Types.hs

-- |
-- Module:     Data.CSS.Properties.Types
-- Copyright:  (c) 2013 Ertugrul Soeylemez
-- License:    BSD3
-- Maintainer: Ertugrul Soeylemez <es@ertes.de>

module Data.CSS.Properties.Types
    ( -- * Lengths
      Length,
      AutoLen,
      FactorLen,

      -- * Generic CSS types
      CssString(..),
      CssUrl(..),

      -- * Edge-oriented
      Edge(..),

      -- * Specific properties
      -- ** Backgrounds
      BackgroundAttachment(..),
      BackgroundRepeat(..),
      -- ** Borders
      BorderStyle(..),
      BorderWidth(..),
      -- ** Fonts
      FontFamily(..),
      FontSize(..),
      FontStyle(..),
      FontVariant(..),
      FontWeight(..),
      -- ** Generated content
      ContentPart(..),
      -- ** Layout
      ClipMode(..),
      DisplayMode(..),
      FloatEdge(..),
      OverflowMode(..),
      PositionMode(..),
      VisibilityMode(..),
      -- ** Lists
      ListPosition(..),
      ListStyle(..),
      -- ** Paged media
      PageBreak(..), AnyBreak, InsideBreak,
      PageSelector(..),
      -- ** Tables
      CaptionSide(..),
      TableLayout(..),
      -- ** Text
      TextAlign(..),
      TextDecoration(..),
      TextDirection(..),
      TextTransform(..),
      TextWrapMode(..),
      UnicodeBidiMode(..),
      VerticalAlign(..),
      -- ** User interface
      Cursor(..)
    )
    where

import Blaze.ByteString.Builder
import Blaze.ByteString.Builder.Char8 hiding (fromString)
import Control.Lens
import Data.ByteString (ByteString)
import Data.CSS.Properties.Classes
import Data.CSS.Properties.Utils
import Data.CSS.Types
import Data.CSS.Utils
import Data.Data
import Data.Foldable (Foldable(fold))
import Data.List
import Data.Monoid
import Data.String
import Data.Text (Text)


-- | Length transformer to add automatic lengths.

data AutoLen len a = AutoLen | NoAutoLen (len a)
    deriving (Eq, Ord, Show)

instance HasAutoLength (AutoLen len) where
    autoLen = AutoLen

instance (HasLength len) => HasLength (AutoLen len) where
    _Cm = _NoAutoLen . _Cm
    _Em = _NoAutoLen . _Em
    _Ex = _NoAutoLen . _Ex
    _Mm = _NoAutoLen . _Mm
    _Px = _NoAutoLen . _Px
    zeroLen = NoAutoLen zeroLen

instance (HasPercent len) => HasPercent (AutoLen len) where
    _Factor = _NoAutoLen . _Factor

instance (ToPropValue (len a)) => ToPropValue (AutoLen len a) where
    toPropBuilder AutoLen       = fromByteString "auto"
    toPropBuilder (NoAutoLen l) = toPropBuilder l


-- | Background attachment.

data BackgroundAttachment
    = FixedBgr   -- ^ @fixed@ background.
    | ScrollBgr  -- ^ @scroll@ background.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue BackgroundAttachment where
    toPropBuilder FixedBgr  = fromByteString "fixed"
    toPropBuilder ScrollBgr = fromByteString "scroll"


-- | Background repeating.

data BackgroundRepeat
    = NoRepeat  -- ^ @no-repeat@.
    | Repeat    -- ^ @repeat@ both axes.
    | RepeatX   -- ^ @repeat-x@ axis.
    | RepeatY   -- ^ @repeat-y@ axis.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue BackgroundRepeat where
    toPropBuilder NoRepeat = fromByteString "no-repeat"
    toPropBuilder Repeat   = fromByteString "repeat"
    toPropBuilder RepeatX  = fromByteString "repeat-x"
    toPropBuilder RepeatY  = fromByteString "repeat-y"


-- | Border style.

