|
| 1 | +package main |
| 2 | + |
| 3 | +import ( |
| 4 | + "bytes" |
| 5 | + "context" |
| 6 | + "encoding/base64" |
| 7 | + "encoding/json" |
| 8 | + "fmt" |
| 9 | + "io" |
| 10 | + "log" |
| 11 | + "mime/multipart" |
| 12 | + "net/http" |
| 13 | + "os" |
| 14 | + "strconv" |
| 15 | + "strings" |
| 16 | + "time" |
| 17 | + |
| 18 | + "golang.org/x/oauth2" |
| 19 | + "golang.org/x/oauth2/google" |
| 20 | + "google.golang.org/api/gmail/v1" |
| 21 | + "google.golang.org/api/option" |
| 22 | +) |
| 23 | + |
| 24 | +// Retrieve a token, saves the token, then returns the generated client. |
| 25 | +func getClient(config *oauth2.Config) *http.Client { |
| 26 | + // The file token.json stores the user's access and refresh tokens, and is |
| 27 | + // created automatically when the authorization flow completes for the first |
| 28 | + // time. |
| 29 | + tokFile := "token.json" |
| 30 | + tok, err := tokenFromFile(tokFile) |
| 31 | + if err != nil { |
| 32 | + tok = getTokenFromWeb(config) |
| 33 | + saveToken(tokFile, tok) |
| 34 | + } |
| 35 | + return config.Client(context.Background(), tok) |
| 36 | +} |
| 37 | + |
| 38 | +// Request a token from the web, then returns the retrieved token. |
| 39 | +func getTokenFromWeb(config *oauth2.Config) *oauth2.Token { |
| 40 | + authURL := config.AuthCodeURL("state-token", oauth2.AccessTypeOffline) |
| 41 | + fmt.Printf("Go to the following link in your browser then type the "+ |
| 42 | + "authorization code: \n%v\n", authURL) |
| 43 | + |
| 44 | + var authCode string |
| 45 | + if _, err := fmt.Scan(&authCode); err != nil { |
| 46 | + log.Fatalf("Unable to read authorization code: %v", err) |
| 47 | + } |
| 48 | + |
| 49 | + tok, err := config.Exchange(context.TODO(), authCode) |
| 50 | + if err != nil { |
| 51 | + log.Fatalf("Unable to retrieve token from web: %v", err) |
| 52 | + } |
| 53 | + return tok |
| 54 | +} |
| 55 | + |
| 56 | +// Retrieves a token from a local file. |
| 57 | +func tokenFromFile(file string) (*oauth2.Token, error) { |
| 58 | + f, err := os.Open(file) |
| 59 | + if err != nil { |
| 60 | + return nil, err |
| 61 | + } |
| 62 | + defer f.Close() |
| 63 | + tok := &oauth2.Token{} |
| 64 | + err = json.NewDecoder(f).Decode(tok) |
| 65 | + return tok, err |
| 66 | +} |
| 67 | + |
| 68 | +// Saves a token to a file path. |
| 69 | +func saveToken(path string, token *oauth2.Token) { |
| 70 | + fmt.Printf("Saving credential file to: %s\n", path) |
| 71 | + f, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600) |
| 72 | + if err != nil { |
| 73 | + log.Fatalf("Unable to cache oauth token: %v", err) |
| 74 | + } |
| 75 | + defer f.Close() |
| 76 | + json.NewEncoder(f).Encode(token) |
| 77 | +} |
| 78 | + |
| 79 | +// Configuration holds the configurable variables |
| 80 | +type Configuration struct { |
| 81 | + PollingInterval time.Duration |
| 82 | + WebhookURL string |
| 83 | + SearchQuery string |
| 84 | +} |
| 85 | + |
| 86 | +func loadConfig() Configuration { |
| 87 | + cfg := Configuration{ |
| 88 | + WebhookURL: "http://localhost:8080/webhook", |
| 89 | + SearchQuery: "label:Assistantis:unread", |
| 90 | + PollingInterval: 60 * time.Second, |
| 91 | + } |
