import 'package:flutter_test/flutter_test.dart';
import 'package:fuel_tax_tracker/services/receipt_parser.dart';

void main() {
  group('ReceiptParser', () {
    test('parses a typical gas station receipt', () {
      const receipt = '''
        SHELL OIL 12345
        123 MAIN ST
        PUMP 04
        GALLONS       12.345
        PRICE/GAL     \$3.599
        FUEL TOTAL    \$44.44
        THANK YOU
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 12.345);
      expect(result.pricePerGallon, 3.599);
      expect(result.totalCost, 44.44);
    });

    test('parses a tabular receipt where labels and values sit on separate lines', () {
      // Mirrors a real Casey's receipt: "Pump / Gallons / Price" is a
      // header row, with the actual values on the next line, and the
      // total is phrased "Total Sale" rather than a bare "Total".
      const receipt = '''
        Casey's
        Store #4021
        420 W. 6TH STREET
        KEARNEY, MO 64060
        Date 08/08/2026
        Time 02:21
        VI
        ########8533
        Pump Gallons Price
        07 32.115 \$ 3.759
        Product Amount
        87E10 \$ 120.72
        Total Sale \$ 120.72
        Auth #
        Visa
        Seq # 008299
        98
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 32.115);
      expect(result.pricePerGallon, 3.759);
      expect(result.totalCost, 120.72);
    });

    test('does not confuse SUBTOTAL with TOTAL', () {
      const receipt = '''
        SUBTOTAL 10.00
        TAX 0.50
        TOTAL 10.50
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.totalCost, 10.50);
    });

    test('derives total when gallons and price per gallon are known', () {
      const receipt = '''
        GALLONS 10.000
        PPG 3.500
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 10.0);
      expect(result.pricePerGallon, 3.5);
      expect(result.totalCost, 35.0);
    });

    test('derives gallons when total and price per gallon are known', () {
      const receipt = '''
        PRICE PER GALLON \$4.000
        TOTAL \$20.00
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.pricePerGallon, 4.0);
      expect(result.totalCost, 20.0);
      expect(result.gallons, 5.0);
    });

    test('returns nulls when nothing recognizable is present', () {
      const receipt = 'THANK YOU FOR YOUR PURCHASE';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, isNull);
      expect(result.pricePerGallon, isNull);
      expect(result.totalCost, isNull);
      expect(result.date, isNull);
    });
  });

  group('ReceiptParser state parsing', () {
    test('detects a state abbreviation directly before a ZIP code', () {
      const receipt = '''
        Casey's
        420 W. 6TH STREET
        KEARNEY, MO 64060
      ''';

      expect(ReceiptParser.parse(receipt).state, 'MO');
    });

    test('detects a non-Missouri state the same way', () {
      const receipt = '''
        Swift Stop #3
        1809 Hobbs Hwy
        Seminole TX 79360
      ''';

      expect(ReceiptParser.parse(receipt).state, 'TX');
    });

    test('falls back to a state right after a comma when no ZIP is nearby', () {
      const receipt = '''
        Buc-ee's
        6988 Buc-ee's Blvd
        Leeds, AL
      ''';

      expect(ReceiptParser.parse(receipt).state, 'AL');
    });

    test('does not mistake "VI" (Visa) for the Virgin Islands', () {
      const receipt = '''
        Casey's
        VI
        ########8533
        Pump Gallons Price
        07 32.115 \$ 3.759
      ''';

      expect(ReceiptParser.parse(receipt).state, isNull);
    });

    test('does not mistake the word "In" for Indiana', () {
      const receipt = '''
        Gallons 10.000
        Price/Gal \$3.399
        Total Fuel \$33.99
        All Taxes Included
        In Fuel Price.
      ''';

      expect(ReceiptParser.parse(receipt).state, isNull);
    });

    test('returns null when no address-like state pattern is present', () {
      expect(ReceiptParser.parse('THANK YOU FOR YOUR PURCHASE').state, isNull);
    });
  });

  group('ReceiptParser date parsing', () {
    test('parses "Date: M/D/YYYY" + "Time: H:MM:SS AM/PM" on separate lines', () {
      const receipt = '''
        Date: 8/22/2024
        Time: 10:11:00 AM
        Gallons        10.000
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.date, DateTime(2024, 8, 22, 10, 11));
    });