data BorderStyle
    = NoBorder
    | HiddenBorder
    | DottedBorder
    | DashedBorder
    | SolidBorder
    | DoubleBorder
    | GrooveBorder
    | RidgeBorder
    | InsetBorder
    | OutsetBorder
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue BorderStyle where
    toPropBuilder NoBorder     = fromByteString "none"
    toPropBuilder HiddenBorder = fromByteString "hidden"
    toPropBuilder DottedBorder = fromByteString "dotted"
    toPropBuilder DashedBorder = fromByteString "dashed"
    toPropBuilder SolidBorder  = fromByteString "solid"
    toPropBuilder DoubleBorder = fromByteString "double"
    toPropBuilder GrooveBorder = fromByteString "groove"
    toPropBuilder RidgeBorder  = fromByteString "ridge"
    toPropBuilder InsetBorder  = fromByteString "inset"
    toPropBuilder OutsetBorder = fromByteString "outset"


-- | Border widths.

data BorderWidth a
    = BorderWidth (Length a)  -- ^ Custom border width.
    | MediumWidth             -- ^ Medium border width.
    | ThickWidth              -- ^ Thick border width.
    | ThinWidth               -- ^ Thin border width.
    deriving (Eq, Ord, Show, Typeable)

instance HasLength BorderWidth where
    _Em = _BorderWidth . _Em
    _Ex = _BorderWidth . _Ex
    _Mm = _BorderWidth . _Mm
    _Px = _BorderWidth . _Px
    zeroLen = BorderWidth zeroLen

instance (Real a) => ToPropValue (BorderWidth a) where
    toPropBuilder (BorderWidth l) = toPropBuilder l
    toPropBuilder MediumWidth     = fromByteString "medium"
    toPropBuilder ThickWidth      = fromByteString "thick"
    toPropBuilder ThinWidth       = fromByteString "thin"


-- | Table caption sides.

data CaptionSide
    = BottomSide  -- ^ Table's @bottom@ side.
    | TopSide     -- ^ Table's @top@ side.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue CaptionSide where
    toPropBuilder BottomSide = fromByteString "bottom"
    toPropBuilder TopSide    = fromByteString "top"


-- | Clipping modes.

data ClipMode a
    -- | Rectangular clipping region.
    = ClipRect (AutoLen Length a)
               (AutoLen Length a)
               (AutoLen Length a)
               (AutoLen Length a)
    deriving (Eq, Ord, Show, Typeable)

instance (Real a) => ToPropValue (ClipMode a) where
    toPropBuilder (ClipRect t r b l) =
        fromByteString "rect(" <>
        toPropBuilder t <> fromChar ',' <>
        toPropBuilder r <> fromChar ',' <>
        toPropBuilder b <> fromChar ',' <>
        toPropBuilder l <> fromChar ')'


-- | Parts for the @content@ property.

data ContentPart url
    = AttrPart ByteString                             -- ^ @attr(x)@ part.
    | CloseQuotePart                                  -- ^ @close-quote@ part.
    | CounterPart ByteString (Maybe ListStyle)        -- ^ @counter(x, y)@ part.
    | CountersPart ByteString Text (Maybe ListStyle)  -- ^ @counters(x, y)@ part.
    | NoCloseQuotePart                                -- ^ @no-close-quote@ part.
    | NoOpenQuotePart                                 -- ^ @no-open-quote@ part.
    | OpenQuotePart                                   -- ^ @open-quote@ part.
    | TextPart (CssString Text)                       -- ^ Text part.
    | UriPart url                                     -- ^ @url(x)@ part.
    deriving (Data, Eq, Functor, Ord, Read, Show, Typeable)

instance IsString (ContentPart url) where
    fromString = TextPart . fromString

instance (ToPropValue url) => ToPropValue (ContentPart url) where
    toPropBuilder part =
        case part of
          AttrPart attr    -> bs "attr(" <> bs attr <> ch ')'
          CloseQuotePart   -> bs "close-quote"
          NoCloseQuotePart -> bs "no-close-quote"
          NoOpenQuotePart  -> bs "no-open-quote"
          OpenQuotePart    -> bs "open-quote"
          UriPart url      -> toPropBuilder url
          CounterPart name (Just DecimalList) ->
              bs "counter(" <> bs name <> ch ')'
          CounterPart name style ->
              bs "counter(" <>
              bs name <> ch ',' <>
              maybeBuilder "none" style <>
              ch ')'
          CountersPart name sep (Just DecimalList) ->
              bs "counters(" <>
              bs name <> ch ',' <>
              cssString sep <>
              ch ')'
          CountersPart name sep style ->
              bs "counters(" <>
              bs name <> ch ',' <>
              cssString sep <> ch ',' <>
              maybeBuilder "none" style <>
              ch ')'
          TextPart text -> toPropBuilder text

        where
        bs = fromByteString
        ch = fromChar


-- | CSS strings.

