class Geoff
  class Error                  < StandardError ; end

  class << self
    def log(message)
      $stdout.puts message unless silent?
    end

    def silent?
      false
    end
  end

  module Importer
    class LockedDatabase         < Geoff::Error ; end
    class MissingIndexedProperty < Geoff::Error  ; end
    class InvalidRules           < Geoff::Error  ; end

    Subgraph   = org.neo4j.geoff.Subgraph
    EmbeddedDB = Java::OrgNeo4jKernel::EmbeddedGraphDatabase
    HaDb       = Java::OrgNeo4jKernel::HighlyAvailableGraphDatabase

    class << self
      def import geoff, db, node_map = {}, options = {}
        @options = options
        
        set_geoff(geoff)
        set_db(db)

        import_geoff(node_map)
        shutdown if db.is_a? String
      end

      private
      def set_db db
        if db.is_a?(String)
          raise Geoff::Importer::LockedDatabase.new('database is running') if locked?(db)
          start_db(db)
        else
          @graph_db = db
        end
      end

      def set_geoff geoff
        @geoff = if geoff.is_a? String
          geoff.split "\n"
        else
          geoff.to_geoff
        end
        raise Geoff::Importer::InvalidRules.new('Invalid rules') unless validate_rules(@geoff)
      end

      def locked?(db)
        Geoff.log 'check if database is running'
        lock_file = File.join(db, 'neostore')
        return false unless File.exist?(lock_file)
        rfile = java.io.RandomAccessFile.new(lock_file, 'rw')
        begin
          lock = rfile.getChannel.tryLock
          lock.release if lock
          return lock == nil
        rescue Exception => e
          return false
        end
      end

      def start_db(db_path)
        Geoff.log 'starting database'
        @graph_db = if ha_enabled?
          start_ha_db(db_path)
        else
         start_embedded_db(db_path)
        end
      end

      def start_embedded_db(db_path)
        EmbeddedDB.new(db_path)
      end

      def start_ha_db(db_path)
        HaDb.new(db_path, @options)
      end

      def ha_enabled?
        !!@options['ha.db']
      end

      def shutdown
        Geoff.log 'shutdown db'
        @graph_db.shutdown
      end

      def import_geoff node_map
        node_map = map_root_node if node_map.empty?
        Geoff.log 'importing geoff'
        sub_graph = Subgraph.new(@geoff)
        org.neo4j.geoff.Geoff.mergeIntoNeo4j(sub_graph, @graph_db, node_map );
      end

      def map_root_node
        Geoff.log 'creating node_map'
        {"ROOT" => @graph_db.reference_node}
      end

      def validate_rules(rules)
        @invalid = Array(rules).map do |r|
          validate_rule(r)
        end.compact

        @invalid.each { |r, message| Geoff.log "Rule '#{r}' is invalid: #{message}" }
        @invalid.empty?
      end

      def validate_rule(rule)
        Subgraph.new(Array(rule))
        nil
      rescue Exception => e
        return [rule, e.message]
      end

    end
  end
end