fix: downloads when no of chunks > 200

pkg/services/common.go

@@ -7,7 +7,10 @@ import (
 	"encoding/binary"
 	"fmt"
 	"io"
+	"math"
+	"sort"
 	"strconv"
+	"sync"
 
 	"github.com/divyam234/teldrive/internal/cache"
 	"github.com/divyam234/teldrive/internal/config"
@@ -54,6 +57,12 @@ func randInt64() (int64, error) {
 	b := &buffer{Buf: buf[:]}
 	return b.long()
 }
+
+type batchResult struct {
+	Index    int
+	Messages *tg.MessagesChannelMessages
+}
+
 func getChunk(ctx context.Context, tgClient *telegram.Client, location tg.InputFileLocationClass, offset int64, limit int64) ([]byte, error) {
 
 	req := &tg.UploadGetFileRequest{
@@ -115,11 +124,37 @@ func getBotInfo(ctx context.Context, KV kv.KV, config *config.TGConfig, token st
 	return &types.BotInfo{Id: user.ID, UserName: user.Username, Token: token}, nil
 }
 
-func getTGMessages(ctx context.Context, client *telegram.Client, parts []schemas.Part, channelId int64, userID string) (*tg.MessagesChannelMessages, error) {
+func getTGMessagesBatch(ctx context.Context, client *telegram.Client, channel *tg.InputChannel, parts []schemas.Part, userID string, index int,
+	results chan<- batchResult, errors chan<- error, wg *sync.WaitGroup) {
+
+	defer wg.Done()
 
 	ids := funk.Map(parts, func(part schemas.Part) tg.InputMessageClass {
-		return tg.InputMessageClass(&tg.InputMessageID{ID: int(part.ID)})
-	})
+		return &tg.InputMessageID{ID: int(part.ID)}
+	}).([]tg.InputMessageClass)
+
+	messageRequest := tg.ChannelsGetMessagesRequest{
+		Channel: channel,
+		ID:      ids,
+	}
+
+	res, err := client.API().ChannelsGetMessages(ctx, &messageRequest)
+	if err != nil {
+		errors <- err
+		return
+	}
+
+	messages, ok := res.(*tg.MessagesChannelMessages)
+
+	if !ok {
+		errors <- fmt.Errorf("unexpected response type: %T", res)
+		return
+	}
+
+	results <- batchResult{Index: index, Messages: messages}
+}
+
+func getTGMessages(ctx context.Context, client *telegram.Client, parts []schemas.Part, channelId int64, userID string) ([]tg.MessageClass, error) {
 
 	channel, err := GetChannelById(ctx, client, channelId, userID)
 
@@ -127,17 +162,49 @@ func getTGMessages(ctx context.Context, client *telegram.Client, parts []schemas
 		return nil, err
 	}
 
-	messageRequest := tg.ChannelsGetMessagesRequest{Channel: channel, ID: ids.([]tg.InputMessageClass)}
+	var wg sync.WaitGroup
 
-	res, err := client.API().ChannelsGetMessages(ctx, &messageRequest)
+	batchSize := 200
 
-	if err != nil {
-		return nil, err
+	batchCount := int(math.Ceil(float64(len(parts)) / float64(batchSize)))
+
+	results := make(chan batchResult, batchCount)
+
+	errors := make(chan error, batchCount)
+
+	for i := 0; i < batchCount; i++ {
+		wg.Add(1)
+		splitParts := parts[i*batchSize : min((i+1)*batchSize, len(parts))]
+		go getTGMessagesBatch(ctx, client, channel, splitParts, userID, i, results, errors, &wg)
 	}
 
-	messages := res.(*tg.MessagesChannelMessages)
+	wg.Wait()
+	close(results)
+	close(errors)
 
-	return messages, nil
+	for err := range errors {
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	channelResult := []batchResult{}
+
+	for result := range results {
+		channelResult = append(channelResult, result)
+	}
+
+	sort.Slice(channelResult, func(i, j int) bool {
+		return channelResult[i].Index < channelResult[j].Index
+	})
+
+	allMessages := []tg.MessageClass{}
+
+	for _, result := range channelResult {
+		allMessages = append(allMessages, result.Messages.GetMessages()...)
+	}
+
+	return allMessages, nil
 }
 
 func getParts(ctx context.Context, client *telegram.Client, file *schemas.FileOutFull, userID string) ([]types.Part, error) {
@@ -158,7 +225,7 @@ func getParts(ctx context.Context, client *telegram.Client, file *schemas.FileOu
 		return nil, err
 	}
 
-	for i, message := range messages.Messages {
+	for i, message := range messages {
 		item := message.(*tg.Message)
 		media := item.Media.(*tg.MessageMediaDocument)
 		document := media.Document.(*tg.Document)

pkg/services/file.go

@@ -330,7 +330,7 @@ func (fs *FileService) CopyFile(c *gin.Context) (*schemas.FileOut, *types.AppErr
 		if err != nil {
 			return err
 		}
-		for i, message := range messages.Messages {
+		for i, message := range messages {
 			item := message.(*tg.Message)
 			media := item.Media.(*tg.MessageMediaDocument)
 			document := media.Document.(*tg.Document)