{ lib, config, stdenv }:

let
  checkMeta = import ./check-meta.nix {
    inherit lib config;
    # Nix itself uses the `system` field of a derivation to decide where
    # to build it. This is a bit confusing for cross compilation.
    inherit (stdenv) hostPlatform;
  };
in rec {
  # `mkDerivation` wraps the builtin `derivation` function to
  # produce derivations that use this stdenv and its shell.
  #
  # See also:
  #
  # * https://nixos.org/nixpkgs/manual/#sec-using-stdenv
  #   Details on how to use this mkDerivation function
  #
  # * https://nixos.org/nix/manual/#ssec-derivation
  #   Explanation about derivations in general
  mkDerivation =
    {

    # These types of dependencies are all exhaustively documented in
    # the "Specifying Dependencies" section of the "Standard
    # Environment" chapter of the Nixpkgs manual.

    # TODO(@Ericson2314): Stop using legacy dep attribute names

    #                           host offset -> target offset
      depsBuildBuild              ? [] # -1 -> -1
    , depsBuildBuildPropagated    ? [] # -1 -> -1
    , nativeBuildInputs           ? [] # -1 ->  0  N.B. Legacy name
    , propagatedNativeBuildInputs ? [] # -1 ->  0  N.B. Legacy name
    , depsBuildTarget             ? [] # -1 ->  1
    , depsBuildTargetPropagated   ? [] # -1 ->  1

    , depsHostHost                ? [] #  0 ->  0
    , depsHostHostPropagated      ? [] #  0 ->  0
    , buildInputs                 ? [] #  0 ->  1  N.B. Legacy name
    , propagatedBuildInputs       ? [] #  0 ->  1  N.B. Legacy name

    , depsTargetTarget            ? [] #  1 ->  1
    , depsTargetTargetPropagated  ? [] #  1 ->  1

    , checkInputs                 ? []
    , installCheckInputs          ? []

    # Configure Phase
    , configureFlags ? []
    , cmakeFlags ? []
    , mesonFlags ? []
    , # Target is not included by default because most programs don't care.
      # Including it then would cause needless mass rebuilds.
      #
      # TODO(@Ericson2314): Make [ "build" "host" ] always the default.
      configurePlatforms ? lib.optionals
        (stdenv.hostPlatform != stdenv.buildPlatform)
        [ "build" "host" ]

    # TODO(@Ericson2314): Make unconditional / resolve #33599
    # Check phase
    , doCheck ? config.doCheckByDefault or false

    # TODO(@Ericson2314): Make unconditional / resolve #33599
    # InstallCheck phase
    , doInstallCheck ? config.doCheckByDefault or false

    , # TODO(@Ericson2314): Make always true and remove
      strictDeps ? stdenv.hostPlatform != stdenv.buildPlatform
    , meta ? {}
    , passthru ? {}
    , pos ? # position used in error messages and for meta.position
        (if attrs.meta.description or null != null
          then builtins.unsafeGetAttrPos "description" attrs.meta
          else if attrs.version or null != null
          then builtins.unsafeGetAttrPos "version" attrs
          else builtins.unsafeGetAttrPos "name" attrs)
    , separateDebugInfo ? false
    , outputs ? [ "out" ]
    , __darwinAllowLocalNetworking ? false
    , __impureHostDeps ? []
    , __propagatedImpureHostDeps ? []
    , sandboxProfile ? ""
    , propagatedSandboxProfile ? ""

    , hardeningEnable ? []
    , hardeningDisable ? []

    , patches ? []

    , ... } @ attrs:

    let
      # TODO(@oxij, @Ericson2314): This is here to keep the old semantics, remove when
      # no package has `doCheck = true`.
      doCheck' = doCheck && stdenv.hostPlatform == stdenv.buildPlatform;
      doInstallCheck' = doInstallCheck && stdenv.hostPlatform == stdenv.buildPlatform;

      separateDebugInfo' = separateDebugInfo && stdenv.hostPlatform.isLinux && !(stdenv.hostPlatform.useLLVM or false);
      outputs' = outputs ++ lib.optional separateDebugInfo' "debug";

