require "gitlab_mr_release"
require "thor"
require "dotenv"

module GitlabMrRelease
  class CLI < Thor
    include Thor::Actions

    GITLAB_ENV_FILES = %w(.env.gitlab ~/.env.gitlab)

    DEFAULT_TITLE_TEMPLATE = "Release <%= Time.now %> <%= source_branch %> -> <%= target_branch %>"

    def self.source_root
      "#{__dir__}/../templates"
    end

    desc "version", "Show gitlab_mr_release version"
    def version
      puts GitlabMrRelease::VERSION
    end

    desc "init", "Copy setting files to current directory"
    def init
      copy_file ".env.gitlab", ".env.gitlab"
      copy_file "gitlab_mr_release.md.erb", "gitlab_mr_release.md.erb"
    end

    desc "create", "Create merge requrst"
    option :source, aliases: "-s", desc: "Source branch (e.g. develop)"
    option :target, aliases: "-t", desc: "Target branch (e.g. master)"
    option :title,  desc: "MergeRequest title (default. 'Release :timestamp :source -> :target')"
    option :labels, aliases: "-l", desc: "Labels for MR as a comma-separated list  (e.g. 'label1,label2')"
    def create
      Dotenv.load(*GITLAB_ENV_FILES)

      assert_env("GITLAB_API_ENDPOINT")
      assert_env("GITLAB_API_PRIVATE_TOKEN")
      assert_env("GITLAB_PROJECT_NAME")

      assert_option_or_env(:source, "DEFAULT_SOURCE_BRANCH")
      assert_option_or_env(:target, "DEFAULT_TARGET_BRANCH")

      template = File.read(template_file)

      project = GitlabMrRelease::Project.new(
        api_endpoint:  ENV["GITLAB_API_ENDPOINT"],
        private_token: ENV["GITLAB_API_PRIVATE_TOKEN"],
        project_name:  ENV["GITLAB_PROJECT_NAME"],
      )

      unless project.api_version >= 4
        raise InvalidApiVersionError, "'#{ENV["GITLAB_API_ENDPOINT"]}' seems not to be GitLab API v4+. gitlab_mr_release requires GitLab API v4+"
      end

      mr = project.create_merge_request(
        source_branch: source_branch,
        target_branch: target_branch,
        labels:        labels,
        title:         generate_title,
        template:      template,
      )

      mr_url = "#{project.web_url}/merge_requests/#{mr.iid}"

      message = <<-EOS
MergeRequest is created

[Title] #{mr.title}

[Description]
#{mr.description}

[Url] #{mr_url}
      EOS

      puts message
    end

    private

    no_commands do
      def assert_env(name)
        if !ENV[name] || ENV[name].empty?
          puts "Error: Environment variable #{name} is required"
          exit!
        end
      end

      def assert_option_or_env(option_name, env_name)
        option_or_env!(option_name, env_name)
      end

      def generate_title
        return options[:title] if options[:title]

        generate_default_title(
          title_template: ENV["DEFAULT_TITLE"],
          source_branch:  source_branch,
          target_branch:  target_branch,
          )
      end

      def generate_default_title(title_template:, source_branch:, target_branch:)
        title_template ||= DEFAULT_TITLE_TEMPLATE
        ERB.new(title_template).result(binding).strip
      end

      def template_file
        ENV["TEMPLATE_FILE"] || "#{__dir__}/../templates/gitlab_mr_release.md.erb"
      end

      def source_branch
        option_or_env(:source, "DEFAULT_SOURCE_BRANCH")
      end

      def target_branch
        option_or_env(:target, "DEFAULT_TARGET_BRANCH")
      end

      def labels
        option_or_env(:labels, "DEFAULT_LABELS")
      end

      def option_or_env(option_name, env_name, default = nil)
        return options[option_name] if options[option_name] && !options[option_name].empty?
        return ENV[env_name] if ENV[env_name] && !ENV[env_name].empty?
        default
      end

      def option_or_env!(option_name, env_name)
        value = option_or_env(option_name, env_name)
        return value if value

        puts "Error: --#{option_name} or #{env_name} is either required!"
        exit!
      end
    end
  end
end