| 92 | + |
| 93 | + if val := os.Getenv("WEBHOOK_URL"); val != "" { |
| 94 | + cfg.WebhookURL = val |
| 95 | + } |
| 96 | + if val := os.Getenv("SEARCH_QUERY"); val != "" { |
| 97 | + cfg.SearchQuery = val |
| 98 | + } |
| 99 | + if val := os.Getenv("POLLING_INTERVAL"); val != "" { |
| 100 | + if i, err := strconv.Atoi(val); err == nil { |
| 101 | + cfg.PollingInterval = time.Duration(i) * time.Second |
| 102 | + } else { |
| 103 | + log.Printf("Invalid POLLING_INTERVAL: %v, using default 60s", err) |
| 104 | + } |
| 105 | + } |
| 106 | + |
| 107 | + return cfg |
| 108 | +} |
| 109 | + |
| 110 | +type emailData struct { |
| 111 | + ID string |
| 112 | + Sender string |
| 113 | + Subject string |
| 114 | + Date string |
| 115 | + Body string |
| 116 | + Attachments []attachment |
| 117 | +} |
| 118 | + |
| 119 | +type attachment struct { |
| 120 | + Filename string |
| 121 | + Data []byte |
| 122 | + MimeType string |
| 123 | +} |
| 124 | + |
| 125 | +func main() { |
| 126 | + cfg := loadConfig() |
| 127 | + log.Printf("Starting Gmail Reader Script with config: %+v\n", cfg) |
| 128 | + |
| 129 | + ctx := context.Background() |
| 130 | + |
| 131 | + b, err := os.ReadFile("credentials.json") |
| 132 | + if err != nil { |
| 133 | + log.Fatalf("Unable to read client secret file: %v. Please make sure credentials.json is present in the current directory.", err) |
| 134 | + } |
| 135 | + |
| 136 | + // If modifying these scopes, delete your previously saved token.json. |
| 137 | + config, err := google.ConfigFromJSON(b, gmail.MailGoogleComScope) |
| 138 | + if err != nil { |
| 139 | + log.Fatalf("Unable to parse client secret file to config: %v", err) |
| 140 | + } |
| 141 | + client := getClient(config) |
| 142 | + |
| 143 | + srv, err := gmail.NewService(ctx, option.WithHTTPClient(client)) |
| 144 | + if err != nil { |
| 145 | + log.Fatalf("Unable to retrieve Gmail client: %v", err) |
| 146 | + } |
| 147 | + |
| 148 | + // Start polling loop |
| 149 | + ticker := time.NewTicker(cfg.PollingInterval) |
| 150 | + defer ticker.Stop() |
| 151 | + |
| 152 | + // Run once immediately |
| 153 | + pollEmails(srv, cfg) |
| 154 | + |
| 155 | + for range ticker.C { |
| 156 | + pollEmails(srv, cfg) |
| 157 | + } |
| 158 | +} |
| 159 | + |
| 160 | +func pollEmails(srv *gmail.Service, cfg Configuration) { |
| 161 | + log.Printf("Polling emails with query: %s\n", cfg.SearchQuery) |
| 162 | + user := "me" |
| 163 | + |
| 164 | + r, err := srv.Users.Messages.List(user).Q(cfg.SearchQuery).MaxResults(5).Do() |
| 165 | + if err != nil { |
| 166 | + log.Printf("Unable to retrieve messages: %v", err) |
| 167 | + return |
| 168 | + } |
| 169 | + |
| 170 | + if len(r.Messages) == 0 { |
| 171 | + log.Println("No matching messages found.") |
| 172 | + return |
| 173 | + } |
| 174 | + |
| 175 | + for _, m := range r.Messages { |
| 176 | + processMessage(srv, user, m.Id, cfg.WebhookURL) |
| 177 | + } |
| 178 | +} |
| 179 | + |
| 180 | +func processMessage(srv *gmail.Service, user string, msgId string, webhookURL string) { |
| 181 | + msg, err := srv.Users.Messages.Get(user, msgId).Format("full").Do() |
| 182 | + if err != nil { |
