// Basic in-memory object store
//
// Licensed under CC0 1.0 Universal:
// https://creativecommons.org/publicdomain/zero/1.0/legalcode
package objectstore

import (
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path"
	"sync"
)

type FileObjectStore struct {
	sync.Mutex
	dataPath string
}

func NewFileBackend(dataPath string) *FileObjectStore {
	err := os.MkdirAll(dataPath, 0755)
	if err != nil {
		panic(err)
	}
	fos := &FileObjectStore{dataPath: dataPath}
	return fos
}

func (fos *FileObjectStore) CreateObject(bucketId string, objectId string, payload []byte) error {
	fos.Lock()
	defer fos.Unlock()

	// Check if the bucket exists
	buckets, err := ioutil.ReadDir(fos.dataPath)
	if err != nil {
		return fmt.Errorf("Error reading data directory")
	}

	bucketFound := false
	for _, f := range buckets {
		if f.Name() == bucketId && f.IsDir() {
			bucketFound = true
			break
		}
	}

	// Create bucket if it doesn't exist
	if !bucketFound {
		err := os.Mkdir(path.Join(fos.dataPath, bucketId), 0755)
		if err != nil {
			return fmt.Errorf("Error creating bucket directory: %v", bucketId)
		}
	}

	// Store the object
	err = os.WriteFile(path.Join(fos.dataPath, bucketId, objectId), payload, 0644)
	if err != nil {
		return fmt.Errorf("Error creating the object file %v", bucketId)
	}

	return nil
}

func (fos *FileObjectStore) GetObject(bucketId string, objectId string) (string, error) {
	fos.Lock()
	defer fos.Unlock()

	objectPath := path.Join(fos.dataPath, bucketId, objectId)
	object, err := os.ReadFile(objectPath)
	if err != nil {
		return "", os.ErrNotExist
	}

	return string(object), nil
}

func (fos *FileObjectStore) DeleteObject(bucketId string, objectId string) error {
	fos.Lock()
	defer fos.Unlock()

	objectPath := path.Join(fos.dataPath, bucketId, objectId)

	// Check whether the file exists
	_, err := os.Stat(objectPath)
	if errors.Is(err, os.ErrNotExist) {
		return err
	}

	// Delete file
	err = os.Remove(objectPath)
	if err != nil {
		return err
	}

	// Delete the bucket directory if it's empty
	bucketPath := path.Join(fos.dataPath, bucketId)
	entries, err := ioutil.ReadDir(bucketPath)
	if err != nil {
		fmt.Println(err)
	}
	if len(entries) == 0 {
		err := os.Remove(bucketPath)
		if err != nil {
			fmt.Println(err)
		}
	}

	return nil
}