package core 

import "fmt"

type Window interface {
	// MaxTimestamp is the maximum time the Window is Open
	MaxTimestamp() int64
	// ToString convert Window to string format
	ToString() string
}

type TimeWindow struct {
	Start int64
	End   int64
}

func (t TimeWindow) MaxTimestamp() int64 {
	// MaxTimestamp is 1ms before the End
	return t.End - 1
}

func (t TimeWindow) ToString() string {
	return fmt.Sprintf("timewindow(%d,%d)", t.Start, t.End)
}

type WindowAssigner[IN any] interface {
	AssignWindows(element IN, timestamp int64) []Window
}

type TumblingWindows[IN any] struct {
	Size int64
}

func NewTumblingWindows[IN any](size int64) *TumblingWindows[IN] {
	return &TumblingWindows[IN]{
		Size: size,
	}
}

func (w *TumblingWindows[IN]) AssignWindows(element IN, timestamp int64) []Window {
	// module to get start end
	// if timestamp = 1200, size 1000
	// so start will 1200 - 200 = 1000, end will 1000 + 1000 = 2000
	start := timestamp - (timestamp % w.Size)

	end := start + w.Size

	return []Window{
		TimeWindow{
			Start: start,
			End: end,
		},
	}
}