// Stylus RFS mixin
//
// Automated responsive values for font sizes, paddings, margins and much more
//
// Licensed under MIT (https://github.com/twbs/rfs/blob/master/LICENSE)

// Configuration

// Base value
$rfs-base-value ?= 1.25rem
$rfs-unit ?= rem

// Breakpoint at where values start decreasing if screen width is smaller
$rfs-breakpoint ?= 1200px
$rfs-breakpoint-unit ?= px

// Resize values based on screen height and width
$rfs-two-dimensional ?= false

// Factor of decrease
$rfs-factor ?= 10

// Mode. Possibilities: "min-media-query", "max-media-query"
$rfs-mode ?= "min-media-query"

// 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-rfs to false
$enable-rfs ?= true

// Cache $rfs-base-value unit
$rfs-base-value-unit = unit($rfs-base-value)

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

if $rfs-breakpoint-unit == px
  $rfs-mq-value = unit($rfs-breakpoint, px)
else
  $rfs-mq-value = unit($rfs-breakpoint / $rfs-rem-value, $rfs-breakpoint-unit)


if $rfs-mode == min-media-query
  $rfs-mq-property-width = min-width
else
  $rfs-mq-property-width = max-width

if $rfs-mode == min-media-query
  $rfs-mq-property-height = min-height
else
  $rfs-mq-property-height = max-height

_rfs-rule()
  if $rfs-class == "disable" and $rfs-mode == max-media-query
    &,
    .disable-rfs &,
    &.disable-rfs
      {block}
  else if $rfs-class == "enable" and $rfs-mode == min-media-query
    .enable-rfs &,
    &.enable-rfs
      {block}
  else
    {block}

_rfs-media-query-rule()
  if $rfs-class == "enable"
    if $rfs-mode == min-media-query
      {block}
    +_rfs-media-query()
      .enable-rfs &,
      &.enable-rfs
        {block}
  else
    if $rfs-class == disable and $rfs-mode == min-media-query
      .disable-rfs &,
      &.disable-rfs
        {block}
    +_rfs-media-query()
      {block}

// Internal mixin used to determine which media query needs to be used
_rfs-media-query()
  if $rfs-two-dimensional
    if $rfs-mode == min-media-query
      @media ({$rfs-mq-property-width}: $rfs-mq-value) and ({$rfs-mq-property-height}: $rfs-mq-value)
        {block}
    else
      @media ({$rfs-mq-property-width}: $rfs-mq-value), ({$rfs-mq-property-height}: $rfs-mq-value)
        {block}
  else
    @media ({$rfs-mq-property-width}: $rfs-mq-value)
      {block}

// Helper function to get the formatted non-responsive value
rfs-value($value)
  if $value == 0
    0

  else if type-of($value) != "unit"
    $value
  else
    $unit = unit($value)

    if $unit == "px"
      if $rfs-unit == "rem"
        unit($value / $rfs-rem-value, rem)
      else
        unit($value, px)

    else if $unit == "rem"
      if $rfs-unit == "rem"
        unit($value, rem)
      else
        unit($value * $rfs-rem-value, px)
    else
      $value


// Helper function to get the responsive value calculated by RFS
rfs-fluid-value($value)
  if $value == 0
    0
  else if type-of($value) != "unit"
    $value
  else if unit($value) != "px" and unit($value) != "rem"
    $value
  else
    if unit($value) == "rem"
      $value = unit($value * $rfs-rem-value, "")
    else
      $value = unit($value, "")

    // Only add the media query if the value is greater than the minimum value
    if abs($value) <= $rfs-base-value or !$enable-rfs
      if $rfs-unit == "rem"
        unit($value / $rfs-rem-value, rem)
      else
        unit($value, px)
    else
      // Calculate the minimum value
      $value-min = $rfs-base-value + (abs($value) - $rfs-base-value) / $rfs-factor;

      // Calculate difference between $value and the minimum value
      $value-diff = abs($value) - $value-min;

      // Base value formatting
      if $rfs-unit == rem
        $min-width = unit($value-min / $rfs-rem-value, rem)
      else
        $min-width = unit($value-min, px)

      // Use `vmin` if two-dimensional is enabled
      if $rfs-two-dimensional
        $variable-unit = vmin
      else
        $variable-unit = vw

      // Calculate the variable width between 0 and $rfs-breakpoint
      $variable-width = unit(round($value-diff * 100) / $rfs-breakpoint, $variable-unit)

      // Return the calculated value
      if $value != abs($value)
        unquote("calc(-" + $min-width + " - " + $variable-width + ")")
      else
        unquote("calc(" + $min-width + " + " + $variable-width + ")")

// RFS mixin
rfs($values, $property = font-size)
  $val = ''
  $fluidVal = ''

  // Loop over each value and calculate responsive & non-responsive values
  for $value in $values
    $val+= ' ' + rfs-value($value)
    $fluidVal+= ' ' + rfs-fluid-value($value)

  // Remove first space
  $val = unquote(slice($val, 1))
  $fluidVal = unquote(slice($fluidVal, 1))

  // Do not print the media query if responsive & non-responsive values are the same
  if $val == $fluidVal
    {$property}: $val
  else
    +_rfs-rule()
      if $rfs-mode == "min-media-query"
        {$property}: $fluidVal
      else
        {$property}: $val

      if $rfs-safari-iframe-resize-bug-fix and $rfs-mode == "min-media-query"
        min-width: 0vw

    +_rfs-media-query-rule()
      if $rfs-mode == "min-media-query"
        {$property}: $val
      else
        {$property}: $fluidVal

rfs-font-size($value)
  rfs($value)

rfs-padding($value, $property = padding)
  rfs($value, $property)

rfs-padding-top($value, $property = padding-top)
  rfs($value, $property)

rfs-padding-right($value, $property = padding-right)
  rfs($value, $property)

rfs-padding-bottom($value, $property = padding-bottom)
  rfs($value, $property)

rfs-padding-left($value, $property = padding-left)
  rfs($value, $property)

rfs-margin($value, $property = margin)
  rfs($value, $property)

rfs-margin-top($value, $property = margin-top)
  rfs($value, $property)

rfs-margin-right($value, $property = margin-right)
  rfs($value, $property)

rfs-margin-bottom($value, $property = margin-bottom)
  rfs($value, $property)

rfs-margin-left($value, $property = margin-left)
  rfs($value, $property)