using Shogi.Contracts.Types;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Text.RegularExpressions;

namespace Shogi.Contracts.Api.Commands;

public partial class MovePieceCommand : IValidatableObject
{
	/// <summary>
	/// For serialization.
	/// </summary>
	public MovePieceCommand()
	{
		To = string.Empty;
	}

	/// <summary>
	/// Move a piece on the board.
	/// </summary>
	public MovePieceCommand(string from, string to, bool isPromotion)
	{
		From = from;
		To = to;
		IsPromotion = isPromotion;
	}

	/// <summary>
	/// Add a piece to the board from the hand.
	/// </summary>
	public MovePieceCommand(WhichPiece pieceFromHand, string to)
	{
		PieceFromHand = pieceFromHand;
		To = to;
	}

	/// <summary>
	/// Mutually exclusive with <see cref="From"/>.
	/// Set this property to indicate moving a piece from the hand onto the board.
	/// </summary>
	public WhichPiece? PieceFromHand { get; set; }

	/// <summary>
	/// Board position notation, like A3 or G1
	/// Mutually exclusive with <see cref="PieceFromHand"/>.
	/// Set this property to indicate moving a piece from the board to another position on the board.
	/// </summary>
	public string? From { get; set; }

	/// <summary>
	/// Board position notation, like A3 or G1
	/// </summary>
	[Required]
	public string To { get; set; }

	public bool? IsPromotion { get; set; }

	public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
	{
		if (PieceFromHand.HasValue && !string.IsNullOrWhiteSpace(From))
		{
			yield return new ValidationResult($"{nameof(PieceFromHand)} and {nameof(From)} are mutually exclusive properties.");
		}
		if (PieceFromHand.HasValue && IsPromotion.HasValue)
		{
			yield return new ValidationResult($"{nameof(PieceFromHand)} and {nameof(IsPromotion)} are mutually exclusive properties.");
		}
		if (!BoardNotationRegex().IsMatch(To))
		{
			yield return new ValidationResult($"{nameof(To)} must be a valid board position, between A1 and I9");
		}
		if (!string.IsNullOrEmpty(From) && !BoardNotationRegex().IsMatch(From))
		{
			yield return new ValidationResult($"{nameof(From)} must be a valid board position, between A1 and I9");
		}
	}

	[GeneratedRegex("[A-I][1-9]")]
	private static partial Regex BoardNotationRegex();
}