    {-# LANGUAGE DeriveDataTypeable #-}
    {-# LANGUAGE DeriveGeneric #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.License
    -- Description :  The License data type.
    -- Copyright   :  Isaac Jones 2003-2005
    --                Duncan Coutts 2008
    -- License     :  BSD3
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- Package descriptions contain fields for specifying the name of a software
    -- license and the name of the file containing the text of that license. While
    -- package authors may choose any license they like, Cabal provides an
    -- enumeration of a small set of common free and open source software licenses.
    -- This is done so that Hackage can recognise licenses, so that tools can detect
    -- <https://en.wikipedia.org/wiki/License_compatibility licensing conflicts>,
    -- and to deter
    -- <https://en.wikipedia.org/wiki/License_proliferation license proliferation>.
    --
    -- It is recommended that all package authors use the @license-file@ or
    -- @license-files@ fields in their package descriptions. Further information
    -- about these fields can be found in the
    -- <http://www.haskell.org/cabal/users-guide/developing-packages.html#package-descriptions Cabal users guide>.
    --
    -- = Additional resources
    --
    -- The following websites provide information about free and open source
    -- software licenses:
    --
    -- * <http://www.opensource.org The Open Source Initiative (OSI)>
    --
    -- * <https://www.fsf.org The Free Software Foundation (FSF)>
    --
    -- = Disclaimer
    --
    -- The descriptions of software licenses provided by this documentation are
    -- intended for informational purposes only and in no way constitute legal
    -- advice. Please read the text of the licenses and consult a lawyer for any
    -- advice regarding software licensing.

    module Distribution.License (
        License(..),
        knownLicenses,
      ) where

    import Distribution.Version (Version(Version))

    import Distribution.Text (Text(..), display)
    import qualified Distribution.Compat.ReadP as Parse
    import qualified Text.PrettyPrint as Disp
    import Text.PrettyPrint ((<>))
    import Distribution.Compat.Binary (Binary)
    import qualified Data.Char as Char (isAlphaNum)
    import Data.Data (Data)
    import Data.Typeable (Typeable)
    import GHC.Generics (Generic)

    -- | Indicates the license under which a package's source code is released.
    -- Versions of the licenses not listed here will be rejected by Hackage and
    -- cause @cabal check@ to issue a warning.
    data License =
        -- TODO: * remove BSD4

        -- | GNU General Public License,
        -- <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html version 2> or
        -- <https://www.gnu.org/licenses/gpl.html version 3>.
        GPL (Maybe Version)

        -- | <https://www.gnu.org/licenses/agpl.html GNU Affero General Public License, version 3>.
      | AGPL (Maybe Version)

        -- | GNU Lesser General Public License,
        -- <https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html version 2.1> or
        -- <https://www.gnu.org/licenses/lgpl.html version 3>.
      | LGPL (Maybe Version)

        -- | <http://www.opensource.org/licenses/bsd-license 2-clause BSD license>.
      | BSD2

        -- | <http://www.opensource.org/licenses/bsd-3-clause 3-clause BSD license>.
      | BSD3

        -- | <http://directory.fsf.org/wiki/License:BSD_4Clause 4-clause BSD license>.
        -- This license has not been approved by the OSI and is incompatible with
        -- the GNU GPL. It is provided for historical reasons and should be avoided.
      | BSD4

        -- | <http://www.opensource.org/licenses/MIT MIT license>.
      | MIT

        -- | <http://www.isc.org/downloads/software-support-policy/isc-license/ ISC license>
      | ISC

        -- | <https://www.mozilla.org/MPL/ Mozilla Public License, version 2.0>.
      | MPL Version

        -- | <https://www.apache.org/licenses/ Apache License, version 2.0>.
      | Apache (Maybe Version)

        -- | The author of a package disclaims any copyright to its source code and
        -- dedicates it to the public domain. This is not a software license. Please
        -- note that it is not possible to dedicate works to the public domain in
        -- every jurisdiction, nor is a work that is in the public domain in one
        -- jurisdiction necessarily in the public domain elsewhere.
      | PublicDomain

        -- | Explicitly 'All Rights Reserved', eg for proprietary software. The
        -- package may not be legally modified or redistributed by anyone but the
        -- rightsholder.
      | AllRightsReserved

        -- | No license specified which legally defaults to 'All Rights Reserved'.
        -- The package may not be legally modified or redistributed by anyone but
        -- the rightsholder.
      | UnspecifiedLicense

        -- | Any other software license.
      | OtherLicense

        -- | Indicates an erroneous license name.
      | UnknownLicense String
      deriving (Generic, Read, Show, Eq, Typeable, Data)

    instance Binary License

    -- | The list of all currently recognised licenses.
    knownLicenses :: [License]
    knownLicenses = [ GPL  unversioned, GPL  (version [2]),    GPL  (version [3])
                    , LGPL unversioned, LGPL (version [2, 1]), LGPL (version [3])
                    , AGPL unversioned,                        AGPL (version [3])
                    , BSD2, BSD3, MIT, ISC
                    , MPL (Version [2, 0] [])
                    , Apache unversioned, Apache (version [2, 0])
                    , PublicDomain, AllRightsReserved, OtherLicense]
     where
       unversioned = Nothing
       version   v = Just (Version v [])

    instance Text License where
      disp (GPL  version)         = Disp.text "GPL"    <> dispOptVersion version
      disp (LGPL version)         = Disp.text "LGPL"   <> dispOptVersion version
      disp (AGPL version)         = Disp.text "AGPL"   <> dispOptVersion version
      disp (MPL  version)         = Disp.text "MPL"    <> dispVersion    version
      disp (Apache version)       = Disp.text "Apache" <> dispOptVersion version
      disp (UnknownLicense other) = Disp.text other
      disp other                  = Disp.text (show other)

      parse = do
        name    <- Parse.munch1 (\c -> Char.isAlphaNum c && c /= '-')
        version <- Parse.option Nothing (Parse.char '-' >> fmap Just parse)
        return $! case (name, version :: Maybe Version) of
          ("GPL",               _      ) -> GPL  version
          ("LGPL",              _      ) -> LGPL version
          ("AGPL",              _      ) -> AGPL version
          ("BSD2",              Nothing) -> BSD2
          ("BSD3",              Nothing) -> BSD3
          ("BSD4",              Nothing) -> BSD4
          ("ISC",               Nothing) -> ISC
          ("MIT",               Nothing) -> MIT
          ("MPL",         Just version') -> MPL version'
          ("Apache",            _      ) -> Apache version
          ("PublicDomain",      Nothing) -> PublicDomain
          ("AllRightsReserved", Nothing) -> AllRightsReserved
          ("OtherLicense",      Nothing) -> OtherLicense
          _                              -> UnknownLicense $ name ++
                                            maybe "" (('-':) . display) version

    dispOptVersion :: Maybe Version -> Disp.Doc
    dispOptVersion Nothing  = Disp.empty
    dispOptVersion (Just v) = dispVersion v

    dispVersion :: Version -> Disp.Doc
    dispVersion v = Disp.char '-' <> disp v