@typeparam T

@*
 *                                dbMango
 *
 * Copyright 2025 Deutsche Bank AG
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *@

<div class="@FormGroupClass">
    @if (!string.IsNullOrWhiteSpace(Name))
    {
        <div class="flex-stack-horizontal form-mw">
            <label for="@_id" class="input-group-text w-100">@Name</label>
        </div>
    }
    <div class="input-group mr-sm-2">
        @if (Icon != null)
        {
            <div class="input-group-prepend">
                <div class="input-group-text">
                    <div class="">
                        <span class="ui-icon-font ui-icon-sm @Icon"></span>
                    </div>
                </div>
            </div>
        }
        @if ( Editable )
        {
            <datalist id="@_dataListId">
                @{
                    var groupedValues = GetGroupedValues();
                    if (groupedValues.Count == 1)
                    {
                        foreach (var v in groupedValues[0].Values)
                        {
                            if (Value?.Equals(v) ?? false)
                            {
                                <option value="@v" selected>@GetText(v)</option>
                            }
                            else
                            {
                                <option value="@v">@GetText(v)</option>
                            }
                        }
                    }
                    else
                    {
                        foreach (var g in groupedValues)
                        {
                            <optgroup label="@g.Name">
                                @foreach (var v in g.Values)
                                {
                                    if (Value?.Equals(v) ?? false)
                                    {
                                        <option value="@v" selected>@GetText(v)</option>
                                    }
                                    else
                                    {
                                        <option value="@v">@GetText(v)</option>
                                    }
                                }
                            </optgroup>
                        }
                    }
                }
            </datalist>
            <input class="form-control" autoComplete="on" list="@_dataListId" disabled="@(!Enabled)" @bind-Value="Value" @bind-Value:event="onchange" />
        }
        else
        {
            <select id="@_id" type="text" class="form-control" placeholder="@Placeholder" @bind="ValueStr" disabled="@(!Enabled)">
                @{
                    var groupedValues = GetGroupedValues();
                    if ( groupedValues.Count == 1)
                    {
                        foreach (var v in groupedValues[0].Values)
                        {
                            if (Value?.Equals(v) ?? false)
                            {
                                <option value="@v" selected>@GetText(v)</option>
                            }
                            else
                            {
                                <option value="@v">@GetText(v)</option>
                            }
                        }
                    }
                    else
                    {
                        foreach ( var g in groupedValues )
                        {
                            <optgroup label="@g.Name">
                                @foreach (var v in g.Values)
                                {
                                    if (Value?.Equals(v) ?? false)
                                    {
                                        <option value="@v" selected>@GetText(v)</option>
                                    }
                                    else
                                    {
                                        <option value="@v">@GetText(v)</option>
                                    }
                                }
                            </optgroup>
                        }
                    }
                }
            </select>
        }
    </div>
</div>




@code {

    [Parameter] public string Name { get; set; } = "";

    [Parameter]
    public T Value
    {
        get;
        set
        {
            if (value == null || (field?.Equals(value) ?? false))
                return;
            field = value;
            ValueChanged.InvokeAsync(value);
        }
    } = default!;

    [Parameter] public EventCallback<T>       ValueChanged { get; set; }
    [Parameter] public IReadOnlyCollection<T> Values       { get; set; } = [];
    [Parameter] public string?                Placeholder  { get; set; } = "";
    [Parameter] public string?                Icon         { get; set; }
    [Parameter] public string                 Class        { get; set; } = "";
    [Parameter] public bool                   Enabled      { get; set; } = true;
    [Parameter] public bool                   Editable     { get; set; }
    [Parameter] public Func<T,bool>           IsSelectable { get; set; } = _ => true;
    [Parameter] public Func<T, string>        GetText      { get; set; } = x => x?.ToString() ?? "<null>";

    private string _id         = $"h{Random.Shared.Next():X8}";
    private string _dataListId = $"h{Random.Shared.Next():X8}";

    private string FormGroupClass => string.IsNullOrWhiteSpace(Name) ? Class : $"form-group {Class}";

    private string ValueStr
    {
        get => Value?.ToString() ?? "";
        set
        {
            var obj = Values.FirstOrDefault(x => x?.ToString() == value);
            if (obj != null)
                Value = obj;
        }
    }

    private class Group
    {
        public string Name { get; set; } = string.Empty;
        public List<T> Values { get; set; } = new ();
    }

    private List<Group> GetGroupedValues()
    {
        var groups = new List<Group>();
        Group? currentGroup = null;

        foreach (var v in Values)
        {
            if (!IsSelectable(v))
            {
                // Start a new group with this name
                currentGroup = new () { Name = GetText(v) };
                groups.Add(currentGroup);
            }
            else
            {
                if (currentGroup == null)
                {
                    // If no group has been started, create a default group
                    currentGroup = new Group { Name = "Not grouped" };
                    groups.Add(currentGroup);
                }
                currentGroup.Values.Add(v);
            }
        }

        return groups;
    }
}