    test('parses "DATE M/D/YY H:MM" on the same line', () {
      const receipt = '''
        DATE 3/26/22 18:12
        PUMP# 06
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.date, DateTime(2022, 3, 26, 18, 12));
    });

    test('parses a 2-digit year and a no-space AM/PM time', () {
      const receipt = '''
        Date  01/23/20
        Time  02:11PM
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.date, DateTime(2020, 1, 23, 14, 11));
    });

    test('12 AM and 12 PM convert correctly (midnight/noon edge case)', () {
      expect(ReceiptParser.parse('Date 1/1/24 12:00 AM').date, DateTime(2024, 1, 1, 0, 0));
      expect(ReceiptParser.parse('Date 1/1/24 12:30 PM').date, DateTime(2024, 1, 1, 12, 30));
    });

    test('falls back to midnight when a date is found but no time is nearby', () {
      // Comfortably more than the 40-character "nearby" search window
      // between the date and the unrelated text before a time appears
      // much later, regardless of how this string literal is indented.
      final filler = 'x' * 100;
      final receipt = 'Date 12/14/16\n$filler\nTime 5:11 PM';

      final result = ReceiptParser.parse(receipt);

      // Too far from the date to count as "nearby", so this should be
      // date-only at midnight — still better than no date at all, and the
      // confirm screen lets the user fix the time manually either way.
      expect(result.date, isNotNull);
      expect(result.date!.year, 2016);
      expect(result.date!.month, 12);
      expect(result.date!.day, 14);
      expect(result.date!.hour, 0);
      expect(result.date!.minute, 0);
    });

    test('returns null when no date-like pattern is present', () {
      final result = ReceiptParser.parse('GALLONS 10.000\nPPG 3.500');

      expect(result.date, isNull);
    });
  });

  // Transcribed from a batch of real photographed receipts across different
  // gas station chains, to catch label/layout variations the handful of
  // hand-written cases above don't happen to cover.
  group('ReceiptParser against real receipt layouts', () {
    test('Break Time — labels adjacent to values on the same line', () {
      const receipt = '''
        Date: 8/22/2024
        Time: 10:11:00 AM
        OXY87
        Pump Number       22
        Gallons        10.000
        Price/Gal      \$3.399
        Total Fuel     \$33.99
        Total Sale     \$33.99
        Visa           \$33.99
        All Taxes Included
        In Fuel Price.
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 10.000);
      expect(result.pricePerGallon, 3.399);
      expect(result.totalCost, 33.99);
    });

    test('Break Time — tabular Pump/Gallons/Price header row', () {
      const receipt = '''
        Member# 111795637651
        Invoice# 11733
        Date: 03/23/22
        Time: 10:05
        Auth# 020413
        VI Acct #
        ************0344
        Pump  Gallons  Price
        14    5.116    \$ 5.499
        Product  Amount
        Regular  \$ 28.13
        Total Sale  \$ 28.13
        SALE- Contactless
        Approved
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 5.116);
      expect(result.pricePerGallon, 5.499);
      expect(result.totalCost, 28.13);
    });

    test('Buc-ee\'s — abbreviated "PRICE/G" label', () {
      const receipt = '''
        BUC-EE'S
        6988 Buc-ee's Blvd
        Leeds AL
        PUMP No.       63
        GALLONS      9.999
        PRICE/G      \$2.499
        TOTAL FUEL   \$24.99
        Regular
        TOTAL SALE   \$24.99
        Visa         \$24.99
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 9.999);
      expect(result.pricePerGallon, 2.499);
      expect(result.totalCost, 24.99);
    });

    test('Costco — tabular header row, "Total Sale" phrasing', () {
      const receipt = '''
        Costco #01448
        1524 Beasie RD
        Murfreesboro TN
        Date: 01/03/24
        Time: 19:31
        Pump  Gallons   Price
        11    12.598    \$ 2.399
        Product  Amount
        Regular  \$ 30.22
        Total Sale  \$ 30.22
        SALE- Contactless
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 12.598);
      expect(result.pricePerGallon, 2.399);
      expect(result.totalCost, 30.22);
    });

