// Kyoo - A portable and vast media library solution.
// Copyright (c) Kyoo.
//
// See AUTHORS.md and LICENSE file in the project root for full license information.
//
// Kyoo is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// any later version.
//
// Kyoo is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Kyoo. If not, see <https://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Kyoo.Abstractions.Models.Permissions;
using NSwag;
using NSwag.Generation.Processors;
using NSwag.Generation.Processors.Contexts;

namespace Kyoo.Swagger;

/// <summary>
/// An operation processor that adds permissions information from the <see cref="PermissionAttribute"/> and the
/// <see cref="PartialPermissionAttribute"/>.
/// </summary>
public class OperationPermissionProcessor : IOperationProcessor
{
	/// <inheritdoc />
	public bool Process(OperationProcessorContext context)
	{
		context.OperationDescription.Operation.Security ??= new List<OpenApiSecurityRequirement>();
		OpenApiSecurityRequirement perms = context
			.MethodInfo.GetCustomAttributes<UserOnlyAttribute>()
			.Aggregate(
				new OpenApiSecurityRequirement(),
				(agg, _) =>
				{
					agg[nameof(Kyoo)] = Array.Empty<string>();
					return agg;
				}
			);

		perms = context
			.MethodInfo.GetCustomAttributes<PermissionAttribute>()
			.Aggregate(
				perms,
				(agg, cur) =>
				{
					ICollection<string> permissions = _GetPermissionsList(agg, cur.Group);
					permissions.Add($"{cur.Type}.{cur.Kind.ToString().ToLower()}");
					agg[nameof(Kyoo)] = permissions;
					return agg;
				}
			);

		PartialPermissionAttribute controller =
			context.ControllerType.GetCustomAttribute<PartialPermissionAttribute>();
		if (controller != null)
		{
			perms = context
				.MethodInfo.GetCustomAttributes<PartialPermissionAttribute>()
				.Aggregate(
					perms,
					(agg, cur) =>
					{
						Group? group =
							controller.Group != Group.Overall ? controller.Group : cur.Group;
						string type = controller.Type ?? cur.Type;
						Kind? kind = controller.Type == null ? controller.Kind : cur.Kind;
						ICollection<string> permissions = _GetPermissionsList(
							agg,
							group ?? Group.Overall
						);
						permissions.Add($"{type}.{kind!.Value.ToString().ToLower()}");
						agg[nameof(Kyoo)] = permissions;
						return agg;
					}
				);
		}

		context.OperationDescription.Operation.Security.Add(perms);
		return true;
	}

	private static ICollection<string> _GetPermissionsList(
		OpenApiSecurityRequirement security,
		Group group
	)
	{
		return security.TryGetValue(group.ToString(), out IEnumerable<string> perms)
			? perms.ToList()
			: new List<string>();
	}
}