MoneyMap/MoneyMap/Services/TransactionCategorizer.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using MoneyMap.Data;

namespace MoneyMap.Services
{
    // ===== Models =====

    public class CategoryMapping
    {
        public int Id { get; set; }
        public required string Category { get; set; }
        public required string Pattern { get; set; }
        public int Priority { get; set; } = 0; // Higher priority = checked first

        // Merchant relationship
        public int? MerchantId { get; set; }
        public Models.Merchant? Merchant { get; set; }
    }

    // ===== Service Interface =====

    public interface ITransactionCategorizer
    {
        Task<CategorizationResult> CategorizeAsync(string merchantName, decimal? amount = null);
        Task<List<CategoryMapping>> GetAllMappingsAsync();
        Task SeedDefaultMappingsAsync();
    }

    public class CategorizationResult
    {
        public string Category { get; set; } = string.Empty;
        public int? MerchantId { get; set; }
    }

    // ===== Service Implementation =====

    public class TransactionCategorizer : ITransactionCategorizer
    {
        private readonly MoneyMapContext _db;
        private const decimal GasStationThreshold = -20m;

        public TransactionCategorizer(MoneyMapContext db)
        {
            _db = db;
        }

        public async Task<CategorizationResult> CategorizeAsync(string merchantName, decimal? amount = null)
        {
            if (string.IsNullOrWhiteSpace(merchantName))
                return new CategorizationResult();

            var merchantUpper = merchantName.ToUpperInvariant();

            // Get all mappings ordered by priority
            var mappings = await _db.CategoryMappings
                .OrderByDescending(m => m.Priority)
                .ThenBy(m => m.Category)
                .ToListAsync();

            // Special case: Gas stations with small purchases
            if (amount.HasValue && amount.Value > GasStationThreshold)
            {
                var gasMapping = mappings.FirstOrDefault(m =>
                    m.Category == "Gas & Auto" &&
                    merchantUpper.Contains(m.Pattern.ToUpperInvariant()));

                if (gasMapping != null)
                    return new CategorizationResult
                    {
                        Category = "Convenience Store",
                        MerchantId = gasMapping.MerchantId
                    };
            }

            // Check each category's patterns
            foreach (var mapping in mappings)
            {
                if (merchantUpper.Contains(mapping.Pattern.ToUpperInvariant()))
                    return new CategorizationResult
                    {
                        Category = mapping.Category,
                        MerchantId = mapping.MerchantId
                    };
            }

            return new CategorizationResult(); // No match - needs manual categorization
        }

        public async Task<List<CategoryMapping>> GetAllMappingsAsync()
        {
            return await _db.CategoryMappings
                .OrderBy(m => m.Category)
                .ThenByDescending(m => m.Priority)
                .ToListAsync();
        }

        public async Task SeedDefaultMappingsAsync()
        {
            // Check if mappings already exist
            if (await _db.CategoryMappings.AnyAsync())
                return;

            var defaultMappings = GetDefaultMappings();

            _db.CategoryMappings.AddRange(defaultMappings);
            await _db.SaveChangesAsync();
        }

        private static List<CategoryMapping> GetDefaultMappings()
        {
            var mappings = new List<CategoryMapping>();

            // Online Shopping
            AddMappings("Online shopping", mappings,
                "AMAZON MKTPL", "AMAZON.COM", "BATHANDBODYWORKS", "BATH AND BODY",
                "SEPHORA.COM", "ULTA.COM", "WWW.KOHLS.COM", "GAPOUTLET.COM",
                "NIKE.COM", "HOMEDEPOT.COM", "TEMU.COM", "APPLE.COM",
                "JOURNEYS.COM", "DECKERS*UGG", "YUNNANSOURCINGUS", "TARGET.COM");

            // Walmart
            AddMappings("Walmart Online", mappings, "WALMART.COM");
            AddMappings("Walmart Pickup/Grocery", mappings, "WALMART.C ", "DEBIT PURCHASE WALMART.C");

            // Pizza
            AddMappings("Pizza", mappings,
                "CHICAGOS PIZZA", "PIZZA KING", "DOMINO", "BIG BOYZ",
                "PAPA JOHN", "PIZZA 3.14", "HUNGRY HOWIES");

            // Retail Stores
            AddMappings("Brick/mortar store", mappings,
                "DOLLAR-GENERAL", "DOLLAR GENERAL", "DOLLAR TREE", "GOODWILL STORE",
                "WAL-MART", "WM SUPERCENTER", "KROGER", "TARGET", "LOWES",
                "GILLMAN HOME CEN", "TRACTOR SUPPLY", "FIVE BELOW", "CLAIRE'S", "SAVE-A-LOT");

            // Restaurants
            AddMappings("Eat out / Restaurants", mappings,
                "KUNKELS DRIVE IN", "MCDONALD", "STARBUCKS", "ASIAN DELIGHT",
                "STACKS PANCAKE", "WENDY", "SUBWAY", "OLIVE GARDEN", "CRACKER BARREL",
                "RED LOBSTER", "NO. 9 GRILL", "LEES FAMOUS", "OLE ROOSTE",
                "EL CABALLO", "WAFFLE HOUSE", "GULF COAST BURG", "LAKEVIEW RESTAUR",
                "ARBY", "BURGER KING", "DAIRY QUEEN", "TACO BELL", "DUNKIN", "CRUMBL");

