//
// Copyright IBM Corp. 2018, 2023
//
// This source code is licensed under the Apache-2.0 license found in the
// LICENSE file in the root directory of this source tree.
//

@use 'sass:map';
@use 'sass:meta';
@use 'config';
@use 'themes';

/// Specify the fallback theme, used as a catch-all for tokens that you may not
/// have defined in your custom theme
$fallback: themes.$white !default;

/// Specify the current theme. This can override existing tokens, or add new
/// tokens. If you are adding new tokens, it's recommended that you set the
/// fallback for your current theme
$theme: () !default;
$theme: map.merge($fallback, $theme);

/// Local component tokens that can be updated with `@mixin add-component-tokens`.
$-component-tokens: ();

/// Include the CSS Custom Properties for the active theme or a given theme on
/// a selector
@mixin theme($active-theme: $theme, $component-tokens...) {
  @each $token, $value in $active-theme {
    @include -custom-property($token, $value);
  }

  @each $group in $component-tokens {
    @each $token, $value in $group {
      @include -custom-property($token, $value);
    }
  }

  @each $token, $value in $-component-tokens {
    @include -custom-property(
      $token,
      -resolve-token-value($active-theme, $value)
    );
  }
}

/// Retrieve the value for the given $token from the current $theme
/// @param {String} $token
@function get($token) {
  @if map.has-key($theme, $token) {
    @return map.get($theme, $token);
  }
  @error "Unable to find token: #{$token} in current $theme";
}

/// Compare two themes to see if the second theme is a superset of the first
/// theme. In other words, this function will return true if every token in the
/// first theme is available in the second theme and has the same value. The
/// second theme is allowed to have additional values and it will still match.
/// @param {Map} $a
/// @param {Map} $b
/// @returns {Boolean}
@function matches($a, $b) {
  @each $key, $value in $a {
    @if map.has-key($b, $key) == false {
      @return false;
    }

    @if map.get($b, $key) != $value {
      @return false;
    }
  }

  @return true;
}

/// Add component tokens which will be included any time the theme mixin is
/// called
@mixin add-component-tokens($token-map) {
  $-component-tokens: map.merge($-component-tokens, $token-map) !global;
}

/// Determine the value from a component token that matches the given theme.
/// This is helpful when a component token may change depending on what theme the
/// component is being rendered in.
@function -resolve-token-value($active-theme: $theme, $token-value) {
  @if meta.type-of($token-value) == map and map.has-key($token-value, values) {
    $fallback: map.get($token-value, fallback);
    $theme-values: map.get($token-value, values);

    @each $theme-value in $theme-values {
      $theme-to-match: map.get($theme-value, theme);
      $value: map.get($theme-value, value);

      @if matches($theme-to-match, $active-theme) {
        @return $value;
      }
    }

    @return $fallback;
  }

  @return $token-value;
}

/// @access private
/// @group @carbon/themes
@mixin -custom-property($name, $value) {
  @if meta.type-of($value) == map {
    @each $property, $property-value in $value {
      // Only support one-level of depth for values that are maps. This is to
      // avoid bringing properties like `breakpoints` on type tokens
      @if meta.type-of($property-value) != map {
        @include -custom-property('#{$name}-#{$property}', $property-value);
      }
    }
  } @else {
    --#{config.$prefix}-#{$name}: #{$value};
  }
}