{-# LANGUAGE UnicodeSyntax #-}
-- | This module implements printing TODOs tree to console. Here is default
-- function, but user can supply his own.
module Todos.Default.Print
  (defaultPrintTodos, showTodos)
  where

import Prelude.Unicode
import Control.Monad
import Control.Monad.Reader
import Data.List
import Data.Tree
import Data.Function (on)
import System.Console.ANSI

import Todos.Types
import Todos.Default.Config
import Todos.Default.Instances ()
import Todos.Formatters

sortBy' ∷ SortingType → [Todo] → [Todo]
sortBy' s | s == DoNotSort = id
          | otherwise = sortBy sorter
  where
    sorter = compare `on` (f ∘ rootLabel)
    f = case s of
          DoNotSort → error "Internal error: sortBy' should not be called when DoNotSort is specified!"
          ByTitle → itemName
          ByStatus → itemStatus
          ByTags → unwords ∘ itemTags
          ByStartDate → show ∘ startDate
          ByEndDate → show ∘ endDate
          ByDeadline → show ∘ deadline 

showT ∷ SortingType → Int → String → Todo → [Formatter DefaultConfig]
showT s n sep (Node item todos) = 
    (sf <++> showId item <++> seps <++> item') :
      (concatMap (showT s (n+1) sep) $ sortBy' s todos)
  where
    sf ∷ Formatter DefaultConfig
    sf = startFormat

    seps = concat (replicate n sep)

    item' ∷ Formatter DefaultConfig
    item' = configShow item

    showId :: TodoItem → Formatter DefaultConfig
    showId item = do
      s ← askBase outIds
      c ← askBase outColors
      if s
        then if c 
               then return [OutSetColor Dull Yellow, OutString $ makeId item ++ " ", ResetAll]
               else return [OutString $ makeId item ++ " "]
        else return [OutString ""]

unlines'' ∷ [Formatter c] → Formatter c
unlines'' lst = concat `fmap` (sequence $ intersperse newLine lst)

showTodo ∷ Todo → Formatter DefaultConfig
showTodo t = do
  conf ← asks toBaseConfig
  sep ← askBase indentString
  let f = case outOnlyFirst conf of
            False → unlines''
            True  → head
  f $ showT (sorting conf) 0 sep t

-- | Prepare TODOs for console output
showTodos ∷ [Todo] → Formatter DefaultConfig
showTodos lst = do
  conf ← asks toBaseConfig
  let f = case outOnlyFirst conf of
            False → unlines''
            True  → head
  f $ map showTodo $ sortBy' (sorting conf) $ nub lst

-- | Default function to output TODOs to console
defaultPrintTodos ∷ PrintConfig DefaultConfig → [Todo] → IO ()
defaultPrintTodos cfg lst = 
  let lst' = runReader (showTodos lst) cfg
  in  forM lst' outItem >> putStrLn ""