# frozen_string_literal: true

module RuboCop
  module Cop
    module Gemspec
      # An attribute assignment method calls should be listed only once
      # in a gemspec.
      #
      # Assigning to an attribute with the same name using `spec.foo =` will be
      # an unintended usage. On the other hand, duplication of methods such
      # as `spec.requirements`, `spec.add_runtime_dependency`, and others are
      # permitted because it is the intended use of appending values.
      #
      # @example
      #   # bad
      #   Gem::Specification.new do |spec|
      #     spec.name = 'rubocop'
      #     spec.name = 'rubocop2'
      #   end
      #
      #   # good
      #   Gem::Specification.new do |spec|
      #     spec.name = 'rubocop'
      #   end
      #
      #   # good
      #   Gem::Specification.new do |spec|
      #     spec.requirements << 'libmagick, v6.0'
      #     spec.requirements << 'A good graphics card'
      #   end
      #
      #   # good
      #   Gem::Specification.new do |spec|
      #     spec.add_runtime_dependency('parallel', '~> 1.10')
      #     spec.add_runtime_dependency('parser', '>= 2.3.3.1', '< 3.0')
      #   end
      class DuplicatedAssignment < Cop
        include RangeHelp

        MSG = '`%<assignment>s` method calls already given on line '\
              '%<line_of_first_occurrence>d of the gemspec.'

        def_node_search :gem_specification, <<~PATTERN
          (block
            (send
              (const
                (const {cbase nil?} :Gem) :Specification) :new)
            (args
              (arg $_)) ...)
        PATTERN

        def_node_search :assignment_method_declarations, <<~PATTERN
          (send
            (lvar #match_block_variable_name?) #assignment_method? ...)
        PATTERN

        def investigate(processed_source)
          return if processed_source.blank?

          duplicated_assignment_method_nodes.each do |nodes|
            nodes[1..-1].each do |node|
              register_offense(
                node,
                node.method_name,
                nodes.first.first_line
              )
            end
          end
        end

        private

        def match_block_variable_name?(receiver_name)
          gem_specification(processed_source.ast) do |block_variable_name|
            return block_variable_name == receiver_name
          end
        end

        def assignment_method?(method_name)
          method_name.to_s.end_with?('=')
        end

        def duplicated_assignment_method_nodes
          assignment_method_declarations(processed_source.ast)
            .group_by(&:method_name)
            .values
            .select { |nodes| nodes.size > 1 }
        end

        def register_offense(node, assignment, line_of_first_occurrence)
          line_range = node.loc.column...node.loc.last_column
          offense_location =
            source_range(processed_source.buffer, node.first_line, line_range)
          message = format(
            MSG,
            assignment: assignment,
            line_of_first_occurrence: line_of_first_occurrence
          )
          add_offense(node, location: offense_location, message: message)
        end
      end
    end
  end
end
