package engine

import (
	"fmt"

	"github.com/influxdb/influxdb/protocol"
)

// Passed to a shard (local datastore or whatever) that gets yielded points from series.
type Processor interface {
	// (true, nil) if the query should continue. False if processing
	// should stop, because of an error in which case error isn't nil or
	// because the desired data was read succesfully and no more data is
	// needed.
	Yield(s *protocol.Series) (bool, error)
	Name() string
	Next() Processor

	// Flush any data that could be in the queue
	Close() error
}

// ProcessorChain returns a string representation of the processors chained together
func ProcessorChain(p Processor) string {
	if p == nil {
		return "<nil>"
	}
	next := p.Next()
	if next != nil {
		return fmt.Sprintf("%s > %s", p.Name(), ProcessorChain(next))
	}
	return p.Name()
}