      noNonNativeDeps = builtins.length (depsBuildTarget ++ depsBuildTargetPropagated
                                      ++ depsHostHost ++ depsHostHostPropagated
                                      ++ buildInputs ++ propagatedBuildInputs
                                      ++ depsTargetTarget ++ depsTargetTargetPropagated) == 0;
      dontAddHostSuffix = attrs ? outputHash && !noNonNativeDeps || (stdenv.noCC or false);
      supportedHardeningFlags = [ "fortify" "stackprotector" "pie" "pic" "strictoverflow" "format" "relro" "bindnow" ];
      defaultHardeningFlags = if stdenv.hostPlatform.isMusl
                              then supportedHardeningFlags
                              else lib.remove "pie" supportedHardeningFlags;
      enabledHardeningOptions =
        if builtins.elem "all" hardeningDisable
        then []
        else lib.subtractLists hardeningDisable (defaultHardeningFlags ++ hardeningEnable);
      # hardeningDisable additionally supports "all".
      erroneousHardeningFlags = lib.subtractLists supportedHardeningFlags (hardeningEnable ++ lib.remove "all" hardeningDisable);
    in if builtins.length erroneousHardeningFlags != 0
    then abort ("mkDerivation was called with unsupported hardening flags: " + lib.generators.toPretty {} {
      inherit erroneousHardeningFlags hardeningDisable hardeningEnable supportedHardeningFlags;
    })
    else let
      doCheck = doCheck';
      doInstallCheck = doInstallCheck';

      outputs = outputs';

      references = nativeBuildInputs ++ buildInputs
                ++ propagatedNativeBuildInputs ++ propagatedBuildInputs;

      dependencies = map (map lib.chooseDevOutputs) [
        [
          (map (drv: drv.__spliced.buildBuild or drv) depsBuildBuild)
          (map (drv: drv.nativeDrv or drv) nativeBuildInputs
             ++ lib.optional separateDebugInfo' ../../build-support/setup-hooks/separate-debug-info.sh
             ++ lib.optional stdenv.hostPlatform.isWindows ../../build-support/setup-hooks/win-dll-link.sh
             ++ lib.optionals doCheck checkInputs
             ++ lib.optionals doInstallCheck' installCheckInputs)
          (map (drv: drv.__spliced.buildTarget or drv) depsBuildTarget)
        ]
        [
          (map (drv: drv.__spliced.hostHost or drv) depsHostHost)
          (map (drv: drv.crossDrv or drv) buildInputs)
        ]
        [
          (map (drv: drv.__spliced.targetTarget or drv) depsTargetTarget)
        ]
      ];
      propagatedDependencies = map (map lib.chooseDevOutputs) [
        [
          (map (drv: drv.__spliced.buildBuild or drv) depsBuildBuildPropagated)
          (map (drv: drv.nativeDrv or drv) propagatedNativeBuildInputs)
          (map (drv: drv.__spliced.buildTarget or drv) depsBuildTargetPropagated)
        ]
        [
          (map (drv: drv.__spliced.hostHost or drv) depsHostHostPropagated)
          (map (drv: drv.crossDrv or drv) propagatedBuildInputs)
        ]
        [
          (map (drv: drv.__spliced.targetTarget or drv) depsTargetTargetPropagated)
        ]
      ];

      computedSandboxProfile =
        lib.concatMap (input: input.__propagatedSandboxProfile or [])
          (stdenv.extraNativeBuildInputs
           ++ stdenv.extraBuildInputs
           ++ lib.concatLists dependencies);

      computedPropagatedSandboxProfile =
        lib.concatMap (input: input.__propagatedSandboxProfile or [])
          (lib.concatLists propagatedDependencies);

      computedImpureHostDeps =
        lib.unique (lib.concatMap (input: input.__propagatedImpureHostDeps or [])
          (stdenv.extraNativeBuildInputs
           ++ stdenv.extraBuildInputs
           ++ lib.concatLists dependencies));

      computedPropagatedImpureHostDeps =
        lib.unique (lib.concatMap (input: input.__propagatedImpureHostDeps or [])
          (lib.concatLists propagatedDependencies));

      derivationArg =
        (removeAttrs attrs
          ["meta" "passthru" "pos"
           "checkInputs" "installCheckInputs"
           "__darwinAllowLocalNetworking"
           "__impureHostDeps" "__propagatedImpureHostDeps"
           "sandboxProfile" "propagatedSandboxProfile"])
        // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) {
          name = "${attrs.pname}-${attrs.version}";
        } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {
          # Fixed-output derivations like source tarballs shouldn't get a host
          # suffix. But we have some weird ones with run-time deps that are
          # just used for their side-affects. Those might as well since the
          # hash can't be the same. See #32986.
          name = "${attrs.name or "${attrs.pname}-${attrs.version}"}-${stdenv.hostPlatform.config}";
        } // {
          builder = attrs.realBuilder or stdenv.shell;
          args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
          inherit stdenv;

