CollapsibleNavMenu/Blazor_Server/Components/Layout/NavMenu.razor

@inject IJSRuntime JSRuntime

<div class="top-row ps-3 navbar navbar-dark">
    <div class="container-fluid">
        @if (!IconMenuActive)
        {
            <a class="navbar-brand" href="">Blazor Server</a>
        }
        else
        {
            <a class="navbar-brand bi bi-window-fullscreen" />
        }
        <button title="Navigation menu" class="navbar-toggler" @onclick="ToggleNavMenu">
            <span class="navbar-toggler-icon"></span>
        </button>
    </div>
</div>

<div class="@NavMenuCssClass">
    <nav class="flex-column">
        <div class="nav-item px-3">
            <NavLink class="nav-link" href="" Match="NavLinkMatch.All">
                <span class="bi bi-house" aria-hidden="true"></span>
                @if (!IconMenuActive)
                {
                    <span><label>Home</label></span>
                }
            </NavLink>
        </div>
        <div class="nav-item px-3">
            <NavLink class="nav-link" href="counter">
                <span class="bi bi-plus-circle" aria-hidden="true"></span>
                @if (!IconMenuActive)
                {
                    <span><label>Counter</label></span>
                }
            </NavLink>
        </div>
        <div class="nav-item px-3">
            <NavLink class="nav-link" href="weather">
                <span class="bi bi-brightness-high" aria-hidden="true"></span>
                @if (!IconMenuActive)
                {
                    <span><label>Fetch data</label></span>
                }
            </NavLink>
        </div>
        <div class="nav-item px-3" @onclick='@(() => ToggleSubMenu("subMenu1"))'>
            <NavLink class="nav-link flex-container" Match="NavLinkMatch.All">
                <span class="bi bi-folder" aria-hidden="true" title="subMenu"></span>
                @if (!IconMenuActive)
                {
                    <span><label>Sub Menu 1</label></span>
                    <span class="bi bi-arrow-icon @(IsSubMenuOpen("subMenu1") ? "bi bi-arrow-up-short" : "bi bi-arrow-down-short")" aria-hidden="true"></span>
                }
            </NavLink>
            <div class="sub-menu" style="display: @(IsSubMenuOpen("subMenu1") ? "block" : "none")">
                <NavLink class="nav-link" href="subitem1">
                    <span class="bi bi-arrow-right-circle" aria-hidden="true" title="Sub Item 1"></span>
                    @if (!IconMenuActive)
                    {
                        <span><label>Sub Menu 1 Item 1</label></span>
                    }
                </NavLink>
                <NavLink class="nav-link" href="subitem2">
                    <span class="bi bi-arrow-right-circle" aria-hidden="true" title="Sub Item 2"></span>
                    @if (!IconMenuActive)
                    {
                        <span><label>Sub Menu 1 Item 2</label></span>
                    }
                </NavLink>
            </div>
        </div>
        <div class="nav-item px-3" @onclick='@(() => ToggleSubMenu("subMenu2"))'>
            <NavLink class="nav-link flex-container" Match="NavLinkMatch.All">
                <span class="bi bi-folder" aria-hidden="true" title="subMenu"></span>
                @if (!IconMenuActive)
                {
                    <span><label>Sub Menu 2</label></span>
                    <span class="bi bi-arrow-icon @(IsSubMenuOpen("subMenu2") ? "bi bi-arrow-up-short" : "bi bi-arrow-down-short")" aria-hidden="true"></span>
                }
            </NavLink>
            <div class="sub-menu" style="display: @(IsSubMenuOpen("subMenu2") ? "block" : "none")">
                <NavLink class="nav-link" href="subitem1">
                    <span class="bi bi-arrow-right-circle" aria-hidden="true" title="Sub Item 1"></span>
                    @if (!IconMenuActive)
                    {
                        <span><label>Sub Menu 2 Item 1</label></span>
                    }
                </NavLink>
                <NavLink class="nav-link" href="subitem2">
                    <span class="bi bi-arrow-right-circle" aria-hidden="true" title="Sub Item 2"></span>
                    @if (!IconMenuActive)
                    {
                        <span><label>Sub Menu 2 Item 2</label></span>
                    }
                </NavLink>
            </div>
        </div>
    </nav>
</div>

<div class="bottom-row">
    <div class="icon-menu-arrow">
        @if (!IconMenuActive)
        {
            <span class="bi bi-arrow-bar-left" style="color: white;" @onclick="ToggleIconMenu"></span>
        }
        else
        {
            <span class="bi bi-arrow-bar-right" style="color: white;" @onclick="ToggleIconMenu"></span>
        }
    </div>
</div>

@code
{
    [Parameter]
    public EventCallback<bool> ShowIconMenu { get; set; }

    private bool IconMenuActive { get; set; } = false;
    private bool collapseNavMenu = true;
    private string? NavMenuCssClass => collapseNavMenu ? "collapse" : null;
    private Dictionary<string, bool> subMenuStates = new Dictionary<string, bool>();

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            await JSRuntime.InvokeVoidAsync("setResizeCallback", DotNetObjectReference.Create(this));
        }
    }

    [JSInvokable]
    public async Task OnResize(bool isBelowThreshold)
    {
        if (isBelowThreshold && IconMenuActive)
        {
            collapseNavMenu = true;
            await ToggleIconMenu();

            await ShowIconMenu.InvokeAsync(IconMenuActive);

            await InvokeAsync(StateHasChanged);
        }
    }

    private void ToggleNavMenu()
    {
        collapseNavMenu = !collapseNavMenu;
    }

    private async Task ToggleIconMenu()
    {
        IconMenuActive = !IconMenuActive;

        await ShowIconMenu.InvokeAsync(IconMenuActive);
    }

    private void ToggleSubMenu(string subMenuKey)
    {
        if (subMenuStates.ContainsKey(subMenuKey) && subMenuStates[subMenuKey])
        {
            subMenuStates[subMenuKey] = false;
        }
        else
        {
            foreach (var key in subMenuStates.Keys.ToList())
            {
                subMenuStates[key] = false;
            }

            if (subMenuStates.ContainsKey(subMenuKey))
            {
                subMenuStates[subMenuKey] = !subMenuStates[subMenuKey];
            }
            else
            {
                subMenuStates[subMenuKey] = true;
            }
        }
    }

    private bool IsSubMenuOpen(string subMenuKey)
    {
        return subMenuStates.ContainsKey(subMenuKey) && subMenuStates[subMenuKey];
    }
}