package action

import (
	"fmt"
	"math/rand"
	"os"
	"path/filepath"

	"gopkg.in/yaml.v3"
)

func SuccessChance(cfg SuccessFormula, level int, requiredLevel int) float64 {
	chance := cfg.Base + float64(level-requiredLevel)*cfg.PerLevel
	if chance > cfg.Cap {
		chance = cfg.Cap
	}
	if chance < 0 {
		chance = 0
	}
	return chance
}

func LoadDropTable(dataDir, id string) (*DropTableDef, error) {
	path := filepath.Join(dataDir, "drops", id+".yaml")
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read drop table %s: %w", id, err)
	}
	var dt DropTableDef
	if err := yaml.Unmarshal(data, &dt); err != nil {
		return nil, fmt.Errorf("parse drop table %s: %w", id, err)
	}
	return &dt, nil
}

func ResolveDrop(dataDir string, drops []DropEntry) *DropEntry {
	if len(drops) == 0 {
		return nil
	}
	total := 0
	for _, d := range drops {
		total += d.Weight
	}
	if total <= 0 {
		return nil
	}
	roll := rand.Intn(total)
	cumulative := 0
	for i := range drops {
		cumulative += drops[i].Weight
		if roll < cumulative {
			if drops[i].Table != "" {
				sub, err := LoadDropTable(dataDir, drops[i].Table)
				if err == nil {
					if resolved := ResolveDrop(dataDir, sub.Drops); resolved != nil {
						qty := drops[i].Quantity
						if qty <= 0 {
							qty = resolved.Quantity
						}
						if qty <= 0 {
							qty = 1
						}
						return &DropEntry{
							ItemID:   resolved.ItemID,
							Quantity: qty,
							Depletes: drops[i].Depletes,
							Message:  drops[i].Message,
						}
					}
				}
				return nil
			}
			return &drops[i]
		}
	}
	return &drops[0]
}