From 97dbdec7f72c3c30cb492ce49d3347d9312ee9e1 Mon Sep 17 00:00:00 2001
From: Antonio Gurgel <antonio@goorzhel.com>
Date: Sun, 3 Dec 2023 19:53:14 -0800
Subject: [PATCH] Re-implement service-builder

`apiVersions` gave me a headache while writing the foldl so I made it
a separate input.

Now the service modules have this signature, without my having to
change any code in the modules themselves:

{charts, etc, ...} -> [apiVersion] -> {out, extra}
---
 flake.nix              | 10 ++------
 lib/builders.nix       |  4 +++
 lib/default.nix        | 47 ++++++++++++++++++++++++++++------
 src/default.nix        | 40 ++++++++++++++++++++---------
 src/flake-builders.nix | 58 ++++++++++++++++++++++++------------------
 5 files changed, 106 insertions(+), 53 deletions(-)

diff --git a/flake.nix b/flake.nix
index 81680f9..64111de 100644
--- a/flake.nix
+++ b/flake.nix
@@ -36,15 +36,9 @@
     in {
       packages = {
         inherit charts lib;
-        default = {
-          # TODO: move to default.nix
-          charts ? charts,
-          lib ? lib,
-          pkgs ? pkgs,
-          user ? {},
-        }:
+        default = user:
           import ./src {
-            inherit charts lib pkgs user;
+            inherit charts haumea lib pkgs user;
           };
       };
       # TODO: make a template
diff --git a/lib/builders.nix b/lib/builders.nix
index 6304575..4d407ca 100644
--- a/lib/builders.nix
+++ b/lib/builders.nix
@@ -38,6 +38,10 @@ in rec {
     # Some charts lack diligence in setting `Release.Namespace`
     # on the objects they create, necessitating a round-trip through
     # yamlStream, which sets namespaces on all objects lacking one.
+
+    # BUG: However, this creates a derivation with no knowledge of
+    # the Helm chart derivation that is its input, which would be
+    # useful to debug with.
   in
     yamlStream {inherit name namespace objs;};
 
diff --git a/lib/default.nix b/lib/default.nix
index 779d143..6dc25ff 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -11,6 +11,13 @@
   parseYAMLsFile = p: kubelib.fromYAML (builtins.readFile p);
   parseYAMLFile = p: builtins.head (parseYAMLsFile p);
 
+  liftDefault =  _: mod:
+      # h.lib.transformers.liftDefault uses pkgs.lib.attrsets.unionOfDisjoint,
+      # which fails here because mod.default is a function, not a set.
+        if mod ? default
+        then mod.default
+        else mod;
+
   # Helm cannot see my cluster from within the sandbox, so it cannot
   # infer capabilities from it. Therefore, API versions must be gathered
   # from charts that provide them.
@@ -60,15 +67,39 @@
       # and remove this transformer
     };
 
-  mkStages = map (src:
+  mkSvcTrees = src:
     haumea.lib.load {
       inherit src;
       loader = haumea.lib.loaders.verbatim;
-      transformer = _: mod:
-        # transformers.liftDefault uses pkgs.lib.attrsets.unionOfDisjoint,
-        # which fails here because mod.default is a function, not a set.
-        if mod ? default
-        then mod.default
-        else mod;
-    });
+      transformer = liftDefault;
+    };
+
+  # Borrowed from divnix/digga, with minor modifications:
+  # https://github.com/divnix/digga/blob/baa54f8/src/importers.nix#L2-L59
+  flattenTree = tree: let
+    op = sum: path: val: let
+      pathStr = builtins.concatStringsSep "/" path;
+    in
+      if builtins.isFunction val
+      then
+        # builtins.trace "${toString val} is a path"
+        (sum
+          // {
+            "${pathStr}" = val;
+          })
+      else if builtins.isAttrs val
+      then
+        # builtins.trace "${builtins.toJSON val} is an attrset"
+        (recurse sum path val)
+      else
+        # builtins.trace "${toString path} is something else"
+        sum; # ignore val
+
+    recurse = sum: path: val:
+      builtins.foldl'
+      (sum: key: op sum (path ++ [key]) val.${key})
+      sum
+      (builtins.attrNames val);
+  in
+    recurse {} [] tree;
 }
diff --git a/src/default.nix b/src/default.nix
index 87c220f..64e4d27 100644
--- a/src/default.nix
+++ b/src/default.nix
@@ -1,20 +1,40 @@
 {
   charts,
+  haumea,
   lib,
   pkgs,
   user ? {},
 }: let
-  mkNamespace = name: extraMetadata: {
-  };
-
   flakeBuilders = (import ./flake-builders.nix) {inherit charts lib pkgs user;};
-
-  buildServices = roots: kubeVersion: {};
 in {
   inherit flakeBuilders; # TODO: remove after debugging
 
   inherit (lib) mkCharts;
 
