/*
Copyright 2020 KubeSphere Authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package s3

import (
	"fmt"
	"io"
	"math"
	"time"

	"code.cloudfoundry.org/bytefmt"
	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/credentials"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/s3"
	"github.com/aws/aws-sdk-go/service/s3/s3manager"
	"k8s.io/klog"
)

type Client struct {
	s3Client  *s3.S3
	s3Session *session.Session
	bucket    string
}

const (
	DefaultPartSize = 5 * bytefmt.MEGABYTE
	// MinConcurrency is the minimum concurrency when uploading a part to Amazon S3,
	// it's also the default value of Concurrency in aws-sdk-go.
	MinConcurrency = 5
	// MaxConcurrency is the maximum concurrency to limit the goroutines.
	MaxConcurrency = 128
)

// calculateConcurrency calculates the concurrency for better performance,
// make the concurrency in range [5, 128].
func calculateConcurrency(size int) int {
	if size <= 0 {
		return MinConcurrency
	}
	c := int(math.Ceil(float64(size) / float64(DefaultPartSize)))
	if c < MinConcurrency {
		return MinConcurrency
	} else if c > MaxConcurrency {
		return MaxConcurrency
	}
	return c
}

// Upload use Multipart upload to upload a single object as a set of parts.
// If the data length is known to be large, it is recommended to pass in the data length,
// it will helps to calculate concurrency. Otherwise, `size` can be 0,
// use 5 as default upload concurrency, same as aws-sdk-go.
// See https://docs.aws.amazon.com/AmazonS3/latest/userguide/mpuoverview.html for more details.
func (s *Client) Upload(key, fileName string, body io.Reader, size int) error {
	uploader := s3manager.NewUploader(s.s3Session, func(uploader *s3manager.Uploader) {
		uploader.PartSize = DefaultPartSize
		uploader.LeavePartsOnError = true
		uploader.Concurrency = calculateConcurrency(size)
	})
	_, err := uploader.Upload(&s3manager.UploadInput{
		Bucket:             aws.String(s.bucket),
		Key:                aws.String(key),
		Body:               body,
		ContentDisposition: aws.String(fmt.Sprintf("attachment; filename=\"%s\"", fileName)),
	})
	return err
}

func (s *Client) Read(key string) ([]byte, error) {

	downloader := s3manager.NewDownloader(s.s3Session)

	writer := aws.NewWriteAtBuffer([]byte{})
	_, err := downloader.Download(writer,
		&s3.GetObjectInput{
			Bucket: aws.String(s.bucket),
			Key:    aws.String(key),
		})

	if err != nil {
		return nil, err
	}

	return writer.Bytes(), nil
}

func (s *Client) GetDownloadURL(key string, fileName string) (string, error) {
	req, _ := s.s3Client.GetObjectRequest(&s3.GetObjectInput{
		Bucket:                     aws.String(s.bucket),
		Key:                        aws.String(key),
		ResponseContentDisposition: aws.String(fmt.Sprintf("attachment; filename=\"%s\"", fileName)),
	})
	return req.Presign(5 * time.Minute)
}

func (s *Client) Delete(key string) error {
	_, err := s.s3Client.DeleteObject(
		&s3.DeleteObjectInput{Bucket: aws.String(s.bucket),
			Key: aws.String(key),
		})
	if err != nil {
		return err
	}
	return nil
}

func NewS3Client(options *Options) (Interface, error) {
	cred := credentials.NewStaticCredentials(options.AccessKeyID, options.SecretAccessKey, options.SessionToken)

	config := aws.Config{
		Region:           aws.String(options.Region),
		Endpoint:         aws.String(options.Endpoint),
		DisableSSL:       aws.Bool(options.DisableSSL),
		S3ForcePathStyle: aws.Bool(options.ForcePathStyle),
		Credentials:      cred,
	}

	s, err := session.NewSession(&config)
	if err != nil {
		klog.Error(err)
		return nil, err
	}

	var c Client

	c.s3Client = s3.New(s)
	c.s3Session = s
	c.bucket = options.Bucket

	return &c, nil
}

func (s *Client) Client() *s3.S3 {
	return s.s3Client
}
func (s *Client) Session() *session.Session {
	return s.s3Session
}

func (s *Client) Bucket() *string {
	return aws.String(s.bucket)
}