package expr

import (
	"github.com/grafana/metrictank/api/models"
)

type FuncMovingAverage struct {
	window int64
	in     GraphiteFunc
}

func NewMovingAverage() GraphiteFunc {
	// TODO: allows both int and string as window. how to handle properly?
	return &FuncMovingAverage{}
}

// note if input is 1 series, then output is too. not sure how to communicate that
func (s *FuncMovingAverage) Signature() ([]Arg, []Arg) {
	return []Arg{
		ArgSeriesList{val: &s.in},
		// this could be an int OR a string.
		// we need to figure out the interval of the data we will consume
		// and request from -= interval * points
		// interestingly the from adjustment might mean the archive TTL is no longer sufficient and push the request into a different rollup archive, which we should probably
		// account for. let's solve all of this later.
		ArgInt{val: &s.window},
	}, []Arg{ArgSeriesList{}}
}

func (s *FuncMovingAverage) Context(context Context) Context {
	context.from -= uint32(s.window)
	return context
}

func (s *FuncMovingAverage) Exec(cache map[Req][]models.Series) ([]models.Series, error) {
	series, err := s.in.Exec(cache)
	if err != nil {
		return nil, err
	}
	//cache[Req{}] = append(cache[Req{}], out)
	return series, nil
}