// Downloaded from https://github.com/malyw/css-vars (and modified)

// global map to be filled via variables
$css-vars: ();

// the variable may be set to "true" anywhere in the code,
// so native CSS custom properties will be used instead of the Sass global map
$css-vars-use-native: false !default;

///
// Assigns a variable to the global map
///
@function css-var-assign($varName: null, $varValue: null) {
  @return map-merge(
    $css-vars,
    (
      $varName: $varValue,
    )
  );
}

///
// Emulates var() CSS native function behavior
//
// $args[0] {String} "--" + variable name
// [$args[1]] Optional default value if variable is not assigned yet
//
// E.G.:
// color: var(--main-color);
// background: var(--main-background, green);
///
@function var($args...) {
  // CHECK PARAMS
  @if (length($args) ==0) {
    @error 'Variable name is expected to be passed to the var() function';
  }
  @if (str-length(nth($args, 1)) < 2 or str-slice(nth($args, 1), 0, 2) != '--') {
    @error "Variable name is expected to start from '--'";
  }

  // PROCESS
  $var-name: nth($args, 1);
  $var-value: map-get($css-vars, $var-name);

  @if ($css-vars-use-native) {
    // CSS variables
    // Native CSS: don't process function in case of native
    @return unquote('var(' + $args + ')');
  } @else {
    @if ($var-value == null) {
      // variable is not provided so far
      @if (length($args) == 2) {
        $var-value: nth($args, 2);
      }
    }

    // Sass: return value from the map
    @return $var-value;
  }
}

///
// SASS mixin to provide variables
// E.G.:
// @include css-vars((
//    --color: rebeccapurple,
//    --height: 68px,
//    --margin-top: calc(2vh + 20px)
// ));
///
@mixin css-vars($var-map: null) {
  // CHECK PARAMS
  @if ($var-map == null) {
    @error 'Map of variables is expected, instead got: null';
  }
  @if (type_of($var-map) != map) {
    @error 'Map of variables is expected, instead got another type passed: #{type_of($var, ap)}';
  }

  // PROCESS
  @if ($css-vars-use-native) {
    // CSS variables
    // Native CSS: assign CSS custom properties to the global scope
    @at-root :root {
      @each $var-name, $var-value in $var-map {
        @if (type_of($var-value) == string) {
          #{$var-name}: $var-value; // to prevent quotes interpolation
        } @else {
          #{$var-name}: #{$var-value};
        }
      }
    }
  } @else {
    // Sass or debug
    // merge variables and values to the global map (provides no output)
    @each $var-name, $var-value in $var-map {
      $css-vars: css-var-assign($varName, $varValue) !global; // store in global variable
    }
  }
}
