namespace Prefab.Web.Client.Models.Shared;

using System.Collections.Generic;
using System.Linq;
using System.Net;
using FluentValidation;

public sealed class ResultProblem 
{
    public string? Title { get; init; }

    public string? Detail { get; init; }

    public int? StatusCode { get; init; }

    public IReadOnlyDictionary<string, string[]>? Errors { get; init; }

    public static ResultProblem FromValidation(ValidationException exception)
    {
        var errors = exception.Errors
            .GroupBy(error => string.IsNullOrWhiteSpace(error.PropertyName) ? string.Empty : error.PropertyName)
            .ToDictionary(
                group => group.Key,
                group => group.Select(error => error.ErrorMessage ?? string.Empty).ToArray());

        return new ResultProblem
        {
            Title = "Validation failed.",
            Detail = "Request did not satisfy validation rules.",
            StatusCode = (int)HttpStatusCode.BadRequest,
            Errors = errors
        };
    }

    public static ResultProblem Unexpected(string title, Exception exception, HttpStatusCode statusCode = HttpStatusCode.InternalServerError) =>
        new()
        {
            Title = title,
            Detail = exception.Message,
            StatusCode = (int)statusCode
        };
}

/// <summary>
/// Represents the outcome of an operation that produces a value of type <typeparamref name="T"/>.
/// </summary>
/// <typeparam name="T">The payload type returned when the operation succeeds.</typeparam>
public sealed class Result<T>
{
    public Result()
    {
    }

    public bool IsSuccess => Problem is null;

    public ResultProblem? Problem { get; init; }

    public int? StatusCode => Problem?.StatusCode;

    public T? Value { get; init; }

    public static Result<T> Success(T value) => new()
    {
        Value = value ?? throw new ArgumentNullException(nameof(value))
    };

    public static Result<T> Failure(ResultProblem problem) => new()
    {
        Problem = problem ?? throw new ArgumentNullException(nameof(problem))
    };
}