radzen-blazor/Radzen.Blazor/FormComponent.cs

using System;
using System.Linq;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Forms;
using Microsoft.AspNetCore.Components.Web;
using Radzen.Blazor;
using Radzen.Blazor.Rendering;

namespace Radzen
{
    /// <summary>
    /// Base class for form input components that support browser autocomplete functionality.
    /// Extends <see cref="FormComponent{T}"/> with properties for controlling browser autocomplete behavior and ARIA autocomplete attributes.
    /// Used by input components like RadzenTextBox, RadzenPassword, RadzenNumeric, and RadzenMask.
    /// Provides standardized autocomplete behavior for better integration with browser password managers and autofill features.
    /// </summary>
    /// <typeparam name="T">The type of the form component's value.</typeparam>
    public class FormComponentWithAutoComplete<T> : FormComponent<T>
    {
        /// <summary>
        /// Gets or sets the browser autocomplete behavior for this input field.
        /// Controls whether browsers should offer to autofill this field based on user history or saved data.
        /// Common values include On (enable), Off (disable), Username, CurrentPassword, Email, etc.
        /// </summary>
        /// <value>The autocomplete type. Default is <see cref="AutoCompleteType.On"/>.</value>
        [Parameter]
        public virtual AutoCompleteType AutoCompleteType { get; set; } = AutoCompleteType.On;

        /// <summary>
        /// Gets the autocomplete attribute's string value.
        /// </summary>
        /// <value>
        /// <c>off</c> if the AutoComplete parameter is false or the
        /// AutoCompleteType parameter is "off". When the AutoComplete
        /// parameter is true, the value is <c>on</c> or, if set, the value of
        /// AutoCompleteType.</value>
        public virtual string AutoCompleteAttribute
        {
            get
            {
                if (Attributes != null && Attributes.TryGetValue("AutoComplete", out var value))
                {
                    var v = (object?)value;
                    var autoCompleteValue = v switch
                    {
                        bool boolValue => boolValue
                            ? AutoCompleteType.GetAutoCompleteValue()
                            : DefaultAutoCompleteAttribute,
                        string stringValue when bool.TryParse(stringValue, out var boolValue) => boolValue
                            ? AutoCompleteType.GetAutoCompleteValue()
                            : DefaultAutoCompleteAttribute,
                        AutoCompleteType typeValue => typeValue.GetAutoCompleteValue(),
                        _ => value != null ? value.ToString() ?? AutoCompleteType.GetAutoCompleteValue() : AutoCompleteType.GetAutoCompleteValue()
                    };

                    return string.Equals(autoCompleteValue, "false", StringComparison.OrdinalIgnoreCase)
                        ? DefaultAutoCompleteAttribute
                        : autoCompleteValue;
                }

                return AutoCompleteType.GetAutoCompleteValue();
            }
        }

        /// <summary>
        /// Gets or sets the default autocomplete attribute's string value.
        /// </summary>
        public virtual string DefaultAutoCompleteAttribute { get; set; } = "off";

        object? ariaAutoComplete;

        /// <inheritdoc />
        public override async Task SetParametersAsync(ParameterView parameters)
        {
            parameters = parameters.TryGetValue("aria-autocomplete", out ariaAutoComplete) ?
                ParameterView.FromDictionary(parameters
                    .ToDictionary().Where(i => i.Key != "aria-autocomplete").ToDictionary(i => i.Key, i => i.Value)
                    .ToDictionary(i => i.Key, i => (object?)i.Value))
                : parameters;

            await base.SetParametersAsync(parameters).ConfigureAwait(false);
        }

        /// <summary>
        /// Gets or sets the default aria-autocomplete attribute's string value.
        /// </summary>
        public virtual string DefaultAriaAutoCompleteAttribute { get; set; } = "none";

        /// <summary>
        /// Gets the aria-autocomplete attribute's string value.
        /// </summary>
        public virtual string? AriaAutoCompleteAttribute
        {
            get => string.Equals(AutoCompleteAttribute, DefaultAutoCompleteAttribute, StringComparison.Ordinal)
                ? DefaultAriaAutoCompleteAttribute
                : ariaAutoComplete as string;
        }

    }

    /// <summary>
    /// Base class for all Radzen form input components providing data binding, validation, and change event capabilities.
    /// FormComponent integrates with Blazor's EditContext for form validation and provides common functionality for all input controls.
    /// This is the base class for components like RadzenTextBox, RadzenCheckBox, RadzenDropDown, RadzenDatePicker, etc.
    /// Provides @bind-Value support for two-way binding, integration with Blazor EditContext and validators, Change and ValueChanged callbacks,
    /// Disable property to prevent user interaction, Placeholder text for empty inputs, Name property for validation and label association,
    /// and TabIndex for keyboard navigation control.
    /// Components inheriting from FormComponent automatically work with RadzenTemplateForm and validators.
    /// </summary>
    /// <typeparam name="T">The type of the component's bound value (string, int, DateTime, etc.).</typeparam>
    public class FormComponent<T> : RadzenComponent, IRadzenFormComponent
    {
        /// <summary>
        /// Gets or sets the unique name identifier for this form component.
        /// Used for validation association (linking with validators and labels) and for identifying the field in form submission.
        /// This name should be unique within the form and match the Component property of associated validators/labels.
        /// </summary>
        /// <value>The component name.</value>
        [Parameter]
        public string? Name { get; set; }

        /// <summary>
        /// Gets or sets the tab order index for keyboard navigation.
        /// Controls the order in which fields receive focus when the user presses the Tab key.
        /// Lower values receive focus first. Use -1 to exclude from tab navigation.
        /// </summary>
        /// <value>The tab index. Default is 0 (natural tab order).</value>
        [Parameter]
        public int TabIndex { get; set; } = 0;

