Add ctx.DownloadMedia method

errors/errors.go

@@ -7,12 +7,13 @@ var (
 )
 
 var (
-	ErrPeerNotFound    = errors.New("peer not found")
-	ErrNotChat         = errors.New("not chat")
-	ErrNotChannel      = errors.New("not channel")
-	ErrNotUser         = errors.New("not user")
-	ErrTextEmpty       = errors.New("text was not provided")
-	ErrTextInvalid     = errors.New("type of text is invalid, provide one from string and []styling.StyledTextOption")
-	ErrMessageNotExist = errors.New("message not exist")
-	ErrReplyNotMessage = errors.New("reply header is not a message")
+	ErrPeerNotFound     = errors.New("peer not found")
+	ErrNotChat          = errors.New("not chat")
+	ErrNotChannel       = errors.New("not channel")
+	ErrNotUser          = errors.New("not user")
+	ErrTextEmpty        = errors.New("text was not provided")
+	ErrTextInvalid      = errors.New("type of text is invalid, provide one from string and []styling.StyledTextOption")
+	ErrMessageNotExist  = errors.New("message not exist")
+	ErrReplyNotMessage  = errors.New("reply header is not a message")
+	ErrUnknownTypeMedia = errors.New("unknown type media")
 )

ext/context.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"math/rand"
 	"strings"
 	"time"
@@ -12,6 +13,7 @@ import (
 	"github.com/celestix/gotgproto/functions"
 	"github.com/celestix/gotgproto/storage"
 	"github.com/celestix/gotgproto/types"
+	"github.com/gotd/td/telegram/downloader"
 	"github.com/gotd/td/telegram/message"
 	"github.com/gotd/td/telegram/message/entity"
 	"github.com/gotd/td/telegram/message/styling"
@@ -683,14 +685,106 @@ func (ctx *Context) GetUserProfilePhotos(userId int64, opts *tg.PhotosGetUserPho
 	return p.GetPhotos(), nil
 }
 
-func (ctx *Context) ForwardMediaGroup() error {
-	_, err := ctx.Raw.MessagesForwardMessages(ctx, &tg.MessagesForwardMessagesRequest{})
-	return err
-}
-
 // ExportSessionString returns session of authorized account in the form of string.
 // Note: This session string can be used to log back in with the help of gotgproto.
 // Check sessionMaker.SessionType for more information about it.
 func (ctx *Context) ExportSessionString() (string, error) {
 	return functions.EncodeSessionToString(ctx.PeerStorage.GetSession())
 }
+
+func getInputFileLocation(media tg.MessageMediaClass) (tg.InputFileLocationClass, error) {
+	switch v := media.(type) {
+	case *tg.MessageMediaPhoto: // messageMediaPhoto#695150d7
+		f, ok := v.Photo.AsNotEmpty()
+		if !ok {
+			return nil, mtp_errors.ErrUnknownTypeMedia
+		}
+		return &tg.InputPhotoFileLocation{
+			ID:            f.ID,
+			AccessHash:    f.AccessHash,
+			FileReference: f.FileReference,
+		}, nil
+	case *tg.MessageMediaDocument: // messageMediaDocument#4cf4d72d
+		f, ok := v.Document.AsNotEmpty()
+		if !ok {
+			return nil, mtp_errors.ErrUnknownTypeMedia
+		}
+		return f.AsInputDocumentFileLocation(), nil
+	case *tg.MessageMediaStory: // messageMediaStory#68cb6283
+		f, ok := v.Story.(*tg.StoryItem)
+		if !ok {
+			return nil, mtp_errors.ErrUnknownTypeMedia
+		}
+		return getInputFileLocation(f.Media)
+	}
+	return nil, mtp_errors.ErrUnknownTypeMedia
+}
+
+// DownloadOutputClass is an interface which is used to download media.
+// It can be one from DownloadOutputStream, DownloadOutputPath and DownloadOutputParallel.
+type DownloadOutputClass interface {
+	run(context.Context, *downloader.Builder) (tg.StorageFileTypeClass, error)
+}
+
+// DownloadOutputStream is used to download media to an io.Writer.
+// It can be used to download media to a file, memory etc.
+type DownloadOutputStream struct {
+	io.Writer
+}
+
+func (d DownloadOutputStream) run(ctx context.Context, b *downloader.Builder) (tg.StorageFileTypeClass, error) {
+	return b.Stream(ctx, d)
+}
+
+// DownloadOutputPath is used to download media to a file.
+type DownloadOutputPath string
+
+func (d DownloadOutputPath) run(ctx context.Context, b *downloader.Builder) (tg.StorageFileTypeClass, error) {
+	return b.ToPath(ctx, string(d))
+}
+
+// DownloadOutputParallel is used to download a media parallely.
+type DownloadOutputParallel struct {
+	io.WriterAt
+}
+
+func (d DownloadOutputParallel) run(ctx context.Context, b *downloader.Builder) (tg.StorageFileTypeClass, error) {
+	return b.Parallel(ctx, d)
+}
+
+// DownloadMediaOpts object contains optional parameters for Context.DownloadMedia.
+// If not provided, default values will be used.
+type DownloadMediaOpts struct {
+	// Threads sets downloading goroutines limit.
+	Threads int
+	//  If verify is true, file hashes will be checked. Verify is true by default for CDN downloads.
+	Verify *bool
+	// PartSize sets chunk size. Must be divisible by 4KB.
+	PartSize int
+}
+
+// DownloadMedia downloads media from the provided MessageMediaClass.
+// DownloadOutputClass can be one from DownloadOutputStream, DownloadOutputPath and DownloadOutputParallel.
+// DownloadMediaOpts can be used to set optional parameters.
+// Returns tg.StorageFileTypeClass and error if any.
+func (ctx *Context) DownloadMedia(media tg.MessageMediaClass, downloadOutput DownloadOutputClass, opts *DownloadMediaOpts) (tg.StorageFileTypeClass, error) {
+	if opts == nil {
+		opts = &DownloadMediaOpts{}
+	}
+	downloader := downloader.NewDownloader()
+	if opts.PartSize > 0 {
+		downloader.WithPartSize(opts.PartSize)
+	}
+	inputFileLocation, err := getInputFileLocation(media)
+	if err != nil {
+		return nil, err
+	}
+	d := downloader.Download(ctx.Raw, inputFileLocation)
+	if opts.Threads > 0 {
+		d.WithThreads(opts.Threads)
+	}
+	if opts.Verify != nil {
+		d.WithVerify(*opts.Verify)
+	}
+	return downloadOutput.run(ctx, d)
+}