@using Microsoft.AspNetCore.Components.Forms

<div class="sender-pdf-dropzone @DropZoneClass">
    <div class="sender-pdf-dropzone__content">
        <div class="sender-pdf-dropzone__title">@CurrentActionText</div>
        @if (!string.IsNullOrWhiteSpace(DragDropHintText))
        {
            <div class="sender-pdf-dropzone__hint">@DragDropHintText</div>
        }
    </div>

    <InputFile OnChange="OnFileSelectedAsync"
               accept="@Accept"
               disabled="@Disabled"
               @ondragenter="OnDragEnter"
               @ondragleave="OnDragLeave"
               @ondragover="OnDragOver"
               @ondrop="OnDrop"
               class="sender-pdf-dropzone__input" />
</div>

@code {
    [Parameter]
    public bool Disabled { get; set; }

    [Parameter]
    public bool HasDocument { get; set; }

    [Parameter]
    public string Accept { get; set; } = ".pdf";

    [Parameter]
    public string UploadText { get; set; } = "PDF hochladen";

    [Parameter]
    public string ReplaceText { get; set; } = "PDF ersetzen";

    [Parameter]
    public string DragDropHintText { get; set; } = "Datei hierhin ziehen oder klicken";

    [Parameter]
    public EventCallback<InputFileChangeEventArgs> FileSelected { get; set; }

    private int _dragDepth;
    private bool _isDragActive;

    private string CurrentActionText => HasDocument ? ReplaceText : UploadText;

    private string DropZoneClass
    {
        get
        {
            if (Disabled)
                return "sender-pdf-dropzone--disabled";

            return _isDragActive ? "sender-pdf-dropzone--drag-active" : string.Empty;
        }
    }

    private void OnDragEnter(DragEventArgs _)
    {
        if (Disabled)
            return;

        _dragDepth++;
        _isDragActive = true;
    }

    private void OnDragLeave(DragEventArgs _)
    {
        if (Disabled)
            return;

        _dragDepth = Math.Max(0, _dragDepth - 1);
        if (_dragDepth == 0)
            _isDragActive = false;
    }

    private void OnDragOver(DragEventArgs _)
    {
        if (Disabled)
            return;

        _isDragActive = true;
    }

    private void OnDrop(DragEventArgs _)
    {
        _dragDepth = 0;
        _isDragActive = false;
    }

    private async Task OnFileSelectedAsync(InputFileChangeEventArgs args)
    {
        _dragDepth = 0;
        _isDragActive = false;

        if (Disabled)
            return;

        if (FileSelected.HasDelegate)
            await FileSelected.InvokeAsync(args);
    }
}