{-|
Module      : Monomer.Widgets.Util.Text
Copyright   : (c) 2018 Francisco Vallarino
License     : BSD-3-Clause (see the LICENSE file)
Maintainer  : fjvallarino@gmail.com
Stability   : experimental
Portability : non-portable

Helper functions to text related operations in widgets.
-}
{-# LANGUAGE Strict #-}

module Monomer.Widgets.Util.Text (
  getTextMetrics,
  getTextSize,
  getTextSize_,
  getSingleTextLineRect,
  getTextGlyphs
) where

import Control.Lens ((&), (^.), (+~))
import Data.Default
import Data.Sequence (Seq(..), (<|), (|>))
import Data.Text (Text)

import Monomer.Core
import Monomer.Graphics

import qualified Monomer.Core.Lens as L

-- | Returns the text metrics of the active style.
getTextMetrics :: WidgetEnv s e -> StyleState -> TextMetrics
getTextMetrics wenv style = textMetrics where
  fontMgr = wenv ^. L.fontManager
  textMetrics = computeTextMetrics fontMgr font fontSize
  font = styleFont style
  fontSize = styleFontSize style

-- | Returns the size of the text using the active style and default options.
getTextSize :: WidgetEnv s e -> StyleState -> Text -> Size
getTextSize wenv style text = size where
  fontMgr = wenv ^. L.fontManager
  size = calcTextSize_ fontMgr style SingleLine KeepSpaces Nothing Nothing text

-- | Returns the size of the text using the active style.
getTextSize_
  :: WidgetEnv s e  -- ^ The widget environment.
  -> StyleState     -- ^ The active style.
  -> TextMode       -- ^ Whether to use single or multi line.
  -> TextTrim       -- ^ Whether to trim spacers or keep them.
  -> Maybe Double   -- ^ Maximum width (required for multi line).
  -> Maybe Int      -- ^ Max lines.
  -> Text           -- ^ Text to measure.
  -> Size           -- ^ The calculated size.
getTextSize_ wenv style mode trim mwidth mlines text = newSize where
  fontMgr = wenv ^. L.fontManager
  newSize = calcTextSize_ fontMgr style mode trim mwidth mlines text

-- | Returns the rect a single line of text needs to be displayed completely.
getSingleTextLineRect
  :: WidgetEnv s e  -- ^ The widget environment.
  -> StyleState     -- ^ The active style.
  -> Rect           -- ^ The bounding rect.
  -> AlignTH        -- ^ The horizontal alignment.
  -> AlignTV        -- ^ The vertical alignment.
  -> Text           -- ^ The text to measure.
  -> Rect           -- ^ The used rect. May be larger than the bounding rect.
getSingleTextLineRect wenv style rect alignH alignV text = textRect where
  fontMgr = wenv ^. L.fontManager
  font = styleFont style
  fSize = styleFontSize style
  fSpcH = styleFontSpaceH style

  Rect x y w h = rect
  Size tw _ = computeTextSize fontMgr font fSize fSpcH text
  TextMetrics asc desc lineh lowerX = computeTextMetrics fontMgr font fSize

  tx | alignH == ATLeft = x
     | alignH == ATCenter = x + (w - tw) / 2
     | otherwise = x + (w - tw)
  ty | alignV == ATTop = y + asc
     | alignV == ATMiddle = y + h + desc - (h - lineh) / 2
     | alignV == ATAscender = y + h - (h - asc) / 2
     | alignV == ATLowerX = y + h - (h - lowerX) / 2
     | otherwise = y + h + desc

  textRect = Rect {
    _rX = tx,
    _rY = ty - lineh,
    _rW = tw,
    _rH = lineh
  }

-- | Returns the glyphs of a single line of text.
getTextGlyphs :: WidgetEnv s e -> StyleState -> Text -> Seq GlyphPos
getTextGlyphs wenv style text = glyphs where
  fontMgr = wenv ^. L.fontManager
  font = styleFont style
  fSize = styleFontSize style
  fSpcH = styleFontSpaceH style
  glyphs = computeGlyphsPos fontMgr font fSize fSpcH text