Add cask-source API

Library/Homebrew/api.rb

@@ -4,6 +4,7 @@
 require "api/analytics"
 require "api/bottle"
 require "api/cask"
+require "api/cask-source"
 require "api/formula"
 require "api/versions"
 require "extend/cachable"
@@ -21,15 +22,19 @@ module Homebrew
 
     API_DOMAIN = "https://formulae.brew.sh/api"
 
-    sig { params(endpoint: String).returns(T.any(String, Hash)) }
-    def fetch(endpoint)
+    sig { params(endpoint: String, json: T::Boolean).returns(T.any(String, Hash)) }
+    def fetch(endpoint, json: true)
       return cache[endpoint] if cache.present? && cache.key?(endpoint)
 
       api_url = "#{API_DOMAIN}/#{endpoint}"
       output = Utils::Curl.curl_output("--fail", "--max-time", "5", api_url)
       raise ArgumentError, "No file found at #{Tty.underline}#{api_url}#{Tty.reset}" unless output.success?
 
-      cache[endpoint] = JSON.parse(output.stdout)
+      cache[endpoint] = if json
+        JSON.parse(output.stdout)
+      else
+        output.stdout
+      end
     rescue JSON::ParserError
       raise ArgumentError, "Invalid JSON file: #{Tty.underline}#{api_url}#{Tty.reset}"
     end

Library/Homebrew/api/cask-source.rb

@@ -0,0 +1,28 @@
+# typed: false
+# frozen_string_literal: true
+
+module Homebrew
+  module API
+    # Helper functions for using the cask source API.
+    #
+    # @api private
+    module CaskSource
+      class << self
+        extend T::Sig
+
+        sig { params(token: String).returns(Hash) }
+        def fetch(token)
+          Homebrew::API.fetch "cask-source/#{token}.rb", json: false
+        end
+
+        sig { params(token: String).returns(T::Boolean) }
+        def available?(token)
+          fetch token
+          true
+        rescue ArgumentError
+          false
+        end
+      end
+    end
+  end
+end

Library/Homebrew/test/api_spec.rb

@@ -14,6 +14,12 @@ describe Homebrew::API do
   end
 
   describe "::fetch" do
+    it "fetches a text file" do
+      mock_curl_output stdout: text
+      fetched_text = described_class.fetch("foo.txt", json: false)
+      expect(fetched_text).to eq text
+    end
+
     it "fetches a JSON file" do
       mock_curl_output stdout: json
       fetched_json = described_class.fetch("foo.json")