////
/// Typography-related functions and mixins
///
/// @group typography
////

// ---- Private helpers -----

/// Returns a given typeface's map
///
/// @param {string} $name - One of the typeface names defined
///             in the `$grav-typefaces` map.
/// @return {map} A map of the typeface's details.
///
/// @access private
@function grav-typeface($name) {
  @if (not map-has-key($grav-typefaces, $name)) {
    @error ('Typeface with name "#{$name}" not found');
  }

  @return map-get($grav-typefaces, $name);
}

/// Returns the CSS `font-weight` value for a given typeface and weight.
///
/// @param {string} $name - One of the typeface names defined
///             in the `$grav-typefaces` map.
/// @param {string} $weight - One of the typeface's weight names.
/// @return {string} The typeface's CSS `font-weight`.
///
/// @access private
@function grav-font-weight($name, $weight) {
  $typeface: grav-typeface($name);

  @if (not map-has-key($typeface, 'weights')) {
    @error ('Typeface "#{$name}" has no weights defined');
  }

  $weights: map-get($typeface, 'weights');

  @if (not map-has-key($weights, $weight)) {
    @error ('Typeface "#{$name}" has no weight called "#{$weight}".');
  }

  @return map-get($weights, $weight);
}

/// Returns font-size CSS custom property name suffix for
/// a given point on our modular scale.
///
/// @param {number} $scale - A point on Gravity's typographic scale.
/// @return {string} The corresponding CSS custom property name suffix.
///
/// @access private
@function grav-font-size-varname-suffix($scale) {
  @if ($scale < $grav-scale-min) or ($scale > $grav-scale-max) {
    @error '#{$scale} is not a valid point on Gravity\'s typographic scale. Values must be in the range from #{$grav-scale-min} to #{$grav-scale-max}.';
  }

  @if $scale < 0 {
    @return 'minus-#{abs($scale)}';
  }

  @else if $scale>0 {
    @return 'plus-#{$scale}';
  }

  @else {
    // No need to use the mixin, this will always be
    // 1rem
    // --grav-fs-base: 1rem;
    @return 'base';
  }
}


// ---- Public API -----

/// Returns the CSS `font-family` stack for the given typeface.
///
/// Intended to be used when setting `font-family` in your CSS code.
///
/// @param {string} $name - One of Gravity's typeface names. Supported
///             values are: `primary` and `mono`.
/// @return {list} The typeface's CSS font stack.
@function grav-font-family-stack($name) {
  $typeface: grav-typeface($name);

  @if (not map-has-key($typeface, 'stack')) {
    @error ('Typeface "#{$name}" has no font stack defined');
  }

  @return map-get($typeface, 'stack');
}

/// Returns the full `font-size` CSS property name for
/// a given point on our modular scale.
///
/// @param {number} $scale - A point on Gravity's typographic scale.
/// @return {string} The corresponding CSS custom property name.
@function grav-font-size-css-propname($scale) {
  @return --grav-fs-#{grav-font-size-varname-suffix($scale)};
}


/// Mixin for setting the font-size at a given point
/// on our modular scale.
///
/// @param {number} $scale - A point on Gravity's typographic scale.
@mixin grav-font-size($scale) {
  font-size: var(#{grav-font-size-css-propname($scale)});
}