{-# LANGUAGE UnicodeSyntax, PatternGuards #-}

-- | Module for parsing command line options and build queries
module CmdLine
  (parseCmdLine,
   glob,
   buildQuery,
   composeAll,
   usage)
  where

import Prelude hiding (putStrLn,readFile,getContents,print)
import IO
import Codec.Binary.UTF8.String
import System (getArgs)
import System.Console.GetOpt
import System.FilePath.Glob
import Data.Maybe
import Data.List (sort)
import Control.Monad.Reader

import Unicode
import Types
import TodoTree
import Dates (parseDate)

-- | Default limit for tree height
pruneByDefault ∷  Limit
pruneByDefault = Limit 20

-- | Compose predicate from Composed
compose ∷ DateTime       -- ^ Current date/time
        → Composed       -- ^ Composed query
        → (TodoItem → 𝔹)
compose _ Empty             = const True
compose _ (Pred NoFilter)   = const True
compose _ (Pred (Tag s))    = tagPred s
compose _ (Pred (Name s))   = grepPred s
compose _ (Pred (Status s)) = statusPred s
compose dt (Pred (StartDateIs d)) = datePred startDate dt d
compose dt (Pred (EndDateIs d)) = datePred endDate dt d
compose dt (Pred (DeadlineIs d)) = datePred deadline dt d
compose dt (Not p)           = not ∘ (compose dt p)
compose dt (And (Pred NoFilter) p) = compose dt p
compose dt (And p (Pred NoFilter)) = compose dt p
compose dt (And p1 p2)      = \item → (compose dt p1 item) ∧ (compose dt p2 item)
compose dt (Or (Pred NoFilter) p) = compose dt p
compose dt (Or p (Pred NoFilter)) = compose dt p
compose dt (Or p1 p2)       = \item → (compose dt p1 item) ∨ (compose dt p2 item)
compose _ x = error $ show x

concatMapM ∷ (Monad m) ⇒ m (t → [t]) → m ([t] → [t])
concatMapM = liftM concatMap

-- | Make a list transformer
composeAll ∷ DateTime → ListTransformer
composeAll date = do
  pred ← asks ((compose date) ∘ query)
  concatMapM (pruneSelector pred)

appendC ∷ Composed → QueryFlag → Composed
appendC (Not (Pred NoFilter))   f = Not (Pred f)
appendC Empty OrCons              = (Pred NoFilter) `Or` (Pred NoFilter)
appendC Empty AndCons             = (Pred NoFilter) `And` (Pred NoFilter)
appendC Empty NotCons             = Not (Pred NoFilter)
appendC Empty f                   = Pred f
appendC c NoFilter                = c
appendC c AndCons                 = c `And` (Pred NoFilter)
appendC c OrCons                  = c `Or`  (Pred NoFilter)
appendC c NotCons                 = c `And` (Pred NoFilter)
appendC (And c (Pred NoFilter)) f = c `And` (Pred f) 
appendC (And (Pred NoFilter) c) f = c `And` (Pred f) 
appendC c@(And _ _)             f = c `And` (Pred f)
appendC (Or c (Pred NoFilter))  f = c `Or`  (Pred f)
appendC (Or (Pred NoFilter) c)  f = c `Or`  (Pred f)
appendC c@(Or _ _)              f = c `Or`  (Pred f)
appendC c@(Pred _)              f = c `And` (Pred f)
appendC c                       f = c `And` (Pred f)

appendF (O q m o l) (QF f) = O (f:q) m o l
appendF (O q m o l) (MF f) = O q (f:m) o l
appendF (O q m o l) (OF f) = O q m (f:o) l
appendF (O q m o l) (LF f) = O q m o (f:l)
appendF _ HelpF = Help

parseFlags ∷ [CmdLineFlag] → Options
parseFlags lst | HelpF ∈ lst = Help
parseFlags [] = O [] [] [] []
parseFlags (f:fs) = (parseFlags fs) `appendF` f

-- | Build Config (with query etc) from Options
buildQuery ∷ Options → Config
buildQuery (O qflags mflags oflags lflags) = Config onlyFirst colors srt limitP limitM command aprefix dformat composedFlags 
  where
    composedFlags = parseQuery qflags
    (limitP,limitM) = parseLimits lflags

    onlyFirst = OnlyFirst ∈ oflags
    colors = Colors ∈ oflags
    srtFlags = filter isSort oflags
    srt | null srtFlags = DoNotSort 
        | otherwise = getSorting (last srtFlags)

    cmdFlags  = filter isCommand mflags
    command | null cmdFlags = Nothing
            | otherwise     = Just $ unExecute (last cmdFlags)

    prefixFlags = filter isPrefix mflags
    aprefix | null prefixFlags = Nothing
            | otherwise        = Just $ unPrefix (last prefixFlags)

    dflags = filter isDescribe mflags
    dformat | null dflags = "%d"
            | otherwise   = unDescribe $ last dflags

    isSort (Sort _) = True
    isSort _        = False
    isDescribe (Describe _) = True
    isDescribe _            = False
    isCommand (Execute _) = True
    isCommand _           = False
    isPrefix (Prefix _) = True
    isPrefix _          = False

