{ go, govers, lib, fetchgit, fetchhg, fetchbzr, rsync, fetchFromGitHub, stdenv
}:

{ buildInputs ? [ ], nativeBuildInputs ? [ ], passthru ? { }, preFixup ? ""
, shellHook ? ""

  # We want parallel builds by default
, enableParallelBuilding ? true

  # Go import path of the package
, goPackagePath

# Go package aliases
, goPackageAliases ? [ ]

  # Extra sources to include in the gopath
, extraSrcs ? [ ]

  # Extra gopaths containing src subfolder
  # with sources to include in the gopath
, extraSrcPaths ? [ ]

  # go2nix dependency file
, goDeps ? null

  # Whether to delete the vendor folder supplied with the source.
, deleteVendor ? false

, dontRenameImports ? false

  # Do not enable this without good reason
  # IE: programs coupled with the compiler
, allowGoReference ? false

, CGO_ENABLED ? go.CGO_ENABLED

, ldflags ? [ ]

, GOFLAGS ? [ ]

  # needed for buildFlags{,Array} warning
, buildFlags ? "", buildFlagsArray ? ""

, meta ? { }, ... }@args:

let
  dep2src = goDep: {
    inherit (goDep) goPackagePath;
    src = if goDep.fetch.type == "git" then
      fetchgit { inherit (goDep.fetch) url rev sha256; }
    else if goDep.fetch.type == "hg" then
      fetchhg { inherit (goDep.fetch) url rev sha256; }
    else if goDep.fetch.type == "bzr" then
      fetchbzr { inherit (goDep.fetch) url rev sha256; }
    else if goDep.fetch.type == "FromGitHub" then
      fetchFromGitHub { inherit (goDep.fetch) owner repo rev sha256; }
    else
      abort "Unrecognized package fetch type: ${goDep.fetch.type}";
  };

  importGodeps = { depsFile }: map dep2src (import depsFile);

  goPath = if goDeps != null then
    importGodeps { depsFile = goDeps; } ++ extraSrcs
  else
    extraSrcs;
  package = stdenv.mkDerivation
    ((builtins.removeAttrs args [ "goPackageAliases" "disabled" "extraSrcs" ])
      // {

        nativeBuildInputs = [ go ] ++ (lib.optional (!dontRenameImports) govers)
          ++ nativeBuildInputs;
        buildInputs = buildInputs;

        inherit (go) GOOS GOARCH GO386;

        GOHOSTARCH = go.GOHOSTARCH or null;
        GOHOSTOS = go.GOHOSTOS or null;

        inherit CGO_ENABLED enableParallelBuilding;

        GO111MODULE = "off";
        GOTOOLCHAIN = "local";
        GOFLAGS = GOFLAGS ++ lib.optional (!allowGoReference) "-trimpath";

        GOARM = toString (lib.intersectLists
          [ (stdenv.hostPlatform.parsed.cpu.version or "") ] [ "5" "6" "7" ]);

        # If not set to an explicit value, set the buildid empty for reproducibility.
        ldflags = ldflags
          ++ lib.optional (!lib.any (lib.hasPrefix "-buildid=") ldflags)
          "-buildid=";

        configurePhase = args.configurePhase or (''
          runHook preConfigure

          # Extract the source
          cd "$NIX_BUILD_TOP"
          mkdir -p "go/src/$(dirname "$goPackagePath")"
          mv "$sourceRoot" "go/src/$goPackagePath"

        '' + lib.optionalString deleteVendor ''
          if [ ! -d "go/src/$goPackagePath/vendor" ]; then
            echo "vendor folder does not exist, 'deleteVendor' is not needed"
            exit 10
          else
            rm -rf "go/src/$goPackagePath/vendor"
          fi
        '' + lib.optionalString (goDeps != null) ''
          if [ -d "go/src/$goPackagePath/vendor" ]; then
            echo "vendor folder exists, 'goDeps' is not needed"
            exit 10
          fi
        '' + lib.flip lib.concatMapStrings goPath ({ src, goPackagePath }: ''
          mkdir goPath
          (cd goPath; unpackFile "${src}")
          mkdir -p "go/src/$(dirname "${goPackagePath}")"
          chmod -R u+w goPath/*
          mv goPath/* "go/src/${goPackagePath}"
          rmdir goPath

        '') + (lib.optionalString (extraSrcPaths != [ ]) ''
          ${rsync}/bin/rsync -a ${
            lib.concatMapStringsSep " " (p: "${p}/src") extraSrcPaths
          } go

        '') + ''
          export GOPATH=$NIX_BUILD_TOP/go:$GOPATH
          export GOCACHE=$TMPDIR/go-cache

