Implement brew bundle add

Part of #818

Author: carlocab

cmd/bundle.rb

@@ -136,7 +136,7 @@ def run
         require_relative "../lib/bundle"
 
         subcommand = args.named.first.presence
-        if subcommand != "exec" && args.named.size > 1
+        if ["exec", "add"].exclude?(subcommand) && args.named.size > 1
           raise UsageError, "This command does not take more than 1 subcommand argument."
         end
 
@@ -240,6 +240,20 @@ def run
             whalebrew: args.whalebrew? || args.all?,
             vscode:    args.vscode? || args.all?,
           )
+        when "add"
+          # We intentionally omit the `s` from `brews` and `casks` for ease of handling later.
+          type_hash = {
+            brew:      args.brews? || no_type_args,
+            cask:      args.casks?,
+            mas:       args.mas?,
+            whalebrew: args.whalebrew?,
+            vscode:    args.vscode?,
+          }
+          selected_types = type_hash.select { |_, v| v }.keys
+          raise UsageError, "`add` supports only one type of entry at a time." if selected_types.count > 1
+
+          _subcommand, *named_args = args.named
+          Bundle::Commands::Add.run(*named_args, type: selected_types.first, global:, file:)
         else
           raise UsageError, "unknown subcommand: #{subcommand}"
         end

lib/bundle.rb

@@ -6,6 +6,7 @@
 require "bundle/brewfile"
 require "bundle/bundle"
 require "bundle/dsl"
+require "bundle/adder"
 require "bundle/checker"
 require "bundle/skipper"
 require "bundle/brew_services"
@@ -31,6 +32,7 @@
 require "bundle/commands/check"
 require "bundle/commands/exec"
 require "bundle/commands/list"
+require "bundle/commands/add"
 require "bundle/whalebrew_installer"
 require "bundle/whalebrew_dumper"
 require "bundle/vscode_extension_checker"

lib/bundle/adder.rb

@@ -0,0 +1,20 @@
+# typed: true
+# frozen_string_literal: true
+
+module Bundle
+  module Adder
+    module_function
+
+    def add(*args, type:, global:, file:)
+      brewfile = Brewfile.read(global:, file:)
+      content = brewfile.input
+      # TODO: - validate formulae and casks
+      #       - support `:describe`
+      content << args.map { |arg| "#{type} \"#{arg}\"" }
+                     .join("\n") << "\n"
+      path = Dumper.brewfile_path(global:, file:)
+
+      Dumper.write_file path, content
+    end
+  end
+end

lib/bundle/commands/add.rb

@@ -0,0 +1,14 @@
+# typed: true
+# frozen_string_literal: true
+
+module Bundle
+  module Commands
+    module Add
+      module_function
+
+      def run(*args, type:, global:, file:)
+        Bundle::Adder.add(*args, type:, global:, file:)
+      end
+    end
+  end
+end

lib/bundle/dsl.rb

@@ -17,7 +17,7 @@ def to_s
       end
     end
 
-    attr_reader :entries, :cask_arguments
+    attr_reader :entries, :cask_arguments, :input
 
     def initialize(path)
       @path = path