parseLimits ∷ [LimitFlag] → (Limit,Limit)
parseLimits flags = (limitP,limitM)
  where
    pruneFlags = filter isPrune flags
    minFlags   = filter isMin flags

    limitP'       = foldl min Unlimited $ map (Limit ∘ unPrune) pruneFlags
    limitP | Unlimited ← limitP' = pruneByDefault
           | otherwise           = limitP'

    limitM'       = foldl max (Limit 0) $ map (Limit ∘ unMin) minFlags
    limitM | Unlimited ← limitM' = pruneByDefault
           | otherwise           = limitM'

    isPrune (Prune _) = True
    isPrune _         = False

    isMin   (Start x) = True
    isMin   _         = False

parseQuery ∷ [QueryFlag] → Composed
parseQuery flags = foldl appendC Empty flags

-- | Parse command line
parseCmdLine ∷ DateTime              -- ^ Current date/time
             → [String]              -- ^ Command line args
             → (Options, [FilePath]) -- ^ (Options, list of files)
parseCmdLine currDate args = 
  case getOpt Permute (options currDate) (map decodeString args) of
        (flags, [],      [])     → (parseFlags flags, ["TODO"])
        (flags, nonOpts, [])     → (parseFlags flags, nonOpts)
        (_,     _,       msgs)   → error $ concat msgs ⧺ usage

isPattern s = ('*' ∈ s) || ('?' ∈ s)

glob ∷ [FilePath] → IO [FilePath]
glob list = do
  let patterns = filter isPattern list
      files = filter (not ∘ isPattern) list
  (matches, _) ← globDir (map compile patterns) "." 
  return $ sort $ files ⧺ concat matches

usage ∷  String
usage = usageInfo header (options undefined)
  where 
    header = "Usage: todos [OPTION...] [INPUT FILES]"

options ∷ DateTime → [OptDescr CmdLineFlag]
options currDate = [
    Option "1" ["only-first"] (NoArg (OF OnlyFirst))                 "show only first matching entry",
    Option "c" ["color"]      (NoArg (OF Colors))                    "show colored output",
    Option "A" ["prefix"]     (OptArg mkPrefix "PREFIX")             "use alternate parser: read only lines starting with PREFIX",
    Option "D" ["describe"]   (OptArg mkDescribe "FORMAT")           "use FORMAT for descriptions",
    Option "p" ["prune"]      (ReqArg mkPrune "N")                   "limit tree height to N",
    Option "m" ["min-depth"]  (ReqArg mkMin "N")                     "show first N levels of tree unconditionally",
    Option "t" ["tag"]        (ReqArg mkTag "TAG")                   "find items marked with TAG",
    Option "g" ["grep"]       (ReqArg mkName "PATTERN")              "find items with PATTERN in name",
    Option "s" ["status"]     (ReqArg mkStatus "STRING")             "find items with status equal to STRING",
    Option "a" ["and"]        (NoArg (QF AndCons))                   "logical AND",
    Option "o" ["or"]         (NoArg (QF OrCons))                    "logical OR",
    Option "n" ["not"]        (NoArg (QF NotCons))                   "logical NOT",
    Option ""  ["sort"]       (ReqArg mkSort "FIELD")                "specify sorting",
    Option "e" ["exec"]       (OptArg mkExecute "COMMAND")           "run COMMAND on each matching entry",
    Option "S" ["start-date"] (ReqArg (mkStartDate currDate) "DATE") "find items with start date bounded with DATE",
    Option "E" ["end-date"]   (ReqArg (mkEndDate currDate) "DATE")   "find items with end date bounded with DATE",
    Option "d" ["deadline"]   (ReqArg (mkDeadline currDate) "DATE")  "find items with deadline bounded with DATE",
    Option "h" ["help"]       (NoArg HelpF)                          "display this help"
  ]

mkSort s = OF $ Sort $ readSort s

mkTag ∷  String → CmdLineFlag
mkTag t = QF $ Tag t

mkName ∷  String → CmdLineFlag
mkName n = QF $ Name n

mkStatus ∷  String → CmdLineFlag
mkStatus s = QF $ Status s

forceEither ∷  (Show t) ⇒ Either t b → b
forceEither (Right x) = x
forceEither (Left x) = error $ show x

mkStartDate ∷  DateTime → String → CmdLineFlag
mkStartDate dt s = QF $ StartDateIs $ forceEither $ parseDate dt s

mkEndDate ∷  DateTime → String → CmdLineFlag
mkEndDate dt s = QF $ EndDateIs $ forceEither $ parseDate dt s

mkDeadline ∷  DateTime → String → CmdLineFlag
mkDeadline dt s = QF $ DeadlineIs $ forceEither $ parseDate dt s

mkDescribe ∷  Maybe String → CmdLineFlag
mkDescribe Nothing = MF $ Describe "%d"
mkDescribe (Just f) = MF $ Describe f

mkPrune ∷  String → CmdLineFlag
mkPrune s = LF $ Prune (read s)

mkMin ∷  String → CmdLineFlag
mkMin s = LF $ Start (read s)

mkPrefix ∷  Maybe [Char] → CmdLineFlag
mkPrefix = MF ∘ Prefix ∘ fromMaybe "TODO:"

mkExecute ∷  Maybe [Char] → CmdLineFlag
mkExecute = MF ∘ Execute ∘ fromMaybe "echo %n %d"