MoneyMap/MoneyMap/Pages/CategoryMappings.cshtml.cs

using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.EntityFrameworkCore;
using MoneyMap.Data;
using MoneyMap.Services;

namespace MoneyMap.Pages
{
    public class CategoryMappingsModel : PageModel
    {
        private readonly MoneyMapContext _db;
        private readonly ITransactionCategorizer _categorizer;

        public CategoryMappingsModel(MoneyMapContext db, ITransactionCategorizer categorizer)
        {
            _db = db;
            _categorizer = categorizer;
        }

        public List<CategoryGroup> CategoryGroups { get; set; } = new();
        public int TotalMappings { get; set; }
        public int TotalCategories { get; set; }

        [TempData]
        public string? SuccessMessage { get; set; }

        [TempData]
        public string? ErrorMessage { get; set; }

        public async Task OnGetAsync()
        {
            await LoadDataAsync();
        }

        public async Task<IActionResult> OnPostSeedDefaultsAsync()
        {
            await _categorizer.SeedDefaultMappingsAsync();
            SuccessMessage = "Default category mappings loaded successfully!";
            return RedirectToPage();
        }

        public async Task<IActionResult> OnPostAddMappingAsync(AddMappingModel model)
        {
            if (!ModelState.IsValid)
            {
                ErrorMessage = "Please fill in all required fields.";
                await LoadDataAsync();
                return Page();
            }

            var mapping = new CategoryMapping
            {
                Category = model.Category.Trim(),
                Pattern = model.Pattern.Trim(),
                Merchant = string.IsNullOrWhiteSpace(model.Merchant) ? null : model.Merchant.Trim(),
                Priority = model.Priority
            };

            _db.CategoryMappings.Add(mapping);
            await _db.SaveChangesAsync();

            SuccessMessage = $"Added pattern '{mapping.Pattern}' to category '{mapping.Category}'.";
            return RedirectToPage();
        }

        public async Task<IActionResult> OnPostUpdateMappingAsync(UpdateMappingModel model)
        {
            if (!ModelState.IsValid)
            {
                ErrorMessage = "Please fill in all required fields.";
                await LoadDataAsync();
                return Page();
            }

            var mapping = await _db.CategoryMappings.FindAsync(model.Id);
            if (mapping == null)
            {
                ErrorMessage = "Mapping not found.";
                return RedirectToPage();
            }

            mapping.Category = model.Category.Trim();
            mapping.Pattern = model.Pattern.Trim();
            mapping.Merchant = string.IsNullOrWhiteSpace(model.Merchant) ? null : model.Merchant.Trim();
            mapping.Priority = model.Priority;

            await _db.SaveChangesAsync();

            SuccessMessage = "Mapping updated successfully.";
            return RedirectToPage();
        }

        public async Task<IActionResult> OnPostDeleteMappingAsync(int id)
        {
            var mapping = await _db.CategoryMappings.FindAsync(id);
            if (mapping == null)
            {
                ErrorMessage = "Mapping not found.";
                return RedirectToPage();
            }

            _db.CategoryMappings.Remove(mapping);
            await _db.SaveChangesAsync();

            SuccessMessage = "Mapping deleted successfully.";
            return RedirectToPage();
        }

        public async Task<IActionResult> OnGetExportAsync()
        {
            var mappings = await _db.CategoryMappings
                .OrderBy(m => m.Category)
                .ThenByDescending(m => m.Priority)
                .ToListAsync();

            var exportData = mappings.Select(m => new CategoryMappingExport
            {
                Category = m.Category,
                Pattern = m.Pattern,
                Merchant = m.Merchant,
                Priority = m.Priority
            }).ToList();

            var json = JsonSerializer.Serialize(exportData, new JsonSerializerOptions
            {
                WriteIndented = true
            });

            var bytes = Encoding.UTF8.GetBytes(json);
            return File(bytes, "application/json", "category-mappings.json");
        }

