nix: Migrate Homebrew configuration to a new module structure and ena…

…ble Homebrew for aarch64-darwin

modules/darwin/system/homebrew/default.nix

@@ -0,0 +1,47 @@
+{
+  lib,
+  config,
+  system,
+  namespace,
+  ...
+}: let
+  cfg = config.${namespace}.system.homebrew;
+in {
+  options.${namespace}.system.homebrew = {
+    enable = lib.mkOption {
+      type = lib.types.bool;
+      default = true;
+      description = "Whether to enable homebrew.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    # Enable Homebrew for casks.
+    homebrew = {
+      enable = true;
+      # Upgrade and uninstall homebrew casks automatically.
+      onActivation = {
+        autoUpdate = true;
+        upgrade = true;
+        # cleanup = "uninstall";
+      };
+    };
+
+    # Add homebrew taps.
+    homebrew.taps = [
+      "buo/cask-upgrade"
+    ];
+
+    # Set environment variables for homebrew mirror.
+    environment.variables = {
+      HOMEBREW_API_DOMAIN = "https://mirrors.tuna.tsinghua.edu.cn/homebrew-bottles/api";
+      HOMEBREW_BOTTLE_DOMAIN = "https://mirrors.tuna.tsinghua.edu.cn/homebrew-bottles";
+      HOMEBREW_BREW_GIT_REMOTE = "https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/brew.git";
+      HOMEBREW_CORE_GIT_REMOTE = "https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-core.git";
+      HOMEBREW_PIP_INDEX_URL = "https://pypi.tuna.tsinghua.edu.cn/simple";
+    };
+
+    # Add homebrew to PATH.
+    environment.systemPath = lib.optional (system == "aarch64-darwin") "/opt/homebrew";
+  };
+}

systems/aarch64-darwin/nano/default.nix

@@ -29,6 +29,12 @@
     };
   };
 
+  nichijou = {
+    system = {
+      homebrew.enable = true;
+    };
+  };
+
   environment.systemPackages = with pkgs; [
     alejandra
     nodejs