// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;

namespace Microsoft.AspNetCore.Mvc.Filters
{
    /// <summary>
    /// A context for page filters, used specifically in 
    /// <see cref="IPageFilter.OnPageHandlerExecuting(PageHandlerExecutingContext)"/> and 
    /// <see cref="IAsyncPageFilter.OnPageHandlerExecutionAsync(PageHandlerExecutingContext, PageHandlerExecutionDelegate)"/>.
    /// </summary>
    public class PageHandlerExecutingContext : FilterContext
    {
        /// <summary>
        /// Creates a new instance of <see cref="PageHandlerExecutingContext"/>.
        /// </summary>
        /// <param name="pageContext">The <see cref="PageContext"/> associated with the current request.</param>
        /// <param name="filters">The set of filters associated with the page.</param>
        /// <param name="handlerMethod">The handler method to be invoked, may be null.</param>
        /// <param name="handlerArguments">The arguments to provide to the handler method.</param>
        /// <param name="handlerInstance">The handler instance associated with the page.</param>
        public PageHandlerExecutingContext(
            PageContext pageContext,
            IList<IFilterMetadata> filters,
            HandlerMethodDescriptor handlerMethod,
            IDictionary<string, object> handlerArguments,
            object handlerInstance)
            : base(pageContext, filters)
        {
            if (handlerArguments == null)
            {
                throw new ArgumentNullException(nameof(handlerArguments));
            }

            if (handlerInstance == null)
            {
                throw new ArgumentNullException(nameof(handlerInstance));
            }

            HandlerMethod = handlerMethod;
            HandlerArguments = handlerArguments;
            HandlerInstance = handlerInstance;
        }

        /// <summary>
        /// Gets the descriptor associated with the current page.
        /// </summary>
        public new virtual CompiledPageActionDescriptor ActionDescriptor => 
            (CompiledPageActionDescriptor)base.ActionDescriptor;

        /// <summary>
        /// Gets or sets the <see cref="IActionResult"/> to execute. Setting <see cref="Result"/> to a non-<c>null</c>
        /// value inside a page filter will short-circuit the page and any remaining page filters.
        /// </summary>
        public virtual IActionResult Result { get; set; }

        /// <summary>
        /// Gets the arguments to pass when invoking the handler method. Keys are parameter names.
        /// </summary>
        public virtual IDictionary<string, object> HandlerArguments { get; }

        /// <summary>
        /// Gets the descriptor for the handler method about to be invoked.
        /// </summary>
        public virtual HandlerMethodDescriptor HandlerMethod { get; }

        /// <summary>
        /// Gets the object instance containing the handler method.
        /// </summary>
        public virtual object HandlerInstance { get; }
    }
}