package pipeline

import (
	"hash/fnv"
	"time"

	"evobgp/internal/store"
)

// SchedulerTickSec matches the scheduler ticker interval (internal/scheduler).
const SchedulerTickSec = 30

// ModuleDueForScheduler reports whether a module's refresh interval bucket rolled since the last scheduler tick.
// A stable per-module offset (fnv32 of ID) spreads bucket boundaries so modules with the same interval
// do not all become due on the same tick (thundering herd).
func ModuleDueForScheduler(mod *store.Module, now time.Time) bool {
	if mod == nil || !mod.Enabled || mod.Type == "IP_RANGES" || mod.RefreshIntervalSec <= 0 {
		return false
	}
	win := int64(mod.RefreshIntervalSec)
	if win < 60 {
		win = 60
	}
	offset := moduleSchedulerOffset(mod.ID, win)
	cur := (now.Unix() - offset) / win
	prev := (now.Unix() - offset - SchedulerTickSec) / win
	return cur != prev
}

func moduleSchedulerOffset(moduleID string, win int64) int64 {
	if win <= 0 {
		return 0
	}
	return int64(fnv32a(moduleID) % uint32(win))
}

func fnv32a(s string) uint32 {
	h := fnv.New32a()
	_, _ = h.Write([]byte(s))
	return h.Sum32()
}