{-# Language BangPatterns #-}

{-|
Module      : Client.Image.Textbox
Description : Textbox renderer
Copyright   : (c) Eric Mertens, 2016
License     : ISC
Maintainer  : emertens@gmail.com

This module provides the renderer for the client's text box input.

-}

module Client.Image.Textbox
  ( textboxImage
  ) where

import           Client.Configuration
import           Client.Commands
import           Client.Commands.Arguments.Renderer
import           Client.Commands.Arguments.Parser
import           Client.Commands.Interpolation
import           Client.Commands.Recognizer
import           Client.Image.LineWrap (fullLineWrap, terminate)
import           Client.Image.Message
import           Client.Image.MircFormatting
import           Client.Image.PackedImage
import           Client.Image.Palette
import           Client.State
import qualified Client.State.EditBox as Edit
import           Control.Lens
import           Data.HashMap.Strict (HashMap)
import           Data.List
import qualified Data.Text as Text
import           Graphics.Vty.Attributes
import qualified Graphics.Vty.Image as Vty
import           Irc.Identifier

textboxImage :: Int -> Int -> ClientState -> (Int, Int, Int, Vty.Image) -- ^ cursor column, new offset, image
textboxImage maxHeight width st =
  case view clientEditMode st of
    SingleLineEditor -> singleLineTextboxImage maxHeight width st
    MultiLineEditor  -> multiLineTextboxImage  maxHeight width st

multiLineTextboxImage :: Int -> Int -> ClientState -> (Int, Int, Int, Vty.Image) -- ^ cursor column, new offset, image
multiLineTextboxImage _maxHeight width st = (cursorRow, cursorCol, view clientTextBoxOffset st, output)
  where
  output = Vty.vertCat (terminate width . unpackImage <$> imgs)

  imgs = as ++ c ++ bs

  content = view (clientTextBox . Edit.content) st

  as  = concatMap (fullLineWrap width)
      $ mapHead (beginning <>)
      $ map (<> plainText "\n")
      $ rndr False <$> reverse (view Edit.above content)

  bs  = concatMap (fullLineWrap width)
      $ endAfters
      $ rndr False <$> view Edit.below content

  cur = view Edit.line content
  curTxt  = view Edit.text cur

  cursorBase
    = imageWidth $ parseIrcText' True
    $ Text.pack
    $ take (view Edit.pos cur) curTxt

  (cursorRow, cursorCol) =
    calcCol (length c + length bs) c (if null as then 1 + cursorBase else cursorBase)

  c = fullLineWrap width
    $ (if null as then beginning else mempty)
   <> rndr True curTxt
   <> (if null bs then ending else plainText "\n")

  rndr = renderLine st pal hilites macros
  pal = clientPalette st
  hilites = clientHighlightsFocus (view clientFocus st) st
  macros = views (clientConfig . configMacros) (fmap macroSpec) st

  attr      = view palTextBox pal
  beginning = char attr '^'
  ending    = char attr '$'

  endAfters [] = []
  endAfters [x] = [x <> ending]
  endAfters (x:xs) = x <> plainText "\n" : endAfters xs

  -- Using fullLineWrap make calculating the cursor much easier
  -- to switch to word-breaking lineWrap we'll need some extra
  -- logic to count skipped spaces.
  calcCol row [] _ = (row, 0)
  calcCol row (i:is) n
    | n < w = (row, n)
    | otherwise = calcCol (row-1) is (n-w)
    where
      w = imageWidth i

mapHead :: (a -> a) -> [a] -> [a]
mapHead f (x:xs) = f x : xs
mapHead _ []     = []

