using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace MoneyMap.Models;

[Index(nameof(Date), nameof(Amount), nameof(Name), nameof(Memo), nameof(AccountId), nameof(CardId), IsUnique = true)]
public class Transaction
{
    [Key]
    public long Id { get; set; }

    [Required]
    public DateTime Date { get; set; }

    [MaxLength(20)]
    public string TransactionType { get; set; } = string.Empty; // "DEBIT"/"CREDIT" if present

    [MaxLength(200)]
    public string Name { get; set; } = string.Empty;

    [MaxLength(500)]
    public string Memo { get; set; } = string.Empty;

    [Column(TypeName = "decimal(18,2)")]
    public decimal Amount { get; set; } // negative = debit, positive = credit

    [MaxLength(100)]
    public string Category { get; set; } = string.Empty;

    // Merchant relationship
    [ForeignKey(nameof(Merchant))]
    public int? MerchantId { get; set; }
    public Merchant? Merchant { get; set; }

    public string Notes { get; set; } = string.Empty;

    // Primary container: Every transaction belongs to an Account (the source of CSV)
    [Required]
    [ForeignKey(nameof(Account))]
    public int AccountId { get; set; }
    public Account Account { get; set; } = null!;

    // Optional: Card used for this transaction (if it was a card payment)
    [ForeignKey(nameof(Card))]
    public int? CardId { get; set; }
    public Card? Card { get; set; }

    // Optional: For transfers between accounts, this links to the destination account
    // This transaction is the "source" side of the transfer (debit)
    // The matching transaction in the destination account has this AccountId as its TransferToAccountId
    [ForeignKey(nameof(TransferToAccount))]
    public int? TransferToAccountId { get; set; }
    public Account? TransferToAccount { get; set; }

    [MaxLength(4)]
    public string? Last4 { get; set; } // parsed from Memo if present

    public ICollection<Receipt> Receipts { get; set; } = new List<Receipt>();

    [NotMapped] public bool IsCredit => Amount > 0;
    [NotMapped] public bool IsDebit => Amount < 0;
    [NotMapped] public bool IsTransfer => TransferToAccountId.HasValue;

    [NotMapped]
    public string PaymentMethodLabel
    {
        get
        {
            // Handle transfers
            if (IsTransfer)
            {
                var toLabel = TransferToAccount?.DisplayLabel ?? "Unknown";
                return $"Transfer → {toLabel}";
            }

            // If card was used, show just the card (since account is implied)
            if (Card != null)
                return Card.DisplayLabel;

            // Direct account transaction (no card)
            return Account?.DisplayLabel ?? $"···· {Last4}";
        }
    }
}