Implement support for flake.nix: nix develop

Author: amadejkastelic

README.md

@@ -3,7 +3,7 @@ Hi folks,
 My name is Roman Valihura. I'm the author of this extension. I'm Ukrainian.
 I was born in Ukraine. I'm living here at the moment.
 
-As you all know Russia invaded my country. 
+As you all know Russia invaded my country.
 Russia has already killed thousands of civilians and continues the war and terror in Ukraine.
 I have the luck that my region is pretty far from the frontline. But even here, I'm living in the air-alarm reality.
 The reality where you should wake up in the middle of the night and go into the shelter. Because a rocket flies over your region.
@@ -49,7 +49,7 @@ However, this process can quickly become tedious.
 -   Install [Nix package manager](https://nixos.org/nix/).
 -   Restart VS Code (to make sure that `nix-shell` is in the PATH)
 -   [Install the extension](https://marketplace.visualstudio.com/items?itemName=arrterian.nix-env-selector).
--   Create the Nix environment config (like `default.nix` or `shell.nix`) in
+-   Create the Nix environment config (like `default.nix` or `shell.nix` or `flake.nix`) in
     the root of your project's workspace.
 -   Open Command Palette (<kbd>Ctrl</kbd> + <kbd>Shift</kbd> + <kbd>P</kbd>)
     and run `Nix-Env: Select Environment` command.
@@ -111,6 +111,8 @@ file (located in the root of the workspace). Here are the configuration settings
 | `nixEnvSelector.packages`     | []      | List packages using as `-p` nix-shell args                    |
 | `nixEnvSelector.args`         | null    | Custom args string for nix-shell. EX: `-A <something> --pure` |
 | `nixEnvSelector.nixShellPath` | null    | Custom path for nix-shell executable                          |
+| `nixEnvSelector.useFlakes` | false    | Enable support for `flake.nix`                          |
+
 
 ## Supported Platforms
 

package-lock.json

@@ -2,7 +2,7 @@
 	"name": "nix-env-selector",
 	"displayName": "Nix Environment Selector",
 	"description": "Allows switch environment for Visual Studio Code and extensions based on Nix config file.",
-	"version": "1.0.12",
+	"version": "1.1.0",
 	"keywords": [
 		"nix",
 		"nix-env",
@@ -69,7 +69,12 @@
 					"type": "string",
 					"deprecationMessage": "[DEPRECATED] Use 'args' instead",
 					"description": "Attribute path (nix-shell -A)"
-				}
+				},
+        "nixEnvSelector.useFlakes": {
+          "type": "boolean",
+          "default": false,
+          "description": "Enable support for Nix flakes"
+        }
 			}
 		},
 		"commands": [

package.json

@@ -16,6 +16,7 @@
                     :nix-args       (-> (workspace/config-get vscode-config :nix-env-selector/args)
                                         (#(when %1 (render-workspace %1 workspace-root))))
                     :nix-shell-path (-> (workspace/config-get vscode-config :nix-env-selector/nix-shell-path)
-                                        (#(when %1 (render-workspace %1 workspace-root))))})))
+                                        (#(when %1 (render-workspace %1 workspace-root))))
+                    :use-flakes     (workspace/config-get vscode-config :nix-env-selector/use-flakes)})))
 
 (workspace/on-config-change update-config!)

src/main/config.cljs

@@ -47,7 +47,8 @@
                      status)
     (->> (env/get-nix-env-async {:nix-config     nix-path
                                  :args           (:nix-args @config)
-                                 :nix-shell-path (:nix-shell-path @config)}
+                                 :nix-shell-path (:nix-shell-path @config)
+                                 :use-flakes     (:use-flakes @config)}
                                 log-channel)
          (p/map (fn [env-vars]
                   (when env-vars

src/main/ext/actions.cljs

@@ -8,6 +8,13 @@
 (defn ^:private list-to-args [pref-arg list]
   (s/join " " (map #(str pref-arg " " %1) list)))
 
