package shortify

import (
	"sync"

	"github.com/hashicorp/golang-lru"
	bolt "go.etcd.io/bbolt"
)

type Shortener struct {
	DataFolder string

	db          *bolt.DB
	cache       *lru.Cache
	accessCache *lru.Cache
	logChan     chan VisitLog
	idPool      *IDPool

	writeChan chan [2]string // queue of writes: [shortID, longURL]
	memStore  sync.Map       // thread-safe built-in

}

type Config struct {
	DataFolder    string
	CacheSize     int
	AccessLogSize int
}

func NewShortener(cfg Config) (*Shortener, error) {
	db, err := bolt.Open(cfg.DataFolder+"/database.db", 0600, nil)
	if err != nil {
		return nil, err
	}

	urlCache, _ := lru.New(cfg.CacheSize)
	accessCache, _ := lru.New(cfg.AccessLogSize)

	idPool, err := NewIDPool(db, 8, 10000, 2000)
	if err != nil {
		return nil, err
	}

	s := &Shortener{
		DataFolder:  cfg.DataFolder,
		db:          db,
		cache:       urlCache,
		accessCache: accessCache,
		logChan:     make(chan VisitLog, 1000),
		writeChan:   make(chan [2]string, 1000),
		idPool:      idPool,
	}

	go s.startLogging()
	go s.asyncDBWriter()

	return s, nil
}