# encoding: utf-8

module Rubocop
  module Cop
    class CorrectionNotPossible < Exception; end

    # Store for all cops with helper functions
    class CopStore < ::Array
      # @return [Array<String>] list of types for current cops.
      def types
        @types = map(&:cop_type).uniq! unless defined? @types
        @types
      end

      # @return [Array<Cop>] Cops for that specific type.
      def with_type(type)
        select { |c| c.cop_type == type }
      end

      # @return [Array<Cop>] Cops not for a specific type.
      def without_type(type)
        reject { |c| c.cop_type == type }
      end
    end

    # A scaffold for concrete cops.
    #
    # The Cop class is meant to be extended.
    #
    # Cops track offences and can autocorrect them of the fly.
    #
    # A commissioner object is responsible for traversing the AST and invoking
    # the specific callbacks on each cop.
    # If a cop needs to do its own processing of the AST or depends on
    # something else it should define the `#investigate` method and do
    # the processing there.
    #
    # @example
    #
    #   class CustomCop < Cop
    #     def investigate(processed_source)
    #       # Do custom processing
    #     end
    #   end
    class Cop
      extend AST::Sexp

      # http://phrogz.net/programmingruby/language.html#table_18.4
      # Backtick is added last just to help editors parse this code.
      OPERATOR_METHODS = %w(
          | ^ & <=> == === =~ > >= < <= << >>
          + - * / % ** ~ +@ -@ [] []= ! != !~
        ).map(&:to_sym) + [:'`']

      attr_reader :config, :offences, :corrections
      attr_accessor :processed_source # TODO: Bad design.

      @all = CopStore.new

      def self.all
        @all.clone
      end

      def self.non_rails
        @all.without_type(:rails)
      end

      def self.inherited(subclass)
        @all << subclass
      end

      def self.cop_name
        name.to_s.split('::').last
      end

      def self.cop_type
        name.to_s.split('::')[-2].downcase.to_sym
      end

      def self.style?
        cop_type == :style
      end

      def self.lint?
        cop_type == :lint
      end

      def self.rails?
        cop_type == :rails
      end

      def initialize(config = nil, options = nil)
        @config = config || Config.new
        @options = options || { auto_correct: false, debug: false }

        @offences = []
        @corrections = []
        @ignored_nodes = []
      end

      def cop_config
        @config.for_cop(self)
      end

      def autocorrect?
        @options[:auto_correct] && support_autocorrect?
      end

      def debug?
        @options[:debug]
      end

      def message(node = nil)
        self.class::MSG
      end

      def support_autocorrect?
        respond_to?(:autocorrect, true)
      end

      def add_offence(severity, node, loc, message = nil)
        location = loc.is_a?(Symbol) ? node.loc.send(loc) : loc

        return if disabled_line?(location.line)

        message = message ? message : message(node)
        message = debug? ? "#{name}: #{message}" : message

        corrected = begin
                      autocorrect(node) if autocorrect?
                      autocorrect?
                    rescue CorrectionNotPossible
                      false
                    end
        @offences << Offence.new(severity, location, message, name, corrected)
      end

      def convention(node, location, message = nil)
        add_offence(:convention, node, location, message)
      end

      def warning(node, location, message = nil)
        add_offence(:warning, node, location, message)
      end

      def cop_name
        self.class.cop_name
      end

      alias_method :name, :cop_name

      def ignore_node(node)
        @ignored_nodes << node
      end

      private

      def disabled_line?(line_number)
        return false unless @processed_source
        disabled_lines = @processed_source.disabled_lines_for_cops[name]
        return false unless disabled_lines
        disabled_lines.include?(line_number)
      end

      def part_of_ignored_node?(node)
        expression = node.loc.expression
        @ignored_nodes.each do |ignored_node|
          if ignored_node.loc.expression.begin_pos <= expression.begin_pos &&
            ignored_node.loc.expression.end_pos >= expression.end_pos
            return true
          end
        end

        false
      end

      def ignored_node?(node)
        @ignored_nodes.any? { |n| n.eql?(node) } # Same object found in array?
      end

      def on_node(syms, sexp, excludes = [])
        yield sexp if Array(syms).include?(sexp.type)

        return if Array(excludes).include?(sexp.type)

        sexp.children.each do |elem|
          if elem.is_a?(Parser::AST::Node)
            on_node(syms, elem, excludes) { |s| yield s }
          end
        end
      end

      def command?(name, node)
        return unless node.type == :send

        receiver, method_name, _args = *node

        # commands have no explicit receiver
        !receiver && method_name == name
      end

      def source_range(source_buffer, preceding_lines, begin_column,
                       column_count)
        newline_length = 1
        begin_pos = preceding_lines.reduce(0) do |a, e|
          a + e.length + newline_length
        end + begin_column
        Parser::Source::Range.new(source_buffer, begin_pos,
                                  begin_pos + column_count)
      end

      def range_with_surrounding_space(range, side = :both)
        src = @processed_source.buffer.source
        go_left = side == :left || side == :both
        go_right = side == :right || side == :both
        begin_pos = range.begin_pos
        begin_pos -= 1 while go_left && src[begin_pos - 1] =~ /[ \t]/
        end_pos = range.end_pos
        end_pos += 1 while go_right && src[end_pos] =~ /[ \t]/
        Parser::Source::Range.new(@processed_source.buffer, begin_pos, end_pos)
      end
    end
  end
end