package main

import (
	"time"
)

const (
	coalesceWorkerRescanEvery time.Duration = 10 * time.Second
	coalesceWorkerExpireAfter time.Duration = 20 * time.Second
)

func coalesceKey(hubNick, message string) string {
	return hubNick + "\x00" + message
}

func (this *NTFServer) coalesceWorker() {
	for {
		time.Sleep(coalesceWorkerRescanEvery)

		deadLine := time.Now().Add(-coalesceWorkerExpireAfter)

		this.coalesceBufferMut.Lock()
		for k, v := range this.coalesceBuffer {
			if v.Before(deadLine) {
				delete(this.coalesceBuffer, k)
			}
		}
		this.coalesceBufferMut.Unlock()
	}
}

// Coalesce returns true if the message sticks to an existing one.
// It adds it into the coalesce buffer anyway.
func (this *NTFServer) Coalesce(hubNick, message string) bool {
	ckey := coalesceKey(hubNick, message)

	this.coalesceBufferMut.Lock()
	if _, ok := this.coalesceBuffer[ckey]; ok {
		this.coalesceBufferMut.Unlock()
		return true // stuck to existing
	} else {
		this.coalesceBuffer[ckey] = time.Now()
		this.coalesceBufferMut.Unlock()
		return false // first we've seen it
	}
}