-- | Compute the UI image for the text input box. This computes
-- the logical cursor position on the screen to compensate for
-- VTY's cursor placement behavior.
singleLineTextboxImage :: Int -> Int -> ClientState -> (Int, Int, Int, Vty.Image) -- ^ cursor column, new offset, image
singleLineTextboxImage _maxHeight width st
  = (1, newPos, newOffset, croppedImage)
  where
  macros = views (clientConfig . configMacros) (fmap macroSpec) st
  (txt, content) =
     renderContent st hilites macros pal
       (view (clientTextBox . Edit.content) st)

  lineImage = unpackImage (beginning <> content <> ending)

  leftOfCurWidth = 1 + txt

  croppedImage = Vty.resizeWidth width
               $ Vty.cropLeft (Vty.imageWidth lineImage - newOffset) lineImage

  cursorAnchor = width * 3 `quot` 4

  -- previous offset value
  oldOffset = view clientTextBoxOffset st

  -- position based on old offset
  oldPos = leftOfCurWidth - oldOffset

  -- new offset (number of columns to trim from left side of text box)
  newOffset
    | 0 <= oldPos, oldPos < width = oldOffset
    | otherwise                   = max 0 (leftOfCurWidth - cursorAnchor)

  newPos = leftOfCurWidth - newOffset

  pal       = clientPalette st
  attr      = view palTextBox pal
  beginning = char attr '^'
  ending    = char attr '$'

  hilites = clientHighlightsFocus (view clientFocus st) st


-- | Renders the whole, uncropped text box as well as the 'String'
-- corresponding to the rendered image which can be used for computing
-- the logical cursor position of the cropped version of the text box.
renderContent ::
  ClientState          {- ^ client state                          -} ->
  HashMap Identifier Highlight {- ^ highlights                    -} ->
  Recognizer MacroSpec {- ^ macro completions                     -} ->
  Palette              {- ^ palette                               -} ->
  Edit.Content         {- ^ content                               -} ->
  (Int, Image')        {- ^ left-of-cursor width, image rendering -}
renderContent st hilites macros pal c = (leftLen, wholeImg)
  where
  as  = reverse (view Edit.above c)
  bs  = view Edit.below c
  cur = view Edit.line c

  curTxt  = view Edit.text cur
  leftCur = take (view Edit.pos cur) (view Edit.text cur)

  -- ["one","two"] "three" --> "two one three"
  leftLen = length leftImgs -- separators
          + sum (map imageWidth leftImgs)
          + imageWidth (parseIrcText' True (Text.pack leftCur))

  rndr = renderLine st pal hilites macros

  leftImgs = map (rndr False) as

  wholeImg = mconcat
           $ intersperse (plainText "\n")
           $ leftImgs
          ++ rndr True curTxt
           : map (rndr False) bs


-- | Render the active text box line using command highlighting and
-- placeholders, and WYSIWYG mIRC formatting control characters.
renderLine ::
  ClientState ->
  Palette ->
  HashMap Identifier Highlight ->
  Recognizer MacroSpec {- ^ commands     -} ->
  Bool                 {- ^ focused      -} ->
  String               {- ^ input text   -} ->
  Image'               {- ^ output image -}
renderLine st pal hilites macros focused input =

  case span (' '==) input of
    (spcs, '/':xs) -> string defAttr spcs <> char defAttr '/'
                   <> string attr cleanCmd <> continue rest
      where
        specAttr spec =
          case parse st spec rest of
            Nothing -> view palCommand      pal
            Just{}  -> view palCommandReady pal

        (cmd, rest) = break (' '==) xs
        cleanCmd = map cleanChar cmd

        allCommands = (Left <$> macros) <> (Right <$> commands)
        (attr, continue)
          = case recognize (Text.toLower (Text.pack cmd)) allCommands of
              Exact (Right Command{cmdArgumentSpec = spec}) ->
                ( specAttr spec
                , render pal st focused spec
                )
              Exact (Left (MacroSpec spec)) ->
                ( specAttr spec
                , render pal st focused spec
                )
              Prefix _ ->
                ( view palCommandPrefix pal
                , parseIrcTextWithNicks pal hilites focused . Text.pack
                )
              Invalid ->
                ( view palCommandError pal
                , parseIrcTextWithNicks pal hilites focused . Text.pack
                )
    _ -> parseIrcTextWithNicks pal hilites focused (Text.pack input)