package battle

import (
	"math/rand"
	"sort"
)

// DefaultNormalAttack 返回普通攻击兜底技能
func DefaultNormalAttack(f *Fighter) *SkillInstance {
	elem := f.Element
	if elem == "" {
		elem = "none"
	}
	return &SkillInstance{
		InstanceID:  "normal_attack",
		SkillID:     "normal_attack",
		Name:        "普通攻击",
		DamageType:  DamageTypePhysical,
		Element:     elem,
		Alignment:   f.Alignment,
		ScalingAttr: "str",
		BaseCoef:    cfgFloat("combat.skill.normal_attack_coef", 1.0),
		CD:          0,
		Cost:        0,
		TriggerRate: 1.0,
		TargetType:  TargetSingle,
	}
}

// SelectSkill 按 GDD-03 ✅24 触发率机制选择技能
// 1. 候选池 = CD=0 且内力够的主动技能
// 2. 触发率 ≥100% 的候选必定释放，取最高者
// 3. 否则对每个候选独立掷骰，命中者取触发率最高者
// 4. 全部未命中或候选池为空则普通攻击
func SelectSkill(actor *Fighter, opponent *Fighter, normal *SkillInstance, rng *rand.Rand) *SkillInstance {
	candidates := make([]*SkillInstance, 0, len(actor.Skills))
	for _, s := range actor.Skills {
		if s == nil {
			continue
		}
		if s.CDRemaining <= 0 && actor.CanSpendMana(s.Cost) {
			candidates = append(candidates, s)
		}
	}
	if len(candidates) == 0 {
		return normal
	}

	// 按触发率降序
	sort.Slice(candidates, func(i, j int) bool {
		return candidates[i].TriggerRate > candidates[j].TriggerRate
	})

	// 必发技能
	if candidates[0].TriggerRate >= 1.0 {
		return candidates[0]
	}

	// 独立掷骰
	var best *SkillInstance
	bestRate := 0.0
	for _, s := range candidates {
		rate := s.TriggerRate
		if rate <= 0 {
			continue
		}
		if rate > 1.0 {
			rate = 1.0
		}
		if rng.Float64() < rate {
			if best == nil || s.TriggerRate > bestRate {
				best = s
				bestRate = s.TriggerRate
			}
		}
	}
	if best != nil {
		return best
	}
	return normal
}