require 'pg_conn'

module PgGraph::Data
  class Database
    # load data from connection
    def read_connection(conn)
      constrain conn, PgConn::Connection
      initialize_impl
      for schema in type.schemas
        for table in schema.tables
          for record in conn.records("select * from #{table.uid}")
            Record.new(self[schema.name][table.name], record)
          end
        end
      end
      self
    end

    # load data from hash. The hash can be produced by #to_h or #to_yaml
    #
    # TODO: Check for unknown keys
    def read_hash(hash)
      constrain hash, Hash
      initialize_impl

      # Works on to #to_h and #to_yaml hashes because it is easier to handle
      # the two formats dynamically than detecting which format to use
      for schema in type.schemas
        next if !hash.key?(schema.name)
        hash_schema = hash[schema.name]
        for table in schema.tables
          next if !hash[schema.name].key?(table.name)
          hash_table = hash_schema[table.name]
          records = hash_table.is_a?(Hash) ? hash_table.values : hash_table
          for record in records
            Record.new(self[schema.name][table.name], record)
          end
        end
      end
      self
    end
  end
end