using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.ApplicationModels;
using Microsoft.AspNetCore.Mvc.Infrastructure;

namespace MAX.Framework.Conventions;

/// <summary>为 API 控制器的属性路由统一添加 api 前缀，已含前缀的路由保持不变。</summary>
public sealed class ApiRoutePrefixConvention : IApplicationModelConvention
{
    public void Apply(ApplicationModel application)
    {
        foreach (var controller in application.Controllers)
        {
            if (!controller.Attributes.OfType<IApiBehaviorMetadata>().Any()
                && !controller.ControllerType.Assembly.IsDefined(typeof(ApiControllerAttribute), true))
            {
                continue;
            }

            var hasControllerRoute = controller.Selectors.Any(selector => selector.AttributeRouteModel != null);
            foreach (var selector in controller.Selectors)
            {
                if (selector.AttributeRouteModel is { } route)
                {
                    AddPrefix(route);
                }
            }

            foreach (var action in controller.Actions)
            foreach (var selector in action.Selectors)
            {
                // 绝对动作路由会覆盖控制器路由，因此需要单独添加前缀。
                if (selector.AttributeRouteModel is { } route
                    && (!hasControllerRoute || route.IsAbsoluteTemplate))
                {
                    AddPrefix(route);
                }
            }
        }
    }

    private static void AddPrefix(AttributeRouteModel route)
    {
        var template = route.Template ?? "";
        var absolute = route.IsAbsoluteTemplate;
        template = template.StartsWith("~/", StringComparison.Ordinal) ? template[2..] : template.TrimStart('/');
        if (!template.Equals("api", StringComparison.OrdinalIgnoreCase)
            && !template.StartsWith("api/", StringComparison.OrdinalIgnoreCase))
        {
            template = string.IsNullOrEmpty(template) ? "api" : $"api/{template}";
        }

        route.Template = absolute ? $"~/{template}" : template;
    }
}