# frozen_string_literal: true

module Bundler
  #
  # This class handles installing and switching to the version of bundler needed
  # by an application.
  #
  class SelfManager
    def restart_with_locked_bundler_if_needed
      return unless needs_switching? && installed?

      restart_with_locked_bundler
    end

    def install_locked_bundler_and_restart_with_it_if_needed
      return unless needs_switching?

      install_and_restart_with_locked_bundler
    end

    private

    def install_and_restart_with_locked_bundler
      bundler_dep = Gem::Dependency.new("bundler", lockfile_version)
      spec = fetch_spec_for(bundler_dep)
      return if spec.nil?

      Bundler.ui.info \
        "Bundler #{current_version} is running, but your lockfile was generated with #{lockfile_version}. " \
        "Installing Bundler #{lockfile_version} and restarting using that version."

      spec.source.install(spec)
    rescue StandardError => e
      Bundler.ui.trace e
      Bundler.ui.warn "There was an error installing the locked bundler version (#{lockfile_version}), rerun with the `--verbose` flag for more details. Going on using bundler #{current_version}."
    else
      restart_with_locked_bundler
    end

    def fetch_spec_for(bundler_dep)
      source = Bundler::Source::Rubygems.new("remotes" => "https://rubygems.org")
      source.remote!
      source.add_dependency_names("bundler")
      spec = source.specs.search(bundler_dep).first
      if spec.nil?
        Bundler.ui.warn "Your lockfile is locked to a version of bundler (#{lockfile_version}) that doesn't exist at https://rubygems.org/. Going on using #{current_version}"
      end
      spec
    end

    def restart_with_locked_bundler
      configured_gem_home = ENV["GEM_HOME"]
      configured_gem_path = ENV["GEM_PATH"]

      cmd = [$PROGRAM_NAME, *ARGV]
      cmd.unshift(Gem.ruby) unless File.executable?($PROGRAM_NAME)

      Bundler.with_original_env do
        Kernel.exec(
          { "GEM_HOME" => configured_gem_home, "GEM_PATH" => configured_gem_path, "BUNDLER_VERSION" => lockfile_version },
          *cmd
        )
      end
    end

    def needs_switching?
      ENV["BUNDLER_VERSION"].nil? &&
        Bundler.rubygems.supports_bundler_trampolining? &&
        SharedHelpers.in_bundle? &&
        lockfile_version &&
        !lockfile_version.end_with?(".dev") &&
        lockfile_version != current_version &&
        !updating?
    end

    def updating?
      "update".start_with?(ARGV.first || " ") && ARGV[1..-1].any? {|a| a.start_with?("--bundler") }
    end

    def installed?
      Bundler.configure

      Bundler.rubygems.find_bundler(lockfile_version)
    end

    def current_version
      @current_version ||= Bundler::VERSION
    end

    def lockfile_version
      @lockfile_version ||= Bundler::LockfileParser.bundled_with
    end
  end
end