package main

import (
	"reflect"
)

func filterChanges(in <-chan RaidState) <-chan RaidState {
	out := make(chan RaidState, 4)

	go func(in <-chan RaidState, out chan<- RaidState) {
		defer close(out)

		currentStates := map[string]RaidState{}

		for state := range in {
			oldState, ok := currentStates[state.Name]
			if !ok || !reflect.DeepEqual(oldState.DevicesUp, state.DevicesUp) {
				currentStates[state.Name] = state
				out <- state
			}
		}
	}(in, out)

	return out
}