Moonlight/Moonlight/Shared/Components/Forms/SmartDropdown.razor

@using Microsoft.AspNetCore.Components.Forms

@typeparam T
@inherits InputBase<T>

<div class="dropdown w-100">
    <div class="input-group">
        @if (CurrentValue == null)
        {
            <input class="form-control" type="text" @bind-value="SearchTerm" @bind-value:event="oninput" placeholder="@(Placeholder)">
        }
        else
        {
            <input class="form-control" type="text" value="@(DisplayFunc(CurrentValue))">
            <button class="btn btn-sm btn-primary" @onclick="() => SelectItem(default(T)!)">
                <i class="bx bx-sm bx-x"></i>
            </button>
        }
    </div>

    @{
        var anyItems = FilteredItems.Any();
    }

    <div class="dropdown-menu w-100 @(anyItems ? "show" : "")" style="max-height: 200px; overflow-y: auto;">
        @if (anyItems)
        {
            foreach (var item in FilteredItems)
            {
                <button class="dropdown-item py-2" type="button" @onclick="() => SelectItem(item)">@DisplayFunc(item)</button>
            }
        }
    </div>
</div>

@code {

    [Parameter]
    public IEnumerable<T> Items { get; set; }

    [Parameter]
    public Func<T, string> DisplayFunc { get; set; }

    [Parameter]
    public Func<T, string> SearchProp { get; set; }
    
    [Parameter]
    public Func<Task>? OnSelected { get; set; }

    [Parameter]
    public string Placeholder { get; set; } = "Search...";

    private string SearchTerm
    {
        get => searchTerm;
        set
        {
            searchTerm = value;
            FilteredItems = Items.OrderByDescending(x => Matches(SearchProp(x), searchTerm)).Take(30).ToList();
        }
    }

    private string searchTerm = "";

    private List<T> FilteredItems = new();

    private async void SelectItem(T item)
    {
        CurrentValue = item;
        SearchTerm = "";
        FilteredItems.Clear();

        if (OnSelected != null)
            await OnSelected.Invoke();
    }

    protected override bool TryParseValueFromString(string? value, out T result, out string? validationErrorMessage)
    {
    // Check if the value is null or empty
        if (string.IsNullOrEmpty(value))
        {
            result = default(T)!;
            validationErrorMessage = "Value cannot be null or empty";
            return false;
        }

    // Try to find an item that matches the search term
        var item = FilteredItems.OrderByDescending(x => Matches(SearchProp(x), value)).FirstOrDefault();
        if (item != null)
        {
            result = item;
            validationErrorMessage = null;
            return true;
        }
        else
        {
            result = default(T)!;
            validationErrorMessage = $"No item found for search term '{value}'";
            return false;
        }
    }

    private float Matches(string input, string search)
    {
        if (string.IsNullOrEmpty(input) || string.IsNullOrEmpty(search))
            return 0;

        var cleanedSearch = search
            .ToLower()
            .Replace(" ", "")
            .Replace("-", "");

        var cleanedInput = input
            .ToLower()
            .Replace(" ", "")
            .Replace("-", "");

        if (cleanedInput == cleanedSearch)
            return 10000;

        float matches = 0;

        int i = 0;
        foreach (var c in cleanedInput)
        {
            if (cleanedSearch.Length > i)
            {
                if (c == cleanedSearch[i])
                    matches++;
                else
                    matches--;
            }

            i++;
        }

        matches = matches / searchTerm.Length;

        return matches;
    }
}