feat: login

internal/client_channel.go

@@ -2,7 +2,9 @@ package internal
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"os"
 	"path/filepath"
 
 	"github.com/gotd/td/telegram/downloader"
@@ -64,3 +66,33 @@ func (t *TClient) Channel(ctx context.Context, channel *tg.Channel, offset int)
 
 	return nil
 }
+
+type ChannelConfig struct {
+	ID     int64 `json:"id"`
+	Offset int   `json:"offset"`
+}
+
+func (t *TClient) SaveChannelConfig(ctx context.Context, channelID int64, offset int) (*ChannelConfig, error) {
+	channelConfigFile := fmt.Sprintf("outputs/%d/config.json", channelID)
+	// if file not exists then create it
+	if _, err := os.Stat(channelConfigFile); os.IsNotExist(err) {
+		// create config file
+		data, _ := json.Marshal(&ChannelConfig{ID: channelID})
+		if err := os.WriteFile(channelConfigFile, data, 0o644); err != nil {
+			return nil, errors.Wrap(err, "write channel config")
+		}
+	}
+
+	// read config file
+	data, err := os.ReadFile(channelConfigFile)
+	if err != nil {
+		return nil, errors.Wrap(err, "read channel config")
+	}
+
+	var config *ChannelConfig
+	if err := json.Unmarshal(data, config); err != nil {
+		return nil, errors.Wrap(err, "unmarshal channel config")
+	}
+
+	return config, nil
+}