    test('Murphy USA — "QTY(GAL)" label instead of "GALLONS"', () {
      const receipt = '''
        PUMP: 8
        PROD: UNLEAD
        PRICE/GAL: \$1.799
        NET/GAL: \$1.799
        QTY(GAL): 13.164
        FUEL TOTAL: \$23.68
        NET TOTAL: \$23.68
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 13.164);
      expect(result.pricePerGallon, 1.799);
      expect(result.totalCost, 23.68);
    });

    test('Phillips 66 — "PRICE/G" label and "FUEL SALE" as the total', () {
      const receipt = '''
        WELCOME
        LAWNSIDE PHILLIPS 66
        355 Warrington Ave
        Lawnside NJ 08045
        DATE 3/26/22  18:12
        TRAN# 060757
        PUMP# 06
        SERVICE LEVEL: FULL
        PRODUCT: REGULAR
        GALLONS       3.642
        PRICE/G       \$4.119
        FUEL SALE     \$15.00
        CREDIT        \$15.00
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 3.642);
      expect(result.pricePerGallon, 4.119);
      expect(result.totalCost, 15.00);
    });

    test('Phillips 66 — second "FUEL SALE" example', () {
      const receipt = '''
        WELCOME
        SWIFT STOP #3
        1809 HOBBS HWY
        SEMINOLE TX 79360
        DATE 5/9/23 11:16
        TRAN#9103742
        PUMP# 10
        SERVICE LEVEL: SELF
        PRODUCT: DIESEL 2
        GALLONS:      29.854
        PRICE/G:      \$3.499
        FUEL SALE     \$181.66
        CREDIT        \$181.66
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 29.854);
      expect(result.pricePerGallon, 3.499);
      expect(result.totalCost, 181.66);
    });

    test('Phillips 66 / Murphy-style — "QTY(GAL)" plus "FUEL TOTAL"', () {
      const receipt = '''
        Verified by PIN
        PIN USED
        PUMP: 5
        PROD: UNLEAD
        PRICE/GAL: \$3.959
        NET/GAL: \$3.959
        QTY(GAL): 11.068
        FUEL TOTAL: \$43.82
        NET TOTAL: \$43.82
        GET REWARDED!
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 11.068);
      expect(result.pricePerGallon, 3.959);
      expect(result.totalCost, 43.82);
    });

    test('QuikTrip — tabular header row, total not printed on receipt (derived)', () {
      const receipt = '''
        QUIKTRIP #01012
        383 George Liles PWK
        Concord, NC
        Invoice # 0000000
        Date  01/23/20
        Time  02:11PM
        Auth # 03581I
        Acct #
        ************1821
        Pump  Gallons  Price
        14    10.496   \$2.359
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 10.496);
      expect(result.pricePerGallon, 2.359);
      // Not printed within the visible receipt text — derived from
      // gallons * price rather than found via a label.
      expect(result.totalCost, closeTo(10.496 * 2.359, 0.01));
    });

    test('Sinclair — unit letter attached with no space, and a negative '
        'per-gallon discount line that must not be mistaken for gallons', () {
      const receipt = '''
        PUMP# 3
        UNLEADED CR 17.364G
        PRICE/GAL \$2.649
        DISCOUNTS BEFORE
        FUELING
        Debit Di/GAL \$-0.100
        FUEL TOTAL \$46.00
        DEBIT \$46.00
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 17.364);
      expect(result.pricePerGallon, 2.649);
      expect(result.totalCost, 46.00);
    });

    test('Sinclair — PPG and GALLONS/FUEL TOTAL both split across header/data rows', () {
      const receipt = '''
        SINCLAIR
        5905 NW 72ND ST
        KANSAS CITY MO
        Date 12/14/16
        Time 5:11 PM
        Auth 068113
        VISA
        Pump  Product  PPG
        05    UNLD     \$1.999
        Gallons  Fuel Total
        9.505    \$19.00
        Thank you
      ''';

      final result = ReceiptParser.parse(receipt);

      expect(result.gallons, 9.505);
      expect(result.pricePerGallon, 1.999);
      // "Fuel Total" is split from its value by a newline in this layout,
      // so it isn't label-matched — derived from gallons * price instead,
      // landing within a cent of the printed $19.00.
      expect(result.totalCost, closeTo(19.00, 0.01));
    });
  });
}