// Less RFS mixin
//
// Automated font-resizing
//
// See https://github.com/twbs/rfs

// Configuration

// Base font size
@rfs-base-font-size: 1.25rem;
@rfs-font-size-unit: rem;

// Breakpoint at where font-size starts decreasing if screen width is smaller
@rfs-breakpoint: 1200px;
@rfs-breakpoint-unit: px;

// Resize font-size based on screen height and width
@rfs-two-dimensional: false;

// Factor of decrease
@rfs-factor: 10;

// Generate enable or disable classes. Possibilities: false, "enable" or "disable"
@rfs-class: false;

// 1 rem = @rfs-rem-value px
@rfs-rem-value: 16;

// Safari iframe resize bug: https://github.com/twbs/rfs/issues/14
@rfs-safari-iframe-resize-bug-fix: false;

// Disable RFS by setting @enable-responsive-font-sizes to false
@enable-responsive-font-sizes: true;

// Responsive font-size mixin
.rfs(@fs, @important: false) {

  & when (not(@important)) {
    ._rfs-prefix(@fs, ~"");
  }

  & when (@important) {
    ._rfs-prefix(@fs, ~" !important");
  }
}

._rfs-prefix(@fs, @suffix) {

  & when ((not(isunit(@fs, px)) and not(isunit(@fs, rem)) and not((isnumber(@fs)) and (get-unit(@fs) = ~""))) or (@fs = 0)) {
    font-size: @fs @suffix;
  }

  & when (((isnumber(@fs)) and (get-unit(@fs) = ~"")) or (isunit(@fs, px)) or (isunit(@fs, rem))) {
    ._rfs-render-base(@fs, @suffix);
  }
}

._rfs-render-base(@fs, @suffix) {

  & when ((isnumber(@fs)) and (get-unit(@fs) = ~"")) {
    ._rfs-render-base-number(@fs, @suffix);
    ._rfs-render-media-query(@fs, @suffix);
  }

  & when ((isunit(@fs, px))) {
    ._rfs-render-base-number(unit(@fs), @suffix);
    ._rfs-render-media-query(unit(@fs), @suffix);
  }

  & when ((isunit(@fs, rem))) {
    ._rfs-render-base-number(unit(@fs/.0625), @suffix);
    ._rfs-render-media-query(unit(@fs/.0625), @suffix);
  }
}

._rfs-render-media-query(@fs, @suffix) {
  & when ((@fs > @rfs-base-font-size) and (@rfs-factor > 1) and (@enable-responsive-font-sizes = true)) {

    & when ((isnumber(@rfs-breakpoint)) and (get-unit(@rfs-breakpoint) = ~"")) {
      ._rfs-render-media-query-breakpoint(@fs, @suffix, @rfs-breakpoint);
    }

    & when ((isunit(@rfs-breakpoint, px))) {
      ._rfs-render-media-query-breakpoint(@fs, @suffix, unit(@rfs-breakpoint));
    }

    & when ((isunit(@rfs-breakpoint, rem))) {
      ._rfs-render-media-query-breakpoint(@fs, @suffix, unit(@rfs-breakpoint * @rfs-rem-value));
    }

    & when ((isunit(@rfs-breakpoint, em))) {
      ._rfs-render-media-query-breakpoint(@fs, @suffix, unit(@rfs-breakpoint * @rfs-rem-value));
    }
  }
}

._rfs-render-media-query-breakpoint(@fs, @suffix, @breakpoint) {
  & when (@rfs-two-dimensional) {
    ._rfs-render-media-query-two-dimensional(@fs, @suffix, @breakpoint);
  }
  & when (not(@rfs-two-dimensional)) {
    ._rfs-render-media-query-one-dimension(@fs, @suffix, @breakpoint);
  }
}

._rfs-render-media-query-one-dimension(@fs, @suffix, @breakpoint) {
  & when (@rfs-breakpoint-unit = px) {
    @media (max-width: unit(@breakpoint, px)) {
      ._rfs-render-media-query-content(@fs, @suffix, @breakpoint);
    }
  }

  & when (@rfs-breakpoint-unit = rem) {
    @media (max-width: unit((@breakpoint / @rfs-rem-value), rem)) {
      ._rfs-render-media-query-content(@fs, @suffix, @breakpoint);
    }
  }

  & when (@rfs-breakpoint-unit = em) {
    @media (max-width: unit((@breakpoint / @rfs-rem-value), em)) {
      ._rfs-render-media-query-content(@fs, @suffix, @breakpoint);
    }
  }
}