newtype CssString a = CssString { getCssString :: a }
    deriving (Data, Eq, Foldable, Functor, Ord, Read, Show, Traversable, Typeable)

instance (IsString a) => IsString (CssString a) where
    fromString = CssString . fromString

instance ToPropValue (CssString Text) where
    toPropBuilder = cssString . getCssString


-- | CSS URLs.

newtype CssUrl a = CssUrl { getCssUrl :: a }
    deriving (Data, Eq, Foldable, Functor, Ord, Read, Show, Traversable, Typeable)

instance (IsString a) => IsString (CssUrl a) where
    fromString = CssUrl . fromString

instance ToPropValue (CssUrl Text) where
    toPropBuilder (CssUrl url) =
        fromByteString "url(" <>
        cssString url <>
        fromChar ')'


-- | Cursors.

data Cursor url
    = CrosshairCursor   -- ^ @crosshair@ cursor.
    | CursorFrom [url]  -- ^ Cursor from one of the given URLs.
    | DefaultCursor     -- ^ @default@ cursor.
    | EResizeCursor     -- ^ @e-resize@ cursor.
    | HelpCursor        -- ^ @help@ cursor.
    | MoveCursor        -- ^ @move@ cursor.
    | NResizeCursor     -- ^ @n-resize@ cursor.
    | NeResizeCursor    -- ^ @ne-resize@ cursor.
    | NwResizeCursor    -- ^ @nw-resize@ cursor.
    | PointerCursor     -- ^ @pointer@ cursor.
    | ProgressCursor    -- ^ @progress@ cursor.
    | SResizeCursor     -- ^ @s-resize@ cursor.
    | SeResizeCursor    -- ^ @se-resize@ cursor.
    | SwResizeCursor    -- ^ @sw-resize@ cursor.
    | TextCursor        -- ^ @text@ cursor.
    | WResizeCursor     -- ^ @w-resize@ cursor.
    | WaitCursor        -- ^ @wait@ cursor.
    deriving (Data, Eq, Foldable, Functor, Ord, Read, Show, Typeable, Traversable)

instance (ToPropValue url) => ToPropValue (Cursor url) where
    toPropBuilder CrosshairCursor = fromByteString "crosshair"
    toPropBuilder DefaultCursor   = fromByteString "default"
    toPropBuilder EResizeCursor   = fromByteString "e-resize"
    toPropBuilder HelpCursor      = fromByteString "help"
    toPropBuilder MoveCursor      = fromByteString "move"
    toPropBuilder NResizeCursor   = fromByteString "n-resize"
    toPropBuilder NeResizeCursor  = fromByteString "ne-resize"
    toPropBuilder NwResizeCursor  = fromByteString "nw-resize"
    toPropBuilder PointerCursor   = fromByteString "pointer"
    toPropBuilder ProgressCursor  = fromByteString "progress"
    toPropBuilder SResizeCursor   = fromByteString "s-resize"
    toPropBuilder SeResizeCursor  = fromByteString "se-resize"
    toPropBuilder SwResizeCursor  = fromByteString "sw-resize"
    toPropBuilder TextCursor      = fromByteString "text"
    toPropBuilder WResizeCursor   = fromByteString "w-resize"
    toPropBuilder WaitCursor      = fromByteString "wait"
    toPropBuilder (CursorFrom us) =
        fold .
        intersperse (fromChar ',') .
        map toPropBuilder $ us


-- | Display modes.

data DisplayMode
    = BlockDisplay        -- ^ @block@ display.
    | InlineBlockDisplay  -- ^ @inline-block@ display.
    | InlineDisplay       -- ^ @inline@ display.
    | ListItemDisplay     -- ^ @list-item@ display
    | NoneDisplay         -- ^ @none@ display.

