improve flake interfaces and apps

- improve exposing apps for other flakes
  - configure overridesDirs via config

flake.nix

@@ -65,20 +65,11 @@
       };
 
       # create a directory containing the files listed in externalPaths
-      makeExternalDir = pkgs: pkgs.runCommand "dream2nix-external" {}
-        (lib.concatStringsSep "\n"
-          (lib.mapAttrsToList
-            (inputName: paths:
-              lib.concatStringsSep "\n"
-                (lib.forEach
-                  paths
-                  (path: ''
-                    mkdir -p $out/${inputName}/$(dirname ${path})
-                    cp ${inp."${inputName}"}/${path} $out/${inputName}/${path}
-                  '')))
-            externalPaths));
+      makeExternalDir = import ./src/utils/external-dir.nix;
 
-      externalDirFor = forAllSystems (system: makeExternalDir);
+      externalDirFor = forAllSystems (system: pkgs: makeExternalDir {
+        inherit externalPaths externalSources pkgs;
+      });
 
       # An interface to access files of external projects.
       # This implementation aceeses the flake inputs directly,
@@ -95,7 +86,10 @@
       # system specific dream2nix api
       dream2nixFor = forAllSystems (system: pkgs: import ./src rec {
         externalDir = externalDirFor."${system}";
-        inherit externalSources lib overridesDirs pkgs;
+        inherit externalSources lib pkgs;
+        config = {
+          inherit overridesDirs;
+        };
       });
 
     in
@@ -112,7 +106,7 @@
         # Similar to drem2nixFor but will require 'system(s)' or 'pkgs' as an argument.
         # Produces flake-like output schema.
         lib = (import ./src/lib.nix {
-          inherit externalSources overridesDirs lib;
+          inherit externalPaths externalSources lib;
           nixpkgsSrc = "${nixpkgs}";
         })
         # system specific dream2nix library
@@ -133,12 +127,7 @@
 
         # all apps including cli, install, etc.
         apps = forAllSystems (system: pkgs:
-          lib.mapAttrs (appName: app:
-            {
-              type = "app";
-              program = b.toString app.program;
-            }
-          ) dream2nixFor."${system}".apps.apps
+          dream2nixFor."${system}".apps.flakeApps
         );
 
         # a dev shell for working on dream2nix

src/apps/default.nix

@@ -1,16 +1,30 @@
 {
+  lib,
   pkgs,
 
   callPackageDream,
   translators,
   ...
 }:
+
+let
+  b = builtins;
+in
+
 rec {
   apps = {
     inherit cli contribute install;
     dream2nix = cli;
   };
 
+  flakeApps =
+    lib.mapAttrs (appName: app:
+      {
+        type = "app";
+        program = b.toString app.program;
+      }
+    ) apps;
+
   # the unified translator cli
   cli = callPackageDream (import ./cli) {};
 

src/config.json

@@ -1,3 +0,0 @@
-{
-
-}

src/default.nix

@@ -12,39 +12,51 @@
     ${pkgs.nixUnstable}/bin/nix --option experimental-features "nix-command flakes" "$@"
   '',
 
+  # default to empty dream2nix config
+  config ?
+    # if called via CLI, load cnfig via env
+    if builtins ? getEnv && builtins.getEnv "d2nConfigFile" != "" then
+      builtins.toPath (builtins.getEnv "d2nConfigFile")
+    # load from default directory
+    else
+      {},
+
   # dependencies of dream2nix
   externalSources ?
     lib.genAttrs
       (lib.attrNames (builtins.readDir externalDir))
       (inputName: "${externalDir}/${inputName}"),
 
+  # will be defined if called via flake
+  externalPaths ? null,
+
   # required for non-flake mode
   externalDir ?
+    # if flake is used, construct external dir from flake inputs
+    if externalPaths != null then
+      (import ./utils/external-dir.nix {
+        inherit externalPaths externalSources pkgs;
+      })
     # if called via CLI, load externals via env
-    if builtins ? getEnv && builtins.getEnv "d2nExternalDir" != "" then
+    else if builtins ? getEnv && builtins.getEnv "d2nExternalDir" != "" then
       builtins.getEnv "d2nExternalDir"
     # load from default directory
     else
       ./external,
 
-  # dream2nix overrides
-  overridesDirs ?
-     # if called via CLI, load externals via env
-    if builtins ? getEnv && builtins.getEnv "d2nOverridesDirs" != "" then
-      lib.splitString ":" (builtins.getEnv "d2nOverridesDirs")
-    # load from default directory
-    else
-      [ ./overrides ],
-}:
+}@args:
 
 let
 
   b = builtins;
 
+  config = (import ./utils/config.nix).loadConfig args.config or {};
+
   # like pkgs.callPackage, but includes all the dream2nix modules
   callPackageDream = f: args: pkgs.callPackage f (args // {
     inherit builders;
     inherit callPackageDream;
+    inherit config;
     inherit externals;
     inherit externalSources;
     inherit fetchers;
@@ -57,8 +69,6 @@ let
 
   utils = callPackageDream ./utils {};
 
