package storage

import (
	"encoding/gob"
	"log"
	"os"
	"path"
	"time"
)

func NewDirStore(clearInterval time.Duration, path string) Store {
	store := &dir{
		clearInterval: clearInterval,
		timeLayout:    time.RFC3339Nano,
		path:          path,
		close:         make(chan bool),
	}

	go store.clearExpired()
	return store
}

type dir struct {
	clearInterval time.Duration
	timeLayout    string
	path          string
	close         chan bool
}

func (store *dir) Create(password []byte, expiresAt time.Time) (string, error) {
	for range 1000 {
		id := generateId(24)
		path := store.getPath(id)

		file, err := os.OpenFile(
			path,
			os.O_CREATE|os.O_EXCL|os.O_WRONLY,
			os.ModePerm,
		)
		switch {
		case os.IsExist(err):
			continue
		case err != nil:
			return "", err
		}

		defer file.Close()

		entry := entry{
			Password:  password,
			ExpiresAt: expiresAt,
		}

		err = gob.NewEncoder(file).Encode(&entry)
		if err != nil {
			log.Printf("%s", err)
			return "", err
		}

		return id, nil
	}

	return "", ErrFull
}

func (store *dir) Get(id string) ([]byte, error) {
	path := store.getPath(id)
	file, err := os.OpenFile(
		path,
		os.O_RDONLY,
		0,
	)
	switch {
	case os.IsNotExist(err):
		return nil, ErrNotFound
	case err != nil:
		return nil, err
	}

	defer file.Close()

	var entry entry
	err = gob.NewDecoder(file).Decode(&entry)
	if err != nil {
		return nil, err
	}

	return entry.Password, nil
}

func (store *dir) Delete(id string) error {
	path := store.getPath(id)
	err := os.Remove(path)
	if err != nil {
		return nil
	}

	return nil
}

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

func (store *dir) clearExpired() error {
	ticker := time.NewTicker(store.clearInterval)
	defer ticker.Stop()

	for {
		select {
		case <-store.close:
			return nil
		case <-ticker.C:
			// TODO: Error handling?
			now := time.Now()

			entries, err := os.ReadDir(store.path)
			if err != nil {
				continue
			}

			for _, file := range entries {
				id := file.Name()
				path := store.getPath(id)
				file, err := os.OpenFile(
					path,
					os.O_RDONLY,
					0,
				)
				if err != nil {
					continue
				}

				defer file.Close()

				var entry entry
				err = gob.NewDecoder(file).Decode(&entry)
				if err != nil {
					continue
				}

				if now.After(entry.ExpiresAt) {
					// Close file early as we need to delete it
					file.Close()
					store.Delete(id)
				}
			}
		}
	}
}

func (store *dir) getPath(id string) string {
	return path.Join(store.path, id)
}