._rfs-render-media-query-two-dimensional(@fs, @suffix, @breakpoint) {
  & when (@rfs-breakpoint-unit = px) {
    @media (max-width: unit(@breakpoint, px)), (max-height: unit(@breakpoint, px)) {
      ._rfs-render-media-query-content(@fs, @suffix, @breakpoint);
    }
  }

  & when (@rfs-breakpoint-unit = rem) {
    @media (max-width: unit((@breakpoint / @rfs-rem-value), rem)), (max-height: unit((@breakpoint / @rfs-rem-value), rem)) {
      ._rfs-render-media-query-content(@fs, @suffix, @breakpoint);
    }
  }

  & when (@rfs-breakpoint-unit = em) {
    @media (max-width: unit((@breakpoint / @rfs-rem-value), em)), (max-height: unit((@breakpoint / @rfs-rem-value), em)) {
      ._rfs-render-media-query-content(@fs, @suffix, @breakpoint);
    }
  }
}

._rfs-render-media-query-content(@fs, @suffix, @breakpoint) {
  & when ((isnumber(@rfs-base-font-size)) and (get-unit(@rfs-base-font-size) = ~"")) {
    ._rfs-render-media-query-content-dimensional(@fs, @suffix, @rfs-base-font-size, @breakpoint);
  }

  & when ((isunit(@rfs-base-font-size, px))) {
    ._rfs-render-media-query-content-dimensional(@fs, @suffix, unit(@rfs-base-font-size), @breakpoint);
  }

  & when ((isunit(@rfs-base-font-size, rem))) {
    ._rfs-render-media-query-content-dimensional(@fs, @suffix, unit(@rfs-base-font-size * @rfs-rem-value), @breakpoint);
  }

  & when (@rfs-safari-iframe-resize-bug-fix) {
    // stylelint-disable-next-line length-zero-no-unit
    min-width: 0vw;
  }
}

._rfs-render-media-query-content-dimensional(@fs, @suffix, @rfs-min, @breakpoint) {
  & when (@rfs-two-dimensional) {
    // Calculate base font-size for given font-size
    @fs-min: @rfs-min + (@fs - @rfs-min) / @rfs-factor;
    // Calculate difference between given font-size and base font-size for given font-size
    @fs-variable-width: unit((@fs - @fs-min) / (@breakpoint / 100), vmin);
    ._rfs-render-enable-class(@fs-min, @fs-variable-width, @suffix);
  }

  & when (not(@rfs-two-dimensional)) {
    // Calculate base font-size for given font-size
    @fs-min: @rfs-min + (@fs - @rfs-min) / @rfs-factor;
    // Calculate difference between given font-size and base font-size for given font-size
    @fs-variable-width: unit((@fs - @fs-min) / (@breakpoint / 100), vw);
    ._rfs-render-enable-class(@fs-min, @fs-variable-width, @suffix);
  }
}

._rfs-render-fluid(@fs-min, @fs-variable-width, @suffix) {

  & when (@rfs-font-size-unit = px) {
    font-size: calc(unit(@fs-min, px) ~"+" @fs-variable-width) @suffix;
  }

  & when (@rfs-font-size-unit = rem) {
    font-size: calc(unit(@fs-min / @rfs-rem-value, rem) ~"+" @fs-variable-width) @suffix;
  }
}

._rfs-render-enable-class(@fs-min, @fs-variable-width, @suffix) {

  & when (@rfs-class = "enable") {
    .enable-responsive-font-size &,
    &.enable-responsive-font-size {
      ._rfs-render-fluid(@fs-min, @fs-variable-width, @suffix);
    }
  }

  & when (not(@rfs-class = "enable")) {
    ._rfs-render-fluid(@fs-min, @fs-variable-width, @suffix);
  }
}

._rfs-render-base-declaration(@fs, @suffix) {

  & when (@rfs-font-size-unit = px) {
    font-size: unit(@fs, px) @suffix;
  }

  & when (@rfs-font-size-unit = rem) {
    font-size: unit((@fs / @rfs-rem-value), rem) @suffix;
  }
}

._rfs-render-base-number(@fs, @suffix) {
  & when (@rfs-class = "disable") {
    &,
    .disable-responsive-font-size &,
    &.disable-responsive-font-size {
      ._rfs-render-base-declaration(@fs, @suffix);
    }
  }

  & when (not(@rfs-class = "disable")) {
    ._rfs-render-base-declaration(@fs, @suffix);
  }
}

// The responsive-font-size mixin uses RFS to rescale font sizes
.responsive-font-size(@fs, @important: false) {
  .rfs(@fs, @important);
}