-  config = builtins.fromJSON (builtins.readFile ./config.json);
-
   # apps for CLI and installation
   apps = callPackageDream ./apps {};
 
@@ -88,7 +98,7 @@ let
   };
 
   dreamOverrides =
-    utils.loadOverridesDirs overridesDirs pkgs;
+    utils.loadOverridesDirs config.overridesDirs pkgs;
 
   # the location of the dream2nix framework for self references (update scripts, etc.)
   dream2nixWithExternals =

src/lib.nix

@@ -6,17 +6,12 @@
   nixpkgsSrc ? <nixpkgs>,
   lib ? (import nixpkgsSrc {}).lib,
 
-  # (if called impurely ./default.nix will handle externals and overrides)
-  externalSources ? null,
+  # default to empty dream2nix config
+  config ? {},
 
-  # dream2nix overrides
-  overridesDirs ?
-     # if called via CLI, load externals via env
-    if builtins ? getEnv && builtins.getEnv "d2nOverridesDirs" != "" then
-      lib.splitString ":" (builtins.getEnv "d2nOverridesDirs")
-    # load from default directory
-    else
-      [ ./overrides ],
+  externalSources,
+
+  externalPaths,
 
 }@args:
 
@@ -24,6 +19,13 @@ let
 
   b = builtins;
 
+  config = (import ./utils/config.nix).loadConfig args.config or {};
+
+  dream2nixForSystem = system: pkgs:
+    import ./default.nix
+      { inherit config externalPaths externalSources pkgs; };
+
+
   # TODO: design output schema for cross compiled packages
   makePkgsKey = pkgs:
     let
@@ -75,28 +77,18 @@ let
     {
       pkgs ? null,
       systems ? [],
-      overridesDirs ? [],
+      config ? {},
     }@argsInit:
     let
 
-      overridesDirs' = args.overridesDirs ++ argsInit.overridesDirs or [];
+      overridesDirs' = config.overridesDirs;
 
       allPkgs = makeNixpkgs pkgs systems;
 
-      dream2nixFor =
-        lib.mapAttrs
-          (system: pkgs:
-            import ./default.nix
-              (
-                {
-                  inherit pkgs;
-                  overridesDirs = overridesDirs';
-                }
-                // (lib.optionalAttrs (externalSources != null) {
-                  inherit externalSources;
-                })
-              ))
-          allPkgs;
+      forAllSystems = f:
+        lib.mapAttrs f allPkgs;
+
+      dream2nixFor = forAllSystems dream2nixForSystem;
     in
       {
         riseAndShine = riseAndShineArgs:
@@ -117,6 +109,17 @@ let
               (allOutputs: output: lib.recursiveUpdate allOutputs output)
               {}
               flakifiedOutputs;
+
+        apps =
+          forAllSystems
+            (system: pkgs:
+              dream2nixFor."${system}".apps.flakeApps);
+              
+        defaultApp =
+          forAllSystems
+            (system: pkgs:
+              dream2nixFor."${system}".apps.flakeApps.dream2nix);
+        
       };
 
   riseAndShine = 
@@ -132,17 +135,7 @@ let
       allPkgs = makeNixpkgs pkgs systems;
 
       dream2nixFor =
-        lib.mapAttrs
-          (system: pkgs:
-            import ./default.nix
-              ({ inherit pkgs; }
-              // (lib.optionalAttrs (externalSources != null) {
-                inherit externalSources;
-              })
-              // (lib.optionalAttrs (overridesDirs != null) {
-                inherit overridesDirs;
-              })))
-          allPkgs;
+        lib.mapAttrs dream2nixForSystem allPkgs;
 
       allBuilderOutputs =
         lib.mapAttrs

src/utils/config.nix

@@ -0,0 +1,32 @@
+let
+
+  b = builtins;
+
+  # loads attrs either from s:
+  #   - json file
+  #   - json string
+  #   - attrset (no changes)
+  loadAttrs = input:
+    if b.isPath input then
+      b.fromJSON (b.readFile input)
+    else if b.isString input then
+      b.fromJSON input
+    else if b.isAttrs input then
+      input
+    else
+      throw "input for loadAttrs must be json file or string or attrs";
+  
+  # load dream2nix config extending with defaults
+  loadConfig = configInput:
+    let
+      config = loadAttrs configInput;
+      defaults =  {
+        overridesDirs = [];
+        packagesDir = null;
+      };
+    in
+      defaults // config;
+in
+{
+  inherit loadConfig;
+}

src/utils/external-dir.nix

@@ -0,0 +1,19 @@
+{
+  lib ? pkgs.lib,
+  pkgs,
+  externalSources,
+  externalPaths,
+}:
+
+pkgs.runCommand "dream2nix-external-dir" {}
+  (lib.concatStringsSep "\n"
+    (lib.mapAttrsToList
+      (inputName: paths:
+        lib.concatStringsSep "\n"
+          (lib.forEach
+            paths
+            (path: ''
+              mkdir -p $out/${inputName}/$(dirname ${path})
+              cp ${externalSources."${inputName}"}/${path} $out/${inputName}/${path}
+            '')))
+      externalPaths))