# frozen_string_literal: true
require_relative 'context_builder'
require_relative 'errors/bad_detector_in_comment_error'
require_relative 'errors/garbage_detector_configuration_in_comment_error'
require_relative 'detector_repository'
require_relative 'source/source_code'

module Reek
  #
  # Applies all available smell detectors to a source.
  #
  # @public
  class Examiner
    INCOMPREHENSIBLE_SOURCE_TEMPLATE = <<-EOS.freeze
      !!!
      Source %s can not be processed by Reek.

      This is most likely either a bug in your Reek configuration (config file or
      source code comments) or a Reek bug.

      Please double check your Reek configuration taking the original exception
      below into account -  you might have misspelled a smell detector for instance.
      (In the future Reek will handle configuration errors more gracefully, something
      we are working on already).

      If you feel that this is not a problem with your Reek configuration but with
      Reek itself it would be great if you could report this back to the Reek
      team by opening up a corresponding issue at https://github.com/troessner/reek/issues.

      Please make sure to include the source in question, the Reek version
      and the original exception below.

      Exception message:

      %s

      Original exception:

      %s

      !!!
    EOS
    #
    # Creates an Examiner which scans the given +source+ for code smells.
    #
    # @param source [File, IO, String]
    #   If +source+ is a String it is assumed to be Ruby source code;
    #   if it is a File or IO, it is opened and Ruby source code is read from it;
    #
    # @param filter_by_smells [Array<String>]
    #   List of smell types to filter by, e.g. "DuplicateMethodCall".
    #
    # @param configuration [Configuration::AppConfiguration]
    #   The configuration for this Examiner.
    #
    # @public
    def initialize(source,
                   filter_by_smells: [],
                   configuration: Configuration::AppConfiguration.default,
                   detector_repository_class: DetectorRepository)
      @source              = Source::SourceCode.from(source)
      @smell_types         = detector_repository_class.eligible_smell_types(filter_by_smells)
      @detector_repository = detector_repository_class.new(smell_types: @smell_types,
                                                           configuration: configuration.directive_for(description))
    end

    # @return [String] origin of the source being analysed
    #
    # @public
    def origin
      @origin ||= source.origin
    end

    # @return [String] description of the source being analysed
    #
    # @public
    # @deprecated Use origin
    def description
      origin
    end

    #
    # @return [Array<SmellWarning>] the smells found in the source
    #
    # @public
    def smells
      @smells ||= run.sort.uniq
    end

    #
    # @return [Integer] the number of smells found in the source
    #
    # @public
    def smells_count
      smells.length
    end

    #
    # @return [Boolean] true if and only if there are code smells in the source.
    #
    # @public
    def smelly?
      !smells.empty?
    end

    private

    attr_reader :source, :detector_repository

    # Runs the Examiner on the given source to scan for code smells.
    #
    # In case one of the smell detectors raises an exception we probably hit a Reek bug.
    # So we catch the exception here, let the user know something went wrong
    # and continue with the analysis.
    #
    # @return [Array<SmellWarning>] the smells found in the source
    #
    # :reek:TooManyStatements { max_statements: 8 }
    def run
      return [] unless syntax_tree
      begin
        examine_tree
      rescue Errors::BadDetectorInCommentError,
             Errors::GarbageDetectorConfigurationInCommentError,
             Errors::BadDetectorConfigurationKeyInCommentError => exception
        warn exception
        []
      rescue StandardError => exception
        warn format(INCOMPREHENSIBLE_SOURCE_TEMPLATE,
                    origin,
                    exception.message,
                    exception.backtrace.join("\n\t"))
        []
      end
    end

    def syntax_tree
      @syntax_tree ||= source.syntax_tree
    end

    def examine_tree
      ContextBuilder.new(syntax_tree).context_tree.flat_map do |element|
        detector_repository.examine(element)
      end
    end
  end
end