// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Server.ProtectedBrowserStorage;
 
namespace Aspire.Dashboard.Components.Pages;
 
/// <summary>
/// Represents a page that can contain state both in the url and in localstorage.
/// Navigating back to the page will restore the previous page state
/// </summary>
/// <typeparam name="TViewModel">The view model containing live state</typeparam>
/// <typeparam name="TSerializableViewModel">A serializable version of <typeparamref name="TViewModel"/> that will be saved in session storage and restored from</typeparam>
public interface IPageWithSessionAndUrlState<TViewModel, TSerializableViewModel>
    where TSerializableViewModel : class
{
    /// <summary>
    /// The base relative path of the page (ie, Metrics for /Metrics)
    /// </summary>
    public string BasePath { get; }
 
    /// <summary>
    /// The key to save page state to
    /// </summary>
    public string SessionStorageKey { get; }
 
    public NavigationManager NavigationManager { get; }
    public ProtectedSessionStorage SessionStorage { get; }
 
    /// <summary>
    /// The view model containing live state, to be instantiated in OnInitialized.
    /// </summary>
    public TViewModel PageViewModel { get; set; }
 
    /// <summary>
    /// Computes the initial view model state based on query param values
    /// </summary>
    public void UpdateViewModelFromQuery(TViewModel viewModel);
 
    /// <summary>
    /// Translates the <param name="serializable">serializable form of the view model</param> to a relative URL associated
    /// with that state
    /// </summary>
    public string GetUrlFromSerializableViewModel(TSerializableViewModel serializable);
 
    /// <summary>
    /// Maps <typeparamref name="TViewModel"/> to <typeparamref name="TSerializableViewModel"/>, which should contain simple types.
    /// </summary>
    public TSerializableViewModel ConvertViewModelToSerializable();
}
 
public static class PageExtensions
{
    /// <summary>
    /// Called after a change in the view model that will affect the url associated with new page state
    /// to navigate to the new url and save new state in localstorage.
    /// </summary>
    public static async Task AfterViewModelChangedAsync<TViewModel, TSerializableViewModel>(this IPageWithSessionAndUrlState<TViewModel, TSerializableViewModel> page) where TSerializableViewModel : class
    {
        var serializableViewModel = page.ConvertViewModelToSerializable();
        var pathWithParameters = page.GetUrlFromSerializableViewModel(serializableViewModel).ToString();
 
        page.NavigationManager.NavigateTo(pathWithParameters);
        await page.SessionStorage.SetAsync(page.SessionStorageKey, serializableViewModel).ConfigureAwait(false);
    }
 
    public static async Task InitializeViewModelAsync<TViewModel, TSerializableViewModel>(this IPageWithSessionAndUrlState<TViewModel, TSerializableViewModel> page) where TSerializableViewModel : class
    {
        if (string.Equals(page.BasePath, page.NavigationManager.ToBaseRelativePath(page.NavigationManager.Uri)))
        {
            var result = await page.SessionStorage.GetAsync<TSerializableViewModel>(page.SessionStorageKey).ConfigureAwait(false);
            if (result is { Success: true, Value: not null })
            {
                var newUrl = page.GetUrlFromSerializableViewModel(result.Value).ToString();
 
                // Don't navigate if the URL redirects to itself.
                if (newUrl != "/" + page.BasePath)
                {
                    page.NavigationManager.NavigateTo(newUrl);
                    return;
                }
            }
        }
 
        ArgumentNullException.ThrowIfNull(page.PageViewModel, nameof(page.PageViewModel));
        page.UpdateViewModelFromQuery(page.PageViewModel);
    }
}