require "fileutils"

module Ddr::Antivirus
  #
  # Adapter for clamd client (clamdscan)
  #
  class ClamdScannerAdapter < ScannerAdapter

    MAX_FILE_SIZE_RE = Regexp.new('^MaxFileSize = "(\d+)"')
    DEFAULT_MAX_FILE_SIZE = 26214400 # 25Mb

    attr_reader :config

    def initialize
      @config = `clamconf` rescue nil
    end

    def scan(path)
      check_file_size(path) # raises Ddr::Antivirus::MaxFileSizeExceeded
      output, exitcode = clamdscan(path)
      # FIXME I don't like where the scanned_at time is set, but I'm nit-picking --DCS
      result = ScanResult.new(path, output, version: version, scanned_at: Time.now.utc)
      case exitcode
      when 0
        result
      when 1
        raise VirusFoundError.new(result)
      when 2
        raise ScannerError.new(result)
      end
    end

    def clamdscan(path)
      output = IO.popen(["clamdscan", "--fdpass", path, err: [:child, :out]]) do |io|
        io.read
      end
      [ output, $?.exitstatus ]
    end

    def version
      @version ||= `clamdscan -V`.strip
    end

    def max_file_size
      @max_file_size ||= if config && (m = MAX_FILE_SIZE_RE.match(config))
                           m[1].to_i
                         else
                           DEFAULT_MAX_FILE_SIZE
                         end
    end

    private

    def check_file_size(path)
      if (file_size = File.size(path)) > max_file_size
        raise MaxFileSizeExceeded,
              "Unable to scan file at \"#{path}\" -- size (#{file_size}) " \
              "exceeds clamd MaxFileSize setting (#{max_file_size})."
      end
    end

  end
end