class RuboCop::ResultCache

def self.allow_symlinks_in_cache_location?(config_store)
  config_store.for_pwd.for_all_cops['AllowSymlinksInCacheRootDirectory']
end

def self.cache_root(config_store)
  CacheConfig.root_dir do
    config_store.for_pwd.for_all_cops['CacheRootDirectory']
  end
end

def self.cleanup(config_store, verbose, cache_root = nil)
  return if inhibit_cleanup # OPTIMIZE: For faster testing
  cache_root ||= cache_root(config_store)
  return unless File.exist?(cache_root)
  files, dirs = Find.find(cache_root).partition { |path| File.file?(path) }
  return unless requires_file_removal?(files.length, config_store)
  remove_oldest_files(files, dirs, cache_root, verbose)
end

def any_symlink?(path)
  while path != File.dirname(path)
    if File.symlink?(path)
      warn "Warning: #{path} is a symlink, which is not allowed."
      return true
    end
    path = File.dirname(path)
  end
  false
end

def context_checksum(team, options)
  Digest::SHA1.hexdigest([team_checksum(team), relevant_options_digest(options)].join)
end

def debug?
  @debug
end

def digest(path)
  content = if path.end_with?(*DL_EXTENSIONS)
              # Shared libraries often contain timestamps of when
              # they were compiled and other non-stable data.
              File.basename(path)
            else
              File.binread(path) # mtime not reliable
            end
  Zlib.crc32(content).to_s
end

def file_checksum(file, config_store)
  digester = Digest::SHA1.new
  mode = File.stat(file).mode
  digester.update("#{file}#{mode}#{config_store.for_file(file).signature}")
  digester.file(file)
  digester.hexdigest
rescue Errno::ENOENT
  # Spurious files that come and go should not cause a crash, at least not
  # here.
  '_'
end

def initialize(file, team, options, config_store, cache_root = nil)
  cache_root ||= File.join(options[:cache_root], 'rubocop_cache') if options[:cache_root]
  cache_root ||= ResultCache.cache_root(config_store)
  @allow_symlinks_in_cache_location =
    ResultCache.allow_symlinks_in_cache_location?(config_store)
  @path = File.join(cache_root,
                    rubocop_checksum,
                    context_checksum(team, options),
                    file_checksum(file, config_store))
  @cached_data = CachedData.new(file)
  @debug = options[:debug]
end

def load
  puts "Loading cache from #{@path}" if debug?
  @cached_data.from_json(File.read(@path, encoding: Encoding::UTF_8))
end

def relevant_options_digest(options)
  options = options.reject { |key, _| NON_CHANGING.include?(key) }
  options.to_s.gsub(/[^a-z]+/i, '_')
end

def remove_files(files, dirs, remove_count)
  # Batch file deletions, deleting over 130,000+ files will crash
  # File.delete.
  files[0, remove_count].each_slice(10_000).each do |files_slice|
    File.delete(*files_slice)
  end
  dirs.each { |dir| Dir.rmdir(dir) if Dir["#{dir}/*"].empty? }
end

def remove_oldest_files(files, dirs, cache_root, verbose)
  # Add 1 to half the number of files, so that we remove the file if
  # there's only 1 left.
  remove_count = (files.length / 2) + 1
  puts "Removing the #{remove_count} oldest files from #{cache_root}" if verbose
  sorted = files.sort_by { |path| File.mtime(path) }
  remove_files(sorted, dirs, remove_count)
rescue Errno::ENOENT
  # This can happen if parallel RuboCop invocations try to remove the
  # same files. No problem.
  puts $ERROR_INFO if verbose
end

def requires_file_removal?(file_count, config_store)
  file_count > 1 && file_count > config_store.for_pwd.for_all_cops['MaxFilesInCache']
end

def rubocop_checksum
  ResultCache.source_checksum ||=
    begin
      digest = Digest::SHA1.new
      rubocop_extra_features
        .select { |path| File.file?(path) }
        .sort!
        .each do |path|
          digest << digest(path)
        end
      digest << RuboCop::Version::STRING << RuboCop::AST::Version::STRING
      digest.hexdigest
    end
end

def rubocop_extra_features
  lib_root = File.join(File.dirname(__FILE__), '..')
  exe_root = File.join(lib_root, '..', 'exe')
  # These are all the files we have `require`d plus everything in the
  # exe directory. A change to any of them could affect the cop output
  # so we include them in the cache hash.
  source_files = $LOADED_FEATURES + Find.find(exe_root).to_a
  source_files -= ResultCache.rubocop_required_features # Rely on gem versions
  source_files
end

def save(offenses)
  dir = File.dirname(@path)
  begin
    FileUtils.mkdir_p(dir)
  rescue Errno::EACCES, Errno::EROFS => e
    warn "Couldn't create cache directory. Continuing without cache.\n  #{e.message}"
    return
  end
  preliminary_path = "#{@path}_#{rand(1_000_000_000)}"
  # RuboCop must be in control of where its cached data is stored. A
  # symbolic link anywhere in the cache directory tree can be an
  # indication that a symlink attack is being waged.
  return if symlink_protection_triggered?(dir)
  File.open(preliminary_path, 'w', encoding: Encoding::UTF_8) do |f|
    f.write(@cached_data.to_json(offenses))
  end
  # The preliminary path is used so that if there are multiple RuboCop
  # processes trying to save data for the same inspected file
  # simultaneously, the only problem we run in to is a competition who gets
  # to write to the final file. The contents are the same, so no corruption
  # of data should occur.
  FileUtils.mv(preliminary_path, @path)
end

def symlink_protection_triggered?(path)
  !@allow_symlinks_in_cache_location && any_symlink?(path)
end

def team_checksum(team)
  @checksum_by_team ||= {}.compare_by_identity
  @checksum_by_team[team] ||= team.external_dependency_checksum
end

def valid?
  File.exist?(@path)
end