          # The `system` attribute of a derivation has special meaning to Nix.
          # Derivations set it to choose what sort of machine could be used to
          # execute the build, The build platform entirely determines this,
          # indeed more finely than Nix knows or cares about. The `system`
          # attribute of `buildPlatfom` matches Nix's degree of specificity.
          # exactly.
          inherit (stdenv.buildPlatform) system;

          userHook = config.stdenv.userHook or null;
          __ignoreNulls = true;

          inherit strictDeps;

          depsBuildBuild              = lib.elemAt (lib.elemAt dependencies 0) 0;
          nativeBuildInputs           = lib.elemAt (lib.elemAt dependencies 0) 1;
          depsBuildTarget             = lib.elemAt (lib.elemAt dependencies 0) 2;
          depsHostHost                = lib.elemAt (lib.elemAt dependencies 1) 0;
          buildInputs                 = lib.elemAt (lib.elemAt dependencies 1) 1;
          depsTargetTarget            = lib.elemAt (lib.elemAt dependencies 2) 0;

          depsBuildBuildPropagated    = lib.elemAt (lib.elemAt propagatedDependencies 0) 0;
          propagatedNativeBuildInputs = lib.elemAt (lib.elemAt propagatedDependencies 0) 1;
          depsBuildTargetPropagated   = lib.elemAt (lib.elemAt propagatedDependencies 0) 2;
          depsHostHostPropagated      = lib.elemAt (lib.elemAt propagatedDependencies 1) 0;
          propagatedBuildInputs       = lib.elemAt (lib.elemAt propagatedDependencies 1) 1;
          depsTargetTargetPropagated  = lib.elemAt (lib.elemAt propagatedDependencies 2) 0;

          # This parameter is sometimes a string, sometimes null, and sometimes a list, yuck
          configureFlags = let inherit (lib) optional elem; in
            (/**/ if lib.isString configureFlags then [configureFlags]
             else if configureFlags == null      then []
             else                                     configureFlags)
            ++ optional (elem "build"  configurePlatforms) "--build=${stdenv.buildPlatform.config}"
            ++ optional (elem "host"   configurePlatforms) "--host=${stdenv.hostPlatform.config}"
            ++ optional (elem "target" configurePlatforms) "--target=${stdenv.targetPlatform.config}";

          inherit patches;

          inherit doCheck doInstallCheck;

          inherit outputs;
        } // lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform) {
          cmakeFlags =
            (/**/ if lib.isString cmakeFlags then [cmakeFlags]
             else if cmakeFlags == null      then []
             else                                     cmakeFlags)
          ++ [ "-DCMAKE_SYSTEM_NAME=${lib.findFirst lib.isString "Generic" (
               lib.optional (!stdenv.hostPlatform.isRedox) stdenv.hostPlatform.uname.system)}"]
          ++ lib.optional (stdenv.hostPlatform.uname.processor != null) "-DCMAKE_SYSTEM_PROCESSOR=${stdenv.hostPlatform.uname.processor}"
          ++ lib.optional (stdenv.hostPlatform.uname.release != null) "-DCMAKE_SYSTEM_VERSION=${stdenv.hostPlatform.release}"
          ++ lib.optional (stdenv.hostPlatform.isDarwin) "-DCMAKE_OSX_ARCHITECTURES=${stdenv.hostPlatform.darwinArch}"
          ++ lib.optional (stdenv.buildPlatform.uname.system != null) "-DCMAKE_HOST_SYSTEM_NAME=${stdenv.buildPlatform.uname.system}"
          ++ lib.optional (stdenv.buildPlatform.uname.processor != null) "-DCMAKE_HOST_SYSTEM_PROCESSOR=${stdenv.buildPlatform.uname.processor}"
          ++ lib.optional (stdenv.buildPlatform.uname.release != null) "-DCMAKE_HOST_SYSTEM_VERSION=${stdenv.buildPlatform.uname.release}";

          mesonFlags = if mesonFlags == null then null else let
            # See https://mesonbuild.com/Reference-tables.html#cpu-families
            cpuFamily = platform: with platform;
              /**/ if isAarch32 then "arm"
              else if isAarch64 then "aarch64"
              else if isx86_32  then "x86"
              else if isx86_64  then "x86_64"
              else platform.parsed.cpu.family + builtins.toString platform.parsed.cpu.bits;
            crossFile = builtins.toFile "cross-file.conf" ''
              [properties]
              needs_exe_wrapper = true