    | TableDisplay             -- ^ @table@ display.
    | InlineTableDisplay       -- ^ @inline-table@ display.
    | TableRowGroupDisplay     -- ^ @table-row-group@ display.
    | TableColumnDisplay       -- ^ @table-column@ display.
    | TableColumnGroupDisplay  -- ^ @table-column-group@ display.
    | TableHeaderGroupDisplay  -- ^ @table-header-group@ display.
    | TableFooterGroupDisplay  -- ^ @table-footer-group@ display.
    | TableRowDisplay          -- ^ @table-row@ display.
    | TableCellDisplay         -- ^ @table-cell@ display.
    | TableCaptionDisplay      -- ^ @table-caption@ display.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue DisplayMode where
    toPropBuilder BlockDisplay            = fromByteString "block"
    toPropBuilder InlineBlockDisplay      = fromByteString "inline-block"
    toPropBuilder InlineDisplay           = fromByteString "inline"
    toPropBuilder InlineTableDisplay      = fromByteString "inline-table"
    toPropBuilder ListItemDisplay         = fromByteString "list-item"
    toPropBuilder NoneDisplay             = fromByteString "none"
    toPropBuilder TableCaptionDisplay     = fromByteString "table-caption"
    toPropBuilder TableCellDisplay        = fromByteString "table-cell"
    toPropBuilder TableColumnDisplay      = fromByteString "table-column"
    toPropBuilder TableColumnGroupDisplay = fromByteString "table-column-group"
    toPropBuilder TableDisplay            = fromByteString "table"
    toPropBuilder TableFooterGroupDisplay = fromByteString "table-footer-group"
    toPropBuilder TableHeaderGroupDisplay = fromByteString "table-header-group"
    toPropBuilder TableRowDisplay         = fromByteString "table-row"
    toPropBuilder TableRowGroupDisplay    = fromByteString "table-row-group"


-- | Edge-oriented specifications.

data Edge a
    = Edges [a]     -- ^ All edges.
    | BottomEdge a  -- ^ Bottom edge.
    | LeftEdge a    -- ^ Left edge.
    | RightEdge a   -- ^ Right edge.
    | TopEdge a     -- ^ Top edge.
    deriving (Data, Eq, Foldable, Functor, Ord, Read, Show, Traversable, Typeable)


-- | Length transformer to add percental lengths.

data FactorLen len a = FactorLen a | NoFactorLen (len a)
    deriving (Eq, Ord, Show)

instance (HasAutoLength len) => HasAutoLength (FactorLen len) where
    autoLen = NoFactorLen autoLen

instance (HasLength len) => HasLength (FactorLen len) where
    _Cm = _NoFactorLen . _Cm
    _Em = _NoFactorLen . _Em
    _Ex = _NoFactorLen . _Ex
    _Mm = _NoFactorLen . _Mm
    _Px = _NoFactorLen . _Px
    zeroLen = NoFactorLen zeroLen

instance HasPercent (FactorLen len) where
    _Factor = prism FactorLen ex
        where
        ex (FactorLen x) = Right x
        ex len           = Left len

instance (Real a, ToPropValue (len a)) => ToPropValue (FactorLen len a) where
    toPropBuilder (FactorLen x)   = showReal (100*x) <> fromChar '%'
    toPropBuilder (NoFactorLen l) = toPropBuilder l


-- | Floating edge.

data FloatEdge = LeftFloat | RightFloat
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue FloatEdge where
    toPropBuilder LeftFloat  = fromByteString "left"
    toPropBuilder RightFloat = fromByteString "right"


-- | Font families.

data FontFamily
    = CursiveFont    -- ^ Generic @cursive@ font.
    | FantasyFont    -- ^ Generic @fantasy@ font.
    | MonospaceFont  -- ^ Generic @monospace@ font.
    | SansSerifFont  -- ^ Generic @sans-serif@ font.
    | SerifFont      -- ^ Generic @serif@ font.
    | NamedFont (CssString Text)  -- ^ Specific named font.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance IsString FontFamily where
    fromString = NamedFont . fromString

instance ToPropValue FontFamily where
    toPropBuilder CursiveFont    = fromByteString "cursive"
    toPropBuilder FantasyFont    = fromByteString "fantasy"
    toPropBuilder MonospaceFont  = fromByteString "monospace"
    toPropBuilder SansSerifFont  = fromByteString "sans-serif"
    toPropBuilder SerifFont      = fromByteString "serif"
    toPropBuilder (NamedFont ff) = toPropBuilder ff


