package s3

import (
	"errors"
	"fmt"
	"io"
	"time"

	"github.com/knadh/listmonk/media"
	"github.com/rhnvrm/simples3"
)

const amznS3PublicURL = "https://%s.s3.%s.amazonaws.com/%s"

// Opts represents AWS S3 specific params
type Opts struct {
	AccessKey  string `koanf:"aws_access_key_id"`
	SecretKey  string `koanf:"aws_secret_access_key"`
	Region     string `koanf:"aws_default_region"`
	Bucket     string `koanf:"bucket"`
	BucketPath string `koanf:"bucket_path"`
	BucketType string `koanf:"bucket_type"`
	Expiry     int    `koanf:"expiry"`
}

// Client implements `media.Store` for S3 provider
type Client struct {
	s3   *simples3.S3
	opts Opts
}

// NewS3Store initialises store for S3 provider. It takes in the AWS configuration
// and sets up the `simples3` client to interact with AWS APIs for all bucket operations.
func NewS3Store(opts Opts) (media.Store, error) {
	var s3svc *simples3.S3
	var err error
	if opts.Region == "" {
		return nil, errors.New("Invalid AWS Region specified. Please check `upload.s3` config")
	}
	// Use Access Key/Secret Key if specified in config.
	if opts.AccessKey != "" && opts.SecretKey != "" {
		s3svc = simples3.New(opts.Region, opts.AccessKey, opts.SecretKey)
	} else {
		// fallback to IAM role if no access key/secret key is provided.
		s3svc, err = simples3.NewUsingIAM(opts.Region)
		if err != nil {
			return nil, err
		}
	}
	return &Client{
		s3:   s3svc,
		opts: opts,
	}, nil
}

// Put takes in the filename, the content type and file object itself and uploads to S3.
func (e *Client) Put(name string, cType string, file io.ReadSeeker) (string, error) {
	// Upload input parameters
	upParams := simples3.UploadInput{
		Bucket:      e.opts.Bucket,
		ObjectKey:   getBucketPath(e.opts.BucketPath, name),
		ContentType: cType,
		FileName:    name,
		Body:        file,
	}
	// Perform an upload.
	_, err := e.s3.FileUpload(upParams)
	if err != nil {
		return "", err
	}
	return name, nil
}

// Get accepts the filename of the object stored and retrieves from S3.
func (e *Client) Get(name string) string {
	// Generate a private S3 pre-signed URL if it's a private bucket.
	if e.opts.BucketType == "private" {
		url := e.s3.GeneratePresignedURL(simples3.PresignedInput{
			Bucket:        e.opts.Bucket,
			ObjectKey:     getBucketPath(e.opts.BucketPath, name),
			Method:        "GET",
			Timestamp:     time.Now(),
			ExpirySeconds: e.opts.Expiry,
		})
		return url
	}
	// Generate a public S3 URL if it's a public bucket.
	url := fmt.Sprintf(amznS3PublicURL, e.opts.Bucket, e.opts.Region, getBucketPath(e.opts.BucketPath, name))
	return url
}

// Delete accepts the filename of the object and deletes from S3.
func (e *Client) Delete(name string) error {
	err := e.s3.FileDelete(simples3.DeleteInput{
		Bucket:    e.opts.Bucket,
		ObjectKey: getBucketPath(e.opts.BucketPath, name),
	})
	return err
}

// getBucketPath constructs the key for the object stored in S3.
// If path is empty, the key is the combination of root of S3 bucket and filename.
func getBucketPath(path string, name string) string {
	if path == "" {
		return fmt.Sprintf("%s", name)
	}
	return fmt.Sprintf("%s/%s", path, name)
}