module Data.Text.ParagraphLayout.Internal.ParagraphOptions
    ( ParagraphOptions (..)
    , defaultParagraphOptions
    )
where

import Data.Int (Int32)
import Data.Text.Glyphize (Font, emptyFont)

import Data.Text.ParagraphLayout.Internal.LineHeight
import Data.Text.ParagraphLayout.Internal.ParagraphAlignment

-- | Defines options relevant to the entire paragraph.
--
-- This record type is likely to be extended in the future.
-- Use `defaultParagraphOptions` and update it with specific record selectors
-- instead of constructing `ParagraphOptions` directly.
--
-- In order to get CSS defaults, use:
--
-- > defaultParagraphOptions { paragraphAlignment = AlignStart }
data ParagraphOptions = ParagraphOptions

    { paragraphFont :: Font
    -- ^ Font to be used for shaping and measurement.
    -- Make sure to set its scale (see `Data.Text.Glyphize.optionScale`) using
    -- the same units that you want in the output.

    , paragraphLineHeight :: LineHeight
    -- ^ Preferred line height of the resulting fragments.

    , paragraphAlignment :: ParagraphAlignment
    -- ^ Alignment of non-overflowing lines within the paragraph.

    , paragraphMaxWidth :: Int32
    -- ^ Line width at which line breaking should occur.
    -- Lines will be broken at language-appropriate boundaries.
    -- If a line still exceeds this limit then, it will be broken at character
    -- boundaries, and if it already consists of a single cluster that cannot
    -- be further broken down, it will overflow.

    }
    deriving (Eq)

-- | `ParagraphOptions` with backwards-compatible values.
--
-- Note that this sets `paragraphAlignment` to `AlignLeft`,
-- whereas the CSS default should be `AlignStart`.
defaultParagraphOptions :: ParagraphOptions
defaultParagraphOptions = ParagraphOptions
    { paragraphFont = emptyFont
    , paragraphLineHeight = Normal
    , paragraphAlignment = AlignLeft
    , paragraphMaxWidth = maxBound
    }