+(defn ^:private has-flake? [dir]
+  (let [fs (js/require "fs")]
+    (try
+      (.existsSync fs (str dir "/flake.nix"))
+      (catch js/Error _
+        false))))
+
 (defn ^:private get-shell-env-cmd [{:keys [packages
                                            nix-shell-path
                                            nix-config
@@ -29,6 +36,17 @@
        (when args
          (str " " args))))
 
+(defn ^:private get-flake-env-cmd [{:keys [nix-path dir args]}]
+  (str (if (empty? nix-path)
+         "nix"
+         (s/replace nix-path #" " "\\ "))
+       " develop "
+       (when dir
+         (str "\"" dir "\""))
+       " --command env"
+       (when args
+         (str " " args))))
+
 (defn ^:private parse-exported-vars [output]
   (->> (s/split output #"declare -x")
        (filter not-empty)
@@ -39,25 +57,43 @@
                             (catch js/Error _ nil))]))))
        (filter not-empty)))
 
-(defn get-nix-env-sync [options log-channel]
-  (let [cmd (get-shell-env-cmd options)]
+(defn ^:private parse-env-vars [output]
+  (->> (s/split output #"\n")
+       (filter not-empty)
+       (map #(s/split %1 #"=" 2))
+       (filter #(= (count %) 2))
+       (map (fn [[name value]]
+              [name value]))))
+
+(defn get-nix-env-sync [{:keys [use-flakes] :as options} log-channel]
+  (let [dir (dirname (:nix-config options))
+        is-flake (and use-flakes (has-flake? dir))
+        cmd (if is-flake
+              (get-flake-env-cmd (assoc options :dir dir))
+              (get-shell-env-cmd options))
+        parser (if is-flake parse-env-vars parse-exported-vars)]
     (w/write-log log-channel (str "Running command synchronously: " cmd))
-    (-> (execSync (clj->js cmd {:cwd (dirname (:nix-config options))}))
+    (-> (execSync (clj->js cmd {:cwd dir}))
         (.toString)
-        (parse-exported-vars))))
+        (parser))))
 
-(defn get-nix-env-async [options log-channel]
+(defn get-nix-env-async [{:keys [use-flakes] :as options} log-channel]
   (let [env-result (p/deferred)
-        cmd (get-shell-env-cmd options)]
-    (w/write-log log-channel (str "Running command asynchronously: " cmd))
-    (exec (clj->js cmd {:cwd (dirname (:nix-config options))})
+        dir (dirname (:nix-config options))
+        is-flake (and use-flakes (has-flake? dir))
+        cmd (if is-flake
+              (get-flake-env-cmd (assoc options :dir dir))
+              (get-shell-env-cmd options))
+        parser (if is-flake parse-env-vars parse-exported-vars)]
+    (w/write-log log-channel (str "Running command " (if is-flake "with flake" "with nix-shell") ": " cmd))
+    (exec (clj->js cmd {:cwd dir})
           (fn [err result stderr]
             (if (nil? err)
               (p/resolve! env-result result)
               (do
                 (w/write-log log-channel (str "Error applying environment: " stderr))
                 (p/reject! env-result err)))))
-    (p/map parse-exported-vars env-result)))
+    (p/map parser env-result)))
 
 (defn set-current-env [env-vars]
   (mapv (fn [[name value]]

src/main/ext/nix_env.cljs

@@ -19,9 +19,10 @@
       (if (or (not-empty (:nix-file @config)) (not-empty (:nix-packages @config)))
         (try
           (-> (env/get-nix-env-sync {:nix-config     (:nix-file @config)
-                                    :packages       (:nix-packages @config)
-                                    :args           (:nix-args @config)
-                                    :nix-shell-path (:nix-shell-path @config)}
+                                     :packages       (:nix-packages @config)
+                                     :args           (:nix-args @config)
+                                     :nix-shell-path (:nix-shell-path @config)
+                                     :use-flakes     (:use-flakes @config)}
                                     log-channel)
               (env/set-current-env))
           (->> status-bar