin: auto;
  //   padding: 0;
  //   // opacity: 0.5;
  //   // transition: opacity var(--fs-lightbox-duration) var(--fs-lightbox-timing);

  //   &_in {
  //     right: calc(env(safe-area-inset-right, 0px) + 40px);

  //     display: block;
  //   }

  //   &_out {
  //     display: block;
  //   }

  //   svg {
  //     width: 28px;
  //   }
  // }

  //

  /**
   * @selector .fs-lightbox-loading
   * @description Loading spinner. Centered in viewport, animated border-spin. Hidden by default,
   * shown via .fs-lightbox-visible modifier during content load.
   */
  &-loading {
    display: flex;
    justify-content: center;
    align-items: center;

    height: var(--fs-lightbox-loading-size);
    width: var(--fs-lightbox-loading-size);

    position: fixed;
    inset: 0;

    animation: fs-lightbox-loading-spin var(--fs-lightbox-loading-duration) linear infinite;
    border: var(--fs-lightbox-loading-spread) solid transparent;
    border-top-color: var(--fs-lightbox-loading-color);
    border-radius: 100%;
    margin: auto;
    opacity: 0;
    transition: opacity var(--fs-lightbox-duration) var(--fs-lightbox-timing);
  }

  /**
   * @modifier .fs-lightbox-visible
   * @description Visible state for loading spinner. Fades to full opacity.
   */
  &-loading&-visible {
    opacity: 1;
  }
}

/**
 * @keyframes fs-lightbox-loading-spin
 * @description Loading spinner rotation animation. Infinite 360-degree rotation.
 */
@keyframes fs-lightbox-loading-spin {

  from {
    transform: rotate(0deg);
  }

  to {
    transform: rotate(360deg);
  }
}