# frozen_string_literal: true

require 'nokogiri'
require 'set'

module PmdTester
  # This class is responsible for generation dynamic configuration
  # according to the difference between base and patch branch of Pmd.
  # Attention: we only consider java rulesets now.
  class RuleSetBuilder
    include PmdTester
    ALL_RULE_SETS = Set['bestpractices', 'codestyle', 'design', 'documentation',
                        'errorprone', 'multithreading', 'performance', 'security'].freeze
    PATH_TO_PMD_JAVA_BASED_RULES =
      'pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule'
    PATH_TO_PMD_XPATH_BASED_RULES = 'pmd-java/src/main/resources/category/java'
    PATH_TO_ALL_JAVA_RULES =
      ResourceLocator.locate('config/all-java.xml')
    PATH_TO_DYNAMIC_CONFIG = 'target/dynamic-config.xml'
    NO_JAVA_RULES_CHANGED_MESSAGE = 'No java rules have been changed!'

    def initialize(options)
      @options = options
    end

    def build
      filenames = diff_filenames
      rule_sets = get_rule_sets(filenames)
      output_filter_set(rule_sets)
      build_config_file(rule_sets)
      logger.debug "Dynamic configuration: #{[rule_sets]}"
    end

    def output_filter_set(rule_sets)
      if rule_sets == ALL_RULE_SETS
        # if `rule_sets` contains all rule sets, than no need to filter the baseline
        @options.filter_set = nil
      else
        @options.filter_set = rule_sets
      end
    end

    def diff_filenames
      filenames = nil
      Dir.chdir(@options.local_git_repo) do
        base = @options.base_branch
        patch = @options.patch_branch
        # We only need to support git here, since PMD's repo is using git.
        diff_cmd = "git diff --name-only #{base}..#{patch} -- pmd-core pmd-java"
        filenames = Cmd.execute(diff_cmd)
      end
      filenames.split("\n")
    end

    def get_rule_sets(filenames)
      rule_sets = Set[]
      filenames.each do |filename|
        match_data = %r{#{PATH_TO_PMD_JAVA_BASED_RULES}/([^/]+)/[^/]+Rule.java}.match(filename)
        if match_data.nil?
          match_data = %r{#{PATH_TO_PMD_XPATH_BASED_RULES}/([^/]+).xml}.match(filename)
        end

        category = if match_data.nil?
                     nil
                   else
                     match_data[1]
                   end

        if category.nil?
          rule_sets = ALL_RULE_SETS
          break
        else
          rule_sets.add(category)
        end
      end
      rule_sets
    end

    def build_config_file(rule_sets)
      if rule_sets.empty?
        logger.info NO_JAVA_RULES_CHANGED_MESSAGE
        exit 0
      end

      doc = Nokogiri::XML(File.read(PATH_TO_ALL_JAVA_RULES))
      doc.search('rule').each do |rule|
        rule.remove unless match_ref?(rule, rule_sets)
      end

      description = doc.at_css('description')
      description.content = 'The ruleset generated by PmdTester dynamically'

      write_dynamic_file(doc)
    end

    def match_ref?(rule_node, rule_sets)
      rule_sets.each do |rule_set|
        return true unless rule_node['ref'].index(rule_set).nil?
      end

      false
    end

    def write_dynamic_file(doc)
      File.open(PATH_TO_DYNAMIC_CONFIG, 'w') do |x|
        x << doc.to_s.gsub(/\n\s+\n/, "\n")
      end
      @options.base_config = PATH_TO_DYNAMIC_CONFIG
      @options.patch_config = PATH_TO_DYNAMIC_CONFIG
    end
  end
end