-- | Font sizes.

data FontSize a
    = XXSmallSize  -- ^ Absolutely @xx-small@ size.
    | XSmallSize   -- ^ Absolutely @x-small@ size.
    | SmallSize    -- ^ Absolutely @small@ size.
    | MediumSize   -- ^ Absolutely @medium@ size.
    | LargeSize    -- ^ Absolutely @large@ size.
    | XLargeSize   -- ^ Absolutely @x-large@ size.
    | XXLargeSize  -- ^ Absolutely @xx-large@ size.

    | LargerSize   -- ^ Relatively @larger@ size.
    | SmallerSize  -- ^ Relatively @smaller@ size.

    | LengthSize (FactorLen Length a)  -- ^ Specific font size.
    deriving (Eq, Ord, Show, Typeable)

instance HasLength FontSize where
    _Em = _LengthSize . _Em
    _Ex = _LengthSize . _Ex
    _Mm = _LengthSize . _Mm
    _Px = _LengthSize . _Px
    zeroLen = LengthSize zeroLen

instance HasPercent FontSize where
    _Factor = _LengthSize . _Factor

instance (Real a) => ToPropValue (FontSize a) where
    toPropBuilder LargeSize      = fromByteString "large"
    toPropBuilder LargerSize     = fromByteString "larger"
    toPropBuilder MediumSize     = fromByteString "medium"
    toPropBuilder SmallSize      = fromByteString "small"
    toPropBuilder SmallerSize    = fromByteString "smaller"
    toPropBuilder XLargeSize     = fromByteString "x-large"
    toPropBuilder XSmallSize     = fromByteString "x-small"
    toPropBuilder XXLargeSize    = fromByteString "xx-large"
    toPropBuilder XXSmallSize    = fromByteString "xx-small"
    toPropBuilder (LengthSize l) = toPropBuilder l


-- | Font styles.

data FontStyle
    = ItalicStyle   -- ^ Select @italic@ style.
    | ObliqueStyle  -- ^ Select @oblique@ style.
    | NormalStyle   -- ^ Select @normal@ style.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue FontStyle where
    toPropBuilder ItalicStyle  = fromByteString "italic"
    toPropBuilder ObliqueStyle = fromByteString "oblique"
    toPropBuilder NormalStyle  = fromByteString "normal"


-- | Font variants.

data FontVariant
    = NormalVariant     -- ^ Select @normal@ font.
    | SmallCapsVariant  -- ^ Select @small-caps@ font.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue FontVariant where
    toPropBuilder NormalVariant    = fromByteString "normal"
    toPropBuilder SmallCapsVariant = fromByteString "small-caps"


-- | Font weight.

data FontWeight
    = BolderWeight    -- ^ Relatively @bolder@ font weight.
    | LighterWeight   -- ^ Relatively @lighter@ font weight.
    | FontWeight Int  -- ^ Specific font weight (1-9), 4 = @normal@, 7 = @bold@.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue FontWeight where
    toPropBuilder BolderWeight   = fromByteString "bolder"
    toPropBuilder LighterWeight  = fromByteString "lighter"
    toPropBuilder (FontWeight 4) = fromByteString "normal"
    toPropBuilder (FontWeight 7) = fromByteString "bold"
    toPropBuilder (FontWeight w) = showReal (100*w)


-- | Length transformer to add lengths in various CSS units.

data Length a
    = EmLen a  -- ^ Font sizes.
    | ExLen a  -- ^ Vertical sizes of the letter @x@.
    | MmLen a  -- ^ Millimeters.
    | PxLen a  -- ^ Pixels.
    | ZeroLen  -- ^ Zero.
    deriving (Eq, Ord, Show, Typeable)

instance HasLength Length where
    _Em = prism (orZeroLen EmLen) ex
        where
        ex (EmLen x) = Right x
        ex ZeroLen   = Right 0
        ex len       = Left len

