a301_server/internal/player/level.go

package player

// MaxLevel is the maximum player level.
const MaxLevel = 50

// RequiredExp returns the experience needed to reach the next level.
// Formula: level^2 * 100
func RequiredExp(level int) int {
	return level * level * 100
}

// CalcStatsForLevel computes combat stats for a given level.
func CalcStatsForLevel(level int) (maxHP, maxMP, attackPower float64) {
	maxHP = 100 + float64(level-1)*10
	maxMP = 50 + float64(level-1)*5
	attackPower = 10 + float64(level-1)*2
	return
}

// LevelUpResult holds the result of applying experience gain.
type LevelUpResult struct {
	OldLevel   int     `json:"oldLevel"`
	NewLevel   int     `json:"newLevel"`
	Experience int     `json:"experience"`
	NextExp    int     `json:"nextExp"`
	MaxHP      float64 `json:"maxHp"`
	MaxMP      float64 `json:"maxMp"`
	AttackPower float64 `json:"attackPower"`
	LeveledUp  bool    `json:"leveledUp"`
}

// ApplyExperience adds exp to current level/exp and applies level ups.
// Returns the result including new stats if leveled up.
func ApplyExperience(currentLevel, currentExp, gainedExp int) LevelUpResult {
	level := currentLevel
	exp := currentExp + gainedExp

	// Process level ups
	for level < MaxLevel {
		required := RequiredExp(level)
		if exp < required {
			break
		}
		exp -= required
		level++
	}

	// Cap at max level
	if level >= MaxLevel {
		level = MaxLevel
		exp = 0 // No more exp needed at max level
	}

	maxHP, maxMP, attackPower := CalcStatsForLevel(level)

	nextExp := 0
	if level < MaxLevel {
		nextExp = RequiredExp(level)
	}

	return LevelUpResult{
		OldLevel:    currentLevel,
		NewLevel:    level,
		Experience:  exp,
		NextExp:     nextExp,
		MaxHP:       maxHP,
		MaxMP:       maxMP,
		AttackPower: attackPower,
		LeveledUp:   level > currentLevel,
	}
}