Common.hs

{-# LANGUAGE OverloadedStrings  #-}
module Codec.Xlsx.Types.Common
       ( CellRef
       , XlsxText (..)
       ) where

import qualified Data.Map                   as Map
import           Data.Text                  (Text)
import           Text.XML
import           Text.XML.Cursor

import           Codec.Xlsx.Parser.Internal
import           Codec.Xlsx.Types.RichText
import           Codec.Xlsx.Writer.Internal


-- | Excel cell reference (e.g. @E3@)
-- see 18.18.62 @ST_Ref@ (p. 2482)
type CellRef = Text

-- | Common type containing either simple string or rich formatted text.
-- Used in @si@, @comment@ and @is@ elements
--
-- E.g. @si@ spec says: "If the string is just a simple string with formatting applied
-- at the cell level, then the String Item (si) should contain a single text
-- element used to express the string. However, if the string in the cell is
-- more complex - i.e., has formatting applied at the character level - then the
-- string item shall consist of multiple rich text runs which collectively are
-- used to express the string.". So we have either a single "Text" field, or
-- else a list of "RichTextRun"s, each of which is some "Text" with layout
-- properties.
--
-- TODO: Currently we do not support @phoneticPr@ (Phonetic Properties, 18.4.3,
-- p. 1723) or @rPh@ (Phonetic Run, 18.4.6, p. 1725).
--
-- Section 18.4.8, "si (String Item)" (p. 1725)
--
-- See @CT_Rst@, p. 3903
data XlsxText = XlsxText Text
              | XlsxRichText [RichTextRun]
              deriving (Show, Eq, Ord)

{-------------------------------------------------------------------------------
  Rendering
-------------------------------------------------------------------------------}

-- | See @CT_Rst@, p. 3903
instance ToElement XlsxText where
  toElement nm si = Element {
      elementName       = nm
    , elementAttributes = Map.empty
    , elementNodes      = map NodeElement $
        case si of
          XlsxText text     -> [elementContent "t" text]
          XlsxRichText rich -> map (toElement "r") rich
    }

{-------------------------------------------------------------------------------
  Parsing
-------------------------------------------------------------------------------}

-- | See @CT_Rst@, p. 3903
instance FromCursor XlsxText where
  fromCursor cur = do
    let
      ts = cur $/ element (n"t") >=> contentOrEmpty
      contentOrEmpty c = case c $/ content of
        [t] -> [t]
        []  -> [""]
        _   -> error "invalid item: more than one text nodes under <t>!"
      rs = cur $/ element (n"r") >=> fromCursor
    case (ts,rs) of
      ([t], []) ->
        return $ XlsxText t
      ([], _:_) ->
        return $ XlsxRichText rs
      _ ->
        fail "invalid item"