/// Receipt parsing entry point: spatial OCR pipeline with text fallback.
library;

import 'package:google_mlkit_text_recognition/google_mlkit_text_recognition.dart';

import '../models/line_item.dart';
import '../models/ocr_element.dart';
import 'receipt_ocr.dart';
import 'receipt_parse_config.dart';
export 'receipt_parse_config.dart' show loadReceiptParseConfig;
export 'receipt_text_parser.dart' show ReceiptParseResult;
import 'receipt_spatial_parser.dart';
import 'receipt_text_parser.dart';

class ReceiptParser {
  ReceiptParser._();

  static Future<void> loadConfig() => loadReceiptParseConfig();

  static List<LineItem> parse(String rawText) => parseReceipt(rawText).items;

  /// Fallback when only flattened OCR text is available (tests, re-parse).
  static ReceiptParseResult parseReceipt(String rawText) =>
      ReceiptTextParser.parseReceipt(rawText);

  /// Primary path: positioned ML Kit elements → row clustering → lookahead.
  static ReceiptParseResult parseReceiptFromOcr(OcrDocument document) =>
      _parseDocument(document);

  static ReceiptParseResult parseRecognizedText(
    RecognizedText recognized, {
    required double imageWidth,
    required double imageHeight,
  }) {
    final document = ReceiptOcr.fromRecognizedText(
      recognized,
      imageWidth: imageWidth,
      imageHeight: imageHeight,
    );
    return _parseDocument(document);
  }

  static ReceiptParseResult _parseDocument(OcrDocument document) {
    if (ReceiptTextParser.looksLikeColumnOcr(document.flattenedText)) {
      return _withImageDimensions(
        ReceiptTextParser.parseReceipt(document.flattenedText),
        document,
      );
    }

    final spatial = ReceiptSpatialParser.parse(document);
    if (_shouldFallbackToText(spatial)) {
      return _withImageDimensions(
        ReceiptTextParser.parseReceipt(document.flattenedText),
        document,
      );
    }
    return spatial;
  }

  static bool _shouldFallbackToText(ReceiptParseResult spatial) {
    if (spatial.items.isEmpty) return true;
    final flagged =
        spatial.items.where((item) => item.needsManualReview).length;
    if (flagged > 0) return true;
    if (spatial.items.any((item) => item.price <= 0)) return true;
    if (spatial.receiptTotal != null && !spatial.validationPassed) return true;
    return false;
  }

  static ReceiptParseResult _withImageDimensions(
    ReceiptParseResult result,
    OcrDocument document,
  ) {
    return ReceiptParseResult(
      items: result.items,
      store: result.store,
      receiptTotal: result.receiptTotal,
      totalDiscount: result.totalDiscount,
      validationPassed: result.validationPassed,
      expectedItemCount: result.expectedItemCount,
      ocrImageWidth: document.imageWidth,
      ocrImageHeight: document.imageHeight,
    );
  }
}