| 183 | + log.Printf("Unable to get message %s: %v", msgId, err) |
| 184 | + return |
| 185 | + } |
| 186 | + |
| 187 | + data := extractEmailData(srv, user, msg) |
| 188 | + |
| 189 | + // Send to webhook |
| 190 | + err = forwardToWebhook(data, webhookURL) |
| 191 | + if err != nil { |
| 192 | + log.Printf("Failed to forward message %s: %v", msgId, err) |
| 193 | + // Leave as unread so it gets picked up again |
| 194 | + return |
| 195 | + } |
| 196 | + |
| 197 | + // Mark as read |
| 198 | + log.Printf("Message %s forwarded successfully, marking as read.", msgId) |
| 199 | + mods := &gmail.ModifyMessageRequest{ |
| 200 | + RemoveLabelIds: []string{"UNREAD"}, |
| 201 | + } |
| 202 | + _, err = srv.Users.Messages.Modify(user, msgId, mods).Do() |
| 203 | + if err != nil { |
| 204 | + log.Printf("Unable to modify message %s: %v", msgId, err) |
| 205 | + } |
| 206 | +} |
| 207 | + |
| 208 | +func extractEmailData(srv *gmail.Service, user string, msg *gmail.Message) emailData { |
| 209 | + data := emailData{ |
| 210 | + ID: msg.Id, |
| 211 | + } |
| 212 | + |
| 213 | + // Extract headers |
| 214 | + for _, header := range msg.Payload.Headers { |
| 215 | + switch strings.ToLower(header.Name) { |
| 216 | + case "from": |
| 217 | + data.Sender = header.Value |
| 218 | + case "subject": |
| 219 | + data.Subject = header.Value |
| 220 | + case "date": |
| 221 | + data.Date = header.Value |
| 222 | + } |
| 223 | + } |
| 224 | + |
| 225 | + // Extract body and attachments |
| 226 | + extractParts(srv, user, msg.Id, msg.Payload, &data) |
| 227 | + |
| 228 | + return data |
| 229 | +} |
| 230 | + |
| 231 | +func extractParts(srv *gmail.Service, user string, msgId string, part *gmail.MessagePart, data *emailData) { |
| 232 | + if part.Filename != "" && part.Body != nil && part.Body.AttachmentId != "" { |
| 233 | + // It's an attachment |
| 234 | + attachObj, err := srv.Users.Messages.Attachments.Get(user, msgId, part.Body.AttachmentId).Do() |
| 235 | + if err != nil { |
| 236 | + log.Printf("Unable to get attachment %s for message %s: %v", part.Filename, msgId, err) |
| 237 | + return |
| 238 | + } |
| 239 | + |
| 240 | + decoded, err := base64.URLEncoding.DecodeString(attachObj.Data) |
| 241 | + if err != nil { |
| 242 | + log.Printf("Unable to decode attachment %s: %v", part.Filename, err) |
| 243 | + return |
| 244 | + } |
| 245 | + |
| 246 | + data.Attachments = append(data.Attachments, attachment{ |
| 247 | + Filename: part.Filename, |
| 248 | + Data: decoded, |
| 249 | + MimeType: part.MimeType, |
| 250 | + }) |
| 251 | + } else if part.MimeType == "text/plain" && part.Body != nil && part.Body.Data != "" { |
| 252 | + // It's the body |
| 253 | + decoded, err := base64.URLEncoding.DecodeString(part.Body.Data) |
| 254 | + if err == nil { |
| 255 | + data.Body += string(decoded) |
| 256 | + } |
| 257 | + } else if part.MimeType == "text/html" && data.Body == "" && part.Body != nil && part.Body.Data != "" { |
| 258 | + // Fallback to HTML body if plain text is not found yet |
| 259 | + decoded, err := base64.URLEncoding.DecodeString(part.Body.Data) |
| 260 | + if err == nil { |
| 261 | + data.Body += string(decoded) |
| 262 | + } |
| 263 | + } |
