using FluentValidation;
using GermanApp.Application.DTOs;

namespace GermanApp.Presentation.Validators;

/// <summary>
/// Validator for CreateLevelDto.
/// Validates input when creating a new CEFR level.
/// </summary>
public class CreateLevelValidator : AbstractValidator<CreateLevelDto>
{
    public CreateLevelValidator()
    {
        RuleFor(x => x.Name)
            .NotEmpty().WithMessage("Level name is required.")
            .MinimumLength(2).WithMessage("Level name must be at least 2 characters long.")
            .MaximumLength(100).WithMessage("Level name must not exceed 100 characters.");

        RuleFor(x => x.Code)
            .NotEmpty().WithMessage("Level code is required.")
            .MinimumLength(1).WithMessage("Level code must be at least 1 character long.")
            .MaximumLength(10).WithMessage("Level code must not exceed 10 characters.")
            .Matches("^[A-Za-z][A-Za-z0-9]*$").WithMessage("Level code must start with a letter and contain only letters and numbers.")
            .Must(BeValidCefrCode).WithMessage("Level code must be a valid CEFR code (A1, A2, B1, B2, C1, C2).");

        RuleFor(x => x.Order)
            .GreaterThan(0).WithMessage("Order must be greater than 0.")
            .LessThanOrEqualTo(100).WithMessage("Order must not exceed 100.");
    }

    private static bool BeValidCefrCode(string code)
    {
        // Normalize to uppercase for comparison
        var upperCode = code.ToUpperInvariant();
        
        // Valid CEFR levels
        var validCodes = new[] { "A1", "A2", "B1", "B2", "C1", "C2" };
        
        return validCodes.Contains(upperCode);
    }
}

/// <summary>
/// Validator for UpdateLevelDto.
/// Validates input when updating an existing CEFR level.
/// </summary>
public class UpdateLevelValidator : AbstractValidator<UpdateLevelDto>
{
    public UpdateLevelValidator()
    {
        RuleFor(x => x.Name)
            .NotEmpty().WithMessage("Level name is required.")
            .MinimumLength(2).WithMessage("Level name must be at least 2 characters long.")
            .MaximumLength(100).WithMessage("Level name must not exceed 100 characters.");

        RuleFor(x => x.Code)
            .NotEmpty().WithMessage("Level code is required.")
            .MinimumLength(1).WithMessage("Level code must be at least 1 character long.")
            .MaximumLength(10).WithMessage("Level code must not exceed 10 characters.")
            .Matches("^[A-Za-z][A-Za-z0-9]*$").WithMessage("Level code must start with a letter and contain only letters and numbers.")
            .Must(BeValidCefrCode).WithMessage("Level code must be a valid CEFR code (A1, A2, B1, B2, C1, C2).");

        RuleFor(x => x.Order)
            .GreaterThan(0).WithMessage("Order must be greater than 0.")
            .LessThanOrEqualTo(100).WithMessage("Order must not exceed 100.");
    }

    private static bool BeValidCefrCode(string code)
    {
        // Normalize to uppercase for comparison
        var upperCode = code.ToUpperInvariant();
        
        // Valid CEFR levels
        var validCodes = new[] { "A1", "A2", "B1", "B2", "C1", "C2" };
        
        return validCodes.Contains(upperCode);
    }
}