        public async Task<IActionResult> OnPostImportAsync(IFormFile jsonFile, bool replaceExisting)
        {
            if (jsonFile == null || jsonFile.Length == 0)
            {
                ErrorMessage = "Please select a JSON file to import.";
                return RedirectToPage();
            }

            try
            {
                using var stream = jsonFile.OpenReadStream();
                var importData = await JsonSerializer.DeserializeAsync<List<CategoryMappingExport>>(stream, new JsonSerializerOptions
                {
                    PropertyNameCaseInsensitive = true
                });

                if (importData == null || !importData.Any())
                {
                    ErrorMessage = "No category mappings found in the file.";
                    return RedirectToPage();
                }

                // Validate the data
                foreach (var item in importData)
                {
                    if (string.IsNullOrWhiteSpace(item.Category) || string.IsNullOrWhiteSpace(item.Pattern))
                    {
                        ErrorMessage = "Invalid data in JSON file. Each mapping must have a category and pattern.";
                        return RedirectToPage();
                    }
                }

                // Replace existing or merge
                if (replaceExisting)
                {
                    var existingMappings = await _db.CategoryMappings.ToListAsync();
                    _db.CategoryMappings.RemoveRange(existingMappings);
                }

                // Add new mappings
                var newMappings = importData.Select(m => new CategoryMapping
                {
                    Category = m.Category.Trim(),
                    Pattern = m.Pattern.Trim(),
                    Merchant = string.IsNullOrWhiteSpace(m.Merchant) ? null : m.Merchant.Trim(),
                    Priority = m.Priority
                }).ToList();

                _db.CategoryMappings.AddRange(newMappings);
                await _db.SaveChangesAsync();

                SuccessMessage = replaceExisting
                    ? $"Successfully replaced all mappings with {importData.Count} mappings from file."
                    : $"Successfully imported {importData.Count} mappings from file.";

                return RedirectToPage();
            }
            catch (JsonException)
            {
                ErrorMessage = "Invalid JSON file format. Please check the file and try again.";
                return RedirectToPage();
            }
            catch (Exception ex)
            {
                ErrorMessage = $"Error importing file: {ex.Message}";
                return RedirectToPage();
            }
        }

        private async Task LoadDataAsync()
        {
            var mappings = await _categorizer.GetAllMappingsAsync();

            CategoryGroups = mappings
                .GroupBy(m => m.Category)
                .Select(g => new CategoryGroup
                {
                    Category = g.Key,
                    Mappings = g.OrderByDescending(m => m.Priority).ToList(),
                    Count = g.Count()
                })
                .OrderBy(g => g.Category)
                .ToList();

            TotalMappings = mappings.Count;
            TotalCategories = CategoryGroups.Count;
        }

        public class CategoryGroup
        {
            public required string Category { get; set; }
            public required List<CategoryMapping> Mappings { get; set; }
            public int Count { get; set; }
        }

        public class AddMappingModel
        {
            [Required(ErrorMessage = "Category is required")]
            [StringLength(100)]
            public string Category { get; set; } = "";

            [StringLength(100)]
            public string? Merchant { get; set; }

            [Required(ErrorMessage = "Pattern is required")]
            [StringLength(200)]
            public string Pattern { get; set; } = "";

            public int Priority { get; set; } = 0;
        }

        public class UpdateMappingModel
        {
            [Required]
            public int Id { get; set; }

            [Required(ErrorMessage = "Category is required")]
            [StringLength(100)]
            public string Category { get; set; } = "";

            [StringLength(100)]
            public string? Merchant { get; set; }

            [Required(ErrorMessage = "Pattern is required")]
            [StringLength(200)]
            public string Pattern { get; set; } = "";

            public int Priority { get; set; } = 0;
        }

        public class CategoryMappingExport
        {
            public string Category { get; set; } = "";
            public string Pattern { get; set; } = "";
            public string? Merchant { get; set; }
            public int Priority { get; set; } = 0;
        }
    }
}