Add rake tasks for GitHub releases and release note

Rakefile

@@ -20,3 +20,115 @@ namespace :test do
     sh "ruby", "bin/output_test.rb"
   end
 end
+
+Rake::Task[:release].enhance do
+  Rake::Task[:"release:note"].invoke
+  Rake::Task[:"release:github"].invoke
+end
+
+namespace :release do
+  desc "Ensure release note"
+  task :note do
+    version = Gem::Version.new(Steep::VERSION)
+    major, minor, patch, pre = Steep::VERSION.split(".", 4)
+    major = major.to_i
+    minor = minor.to_i
+    patch = patch.to_i
+
+    wiki_url = "https://github.com/soutaro/steep/wiki/Release-Note-#{major}.#{minor}"
+
+    puts "🧐 Checking if Release note page already exists..."
+
+    unless `curl --silent -o/dev/null --head #{wiki_url} -w '%{http_code}'` == "200"
+      pre_flag = version.prerelease? ? " --pre" : ""
+      pre_requirement = version.prerelease? ? ", '~> #{major}.#{minor}.#{patch}.#{pre}'" : ""
+
+      puts "----"
+
+      puts <<~PREFIX if patch
+        **The latest version of Steep #{major}.#{minor} is `#{pre}`.**
+
+      PREFIX
+
+      puts <<~TEMPLATE
+        Some of the highlights in Steep #{major}.#{minor} are:
+
+        * New feature 1 (URL)
+        * New feature 2 (URL)
+        * New feature 3 (URL)
+
+        You can install it with `$ gem install steep#{pre_flag}` or using Bundler.
+
+        ```rb
+        gem 'steep', require: false#{pre_requirement}
+        ```
+
+        See the [CHANGELOG](https://github.com/soutaro/steep/blob/master/CHANGELOG.md) for the details.
+
+        ## New feature 1
+
+        ## New feature 2
+
+        ## New feature 3
+
+        ## Diagnostics updates
+
+        ## Updating Steep
+
+      TEMPLATE
+      puts "----"
+      puts
+
+      puts "  ⏩️ Create the release note with the template: #{wiki_url}"
+    else
+      if patch == 0 || version.prerelease?
+        puts "  ⏩️ Open the release note and update it at: #{wiki_url}"
+      else
+        puts "  ✅ Release note is ready!"
+      end
+    end
+    puts
+  end
+
+  desc "Create GitHub release automatically"
+  task :github do
+    version = Gem::Version.new(Steep::VERSION)
+    major, minor, patch, *_ = Steep::VERSION.split(".")
+    major = major.to_i
+    minor = minor.to_i
+    patch = patch.to_i
+
+    puts "✏️ Making a draft release on GitHub..."
+
+    content = File.read(File.join(__dir__, "CHANGELOG.md"))
+    changelog = content.scan(/^## \d.*?(?=^## \d)/m)[0]
+    changelog = changelog.sub(/^.*\n^.*\n/, "").rstrip
+
+    notes = <<NOTES
+[Release note](https://github.com/soutaro/steep/wiki/Release-Note-#{major}.#{minor})
+
+#{changelog}
+NOTES
+
+    command = [
+      "gh",
+      "release",
+      "create",
+      "--draft",
+      "v#{Steep::VERSION}",
+      "--title=#{Steep::VERSION}",
+      "--notes=#{notes}"
+    ]
+
+    if version.prerelease?
+      command << "--prerelease"
+    end
+
+    require "open3"
+    output, status = Open3.capture2(*command)
+    if status.success?
+      puts "  ⏩️ Done! Open #{output.chomp} and publish the release!"
+      puts
+    end
+  end
+end