{-# LANGUAGE CPP                     #-}
{-# LANGUAGE ConstraintKinds         #-}
{-# LANGUAGE FunctionalDependencies  #-}
{-# LANGUAGE RankNTypes              #-}
{-# LANGUAGE ScopedTypeVariables     #-}
{-# LANGUAGE UndecidableSuperClasses #-}
module Distribution.FieldGrammar.Class (
    FieldGrammar (..),
    uniqueField,
    optionalField,
    optionalFieldDef,
    monoidalField,
    defaultFreeTextFieldDefST,
) where

import Distribution.Compat.Lens
import Distribution.Compat.Prelude
import Prelude ()

import Distribution.CabalSpecVersion      (CabalSpecVersion)
import Distribution.Compat.Newtype        (Newtype)
import Distribution.FieldGrammar.Newtypes
import Distribution.Fields.Field
import Distribution.Utils.ShortText

-- | 'FieldGrammar' is parametrised by
--
-- * @s@ which is a structure we are parsing. We need this to provide prettyprinter
-- functionality
--
-- * @a@ type of the field.
--
-- /Note:/ We'd like to have @forall s. Applicative (f s)@ context.
--
class
    ( c SpecVersion, c TestedWith, c SpecLicense, c Token, c Token', c FilePathNT
    )
    => FieldGrammar c g | g -> c
  where
    -- | Unfocus, zoom out, /blur/ 'FieldGrammar'.
    blurFieldGrammar :: ALens' a b -> g b d -> g a d

    -- | Field which should be defined, exactly once.
    uniqueFieldAla
        :: (c b, Newtype a b)
        => FieldName   -- ^ field name
        -> (a -> b)    -- ^ 'Newtype' pack
        -> ALens' s a  -- ^ lens into the field
        -> g s a

    -- | Boolean field with a default value.
    booleanFieldDef
        :: FieldName     -- ^ field name
        -> ALens' s Bool -- ^ lens into the field
        -> Bool          -- ^ default
        -> g s Bool

    -- | Optional field.
    optionalFieldAla
        :: (c b, Newtype a b)
        => FieldName          -- ^ field name
        -> (a -> b)           -- ^ 'pack'
        -> ALens' s (Maybe a) -- ^ lens into the field
        -> g s (Maybe a)

    -- | Optional field with default value.
    optionalFieldDefAla
        :: (c b, Newtype a b, Eq a)
        => FieldName   -- ^ field name
        -> (a -> b)    -- ^ 'Newtype' pack
        -> ALens' s a  -- ^ @'Lens'' s a@: lens into the field
        -> a           -- ^ default value
        -> g s a

    --  | Free text field is essentially 'optionalFieldDefAla` with @""@
    --  as the default and "accept everything" parser.
    --
    -- @since 3.0.0.0
    freeTextField
        :: FieldName
        -> ALens' s (Maybe String) -- ^ lens into the field
        -> g s (Maybe String)

    --  | Free text field is essentially 'optionalFieldDefAla` with @""@
    --  as the default and "accept everything" parser.
    --
    -- @since 3.0.0.0
    freeTextFieldDef
        :: FieldName
        -> ALens' s String -- ^ lens into the field
        -> g s String

    -- | @since 3.2.0.0
    freeTextFieldDefST
        :: FieldName
        -> ALens' s ShortText -- ^ lens into the field
        -> g s ShortText

    -- | Monoidal field.
    --
    -- Values are combined with 'mappend'.
    --
    -- /Note:/ 'optionalFieldAla' is a @monoidalField@ with 'Last' monoid.
    --
    monoidalFieldAla
        :: (c b, Monoid a, Newtype a b)
        => FieldName   -- ^ field name
        -> (a -> b)    -- ^ 'pack'
        -> ALens' s a  -- ^ lens into the field
        -> g s a

    -- | Parser matching all fields with a name starting with a prefix.
    prefixedFields
        :: FieldName                    -- ^ field name prefix
        -> ALens' s [(String, String)]  -- ^ lens into the field
        -> g s [(String, String)]

    -- | Known field, which we don't parse, nor pretty print.
    knownField :: FieldName -> g s ()

    -- | Field which is parsed but not pretty printed.
    hiddenField :: g s a -> g s a

    -- | Deprecated since
    deprecatedSince
        :: CabalSpecVersion   -- ^ version
        -> String             -- ^ deprecation message
        -> g s a
        -> g s a

    -- | Removed in. If we encounter removed field, parsing fails.
    removedIn
        :: CabalSpecVersion   -- ^ version
        -> String             -- ^ removal message
        -> g s a
        -> g s a

    -- | Annotate field with since spec-version.
    availableSince
        :: CabalSpecVersion  -- ^ spec version
        -> a                 -- ^ default value
        -> g s a
        -> g s a

    -- | Annotate field with since spec-version.
    -- This is used to recognise, but warn about the field.
    -- It is used to process @other-extensions@ field.
    --
    -- Default implementation is to not warn.
    --
    -- @since 3.4.0.0
    availableSinceWarn
        :: CabalSpecVersion  -- ^ spec version
        -> g s a
        -> g s a
    availableSinceWarn _ = id

-- | Field which can be defined at most once.
uniqueField
    :: (FieldGrammar c g, c (Identity a))
    => FieldName   -- ^ field name
    -> ALens' s a  -- ^ lens into the field
    -> g s a
uniqueField fn l = uniqueFieldAla fn Identity l

-- | Field which can be defined at most once.
optionalField
    :: (FieldGrammar c g, c (Identity a))
    => FieldName          -- ^ field name
    -> ALens' s (Maybe a) -- ^ lens into the field
    -> g s (Maybe a)
optionalField fn l = optionalFieldAla fn Identity l

-- | Optional field with default value.
optionalFieldDef
    :: (FieldGrammar c g, Functor (g s), c (Identity a), Eq a)
    => FieldName   -- ^ field name
    -> ALens' s a  -- ^ @'Lens'' s a@: lens into the field
    -> a           -- ^ default value
    -> g s a
optionalFieldDef fn l x = optionalFieldDefAla fn Identity l x

-- | Field which can be define multiple times, and the results are @mappend@ed.
monoidalField
    :: (FieldGrammar c g, c (Identity a), Monoid a)
    => FieldName   -- ^ field name
    -> ALens' s a  -- ^ lens into the field
    -> g s a
monoidalField fn l = monoidalFieldAla fn Identity l

-- | Default implementation for 'freeTextFieldDefST'.
defaultFreeTextFieldDefST
    :: (Functor (g s), FieldGrammar c g)
    => FieldName
    -> ALens' s ShortText -- ^ lens into the field
    -> g s ShortText
defaultFreeTextFieldDefST fn l =
    toShortText <$> freeTextFieldDef fn (cloneLens l . st)
  where
    st :: Lens' ShortText String
    st f s = toShortText <$> f (fromShortText s)
