{-|
Module      : Prosidy.Compile
Description : Compile Prosidy documents into other shapes
Copyright   : ©2020 James Alexander Feldman-Crough
License     : MPL-2.0
Maintainer  : alex@fldcr.com
-}
{-# LANGUAGE ApplicativeDo #-}
{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE DerivingVia #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE UndecidableInstances #-}
module Prosidy.Compile
    ( escapeHatch
    , getContent
    , matchContent
    , optParse
    , prop
    , reqParse
    , traversing
    , self
    , strict
    , RuleT
    , Rule
    , CanMatch
    , Error(..)
    , ErrorSet
    , Error'
    , ErrorSet'
    , FromSetting(..)
    , req
    , opt
    , module Prosidy.Compile.Match
    , module Prosidy.Compile.Run
    )
where

import           Prelude                 hiding ( break )
import           Prosidy.Compile.Core
import           Prosidy.Compile.Error
import           Prosidy.Compile.Match
import           Prosidy.Compile.Run
import           Prosidy.Compile.Strict
import           Prosidy.Compile.FromSetting

import           Data.Text                      ( Text )

import qualified Prosidy                       as P

-------------------------------------------------------------------------------
-- | Access the inner 'Prosidy.Types.Content' of a node.
getContent :: P.HasContent i => RuleT (P.Content i) e f a -> RuleT i e f a
getContent = rule . GetContent

-- | Traverse over each item in a node's 'P.Content' via fallible matches.
matchContent
    :: ( Applicative f
       , Traversable t
       , P.HasContent i
       , t x ~ P.Content i
       , CanMatch x
       )
    => Match x e f a
    -> RuleT i e f (t a)
matchContent = getContent . traversing . match

-- | Parse an optional setting from a node with attached 'P.Metadata'.
optParse
    :: P.HasMetadata i
    => P.Key
    -> (Text -> Either String a)
    -> RuleT i e f (Maybe a)
optParse key = rule . GetSetting id key

-- | Check if a property is set on a node with attached 'P.Metadata'.
prop :: P.HasMetadata i => P.Key -> RuleT i e f Bool
prop = rule . GetProperty id

-- | Parse an required setting from a node with attached 'P.Metadata'.
reqParse
    :: P.HasMetadata i => P.Key -> (Text -> Either String a) -> RuleT i e f a
reqParse key = rule . GetRequiredSetting key

-- | Lift a 'RuleT' so that it operates on a traversable structure.
traversing :: Traversable t => RuleT i e f a -> RuleT (t i) e f (t a)
traversing = rule . Traverse id id

-- | Access the contents of a node.
self :: RuleT i e f i
self = rule $ GetSelf id

-- | Do anything you want with a node. This should be used sparingly! The
-- actions you perform inside of this function are invisible to inspection.
escapeHatch :: (i -> f (Either (Error e) a)) -> RuleT i e f a
escapeHatch = rule . Lift

-------------------------------------------------------------------------------
-- | Retrieve an optional setting, parsing using its 'FromSetting' instance. 
opt :: (FromSetting a, P.HasMetadata i) => P.Key -> RuleT i e f (Maybe a)
opt key = optParse key fromSetting

-- | Retrieve an required setting, parsing using its 'FromSetting' instance. 
req :: (FromSetting a, P.HasMetadata i) => P.Key -> RuleT i e f a
req key = reqParse key fromSetting