              [host_machine]
              system = '${stdenv.targetPlatform.parsed.kernel.name}'
              cpu_family = '${cpuFamily stdenv.targetPlatform}'
              cpu = '${stdenv.targetPlatform.parsed.cpu.name}'
              endian = ${if stdenv.targetPlatform.isLittleEndian then "'little'" else "'big'"}
            '';
          in [ "--cross-file=${crossFile}" ] ++ mesonFlags;
        } // lib.optionalAttrs (attrs.enableParallelBuilding or false) {
          enableParallelChecking = attrs.enableParallelChecking or true;
        } // lib.optionalAttrs (hardeningDisable != [] || hardeningEnable != [] || stdenv.hostPlatform.isMusl) {
          NIX_HARDENING_ENABLE = enabledHardeningOptions;
        } // lib.optionalAttrs (stdenv.hostPlatform.isx86_64 && stdenv.hostPlatform ? gcc.arch) {
          requiredSystemFeatures = attrs.requiredSystemFeatures or [] ++ [ "gccarch-${stdenv.hostPlatform.gcc.arch}" ];
        } // lib.optionalAttrs (stdenv.buildPlatform.isDarwin) {
          inherit __darwinAllowLocalNetworking;
          # TODO: remove lib.unique once nix has a list canonicalization primitive
          __sandboxProfile =
          let profiles = [ stdenv.extraSandboxProfile ] ++ computedSandboxProfile ++ computedPropagatedSandboxProfile ++ [ propagatedSandboxProfile sandboxProfile ];
              final = lib.concatStringsSep "\n" (lib.filter (x: x != "") (lib.unique profiles));
          in final;
          __propagatedSandboxProfile = lib.unique (computedPropagatedSandboxProfile ++ [ propagatedSandboxProfile ]);
          __impureHostDeps = computedImpureHostDeps ++ computedPropagatedImpureHostDeps ++ __propagatedImpureHostDeps ++ __impureHostDeps ++ stdenv.__extraImpureHostDeps ++ [
            "/dev/zero"
            "/dev/random"
            "/dev/urandom"
            "/bin/sh"
          ];
          __propagatedImpureHostDeps = computedPropagatedImpureHostDeps ++ __propagatedImpureHostDeps;
        };

      validity = checkMeta { inherit meta attrs; };

      # The meta attribute is passed in the resulting attribute set,
      # but it's not part of the actual derivation, i.e., it's not
      # passed to the builder and is not a dependency.  But since we
      # include it in the result, it *is* available to nix-env for queries.
      meta = {
          # `name` above includes cross-compilation cruft (and is under assert),
          # lets have a clean always accessible version here.
          name = attrs.name or "${attrs.pname}-${attrs.version}";

          # If the packager hasn't specified `outputsToInstall`, choose a default,
          # which is the name of `p.bin or p.out or p` along with `p.man` when
          # present.
          #
          # If the packager has specified it, it will be overridden below in
          # `// meta`.
          #
          #   Note: This default probably shouldn't be globally configurable.
          #   Services and users should specify outputs explicitly,
          #   unless they are comfortable with this default.
          outputsToInstall =
            let
              hasOutput = out: builtins.elem out outputs;
            in [( lib.findFirst hasOutput null (["bin" "out"] ++ outputs) )]
              ++ lib.optional (hasOutput "man") "man";
        }
        // attrs.meta or {}
        # Fill `meta.position` to identify the source location of the package.
        // lib.optionalAttrs (pos != null) {
          position = pos.file + ":" + toString pos.line;
        } // {
          # Expose the result of the checks for everyone to see.
          inherit (validity) unfree broken unsupported insecure;
          available = validity.valid
                   && (if config.checkMetaRecursively or false
                       then lib.all (d: d.meta.available or true) references
                       else true);
        };

    in

      lib.extendDerivation
        validity.handled
        ({
           overrideAttrs = f: mkDerivation (attrs // (f attrs));

           # A derivation that always builds successfully and whose runtime
           # dependencies are the original derivations build time dependencies
           # This allows easy building and distributing of all derivations
           # needed to enter a nix-shell with
           #   nix-build shell.nix -A inputDerivation
           inputDerivation = derivation (derivationArg // {
             # Add a name in case the original drv didn't have one
             name = derivationArg.name or "inputDerivation";
             # This always only has one output
             outputs = [ "out" ];

             # Propagate the original builder and arguments, since we override
             # them and they might contain references to build inputs
             _derivation_original_builder = derivationArg.builder;
             _derivation_original_args = derivationArg.args;

             builder = stdenv.shell;
             # The bash builtin `export` dumps all current environment variables,
             # which is where all build input references end up (e.g. $PATH for
             # binaries). By writing this to $out, Nix can find and register
             # them as runtime dependencies (since Nix greps for store paths
             # through $out to find them)
             args = [ "-c" "export > $out" ];
           });

           inherit meta passthru;
         } //
         # Pass through extra attributes that are not inputs, but
         # should be made available to Nix expressions using the
         # derivation (e.g., in assertions).
         passthru)
        (derivation derivationArg);

}