        /// <summary>
        /// Gets or sets the placeholder.
        /// </summary>
        /// <value>The placeholder.</value>
        [Parameter]
        public string? Placeholder { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether this <see cref="FormComponent{T}"/> is disabled.
        /// </summary>
        /// <value><c>true</c> if disabled; otherwise, <c>false</c>.</value>
        [Parameter]
        public bool Disabled { get; set; }

        /// <summary>
        /// The form
        /// </summary>
        IRadzenForm? _form;

        /// <summary>
        /// Gets or sets the edit context.
        /// </summary>
        /// <value>The edit context.</value>
        [CascadingParameter]
        public EditContext? EditContext { get; set; }

        /// <summary>
        /// Gets or sets the form.
        /// </summary>
        /// <value>The form.</value>
        [CascadingParameter]
        public IRadzenForm? Form
        {
            get
            {
                return _form;
            }
            set
            {
                _form = value;
                _form?.AddComponent(this);
            }
        }

        /// <summary>
        /// Gets or sets the value changed.
        /// </summary>
        /// <value>The value changed.</value>
        [Parameter]
        public EventCallback<T> ValueChanged { get; set; }

        /// <summary>
        /// Gets a value indicating whether this instance has value.
        /// </summary>
        /// <value><c>true</c> if this instance has value; otherwise, <c>false</c>.</value>
        public virtual bool HasValue
        {
            get
            {
                if (typeof(T) == typeof(string))
                {
                    return !string.IsNullOrEmpty($"{Value}");
                }
                return !object.Equals(Value, default(T));
            }
        }

        /// <summary>
        /// Gets a value indicating whether this instance is bound.
        /// </summary>
        /// <value><c>true</c> if this instance is bound; otherwise, <c>false</c>.</value>
        public bool IsBound
        {
            get
            {
                return ValueChanged.HasDelegate;
            }
        }

        /// <summary>
        /// The value
        /// </summary>
        protected T? _value;

        /// <summary>
        /// Gets or sets the value.
        /// </summary>
        /// <value>The value.</value>
        [Parameter]
        public virtual T? Value
        {
            get
            {
                return _value;
            }
            set
            {
                if (!EqualityComparer<T>.Default.Equals(value, _value))
                {
                    _value = value;
                }
            }
        }


        /// <summary>
        /// Gets or sets the change.
        /// </summary>
        /// <value>The change.</value>
        [Parameter]
        public EventCallback<T> Change { get; set; }
        /// <summary>
        /// Gets the field identifier.
        /// </summary>
        /// <value>The field identifier.</value>
        [Parameter]
        public FieldIdentifier FieldIdentifier { get; set; }

        /// <summary>
        /// Gets or sets the value expression.
        /// </summary>
        /// <value>The value expression.</value>
        [Parameter]
        public Expression<Func<T>>? ValueExpression { get; set; }
        /// <summary>
        /// Sets the parameters asynchronous.
        /// </summary>
        /// <param name="parameters">The parameters.</param>
        /// <returns>Task.</returns>
        public override Task SetParametersAsync(ParameterView parameters)
        {
            var disabledChanged = parameters.DidParameterChange(nameof(Disabled), Disabled);

            var result = base.SetParametersAsync(parameters);

            if (EditContext != null && ValueExpression != null && FieldIdentifier.Model != EditContext.Model)
            {
                FieldIdentifier = FieldIdentifier.Create(ValueExpression);
                EditContext.OnValidationStateChanged -= ValidationStateChanged;
                EditContext.OnValidationStateChanged += ValidationStateChanged;
            }

            if (disabledChanged)
            {
                FormFieldContext?.DisabledChanged(Disabled);
            }

            return result;
        }

        /// <summary>
        /// Validations the state changed.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="ValidationStateChangedEventArgs"/> instance containing the event data.</param>
        private void ValidationStateChanged(object? sender, ValidationStateChangedEventArgs e)
        {
            StateHasChanged();
        }

        /// <summary>
        /// Disposes this instance.
        /// </summary>
        public override void Dispose()
        {
            base.Dispose();

            if (EditContext != null)
            {
                EditContext.OnValidationStateChanged -= ValidationStateChanged;
            }

            Form?.RemoveComponent(this);

            GC.SuppressFinalize(this);
        }

        /// <summary>
        /// Gets the value.
        /// </summary>
        /// <returns>System.Object.</returns>
        public object? GetValue()
        {
            return Value;
        }

        /// <summary>
        /// Handles the ContextMenu event.
        /// </summary>
        /// <param name="args">The <see cref="MouseEventArgs"/> instance containing the event data.</param>
        /// <returns>Task.</returns>
        public override Task OnContextMenu(MouseEventArgs args)
        {
            if (!Disabled)
            {
                return base.OnContextMenu(args);
            }

            return Task.CompletedTask;
        }

        /// <summary>
        /// Gets the class list.
        /// </summary>
        /// <param name="className">Name of the class.</param>
        /// <returns>ClassList.</returns>
        protected ClassList GetClassList(string className) => ClassList.Create(className)
                                                                       .AddDisabled(Disabled)
                                                                       .Add(FieldIdentifier, EditContext)
                                                                       .Add("rz-state-empty", !HasValue);

        /// <summary> Provides support for RadzenFormField integration. </summary>
        [CascadingParameter]
        public IFormFieldContext? FormFieldContext { get; set; }

        /// <summary> Gets the current placeholder. Returns empty string if this component is inside a RadzenFormField.</summary>
        protected string? CurrentPlaceholder => FormFieldContext?.AllowFloatingLabel == true ? " " : Placeholder;

        /// <inheritdoc/>
        public virtual async ValueTask FocusAsync()
        {
            await Element.FocusAsync();
        }
    }
}