    _Ex = prism (orZeroLen ExLen) ex
        where
        ex (ExLen x) = Right x
        ex ZeroLen   = Right 0
        ex len       = Left len

    _Mm = prism (orZeroLen MmLen) ex
        where
        ex (MmLen x) = Right x
        ex ZeroLen   = Right 0
        ex len       = Left len

    _Px = prism (orZeroLen PxLen) ex
        where
        ex (PxLen x) = Right x
        ex ZeroLen   = Right 0
        ex len       = Left len

    zeroLen = ZeroLen

instance (Real a) => ToPropValue (Length a) where
    toPropBuilder (EmLen x) = showReal x <> fromByteString "em"
    toPropBuilder (ExLen x) = showReal x <> fromByteString "ex"
    toPropBuilder (MmLen x) = showReal x <> fromByteString "mm"
    toPropBuilder (PxLen x) = showReal x <> fromByteString "px"
    toPropBuilder ZeroLen   = fromChar '0'


-- | List number/bullet position.

data ListPosition
    = InsideList   -- ^ @inside@ the box.
    | OutsideList  -- ^ @outside@ of the box.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue ListPosition where
    toPropBuilder InsideList  = fromByteString "inside"
    toPropBuilder OutsideList = fromByteString "outside"


-- | List number/bullet styles.

data ListStyle
    = ArmenianList            -- ^ @armenian@ numbering.
    | CircleList              -- ^ @circle@ bullets.
    | DecimalLeadingZeroList  -- ^ @decimal-leading-zero@ numbering.
    | DecimalList             -- ^ @decimal@ numbering.
    | DiscList                -- ^ @disc@ bullets.
    | GeorgianList            -- ^ @georgian@ numbering.
    | LowerAlphaList          -- ^ @lower-alpha@ numbering.
    | LowerGreekList          -- ^ @lower-greek@ numbering.
    | LowerLatinList          -- ^ @lower-latin@ numbering.
    | LowerRomanList          -- ^ @lower-roman@ numbering.
    | SquareList              -- ^ @square@ bullets.
    | UpperAlphaList          -- ^ @upper-alpha@ numbering.
    | UpperLatinList          -- ^ @upper-latin@ numbering.
    | UpperRomanList          -- ^ @upper-roman@ numbering.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue ListStyle where
    toPropBuilder ArmenianList           = fromByteString "armenian"
    toPropBuilder CircleList             = fromByteString "circle"
    toPropBuilder DecimalLeadingZeroList = fromByteString "decimal-leading-zero"
    toPropBuilder DecimalList            = fromByteString "decimal"
    toPropBuilder DiscList               = fromByteString "disc"
    toPropBuilder GeorgianList           = fromByteString "georgian"
    toPropBuilder LowerAlphaList         = fromByteString "lower-alpha"
    toPropBuilder LowerGreekList         = fromByteString "lower-greek"
    toPropBuilder LowerLatinList         = fromByteString "lower-latin"
    toPropBuilder LowerRomanList         = fromByteString "lower-roman"
    toPropBuilder SquareList             = fromByteString "square"
    toPropBuilder UpperAlphaList         = fromByteString "upper-alpha"
    toPropBuilder UpperLatinList         = fromByteString "upper-latin"
    toPropBuilder UpperRomanList         = fromByteString "upper-roman"


-- | Overflow handling mode.

data OverflowMode
    = AutoOverflow     -- ^ @auto@ overflow handling.
    | HiddenOverflow   -- ^ @hidden@ overflow handling.
    | ScrollOverflow   -- ^ @scroll@ overflow handling.
    | VisibleOverflow  -- ^ @visible@ overflow handling.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue OverflowMode where
    toPropBuilder AutoOverflow    = fromByteString "auto"
    toPropBuilder HiddenOverflow  = fromByteString "hidden"
    toPropBuilder ScrollOverflow  = fromByteString "scroll"
    toPropBuilder VisibleOverflow = fromByteString "visible"


-- | Page break rules.

