feat: service.postgresql module extension

nixos/module/generic/placeholder.nix

@@ -1 +0,0 @@
-{ ... }: {}

nixos/module/generic/postgresql.nix

@@ -0,0 +1,67 @@
+{ 
+  inputs,
+  self,
+  flake
+}:
+{ 
+  pkgs,
+  config,
+  lib,
+  ...
+}: let
+  system = pkgs.system;
+  cfg = config.services.postgresql;
+  extensionFlags = {
+    pg_cron = false;
+    pgjwt = false;
+    pg_net = false;
+    pg_smtp_client = false;
+    http = false;
+    plsh = false;
+    hemar = false;
+  };
+in {
+  options = {
+    services.postgresql = {
+      lazzyExtensions = lib.mkOption {
+        type = lib.types.attrsOf lib.types.bool;
+        default = extensionFlags;
+      };
+      environment = lib.mkOption {
+        type    = lib.types.attrsOf lib.types.str;
+        default = {};
+      };
+    };
+  };
+  config = lib.mkIf cfg.enable {
+    systemd.services.postgresql.environment = cfg.environment;
+    services.postgresql = {
+      settings.shared_preload_libraries =
+        lib.concatStringsSep ", "
+          (lib.attrNames (
+  	    lib.filterAttrs (n: v: v && 
+  	         n != "http" 
+  	      && n != "plsh" 
+  	      && n != "pgjwt" 
+  	      && n != "pg_smtp_client"
+  	  ) cfg.lazzyExtensions));
+
+      extensions = let
+        packages = {
+          inherit (cfg.package.pkgs) pg_net pgjwt pg_cron http pg_smtp_client plsh;
+          hemar = inputs.hutil.packages.${system}.pg-15-hemar;
+        };
+      in
+        lib.attrValues (
+          lib.filterAttrs (n: v: v != null)
+          (lib.mapAttrs' (
+              name: enabled:
+                if enabled
+                then lib.nameValuePair name (packages.${name} or (throw "Package ${name} not found in pkgs"))
+                else null
+            )
+            cfg.lazzyExtensions)
+        );
+    };
+  };
+}