aurak/server/src/ocr/ocr.service.ts

import { Injectable, Logger } from '@nestjs/common';
import { createWorker, Worker } from 'tesseract.js';
import { I18nService } from '../i18n/i18n.service';

@Injectable()
export class OcrService {
  private readonly logger = new Logger(OcrService.name);

  constructor(private readonly i18n: I18nService) {}

  async extractTextFromImage(imageBuffer: Buffer): Promise<string> {
    this.logger.log(
      `Starting OCR extraction from image (${imageBuffer.length} bytes)...`,
    );

    // Create worker for this request to ensure stability
    let worker: any = null;
    try {
      worker = await createWorker('chi_sim+eng+jpn');

      const {
        data: { text },
      } = await worker.recognize(imageBuffer);
      this.logger.log(
        `OCR extraction completed. ${text.length} characters extracted.`,
      );

      if (text.length === 0) {
        this.logger.warn('OCR returned empty text.');
      }

      await worker.terminate();
      return text.trim();
    } catch (error) {
      this.logger.error(`OCR text extraction failed: ${error.message}`);
      if (worker) {
        try {
          await worker.terminate();
        } catch (e) {}
      }
      throw new Error(
        this.i18n.formatMessage('ocrFailed', { message: error.message }),
      );
    }
  }

  async extractTextWithConfidence(imageBuffer: Buffer): Promise<{
    text: string;
    confidence: number;
  }> {
    this.logger.log(
      `Starting OCR extraction with confidence (${imageBuffer.length} bytes)...`,
    );

    let worker: any = null;
    try {
      worker = await createWorker('chi_sim+eng+jpn');
      const { data } = await worker.recognize(imageBuffer);
      this.logger.log(
        `OCR extraction completed. Confidence: ${data.confidence}%`,
      );

      await worker.terminate();
      return {
        text: data.text.trim(),
        confidence: data.confidence,
      };
    } catch (error) {
      this.logger.error(`OCR text extraction failed: ${error.message}`);
      if (worker) {
        try {
          await worker.terminate();
        } catch (e) {}
      }
      throw new Error(
        this.i18n.formatMessage('ocrFailed', { message: error.message }),
      );
    }
  }
}