data PageBreak :: * -> * where
    AlwaysBreak :: PageBreak AnyBreak
    AvoidBreak  :: PageBreak InsideBreak
    LeftBreak   :: PageBreak AnyBreak
    RightBreak  :: PageBreak AnyBreak

instance ToPropValue (PageBreak a) where
    toPropBuilder AlwaysBreak = fromByteString "always"
    toPropBuilder AvoidBreak  = fromByteString "avoid"
    toPropBuilder LeftBreak   = fromByteString "left"
    toPropBuilder RightBreak  = fromByteString "right"

-- | Page break context: any.
data AnyBreak

-- | Page break context: @page-break-inside@.
data InsideBreak


-- | Page selectors for paged media.

data PageSelector
    = AllPages    -- ^ Select all pages (@\@page@).
    | FirstPage   -- ^ Select first page (@\@page :first@).
    | LeftPages   -- ^ Select all left pages (@\@page :left@).
    | RightPages  -- ^ Select all right pages (@\@page :right@).
    deriving (Data, Eq, Ord, Read, Show, Typeable)


-- | Position modes.

data PositionMode
    = AbsolutePos  -- ^ @absolute@ positioning.
    | FixedPos     -- ^ @fixed@ positioning.
    | RelativePos  -- ^ @relative@ positioning.
    | StaticPos    -- ^ @static@ positioning.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue PositionMode where
    toPropBuilder AbsolutePos = fromByteString "absolute"
    toPropBuilder FixedPos    = fromByteString "fixed"
    toPropBuilder RelativePos = fromByteString "relative"
    toPropBuilder StaticPos   = fromByteString "static"


-- | Table layout.

data TableLayout
    = AutoLayout   -- ^ @auto@ layout.
    | FixedLayout  -- ^ @fixed@ layout.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue TableLayout where
    toPropBuilder AutoLayout  = fromByteString "auto"
    toPropBuilder FixedLayout = fromByteString "fixed"


-- | Text alignment.

data TextAlign
    = CenterAlign   -- ^ @center@ alignment.
    | JustifyAlign  -- ^ @justify@ alignment.
    | LeftAlign     -- ^ @left@ alignment.
    | RightAlign    -- ^ @right@ alignment.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue TextAlign where
    toPropBuilder CenterAlign  = fromByteString "center"
    toPropBuilder JustifyAlign = fromByteString "justify"
    toPropBuilder LeftAlign    = fromByteString "left"
    toPropBuilder RightAlign   = fromByteString "right"


-- | Text decoration.

data TextDecoration
    = BlinkText        -- ^ @blink@ text.
    | LineThroughText  -- ^ @line-through@ text.
    | OverlineText     -- ^ @overline@ text.
    | UnderlineText    -- ^ @underline@ text.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue TextDecoration where
    toPropBuilder BlinkText       = fromByteString "blink"
    toPropBuilder LineThroughText = fromByteString "line-through"
    toPropBuilder OverlineText    = fromByteString "overline"
    toPropBuilder UnderlineText   = fromByteString "underline"


-- | Text direction.

data TextDirection
    = LeftToRight
    | RightToLeft
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue TextDirection where
    toPropBuilder LeftToRight = fromByteString "ltr"
    toPropBuilder RightToLeft = fromByteString "rtl"


-- | Text transformation modes.

data TextTransform
    = CapitalizeText  -- ^ @capitalize@ transform.
    | LowercaseText   -- ^ @lowercase@ transform.
    | UppercaseText   -- ^ @uppercase@ transform.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue TextTransform where
    toPropBuilder CapitalizeText = fromByteString "capitalize"
    toPropBuilder LowercaseText  = fromByteString "lowercase"
    toPropBuilder UppercaseText  = fromByteString "uppercase"


-- | Text wrapping modes.

data TextWrapMode
    = NormalWrapping   -- ^ @normal@ wrapping.
    | NowrapWrapping   -- ^ @nowrap@ wrapping.
    | PreLineWrapping  -- ^ @pre-line@ wrapping.
    | PreWrapWrapping  -- ^ @pre-wrap@ wrapping.
    | PreWrapping      -- ^ @pre@ wrapping.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue TextWrapMode where
    toPropBuilder NormalWrapping  = fromByteString "normal"
    toPropBuilder NowrapWrapping  = fromByteString "nowrap"
    toPropBuilder PreLineWrapping = fromByteString "pre-line"
    toPropBuilder PreWrapWrapping = fromByteString "pre-wrap"
    toPropBuilder PreWrapping     = fromByteString "pre"


