package drivers

import (
	"bytes"
	"context"
	"fmt"
	"io/ioutil"

	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
)

// S3Driver provides basic interface for S3 storage compatible with Driver interface
type S3Driver struct {
	// S3 storage related things
	S3AccessKey string
	S3SecretKey string
	S3Endpoint  string
	S3SSL       bool
	Bucket      string
}

// Returns S3 client structure
func (s *S3Driver) getMinioClient() (*minio.Client, error) {
	client, err := minio.New(s.S3Endpoint, &minio.Options{
		Creds:  credentials.NewStaticV4(s.S3AccessKey, s.S3SecretKey, ""),
		Secure: s.S3SSL,
	})

	if err == nil {
		return client, s.prepareBucket(client)
	}

	return client, err
}

// Create configured bucket if it doesn't exist
func (s *S3Driver) prepareBucket(client *minio.Client) error {
	bucketInfos, err := client.ListBuckets(context.Background())
	if err != nil {
		return err
	}

	var found bool
	for _, info := range bucketInfos {
		if info.Name == s.Bucket {
			found = true
			break
		}
	}

	if !found {
		err = client.MakeBucket(context.Background(), s.Bucket, minio.MakeBucketOptions{})
		if err != nil {
			return err
		}
	}

	return nil
}

// Create creates a new object in the storage with given body
func (s S3Driver) Create(key string, filePath string) error {
	client, err := s.getMinioClient()
	if err != nil {
		return fmt.Errorf("getting minio client error: %v", err)
	}

	_, err = client.FPutObject(context.TODO(), s.Bucket, key, filePath, minio.PutObjectOptions{})
	if err != nil {
		return fmt.Errorf("copying object into S3 error: %v", err)
	}

	return nil
}

// Get copies file from S3 into a local file
// filePath tells the method where the file should be stored
func (s S3Driver) Get(key string, filePath string) error {
	client, err := s.getMinioClient()
	if err != nil {
		return fmt.Errorf("getting minio client error: %v", err)
	}

	err = client.FGetObject(context.TODO(), s.Bucket, key, filePath, minio.GetObjectOptions{})
	if err != nil {
		return fmt.Errorf("getting the object from S3 error: %v", err)
	}

	return nil
}

// Write writes content of body into key
func (s S3Driver) Write(key string, body []byte) error {
	client, err := s.getMinioClient()
	if err != nil {
		return fmt.Errorf("getting minio client error: %v", err)
	}

	_, err = client.PutObject(context.TODO(), s.Bucket, key, bytes.NewReader(body), int64(len(body)), minio.PutObjectOptions{})
	if err != nil {
		return fmt.Errorf("getting the object from S3 error: %v", err)
	}

	return nil
}

// Read returns content of given key
func (s S3Driver) Read(key string) ([]byte, error) {
	client, err := s.getMinioClient()
	if err != nil {
		return []byte(""), fmt.Errorf("getting minio client error: %v", err)
	}

	object, err := client.GetObject(context.TODO(), s.Bucket, key, minio.GetObjectOptions{})
	if err != nil {
		return []byte(""), fmt.Errorf("getting the object from S3 error: %v", err)
	}

	body, err := ioutil.ReadAll(object)
	if err != nil {
		return []byte(""), fmt.Errorf("reading the object from S3 error: %v", err)
	}

	return body, nil
}

// List returns list of objects in fiven prefix
func (s S3Driver) List(prefix string) ([]string, error) {
	keys := []string{}

	client, err := s.getMinioClient()
	if err != nil {
		return keys, fmt.Errorf("getting minio client error: %v", err)
	}

	for info := range client.ListObjects(context.TODO(), s.Bucket, minio.ListObjectsOptions{Prefix: ""}) {
		keys = append(keys, info.Key)
	}

	return keys, nil
}

// Delete deletes one object
func (s S3Driver) Delete(key string) error {
	client, err := s.getMinioClient()
	if err != nil {
		return fmt.Errorf("getting minio client error: %v", err)
	}

	err = client.RemoveObject(context.Background(), s.Bucket, key, minio.RemoveObjectOptions{})
	if err != nil {
		return fmt.Errorf("removing object error: %v", err)
	}

	return nil
}