| 264 | + |
| 265 | + // Recursively check parts |
| 266 | + for _, p := range part.Parts { |
| 267 | + extractParts(srv, user, msgId, p, data) |
| 268 | + } |
| 269 | +} |
| 270 | + |
| 271 | +func forwardToWebhook(data emailData, webhookURL string) error { |
| 272 | + body := &bytes.Buffer{} |
| 273 | + writer := multipart.NewWriter(body) |
| 274 | + |
| 275 | + // Add metadata fields |
| 276 | + _ = writer.WriteField("Sender", data.Sender) |
| 277 | + _ = writer.WriteField("Subject", data.Subject) |
| 278 | + _ = writer.WriteField("Date", data.Date) |
| 279 | + |
| 280 | + // Add body if no attachments or to provide context |
| 281 | + if data.Body != "" { |
| 282 | + _ = writer.WriteField("Body", data.Body) |
| 283 | + } |
| 284 | + |
| 285 | + // Add attachments |
| 286 | + for _, att := range data.Attachments { |
| 287 | + // According to requirements, add as multiple files with name "payload" |
| 288 | + // or whatever array name is expected. I will use "payload" as array name |
| 289 | + // For proper boundary format, we use CreatePart instead of CreateFormFile |
| 290 | + // to set the content-disposition and content-type precisely |
| 291 | + h := make(map[string][]string) |
| 292 | + h["Content-Disposition"] = []string{fmt.Sprintf(`form-data; name="payload"; filename="%s"`, escapeQuotes(att.Filename))} |
| 293 | + if att.MimeType != "" { |
| 294 | + h["Content-Type"] = []string{att.MimeType} |
| 295 | + } else { |
| 296 | + h["Content-Type"] = []string{"application/octet-stream"} |
| 297 | + } |
| 298 | + |
| 299 | + part, err := writer.CreatePart(h) |
| 300 | + if err != nil { |
| 301 | + return fmt.Errorf("could not create form file for %s: %v", att.Filename, err) |
| 302 | + } |
| 303 | + _, err = io.Copy(part, bytes.NewReader(att.Data)) |
| 304 | + if err != nil { |
| 305 | + return fmt.Errorf("could not copy file data for %s: %v", att.Filename, err) |
| 306 | + } |
| 307 | + } |
| 308 | + |
| 309 | + err := writer.Close() |
| 310 | + if err != nil { |
| 311 | + return fmt.Errorf("failed to close multipart writer: %v", err) |
| 312 | + } |
| 313 | + |
| 314 | + req, err := http.NewRequest("POST", webhookURL, body) |
| 315 | + if err != nil { |
| 316 | + return fmt.Errorf("failed to create HTTP request: %v", err) |
| 317 | + } |
| 318 | + |
| 319 | + req.Header.Set("Content-Type", writer.FormDataContentType()) |
| 320 | + |
| 321 | + client := &http.Client{Timeout: 30 * time.Second} |
| 322 | + resp, err := client.Do(req) |
| 323 | + if err != nil { |
| 324 | + return fmt.Errorf("failed to send HTTP request: %v", err) |
| 325 | + } |
| 326 | + defer resp.Body.Close() |
| 327 | + |
| 328 | + if resp.StatusCode < 200 || resp.StatusCode >= 300 { |
| 329 | + respBody, _ := io.ReadAll(resp.Body) |
| 330 | + return fmt.Errorf("webhook returned non-2xx status code: %d, body: %s", resp.StatusCode, string(respBody)) |
| 331 | + } |
| 332 | + |
| 333 | + return nil |
| 334 | +} |
| 335 | + |
| 336 | +// escapeQuotes escapes double quotes for header values |
| 337 | +func escapeQuotes(s string) string { |
| 338 | + return strings.ReplaceAll(s, `"`, `\"`) |
| 339 | +} |
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