package level

import (
	"fmt"
	"math"

	"PermissionGacha/db"
	"PermissionGacha/modules/config"
)

var levelUpRequirementCache = make([]int, len(config.LevelRoles))

func init() {
	for i := 1; i <= len(config.LevelRoles); i++ {
		//Constructed on Desmos:
		//y=2^{\frac{x}{2}}+.1x^{2}+1.2x-1
		fi := float64(i)
		levelUpRequirementCache[i-1] = int(10000 * (math.Pow(2, fi/2) + 0.1*fi*fi + 1.2*fi - 1))
	}
}

func GetLevelAndXP(discordID string) (int, int, error) {
	rawXP, err := db.GetXP(discordID)
	if err != nil {
		return 1, 0, fmt.Errorf("level: GetLevelAndXP: error requesting XP: %w", err)
	}
	level, xp := ConvertXPIntoLevel(rawXP)
	return level, xp, nil
}

func GetLevelUpRequirement(level int) int {
	if level <= 0 {
		return 0
	}
	if level == 1 {
		return levelUpRequirementCache[0]
	}
	if level > len(config.LevelRoles) {
		return levelUpRequirementCache[len(levelUpRequirementCache)-1]
	}
	return levelUpRequirementCache[level-1] - levelUpRequirementCache[level-2]
}

func ConvertXPIntoLevel(xp int) (int, int) {
	if xp < levelUpRequirementCache[0] {
		return 1, xp
	}
	for i := 0; i < len(config.LevelRoles); i++ {
		if levelUpRequirementCache[i] > xp {
			return i + 1, xp - levelUpRequirementCache[i-1]
		}
	}
	return len(config.LevelRoles), xp - levelUpRequirementCache[len(config.LevelRoles)-1]
}