package avgcachestate

import (
	"s1d3sw1ped/SteamCache2/vfs/cachestate"
	"sync"
)

// AvgCacheState is a cache state that averages the last N cache states.
type AvgCacheState struct {
	size int
	avgs []cachestate.CacheState
	mu   sync.Mutex
}

// New creates a new average cache state with the given size.
func New(size int) *AvgCacheState {
	return &AvgCacheState{
		size: size,
		avgs: make([]cachestate.CacheState, size),
		mu:   sync.Mutex{},
	}
}

// Clear resets the average cache state to zero.
func (a *AvgCacheState) Clear() {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.avgs = make([]cachestate.CacheState, a.size) // zeroed
}

// Add adds a cache state to the average cache state.
func (a *AvgCacheState) Add(cs cachestate.CacheState) {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.avgs = append(a.avgs, cs)
	if len(a.avgs) > a.size {
		a.avgs = a.avgs[1:]
	}
}

// Avg returns the average cache state.
func (a *AvgCacheState) Avg() float64 {
	a.mu.Lock()
	defer a.mu.Unlock()

	var hits, misses int
	for _, cs := range a.avgs {
		switch cs {
		case cachestate.CacheStateHit:
			hits++
		case cachestate.CacheStateMiss:
			misses++
		}
	}
	total := hits + misses

	return float64(hits) / float64(total)
}