package points

import (
	"encoding/json"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"sync"
)

const (
	dataDir = "internal/storage"
	pointsFile = "points.json"
)

var (
	mu sync.Mutex
	pts map[string]int
)

const DefaultPoints = 100000

// init or load points from disk
func LoadPoints() error {
	mu.Lock()
	defer mu.Unlock()
	pts = make(map[string]int)
	path := filepath.Join(dataDir, pointsFile)

	data, err := ioutil.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}
	return json.Unmarshal(data, &pts)
}

// save balances to disk
func SavePoints() error {
	mu.Lock()
	data, err := json.MarshalIndent(pts, "", "  ")
	mu.Unlock()
	if err != nil {
		return err
	}
	if err := os.MkdirAll(dataDir, 0755); err != nil {
		return err
	}
	return ioutil.WriteFile(filepath.Join(dataDir, pointsFile), data, 0644)
}

// return point balance for user, init if needed
func GetPoints(user string) int {
	mu.Lock()
	defer mu.Unlock()
	key := strings.ToLower(user)
	bal, ok := pts[key]
	if !ok {
		pts[key] = DefaultPoints
		bal = DefaultPoints
	}
	return bal
}

// add points to user's bal, save & return new bal
func AddPoints(user string, delta int) (int error) {
	mu.Lock()
	key := strings.ToLower(user)
	bal, ok := pts[key]
	if !ok {
		bal = DefaultPoints
	}
	bal += delta
	pts[key] = bal
	mu.Unlock()

	if err := SavePoints(); err != nil {
		return bal, err
	}
	return bal, nil
}