Always build from dream-lock.json if exists

- add an invalidationHash to dream-lock.json
- always evaluate dream-lock.json if exists
- warn user if dream-lock.json doesn't exist

src/apps/cli/commands/add.py

@@ -63,6 +63,7 @@ class AddCommand(Command):
     ),
     option("force", None, "override existing files", flag=True),
     option("no-default-nix", None, "create default.nix", flag=True),
+    option("invalidation-hash", None, "invalidation hash to attach", flag=False),
   ]
 
   def handle(self):
@@ -383,6 +384,7 @@ class AddCommand(Command):
       ) + [
         f"--arg {n}={v}" for n, v in specified_extra_args.items()
       ])
+    lock['_generic']['invalidationHash'] = self.option('invalidation-hash')
 
   def calc_outputs(self, main_package_dir_name, packages_root):
     if self.option('target'):
@@ -504,7 +506,7 @@ class AddCommand(Command):
 
     # assume defaults for unspecified extra args
     specified_extra_args.update(
-      {n: (True if v['type'] == 'flag' else v['default']) \
+      {n: (False if v['type'] == 'flag' else v['default']) \
         for n, v in translator['extraArgs'].items() \
         if n not in specified_extra_args}
     )

src/default.nix

@@ -15,9 +15,9 @@
 
   # 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")
+    # if called via CLI, load config via env
+    if builtins ? getEnv && builtins.getEnv "dream2nixConfig" != "" then
+      builtins.toPath (builtins.getEnv "dream2nixConfig")
     # load from default directory
     else
       {},

src/lib.nix

@@ -110,6 +110,7 @@ let
 
   riseAndShineFunc =
     {
+      pname,
       pkgs ? null,
       source,
       systems ? [],
@@ -121,12 +122,12 @@ let
 
       config = args.config or ((import ./utils/config.nix).loadConfig {});
 
-      argsForward = b.removeAttrs args [ "config" "pkgs" "systems" ];
+      argsForward = b.removeAttrs args [ "config" "pname" "pkgs" "systems" ];
 
       allPkgs = makeNixpkgs pkgs systems;
 
       dream2nixFor =
-        lib.mapAttrs (dream2nixForSystem {}) allPkgs;
+        lib.mapAttrs (dream2nixForSystem config) allPkgs;
 
       allBuilderOutputs =
         lib.mapAttrs
@@ -139,18 +140,65 @@ let
                 translatorName = args.translator or null;
               };
 
-              result = translator:
-                dream2nix.riseAndShine (argsForward // {
+              invalidationHash = dream2nix.utils.calcInvalidationHash {
+                inherit source translatorArgs;
+                translator = translatorFound.name;
+              };
+
+              dreamLockJsonPath = with config;
+                "${projectRoot}/${packagesDir}/${pname}/dream-lock.json";
+
+              dreamLock = dream2nix.utils.readDreamLock {
+                dreamLock = dreamLockJsonPath;
+              };
+
+              dreamLockExistsAndValid =
+                b.pathExists dreamLockJsonPath
+                && dreamLock.lock._generic.invalidationHash or "" == invalidationHash;
+
+              result = translator: args:
+                dream2nix.riseAndShine (argsForward // args // {
                   # TODO: this triggers the translator finding routine a second time
                   translator = translatorFound.name;
                 });
             in
-              if b.elem translatorFound.type [ "pure" "ifd" ] then
-                result translatorFound
-              else
+
+              if dreamLockExistsAndValid then
+                # we need to override the source here as it is coming from
+                # a flake input
+                let
+                  defaultPackage = dreamLock.lock._generic.defaultPackage;
+                  defaultPackageVersion =
+                    dreamLock.lock._generic.packages."${defaultPackage}";
+                in
+                  result translatorFound {
+                    source = dreamLockJsonPath;
+                    sourceOverrides = oldSources: {
+                      "${defaultPackage}"."${defaultPackageVersion}" =
+                        args.source;
+                    };
+                  }
+
+              else if b.elem translatorFound.type [ "pure" "ifd" ] then
+                # warn the user about potentially slow on-the-fly evaluation
                 b.trace ''
-                  Some information is missing to build this project reproducibly.
-                  Please execute nix run .#resolve to resolve impurities.
+                  ${"\n"}
+                  The dream-lock.json for input '${pname}' doesn't exist or is outdated.
+                  ...Falling back to on-the-fly evaluation (possibly slow).
+                  To speed up future evalutations run once:
+                    nix run .#resolve
+                ''
+                result translatorFound {}
+
+              else
+                # print error because impure translation is required first.
+                # continue the evaluation anyways, as otherwise we won't have
+                # the `resolve` app
+                b.trace ''
+                  ${"\n"}
+                  ERROR:
+                    Some information is missing to build this project reproducibly.
+                    Please execute nix run .#resolve to resolve all impurities.
                 ''
                 {})
 
@@ -178,11 +226,20 @@ let
             resolve.program =
               let
                 utils = (dream2nixFor."${system}".utils);
+
+                # TODO: Too many calls to findOneTranslator.
+                #   -> make findOneTranslator system independent
+                translatorFound =
+                  dream2nixFor."${system}".translators.findOneTranslator {
+                    inherit source;
+                    translatorName = args.translator or null;
+                  };
               in
                 b.toString
                   (utils.makePackageLockScript {
-                    inherit source translator translatorArgs;
+                    inherit source translatorArgs;
                     packagesDir = config.packagesDir;
+                    translator = translatorFound.name;
                   });
           });
         };

src/specifications/dream-lock-schema.json

@@ -154,6 +154,7 @@
       "type": "object",
       "properties": {
         "defaultPackage": { "type": ["string", "null"] },
+        "invalidationHash": { "type": ["string", "null"] },
         "packages": { "type": "object" },
         "sourcesAggregatedHash":  { "type": ["string", "null"] },
         "subsystem": { "type": "string" },

src/utils/config.nix

@@ -23,7 +23,8 @@ let
       defaults =  {
         overridesDirs = [];
         packagesDir = null;
-        repoName = "this repo";
+        projectRoot = throw "projectRoot not specified in dream2nix config";
+        repoName = null;
       };
     in
       defaults // config;

src/utils/default.nix

@@ -198,6 +198,19 @@ rec {
   recursiveUpdateUntilDepth = depth: lhs: rhs:
     lib.recursiveUpdateUntil (path: l: r: (b.length path) > depth) lhs rhs;
 
+  # calculate an invalidation hash for given source translation inputs
+  calcInvalidationHash =
+    {
+      source,
+      translator,
+      translatorArgs,
+    }:
+    b.hashString "sha256" ''
+      ${source}
+      ${translator}
+      ${b.toString
+        (lib.mapAttrsToList (k: v: "${k}=${v}") translatorArgs)}
+    '';
 
   # a script that produces and dumps the dream-lock json for a given source
   makePackageLockScript =
@@ -210,10 +223,14 @@ rec {
     writePureShellScript
       []
       ''
+        cd $WORKDIR
         ${apps.cli.program} add ${source} \
           --force \
           --no-default-nix \
           --translator ${translator} \
+          --invalidation-hash ${calcInvalidationHash {
+            inherit source translator translatorArgs;
+          }} \
           --packages-root $WORKDIR/${packagesDir} \
           ${lib.concatStringsSep " \\\n"
             (lib.mapAttrsToList