+  mkServices = src: kubeVersion: let
+    modules = haumea.lib.load {
+      inherit src;
+      inputs = {inherit charts lib pkgs user kubeVersion;};
+      loader = flakeBuilders.serviceLoader;
+      transformer = lib.liftDefault;
+    };
+    folder = acc: path: mod: let
+      module = mod acc.apis;
+      outPath = "${module.srcPath}/SERVICE.yaml:${module.out.outPath}";
+      outPaths =
+        if module ? extra
+        then [outPath "${module.srcPath}/EXTRA.yaml:${module.extra.outPath}"]
+        else [outPath];
+    in {
+      apis = acc.apis ++ (lib.gatherApis module.out.outPath);
+      paths = acc.paths ++ outPaths;
+    };
+  in
+    pkgs.lib.attrsets.foldlAttrs
+    folder
+    { apis = []; paths = []; }
+    (lib.flattenTree modules);
+
   mkNamespaces = {
     roots,
     extraMetadata ? {},
@@ -48,15 +68,11 @@ in {
     namespaceData,
     kubeVersion,
     src,
-  }: let
-    builtServices = buildServices serviceData kubeVersion;
-  in
+  }:
     pkgs.stdenv.mkDerivation {
       inherit pname version src;
-      derivation_paths = flakeBuilders.paths {
-        services = builtServices;
-      };
-      namespace_drv = flakeBuilders.namespaces namespaceData;
+      derivation_paths = []; # TODO
+      namespace_drv = []; # TODO:
 
       phases = ["installPhase"];
       installPhase = builtins.readFile ./src/output.sh;
diff --git a/src/flake-builders.nix b/src/flake-builders.nix
index caf156a..71d5fb5 100644
--- a/src/flake-builders.nix
+++ b/src/flake-builders.nix
@@ -10,32 +10,40 @@
   mapAttrs = builtins.mapAttrs;
 in {
   serviceLoader = {
-    inputs, # {charts, lib, pkgs, user, kubeVersion, apiVersions}
+    charts,
+    lib,
+    pkgs,
+    user,
+    kubeVersion,
     ...
-  }: p: let
+  } @ inputs: p: let
     module = import p inputs;
-    name = builtins.baseNameOf p;
-    namespace = builtins.baseNameOf (builtins.dirOf p);
-  in {
-    out = module.builder (module.args
-      // {
-        # By injecting `name` and `namespace` here, I remove
-        # the need to specify it in every service in the flake;
-        # the directory structure can speak for me instead.
-        inherit name namespace;
-
-        # Values understood by lib.builders.helmChart
-        # and ignored by the rest.
-        inherit (inputs) kubeVersion apiVersions;
-      });
-
-    extra =
-      if module ? extraObjects
-      then
-        lib.builders.yamlStream {
+    # p is `.../${ns}/${name}/default.nix`
+    name = with builtins; baseNameOf (dirOf p);
+    namespace = with builtins; baseNameOf (dirOf (dirOf p));
+  in
+    apiVersions: {
+      out = module.builder (module.args
+        // {
+          # By injecting `name` and `namespace` here, I remove
+          # the need to specify it in every service in the flake;
+          # the directory structure can speak for me instead.
           inherit name namespace;
-          objs = module.extraObjects;
-        }
-      else null;
-  };
+
+          # Values understood by lib.builders.helmChart
+          # and ignored by the rest.
+          inherit (inputs) kubeVersion;
+        });
+
+      extra =
+        if module ? extraObjects
+        then
+          lib.builders.yamlStream {
+            inherit name namespace;
+            objs = module.extraObjects;
+          }
+        else null;
+
+      srcPath = builtins.dirOf p;
+    };
 }