require 'pdk'

module PDK
  module Validate
    module Metadata
      class MetadataSyntaxValidator < InternalRubyValidator
        def name
          'metadata-syntax'
        end

        def pattern
          contextual_pattern(['metadata.json', 'tasks/*.json'])
        end

        def spinner_text
          _('Checking metadata syntax (%{patterns}).') % {
            patterns: pattern.join(' '),
          }
        end

        def invoke(report)
          super
        ensure
          JSON.parser = JSON::Ext::Parser if defined?(JSON::Ext::Parser)
        end

        def before_validation
          # The pure ruby JSON parser gives much nicer parse error messages than
          # the C extension at the cost of slightly slower parsing. We require it
          # here and restore the C extension at the end of the method (if it was
          # being used).
          require 'json/pure'
          JSON.parser = JSON::Pure::Parser
        end

        def validate_target(report, target)
          unless PDK::Util::Filesystem.readable?(target)
            report.add_event(
              file: target,
              source: name,
              state: :failure,
              severity: 'error',
              message: _('Could not be read.'),
            )
            return 1
          end

          begin
            JSON.parse(PDK::Util::Filesystem.read_file(target))

            report.add_event(
              file:     target,
              source:   name,
              state:    :passed,
              severity: 'ok',
            )
            return 0
          rescue JSON::ParserError => e
            # Because the message contains a raw segment of the file, we use
            # String#dump here to unescape any escape characters like newlines.
            # We then strip out the surrounding quotes and the exclaimation
            # point that json_pure likes to put in exception messages.
            sane_message = e.message.dump[%r{\A"(.+?)!?"\Z}, 1]

            report.add_event(
              file:     target,
              source:   name,
              state:    :failure,
              severity: 'error',
              message:  sane_message,
            )
            return 1
          end
        end
      end
    end
  end
end