package storage

import (
	"math/rand/v2"
	"sync"
	"time"
)

func NewRamStore() Store {
	store := &ram{
		passwords: make(map[string]entry),
		lock:      sync.Mutex{},
		close:     make(chan bool),
	}

	go store.clearExpired()
	return store
}

type ram struct {
	passwords map[string]entry
	lock      sync.Mutex
	close     chan bool
}

func (store *ram) CreatePassword(password []byte, expiresAt time.Time) (string, error) {
	store.lock.Lock()
	defer store.lock.Unlock()

	for range 1000 {
		id := store.generateId(24)
		_, found := store.passwords[id]
		if found {
			continue
		}

		store.passwords[id] = entry{
			password:  password,
			expiresAt: expiresAt,
		}

		return id, nil
	}

	return "", ErrFull
}

func (store *ram) GetPassword(id string) ([]byte, error) {
	store.lock.Lock()
	defer store.lock.Unlock()

	password, found := store.passwords[id]
	if !found {
		return nil, ErrNotFound
	}

	delete(store.passwords, id)
	return password.password, nil
}

func (store *ram) Close() error {
	store.close <- true
	return nil
}

func (store *ram) clearExpired() error {
	ticker := time.NewTicker(20 * time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-store.close:
			return nil
		case <-ticker.C:
			store.lock.Lock()
			defer store.lock.Unlock()
			time := time.Now()

			for id, password := range store.passwords {
				if time.After(password.expiresAt) {
					delete(store.passwords, id)
				}
			}
		}
	}
}

func (store *ram) generateId(length int) string {
	runes := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")

	str := make([]rune, length)
	for i := range str {
		str[i] = runes[rand.IntN(len(runes))]
	}

	return string(str)
}