using FluentValidation;
using FluentValidation.Results;
using FluentValidation.Validators;
using Serilog.Events;

namespace Recyclarr.Common.FluentValidation;

public static class FluentValidationExtensions
{
    // From: https://github.com/FluentValidation/FluentValidation/issues/1648
    // ReSharper disable once UnusedMethodReturnValue.Global
    public static IRuleBuilderOptions<T, TProperty?> SetNonNullableValidator<T, TProperty>(
        this IRuleBuilder<T, TProperty?> ruleBuilder,
        IValidator<TProperty> validator,
        params string[] ruleSets)
    {
        var adapter = new ChildValidatorAdaptor<T, TProperty?>(validator!, validator.GetType())
        {
            RuleSets = ruleSets
        };

        return ruleBuilder.SetAsyncValidator(adapter);
    }

    // ReSharper disable once UnusedMethodReturnValue.Global
    public static IRuleBuilderOptions<T, TProperty?> SetNonNullableValidator<T, TProperty, TValidator>(
        this IRuleBuilder<T, TProperty?> ruleBuilder,
        Func<T, TValidator> validatorProvider,
        params string[] ruleSets)
        where TValidator : IValidator<TProperty>
    {
        var adapter = new ChildValidatorAdaptor<T, TProperty?>(
            (context, _) => validatorProvider(context.InstanceToValidate), typeof(TValidator))
        {
            RuleSets = ruleSets
        };

        return ruleBuilder.SetAsyncValidator(adapter);
    }

    public static IEnumerable<TSource> IsValid<TSource, TValidator>(
        this IEnumerable<TSource> source,
        TValidator validator,
        Action<IReadOnlyCollection<ValidationFailure>, TSource>? handleInvalid = null)
        where TValidator : IValidator<TSource>
    {
        foreach (var s in source)
        {
            var result = validator.Validate(s);
            if (result is {IsValid: true})
            {
                yield return s;
            }
            else
            {
                handleInvalid?.Invoke(result.Errors, s);
            }
        }
    }

    public static LogEventLevel ToLogLevel(this Severity severity)
    {
        return severity switch
        {
            Severity.Error => LogEventLevel.Error,
            Severity.Warning => LogEventLevel.Warning,
            Severity.Info => LogEventLevel.Information,
            _ => LogEventLevel.Debug
        };
    }

    public static int LogValidationErrors(
        this IReadOnlyCollection<ValidationFailure> errors,
        ILogger log,
        string errorPrefix)
    {
        var numErrors = 0;

        foreach (var (error, level) in errors.Select(x => (x, x.Severity.ToLogLevel())))
        {
            if (level == LogEventLevel.Error)
            {
                ++numErrors;
            }

            log.Write(level, "{ErrorPrefix}: {Msg}", errorPrefix, error.ErrorMessage);
        }

        return numErrors;
    }
}