class Embulk::Schema

def initialize(columns)
  columns = columns.map.with_index {|c,index|
    if c.index && c.index != index
      # TODO ignore this error?
      raise "Index of column '#{c.name}' is #{c.index} but it is at column #{index}."
    end
    Column.new(index, c.name, c.type, c.format)
  }
  super(columns)
  record_reader_script =
    "lambda do |reader|\n" <<
    "record = []\n"
  each do |column|
    idx = column.index
    column_script =
      "if reader.isNull(#{idx})\n" <<
      "record << nil\n" <<
      "else\n" <<
      case column.type
      when :boolean
        "record << reader.getBoolean(#{idx})"
      when :long
        "record << reader.getLong(#{idx})"
      when :double
        "record << reader.getDouble(#{idx})"
      when :string
        "record << reader.getString(#{idx})"
      when :timestamp
        # https://ruby-doc.org/core-2.3.3/Time.html#method-c-at
        "record << (java_instant = reader.getTimestampInstant(#{idx}); Time.at(java_instant.getEpochSecond(), Rational(java_instant.getNano(), 1000)))"
      when :json
        "record << MessagePack.unpack(String.from_java_bytes((::Java::org.msgpack.core.MessagePack.newDefaultBufferPacker()).packValue(reader.getJson(#{idx})).toMessageBuffer().toByteArray()))"
      else
        raise "Unknown type #{column.type.inspect}"
      end <<
      "end\n"
    record_reader_script << column_script << "\n"
  end
  record_reader_script << "record\n"
  record_reader_script << "end"
  @record_reader = eval(record_reader_script)
  record_writer_script = "lambda do |builder,record|\n"
  each do |column|
    idx = column.index
    column_script =
      "if record[#{idx}].nil?\n" <<
      "builder.setNull(#{idx})\n" <<
      "else\n" <<
      case column.type
      when :boolean
        "builder.setBoolean(#{idx}, record[#{idx}])"
      when :long
        "builder.setLong(#{idx}, record[#{idx}])"
      when :double
        "builder.setDouble(#{idx}, record[#{idx}])"
      when :string
        "builder.setString(#{idx}, record[#{idx}])"
      when :timestamp
        "builder.setTimestamp(#{idx}, case record[#{idx}] when Java::org.embulk.spi.time.Timestamp then record[#{idx}].getInstant() when Java::java.time.Instant then record[#{idx}] when Time then Java::java.time.Instant.ofEpochSecond(record[#{idx}].to_i, record[#{idx}].nsec) end)"
      when :json
        "builder.setJson(#{idx}, ::Java::org.msgpack.core.MessagePack.newDefaultUnpacker(MessagePack.pack(record[#{idx}]).to_java_bytes).unpackValue())"
      else
        raise "Unknown type #{column.type.inspect}"
      end <<
      "end\n"
    record_writer_script << column_script << "\n"
  end
  record_writer_script << "builder.addRecord\n"
  record_writer_script << "end"
  @record_writer = eval(record_writer_script)
  @names = map {|c| c.name }
  @types = map {|c| c.type }
  freeze
end