{-# LANGUAGE NoImplicitPrelude, OverloadedStrings, RecordWildCards #-}
{-|
Description: Generate nix expression for 'NP.Package'
-}
module Distribution.Nixpkgs.Nodejs.FromPackage
( genTemplate
) where

import Protolude

import Nix.Expr
import Nix.Expr.Additions

import Distribution.Nixpkgs.Nodejs.Utils (packageKeyToSymbol, attrSetMayStr, attrSetMay)
import qualified Distribution.Nodejs.Package as NP
import qualified Distribution.Nixpkgs.Nodejs.License as NL
import qualified Yarn.Lock.Types as YLT
import qualified Data.Aeson.KeyMap as KeyMap
import qualified Data.Aeson.Key as Key

depsToPkgKeys :: NP.Dependencies -> [YLT.PackageKey]
depsToPkgKeys deps =
  deps
  & KeyMap.toList
  <&> first Key.toText
  <&> toPkgKey
  where
    toPkgKey (k, v) =
      YLT.PackageKey (NP.parsePackageKeyName k) v

-- | generate a nix expression that translates your package.nix
--
-- and can serve as template for manual adjustments
genTemplate :: Maybe NL.LicensesBySpdxId -> NP.Package -> NExpr
genTemplate licSet NP.Package{..} =
  -- reserved for possible future arguments (to prevent breakage)
  simpleParamSet []
  ==> Param nodeDepsSym
  ==> (mkNonRecSet
        [ "key" $= packageKeyToSet (NP.parsePackageKeyName name)
        , "version" $= mkStr version
        , "nodeBuildInputs"  $= (letE "a" (mkSym nodeDepsSym)
                                  $ mkList (map (pkgDep "a") depPkgKeys))
        , "meta"      $= (mkNonRecSet
           $ attrSetMayStr "description" description
          <> attrSetMay    "license" (NL.nodeLicenseToNixpkgs <$> license <*> licSet)
          <> attrSetMayStr "homepage" homepage)
        ])
  where
    -- TODO: The devDependencies are only needed for the build
    -- and probably also only from packages not stemming from
    -- a npm registry (e.g. a git package). It would be cool
    -- if these dependencies were gone in the final output.
    -- See https://github.com/Profpatsch/yarn2nix/issues/5
    depPkgKeys = depsToPkgKeys (dependencies <> devDependencies)
    pkgDep depsSym pk = mkSym depsSym !!. packageKeyToSymbol pk
    nodeDepsSym = "allDeps"
    packageKeyToSet (YLT.SimplePackageKey n) =
      packageKeyToSet $ YLT.ScopedPackageKey "" n
    packageKeyToSet (YLT.ScopedPackageKey s n) = mkNonRecSet $
      [ bindTo "name"  $ mkStrQ [ StrQ n ]
      , bindTo "scope" $ mkStrQ [ StrQ s ]
      ]