          # currently pie is only enabled by default in pkgsMusl
          # this will respect the `hardening{Disable,Enable}` flags if set
          if [[ $NIX_HARDENING_ENABLE =~ "pie" ]]; then
            export GOFLAGS="-buildmode=pie $GOFLAGS"
          fi

          runHook postConfigure
        '');

        renameImports = args.renameImports or (let
          inputsWithAliases = lib.filter (x: x ? goPackageAliases)
            (buildInputs ++ (args.propagatedBuildInputs or [ ]));
          rename = to: from:
            "echo Renaming '${from}' to '${to}'; govers -d -m ${from} ${to}";
          renames = p:
            lib.concatMapStringsSep "\n" (rename p.goPackagePath)
            p.goPackageAliases;
        in lib.concatMapStringsSep "\n" renames inputsWithAliases);

        buildPhase = args.buildPhase or (''
          runHook preBuild

          runHook renameImports

          exclude='\(/_\|examples\|Godeps\|testdata'
          if [[ -n "$excludedPackages" ]]; then
            IFS=' ' read -r -a excludedArr <<<$excludedPackages
            printf -v excludedAlternates '%s\\|' "''${excludedArr[@]}"
            excludedAlternates=''${excludedAlternates%\\|} # drop final \| added by printf
            exclude+='\|'"$excludedAlternates"
          fi
          exclude+='\)'

          buildGoDir() {
            local cmd="$1" dir="$2"

            . $TMPDIR/buildFlagsArray

            declare -a flags
            flags+=($buildFlags "''${buildFlagsArray[@]}")
            flags+=(''${tags:+-tags=''${tags// /,}})
            flags+=(''${ldflags:+-ldflags="$ldflags"})
            flags+=("-p" "$NIX_BUILD_CORES")

            if [ "$cmd" = "test" ]; then
              flags+=(-vet=off)
              flags+=($checkFlags)
            fi

            local OUT
            if ! OUT="$(go $cmd "''${flags[@]}" $dir 2>&1)"; then
              if ! echo "$OUT" | grep -qE '(no( buildable| non-test)?|build constraints exclude all) Go (source )?files'; then
                echo "$OUT" >&2
                return 1
              fi
            fi
            if [ -n "$OUT" ]; then
              echo "$OUT" >&2
            fi
            return 0
          }

          getGoDirs() {
            local type;
            type="$1"
            if [ -n "$subPackages" ]; then
              echo "$subPackages" | sed "s,\(^\| \),\1$goPackagePath/,g"
            else
              pushd "$NIX_BUILD_TOP/go/src" >/dev/null
              find "$goPackagePath" -type f -name \*$type.go -exec dirname {} \; | grep -v "/vendor/" | sort | uniq | grep -v "$exclude"
              popd >/dev/null
            fi
          }

          if (( "''${NIX_DEBUG:-0}" >= 1 )); then
            buildFlagsArray+=(-x)
          fi

          if [ ''${#buildFlagsArray[@]} -ne 0 ]; then
            declare -p buildFlagsArray > $TMPDIR/buildFlagsArray
          else
            touch $TMPDIR/buildFlagsArray
          fi
          if [ -z "$enableParallelBuilding" ]; then
              export NIX_BUILD_CORES=1
          fi
          for pkg in $(getGoDirs ""); do
            echo "Building subPackage $pkg"
            buildGoDir install "$pkg"
          done
        '' + lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
          # normalize cross-compiled builds w.r.t. native builds
          (
            dir=$NIX_BUILD_TOP/go/bin/${go.GOOS}_${go.GOARCH}
            if [[ -n "$(shopt -s nullglob; echo $dir/*)" ]]; then
              mv $dir/* $dir/..
            fi
            if [[ -d $dir ]]; then
              rmdir $dir
            fi
          )
        '' + ''
          runHook postBuild
        '');

        doCheck = args.doCheck or false;
        checkPhase = args.checkPhase or ''
          runHook preCheck
          # We do not set trimpath for tests, in case they reference test assets
          export GOFLAGS=''${GOFLAGS//-trimpath/}

          for pkg in $(getGoDirs test); do
            buildGoDir test "$pkg"
          done

          runHook postCheck
        '';

        installPhase = args.installPhase or ''
          runHook preInstall

          mkdir -p $out
          dir="$NIX_BUILD_TOP/go/bin"
          [ -e "$dir" ] && cp -r $dir $out

          runHook postInstall
        '';

        strictDeps = true;

        shellHook = ''
          d=$(mktemp -d "--suffix=-$name")
        '' + toString (map (dep: ''
          mkdir -p "$d/src/$(dirname "${dep.goPackagePath}")"
          ln -s "${dep.src}" "$d/src/${dep.goPackagePath}"
        '') goPath) + ''
          export GOPATH=${
            lib.concatStringsSep ":"
            ([ "$d" ] ++ [ "$GOPATH" ] ++ [ "$PWD" ] ++ extraSrcPaths)
          }
        '' + shellHook;

        disallowedReferences = lib.optional (!allowGoReference) go
          ++ lib.optional (!dontRenameImports) govers;

        passthru = passthru // {
          inherit go;
        } // lib.optionalAttrs (goPackageAliases != [ ]) {
          inherit goPackageAliases;
        };

        meta = {
          # Add default meta information
          homepage = "https://${goPackagePath}";
          platforms = go.meta.platforms or lib.platforms.all;
        } // meta;
      });
in lib.warnIf (buildFlags != "" || buildFlagsArray != "")
"Use the `ldflags` and/or `tags` attributes instead of `buildFlags`/`buildFlagsArray`"
lib.warnIf (builtins.elem "-buildid=" ldflags)
"`-buildid=` is set by default as ldflag by buildGoModule" lib.warnIf
(builtins.elem "-trimpath" GOFLAGS)
"`-trimpath` is added by default to GOFLAGS by buildGoModule when allowGoReference isn't set to true"
package