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51 lines
1.6 KiB
Go

package storage
import (
"math/rand/v2"
"slices"
"github.com/denisovdennis/autohero/internal/model"
)
// FilterCapOfferableQuests drops quest templates whose id is in taken, then shuffles the rest
// deterministically from seed and returns at most limit entries. If limit <= 0, returns all offerable quests (still filtered).
func FilterCapOfferableQuests(all []model.Quest, taken map[int64]struct{}, limit int, seed int64) []model.Quest {
var offer []model.Quest
for _, q := range all {
if _, skip := taken[q.ID]; skip {
continue
}
offer = append(offer, q)
}
if len(offer) == 0 {
return offer
}
if limit <= 0 || len(offer) <= limit {
return offer
}
shuffled := slices.Clone(offer)
rng := rand.New(rand.NewPCG(uint64(seed), uint64(seed>>32)^0x9e3779b97f4a7c15))
for i := len(shuffled) - 1; i > 0; i-- {
j := rng.IntN(i + 1)
shuffled[i], shuffled[j] = shuffled[j], shuffled[i]
}
return shuffled[:limit]
}
// questOfferDrySpellSalt mixes into the RNG seed so dry-spell draws are independent of quest shuffle draws.
const questOfferDrySpellSalt int64 = 0x8BADF00D
// QuestOfferDrySpellThisPeriod reports whether this hero/NPC/time bucket is a "dry spell" (no offers shown).
// Deterministic: same inputs always yield the same result. dryChance in [0,1]; 0 disables, 1 always dry.
func QuestOfferDrySpellThisPeriod(npcID, heroID, timeBucket int64, dryChance float64) bool {
if dryChance <= 0 {
return false
}
if dryChance >= 1 {
return true
}
seed := npcID ^ heroID ^ timeBucket ^ questOfferDrySpellSalt
rng := rand.New(rand.NewPCG(uint64(seed), uint64(seed>>32)^0x9e3779b97f4a7c15))
return rng.Float64() < dryChance
}