-- | Unicode bidi embedding mode.

data UnicodeBidiMode
    = EmbedBidi     -- ^ @embed@ mode.
    | NormalBidi    -- ^ @normal@ mode.
    | OverrideBidi  -- ^ @bidi-override@ mode.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue UnicodeBidiMode where
    toPropBuilder EmbedBidi    = fromByteString "embed"
    toPropBuilder NormalBidi   = fromByteString "normal"
    toPropBuilder OverrideBidi = fromByteString "bidi-override"


-- | Vertical text/box alignment.

data VerticalAlign a
    = BaselineAlign
    | BottomAlign
    | LengthAlign (FactorLen Length a)
    | MiddleAlign
    | SubAlign
    | SuperAlign
    | TextBottomAlign
    | TextTopAlign
    | TopAlign
    deriving (Eq, Ord, Show, Typeable)

instance HasLength VerticalAlign where
    _Em = _LengthAlign . _Em
    _Ex = _LengthAlign . _Ex
    _Mm = _LengthAlign . _Mm
    _Px = _LengthAlign . _Px
    zeroLen = LengthAlign zeroLen

instance HasPercent VerticalAlign where
    _Factor = _LengthAlign . _Factor

instance (Real a) => ToPropValue (VerticalAlign a) where
    toPropBuilder BaselineAlign   = fromByteString "baseline"
    toPropBuilder BottomAlign     = fromByteString "bottom"
    toPropBuilder MiddleAlign     = fromByteString "middle"
    toPropBuilder SubAlign        = fromByteString "sub"
    toPropBuilder SuperAlign      = fromByteString "super"
    toPropBuilder TextBottomAlign = fromByteString "text-bottom"
    toPropBuilder TextTopAlign    = fromByteString "text-top"
    toPropBuilder TopAlign        = fromByteString "top"
    toPropBuilder (LengthAlign x) = toPropBuilder x


-- | Visibility modes.

data VisibilityMode
    = CollapseVisibility  -- ^ @collapse@ visibility.
    | HiddenVisibility    -- ^ @hidden@ visibility.
    | VisibleVisibility   -- ^ @visible@ visibility.
    deriving (Data, Eq, Ord, Read, Show, Typeable)

instance ToPropValue VisibilityMode where
    toPropBuilder CollapseVisibility = fromByteString "collapse"
    toPropBuilder HiddenVisibility   = fromByteString "hidden"
    toPropBuilder VisibleVisibility  = fromByteString "visible"


-- | Helper prism for border widths.

_BorderWidth :: Prism' (BorderWidth a) (Length a)
_BorderWidth = prism BorderWidth ex
    where
    ex (BorderWidth l) = Right l
    ex w               = Left w


-- | Helper prism for 'VerticalAlign'.

_LengthAlign :: Prism' (VerticalAlign a) (FactorLen Length a)
_LengthAlign = prism LengthAlign ex
    where
    ex (LengthAlign x) = Right x
    ex va              = Left va


-- | Helper prism for 'FontSize'.

_LengthSize :: Prism' (FontSize a) (FactorLen Length a)
_LengthSize = prism LengthSize ex
    where
    ex (LengthSize x) = Right x
    ex fs             = Left fs


-- | Helper prism for non-automatic lengths.

_NoAutoLen :: Prism' (AutoLen len a) (len a)
_NoAutoLen = prism NoAutoLen ex
    where
    ex (NoAutoLen l) = Right l
    ex len           = Left len


-- | Helper prism for non-automatic lengths.

_NoFactorLen :: Prism' (FactorLen len a) (len a)
_NoFactorLen = prism NoFactorLen ex
    where
    ex (NoFactorLen l) = Right l
    ex len             = Left len


-- | Helper function to convert a length to 'zeroLen' if it's zero.

orZeroLen :: (Eq a, HasLength len, Num a) => (a -> len a) -> (a -> len a)
orZeroLen _ 0 = zeroLen
orZeroLen f x = f x