Refactor media provider.

- Rename `Get()` to `GetURL()`.
- Add `GetBlob()` to retrieve the media file blobs in
  filesystem and and s3 media providers.

This enables reading media files inside listmonk paving the way to
campaign file attachments.

internal/core/media.go

@@ -19,8 +19,8 @@ func (c *Core) GetAllMedia(provider string, s media.Store) ([]media.Media, error
 	}
 
 	for i := 0; i < len(out); i++ {
-		out[i].URL = s.Get(out[i].Filename)
-		out[i].ThumbURL = s.Get(out[i].Thumb)
+		out[i].URL = s.GetURL(out[i].Filename)
+		out[i].ThumbURL = s.GetURL(out[i].Thumb)
 	}
 
 	return out, nil
@@ -39,8 +39,8 @@ func (c *Core) GetMedia(id int, uuid string, s media.Store) (media.Media, error)
 			c.i18n.Ts("globals.messages.errorFetching", "name", "{globals.terms.media}", "error", pqErrMsg(err)))
 	}
 
-	out.URL = s.Get(out.Filename)
-	out.ThumbURL = s.Get(out.Thumb)
+	out.URL = s.GetURL(out.Filename)
+	out.ThumbURL = s.GetURL(out.Thumb)
 
 	return out, nil
 }

internal/media/media.go

@@ -24,5 +24,6 @@ type Media struct {
 type Store interface {
 	Put(string, string, io.ReadSeeker) (string, error)
 	Delete(string) error
-	Get(string) string
+	GetURL(string) string
+	GetBlob(string) ([]byte, error)
 }

internal/media/providers/filesystem/filesystem.go

@@ -4,6 +4,7 @@ import (
 	"crypto/rand"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -59,11 +60,17 @@ func (c *Client) Put(filename string, cType string, src io.ReadSeeker) (string,
 	return filename, nil
 }
 
-// Get accepts a filename and retrieves the full path from disk.
-func (c *Client) Get(name string) string {
+// GetURL accepts a filename and retrieves the full path from disk.
+func (c *Client) GetURL(name string) string {
 	return fmt.Sprintf("%s%s/%s", c.opts.RootURL, c.opts.UploadURI, name)
 }
 
+// GetBlob accepts a URL, reads the file, and returns the blob.
+func (c *Client) GetBlob(url string) ([]byte, error) {
+	b, err := ioutil.ReadFile(filepath.Join(getDir(c.opts.UploadPath), filepath.Base(url)))
+	return b, err
+}
+
 // Delete accepts a filename and removes it from disk.
 func (c *Client) Delete(file string) error {
 	dir := getDir(c.opts.UploadPath)

internal/media/providers/s3/s3.go

@@ -3,6 +3,8 @@ package s3
 import (
 	"fmt"
 	"io"
+	"io/ioutil"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -80,7 +82,7 @@ func (c *Client) Put(name string, cType string, file io.ReadSeeker) (string, err
 }
 
 // Get accepts the filename of the object stored and retrieves from S3.
-func (c *Client) Get(name string) string {
+func (c *Client) GetURL(name string) string {
 	// Generate a private S3 pre-signed URL if it's a private bucket, and there
 	// is no public URL provided.
 	if c.opts.BucketType == "private" && c.opts.PublicURL == "" {
@@ -99,6 +101,25 @@ func (c *Client) Get(name string) string {
 	return c.makeFileURL(name)
 }
 
+// GetBlob reads a file from S3 and returns the raw bytes.
+func (c *Client) GetBlob(url string) ([]byte, error) {
+	file, err := c.s3.FileDownload(simples3.DownloadInput{
+		Bucket:    c.opts.Bucket,
+		ObjectKey: c.makeBucketPath(filepath.Base(url)),
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	b, err := ioutil.ReadAll(file)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	return b, nil
+}
+
 // Delete accepts the filename of the object and deletes from S3.
 func (c *Client) Delete(name string) error {
 	err := c.s3.FileDelete(simples3.DeleteInput{