vision_service.js

/**
 * VisionService
 * Wraps Google Vision API document text detection.
 */
const VisionService = {
  extractText(file) {
    const apiKey = PropertiesService.getScriptProperties().getProperty("VISION_API_KEY");
    if (!apiKey) { LoggerService.error("VISION_API_KEY not set"); return null; }

    const mime = file.getMimeType();
    if (!mime.includes("image") && mime !== APP_DEFAULTS.PDF_MIME)
      LoggerService.warn("File may not be supported by Vision OCR: " + mime);

    try {
      LoggerService.info(`Sending file "${file.getName()}" to Vision API`);
      const base64Image = Utilities.base64Encode(file.getBlob().getBytes());
      const payload = { requests: [{ image: { content: base64Image }, features: [{ type: "DOCUMENT_TEXT_DETECTION" }] }] };
      const options = { method: "POST", contentType: "application/json", payload: JSON.stringify(payload), muteHttpExceptions: true };
      const response = UrlFetchApp.fetch(`https://vision.googleapis.com/v1/images:annotate?key=${apiKey}`, options);
      const result = JSON.parse(response.getContentText());

      // Top-level error (e.g. auth failure, quota exceeded)
      if (result.error) { LoggerService.error("Vision API error: " + JSON.stringify(result.error)); return null; }

      const response0 = result.responses?.[0];

      // Bug 3 fix: Vision API also returns per-image errors inside responses[0].error
      // (e.g. invalid image format, unsupported file type). The original code only
      // checked result.error (top-level), so these silently fell through and logged
      // "Vision API returned no text" with no indication of why.
      if (response0?.error) { LoggerService.error("Vision API response error: " + JSON.stringify(response0.error)); return null; }

      const annotation = response0?.fullTextAnnotation;
      if (annotation?.text) { LoggerService.info(`Vision API extracted ${annotation.text.length} chars`); return annotation.text; }

      LoggerService.warn("Vision API returned no text");
      return null;
    } catch (e) { LoggerService.error("Vision API failed: " + e.toString()); return null; }
  }
};