module Homebrew
  module Style
    module_function

    # Checks style for a list of files, printing simple RuboCop output.
    # Returns true if violations were found, false otherwise.
    def check_style_and_print(files, options = {})
      check_style_impl(files, :print, options)
    end

    # Checks style for a list of files, returning results as a RubocopResults
    # object parsed from its JSON output.
    def check_style_json(files, options = {})
      check_style_impl(files, :json, options)
    end

    def check_style_impl(files, output_type, options = {})
      fix = options[:fix]

      Homebrew.install_gem_setup_path! "rubocop", HOMEBREW_RUBOCOP_VERSION
      require "rubocop"
      require "rubocops"

      args = %w[
        --force-exclusion
      ]
      if fix
        args << "--auto-correct"
      else
        args << "--parallel"
      end

      if ARGV.include?("--rspec")
        Homebrew.install_gem! "rubocop-rspec"
        args += %w[--require rubocop-rspec]
      end

      if options[:except_cops]
        options[:except_cops].map! { |cop| RuboCop::Cop::Cop.registry.qualified_cop_name(cop.to_s, "") }
        cops_to_exclude = options[:except_cops].select do |cop|
          RuboCop::Cop::Cop.registry.names.include?(cop) ||
            RuboCop::Cop::Cop.registry.departments.include?(cop.to_sym)
        end

        args << "--except" << cops_to_exclude.join(",") unless cops_to_exclude.empty?
      elsif options[:only_cops]
        options[:only_cops].map! { |cop| RuboCop::Cop::Cop.registry.qualified_cop_name(cop.to_s, "") }
        cops_to_include = options[:only_cops].select do |cop|
          RuboCop::Cop::Cop.registry.names.include?(cop) ||
            RuboCop::Cop::Cop.registry.departments.include?(cop.to_sym)
        end

        if cops_to_include.empty?
          odie "RuboCops #{options[:only_cops].join(",")} were not found"
        end

        args << "--only" << cops_to_include.join(",")
      end

      has_non_formula = Array(files).any? do |file|
        File.expand_path(file).start_with? HOMEBREW_LIBRARY_PATH
      end
      config_file = if files.nil? || has_non_formula
        if ARGV.include?("--rspec")
          HOMEBREW_LIBRARY_PATH/".rubocop-rspec.yml"
        else
          HOMEBREW_LIBRARY_PATH/".rubocop.yml"
        end
      else
        HOMEBREW_LIBRARY/".rubocop_audit.yml"
      end

      args << "--config" << config_file

      if files.nil?
        args << HOMEBREW_LIBRARY_PATH
      else
        args += files
      end

      cache_env = { "XDG_CACHE_HOME" => "#{HOMEBREW_CACHE}/style" }

      case output_type
      when :print
        args << "--debug" if ARGV.debug?
        args << "--display-cop-names" if ARGV.include? "--display-cop-names"
        args << "--format" << "simple" if files
        system(cache_env, "rubocop", "_#{HOMEBREW_RUBOCOP_VERSION}_", *args)
        !$CHILD_STATUS.success?
      when :json
        json, err, status = Open3.capture3(cache_env, "rubocop", "_#{HOMEBREW_RUBOCOP_VERSION}_", "--format", "json", *args)
        # exit status of 1 just means violations were found; other numbers mean
        # execution errors.
        # exitstatus can also be nil if RuboCop process crashes, e.g. due to
        # native extension problems.
        # JSON needs to be at least 2 characters.
        if !(0..1).cover?(status.exitstatus) || json.to_s.length < 2
          raise "Error running `rubocop --format json #{args.join " "}`\n#{err}"
        end
        RubocopResults.new(JSON.parse(json))
      else
        raise "Invalid output_type for check_style_impl: #{output_type}"
      end
    end

    class RubocopResults
      def initialize(json)
        @metadata = json["metadata"]
        @file_offenses = {}
        json["files"].each do |f|
          next if f["offenses"].empty?
          file = File.realpath(f["path"])
          @file_offenses[file] = f["offenses"].map { |x| RubocopOffense.new(x) }
        end
      end

      def file_offenses(path)
        @file_offenses[path.to_s]
      end
    end

    class RubocopOffense
      attr_reader :severity, :message, :corrected, :location, :cop_name

      def initialize(json)
        @severity = json["severity"]
        @message = json["message"]
        @cop_name = json["cop_name"]
        @corrected = json["corrected"]
        @location = RubocopLineLocation.new(json["location"])
      end

      def severity_code
        @severity[0].upcase
      end

      def to_s(options = {})
        if options[:display_cop_name]
          "#{severity_code}: #{location.to_short_s}: #{cop_name}: #{message}"
        else
          "#{severity_code}: #{location.to_short_s}: #{message}"
        end
      end
    end

    class RubocopLineLocation
      attr_reader :line, :column, :length

      def initialize(json)
        @line = json["line"]
        @column = json["column"]
        @length = json["length"]
      end

      def to_s
        "#{line}: col #{column} (#{length} chars)"
      end

      def to_short_s
        "#{line}: col #{column}"
      end
    end
  end
end