using Microsoft.EntityFrameworkCore;
using MoneyMap.Data;
using MoneyMap.Models;

namespace MoneyMap.Services;

/// <summary>
/// Service for retrieving reference/lookup data used in dropdowns and filters.
/// </summary>
public interface IReferenceDataService
{
    /// <summary>
    /// Gets all distinct categories from transactions, sorted alphabetically.
    /// </summary>
    Task<List<string>> GetAvailableCategoriesAsync();

    /// <summary>
    /// Gets all merchants, sorted by name.
    /// </summary>
    Task<List<Merchant>> GetAvailableMerchantsAsync();

    /// <summary>
    /// Gets all cards with optional account information included.
    /// </summary>
    Task<List<Card>> GetAvailableCardsAsync(bool includeAccount = true);

    /// <summary>
    /// Gets all accounts, sorted by institution and last4.
    /// </summary>
    Task<List<Account>> GetAvailableAccountsAsync();
}

public class ReferenceDataService : IReferenceDataService
{
    private readonly MoneyMapContext _db;

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

    public async Task<List<string>> GetAvailableCategoriesAsync()
    {
        return await _db.Transactions
            .Select(t => t.Category ?? "")
            .Where(c => !string.IsNullOrWhiteSpace(c))
            .Distinct()
            .OrderBy(c => c)
            .ToListAsync();
    }

    public async Task<List<Merchant>> GetAvailableMerchantsAsync()
    {
        return await _db.Merchants
            .OrderBy(m => m.Name)
            .ToListAsync();
    }

    public async Task<List<Card>> GetAvailableCardsAsync(bool includeAccount = true)
    {
        var query = _db.Cards.AsQueryable();

        if (includeAccount)
        {
            query = query.Include(c => c.Account);
        }

        return await query
            .OrderBy(c => c.Owner)
            .ThenBy(c => c.Last4)
            .ToListAsync();
    }

    public async Task<List<Account>> GetAvailableAccountsAsync()
    {
        return await _db.Accounts
            .OrderBy(a => a.Institution)
            .ThenBy(a => a.Last4)
            .ToListAsync();
    }
}