            // School
            AddMappings("School", mappings,
                "INTER-STATE STUD", "CREATIVE STEPS", "CPP*CONNERSVILLE");

            // Health
            AddMappings("Health", mappings,
                "MEDICENTER", "REID HEALTH", "PHARMACY", "CVS", "WALGREENS",
                "WHITEWATER EYE", "GIESTING FAMILY DENTIS");

            // Gas & Auto (higher priority for special handling)
            AddMappings("Gas & Auto", mappings, 100,
                "SPEEDWAY", "MARATHON", "SHELL OIL", "BP#", "SUNOCO",
                "WASH & LU", "WASH  LUB", "CAR WASH", "MCDIVITT FAR",
                "COUNTY TIRE", "BROOKVILLE SHELL", "BUC-EE'S", "CIRCLE K", "MAIN STREET QUIC");

            // Utilities
            AddMappings("Utilities/Services", mappings,
                "SMARTSTOP", "VZWRLSS", "VERIZON", "COMCAST", "XFINIT",
                "US MOBILE", "WHITEWATER VALLE", "RUMPKE");

            // Entertainment
            AddMappings("Entertainment", mappings,
                "SHOWTIME CINEMA", "SHOWPLACE CINEMA", "RICHMOND CIV", "KINDLE",
                "GOOGLE *Google S", "NINTENDO", "HLU*HULU", "HULU", "NETFLIX",
                "SPOTIFY", "STEAMGAMES", "WL *STEAM PURCHASE", "ETSY", "GEEK-HUB");

            // Banking (high priority to catch these first)
            AddMappings("Banking", mappings, 200,
                "ATM WITHDRAWAL", "ATM FEE", "MOBILE BANKING ADVANCE",
                "MOBILE BANKING PAYMENT", "MOBILE BANKING TRANSFER", "OVERDRAFT",
                "MONTHLY MAINTENANCE FEE", "OD PROTECTION", "RESERVE LINE",
                "FRGN TRANS FEE", "START SCHEDULED TRANSFER");

            // Mortgage
            AddMappings("Mortgage", mappings, "WAYNE BANK");

            // Car Payment
            AddMappings("Car Payment", mappings, "UNION SAVINGS AN");

            // Convenience Store
            AddMappings("Convenience Store", mappings,
                "PAVEYS COUNTRY", "CAMBRIDGE CITY M", "WHITEWATER QUICK");

            // Income (high priority)
            AddMappings("Income", mappings, 200,
                "MOBILE CHECK DEPOSIT", "ELECTRONIC DEPOSIT", "IRS  TREAS",
                "RPA PA", "REWARDS REDEEMED");

            // Taxes
            AddMappings("Taxes", mappings, "MYERS INCOME TAX");

            // Insurance
            AddMappings("Insurance", mappings,
                "BOSTON MUTUAL", "IND FARMERS INS", "GERBER LIFE INS");

            // Credit Card Payment (high priority to catch before Banking)
            AddMappings("Credit Card Payment", mappings, 200,
                "PAYMENT TO CREDIT CARD", "CAPITAL ONE", "MOBILE PAYMENT THANK YOU");

            // Ice Cream
            AddMappings("Ice Cream / Treats", mappings, "DAIRY TWIST", "URANUS FUDGE");

            // Government
            AddMappings("Government/DMV", mappings, "IN BMV", "KY-IN RIVERLINK");

            // Home Services
            AddMappings("Home Services", mappings, "DUNGAN PLUMBING");

            // Special Occasions
            AddMappings("Special Occasions", mappings,
                "CLARKS FLOWER", "THE CAKE BAK", "DOUGHERTY OR");

            // Home Improvement
            AddMappings("Home Improvement", mappings,
                "SHERWIN-WILLIAMS", "PAINTERS SUPPLY", "MENARDS", "LOWES #00907",
                "123FILTER", "O-RING STORE");

            // Software/Subscriptions
            AddMappings("Software/Subscriptions", mappings,
                "GOOGLE *ChatGPT", "CLAUDE.AI", "OPENAI", "NAME-CHEAP",
                "AMAZON PRIME*", "BITWARDEN", "GOOGLE *Shopping List");

            return mappings;
        }

        private static void AddMappings(string category, List<CategoryMapping> mappings, params string[] patterns)
        {
            AddMappings(category, mappings, 0, patterns);
        }

        private static void AddMappings(string category, List<CategoryMapping> mappings, int priority, params string[] patterns)
        {
            foreach (var pattern in patterns)
            {
                mappings.Add(new CategoryMapping
                {
                    Category = category,
                    Pattern = pattern,
                    MerchantId = null, // Will be set by users via UI
                    Priority = priority
                });
            }
        }
    }

    // ===== Database Migration =====
    // Add this to your DbContext:
    // public DbSet<CategoryMapping> CategoryMappings { get; set; }
    //
    // Then create a migration:
    // dotnet ef migrations add AddCategoryMappings
    // dotnet ef database update
}