// stylelint-disable declaration-property-value-blacklist

// Stylus 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

// Cache $rfs-base-font-size unit
$rfs-base-font-size-unit = unit($rfs-base-font-size)

// Remove px-unit from $rfs-base-font-size for calculations
if $rfs-base-font-size-unit == "px"
  $rfs-base-font-size = unit($rfs-base-font-size, "")
else if $rfs-base-font-size-unit == "rem"
  $rfs-base-font-size = unit($rfs-base-font-size * $rfs-rem-value, "")

// Cache $rfs-breakpoint unit to prevent multiple calls
$rfs-breakpoint-unit-cache = unit($rfs-breakpoint)

// Remove unit from $rfs-breakpoint for calculations
if $rfs-breakpoint-unit-cache == "px"
  $rfs-breakpoint = unit($rfs-breakpoint, "")
else if $rfs-breakpoint-unit-cache == "rem" or $rfs-breakpoint-unit-cache == "em"
  $rfs-breakpoint = unit($rfs-breakpoint * $rfs-rem-value, "")

// Responsive font-size mixin
rfs($fs, $important = false)
  $rfs-suffix = "%s" % ()

  if type-of($fs) == "unit"
    $fs-unit = unit($fs)

  // Add !important suffix if needed
  if $important
    $rfs-suffix = !important

  // If $fs is not a number (like inherit) or $fs has a unit (not px or rem, like 1.5em) or $ is 0, just print the value
  if type-of($fs) != "unit" or ($fs-unit != "" and $fs-unit != "px" and $fs-unit != "rem") or $fs == 0
    font-size: "%s%s" % ($fs $rfs-suffix)
  else
    // Variables for storing static and fluid rescaling
    $rfs-static = null
    $rfs-fluid = null

    // Remove px-unit from $fs for calculations
    if $fs-unit == px
      $fs = unit($fs, "")
    else if $fs-unit == rem
      $fs = unit($fs * $rfs-rem-value, "")

    // Set default font-size.
    if $rfs-font-size-unit == rem
      $rfs-static = "%s%s" % (unit(($fs / $rfs-rem-value), rem)  $rfs-suffix)
    else if $rfs-font-size-unit == px
      $rfs-static = "%s%s" % (unit($fs, px)  $rfs-suffix)
    else
      error("`$rfs-font-size-unit` is not a valid unit for $rfs-font-size-unit. Use `px` or `rem`.")

    if type-of($rfs-factor) != "unit" or $rfs-factor < 1
      error("`$rfs-factor` is not a valid  $rfs-factor, it must be greater or equal to 1.")

    // Only add media query if font-size is bigger as the minimum font-size
    // If $rfs-factor == 1, no rescaling will take place
    if $fs > $rfs-base-font-size and $rfs-factor != 1 and $enable-responsive-font-sizes
      $min-width = null
      $variable-unit = null

      // Calculate minimum font-size for given font-size
      $fs-min = $rfs-base-font-size + ($fs - $rfs-base-font-size) / $rfs-factor

      // Calculate difference between given font-size and minimum font-size for given font-size
      $fs-diff = $fs - $fs-min

      // Base font-size formatting
      // No need to check if the unit is valid, because we did that before
      if $rfs-font-size-unit == rem
        $min-width = unit($fs-min / $rfs-rem-value, rem)
      else
        $min-width = unit($fs-min, px)

      // If two-dimensional, use smallest of screen width and height
      if $rfs-two-dimensional
        $variable-unit = vmin
      else
        $variable-unit = vw

      // Calculate the variable width between 0 and $rfs-breakpoint
      $variable-width = "%s%s" % ($fs-diff * 100 / $rfs-breakpoint $variable-unit)

      // Set the calculated font-size
      $rfs-fluid = "calc(%s + %s)%s" % ($min-width $variable-width $rfs-suffix)

    // Rendering
    if $rfs-fluid == null
      // Only render static font-size if no fluid font-size is available
      font-size: $rfs-static
    else
      $mq-value = null

      // RFS breakpoint formatting
      if $rfs-breakpoint-unit == em or $rfs-breakpoint-unit == rem
        $mq-value = unit($rfs-breakpoint / $rfs-rem-value, $rfs-breakpoint-unit)
      else if $rfs-breakpoint-unit == px
        $mq-value = unit($rfs-breakpoint, px)
      else
        error("`$rfs-breakpoint-unit` is not a valid unit for $rfs-breakpoint-unit. Use `px`, `em` or `rem`.")

      if $rfs-class == "disable"
        // Adding an extra class increases specificity,
        // which prevents the media query to override the font size
        &,
        .disable-responsive-font-size &,
        &.disable-responsive-font-size
          font-size: $rfs-static
      else
        font-size: $rfs-static

      if $rfs-two-dimensional
        @media (max-width: $mq-value), (max-height: $mq-value)
          if $rfs-class == "enable"
            .enable-responsive-font-size &,
            &.enable-responsive-font-size
              font-size: $rfs-fluid
          else
            font-size: $rfs-fluid

          if $rfs-safari-iframe-resize-bug-fix
            // stylelint-disable-next-line length-zero-no-unit
            min-width: 0vw
      else
        @media (max-width: $mq-value)
          if $rfs-class == "enable"
            .enable-responsive-font-size &,
            &.enable-responsive-font-size
              font-size: $rfs-fluid
          else
            font-size: $rfs-fluid

          if $rfs-safari-iframe-resize-bug-fix
            // stylelint-disable-next-line length-zero-no-unit
            min-width: 0vw

// The responsive-font-size mixin uses RFS to rescale font sizes
responsive-font-size($fs, $important = false)
  rfs($fs, $important)