require 'pathname'
require 'colorize'
require 'yaml'

require_relative 'analyzer'

module Fasterer
  class FileTraverser

    CONFIG_FILE_NAME  = '.fasterer.yml'
    SPEEDUPS_KEY      = 'speedups'
    EXCLUDE_PATHS_KEY = 'exclude_paths'

    def initialize(path)
      @path = Pathname(path)
      @parse_error_paths = []
    end

    def traverse
      if @path.directory?
        scannable_files.each { |ruby_file| scan_file(ruby_file) }
      else
        scan_file(@path)
      end
      output_parse_errors if parse_error_paths.any?
    end

    def ignored_speedups
      @ignored_speedups ||=
        config_file[SPEEDUPS_KEY].select { |_, value| value == false }.keys.map(&:to_sym)
    end

    def ignored_files
      @ignored_files ||=
        config_file[EXCLUDE_PATHS_KEY].flat_map { |path| Dir[path] }
    end

    def config_file
      @config_file ||= if File.exists?(CONFIG_FILE_NAME)
        YAML.load_file(CONFIG_FILE_NAME)
      else
        nil_config_file
      end
    end

    private

    attr_reader :parse_error_paths

    def nil_config_file
      { SPEEDUPS_KEY => {}, EXCLUDE_PATHS_KEY => [] }
    end

    def scan_file(path)
      analyzer = Analyzer.new(path)
      analyzer.scan
    rescue RubyParser::SyntaxError, Racc::ParseError, Timeout::Error
      parse_error_paths.push(path)
    else
      output(analyzer) if offenses_grouped_by_type(analyzer).any?
    end

    def scannable_files
      all_files - ignored_files
    end

    def all_files
      Dir["#{@path}/**/*.rb"].map do |ruby_file_path|
        Pathname(ruby_file_path).relative_path_from(@path).to_s
      end
    end

    def output(analyzer)
      puts analyzer.file_path.colorize(:red)

      offenses_grouped_by_type(analyzer).each do |error_group_name, error_occurences|
        puts "#{Fasterer::Offense::EXPLANATIONS[error_group_name]}."\
             " Occurred at lines: #{error_occurences.map(&:line_number).join(', ')}."
      end

      puts
    end

    def offenses_grouped_by_type(analyzer)
      analyzer.errors.group_by(&:name).delete_if do |offense_name, _|
        ignored_speedups.include?(offense_name)
      end
    end

    def output_parse_errors
      puts 'Fasterer was unable to process some files because the'
      puts 'internal parser is not able to read some characters or'
      puts 'has timed out. Unprocessable files were:'
      puts '-----------------------------------------------------'
      puts parse_error_paths
      puts
    end
  end
end