//------------------------------------------------------------------------------
// <copyright file="HtmlButton.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
//------------------------------------------------------------------------------

/*
 * HtmlButton.cs
 *
 * Copyright (c) 2000 Microsoft Corporation
 */

namespace System.Web.UI.HtmlControls {
    using System.ComponentModel;
    using System;
    using System.Collections;
    using System.Web;
    using System.Web.UI;
    using System.Security.Permissions;


    /// <devdoc>
    /// <para>The <see langword='HtmlButton'/> 
    /// class defines the methods, properties and events for the
    /// <see langword='HtmlButton'/>
    /// control. This
    /// class allows programmatic access to the HTML &lt;button&gt; element
    /// on the server.</para>
    /// </devdoc>
    [
    DefaultEvent("ServerClick"),
    SupportsEventValidation,
    ]
    public class HtmlButton : HtmlContainerControl, IPostBackEventHandler {

        private static readonly object EventServerClick = new object();


        /*
         *  Creates an intrinsic Html BUTTON control.
         */

        /// <devdoc>
        /// <para>Initializes a new instance of a <see cref='System.Web.UI.HtmlControls.HtmlButton'/> class.</para>
        /// </devdoc>
        public HtmlButton() : base("button") {
        }


        /// <devdoc>
        ///    <para>Gets or sets whether pressing the button causes page validation to fire. This defaults to True so that when
        ///          using validation controls, the validation state of all controls are updated when the button is clicked, both
        ///          on the client and the server. Setting this to False is useful when defining a cancel or reset button on a page
        ///          that has validators.</para>
        /// </devdoc>
        [
        WebCategory("Behavior"),
        DefaultValue(true),
        ]
        public virtual bool CausesValidation {
            get {
                object b = ViewState["CausesValidation"];
                return((b == null) ? true : (bool)b);
            }
            set {
                ViewState["CausesValidation"] = value;
            }
        }


        [
        WebCategory("Behavior"),
        DefaultValue(""),
        WebSysDescription(SR.PostBackControl_ValidationGroup)
        ]
        public virtual string ValidationGroup {
            get {
                string s = (string)ViewState["ValidationGroup"];
                return((s == null) ? String.Empty : s);
            }
            set {
                ViewState["ValidationGroup"] = value;
            }
        }


        /// <devdoc>
        /// <para>Occurs when the user clicks an <see cref='System.Web.UI.HtmlControls.HtmlButton'/> control on the
        ///    browser.</para>
        /// </devdoc>
        [
        WebCategory("Action"),
        WebSysDescription(SR.HtmlControl_OnServerClick)
        ]
        public event EventHandler ServerClick {
            add {
                Events.AddHandler(EventServerClick, value);
            }
            remove {
                Events.RemoveHandler(EventServerClick, value);
            }
        }


        /// <internalonly/>
        protected internal override void OnPreRender(EventArgs e) {
            base.OnPreRender(e);
            if (Page != null && Events[EventServerClick] != null)
                Page.RegisterPostBackScript();
        }

        /*
         * Override to generate postback code for onclick.
         */

        /// <internalonly/>
        /// <devdoc>
        /// </devdoc>
        protected override void RenderAttributes(HtmlTextWriter writer) {

            bool submitsProgramatically = (Events[EventServerClick] != null);
            if (Page != null && submitsProgramatically) {
                Util.WriteOnClickAttribute(
                        writer, this, false, true,
                        (CausesValidation && Page.GetValidators(ValidationGroup).Count > 0),
                        ValidationGroup);
            }

            base.RenderAttributes(writer);
        }


        /// <devdoc>
        /// <para>Raises the <see langword='ServerClick'/>
        /// event.</para>
        /// </devdoc>
        protected virtual void OnServerClick(EventArgs e) {
            EventHandler handler = (EventHandler)Events[EventServerClick];
            if (handler != null) handler(this, e);
        }

        /*
         * Method of IPostBackDataHandler interface to raise events on post back.
         * Button fires an OnServerClick event.
         */

        /// <internalonly/>
        /// <devdoc>
        /// </devdoc>
        void IPostBackEventHandler.RaisePostBackEvent(string eventArgument) {
            RaisePostBackEvent(eventArgument);
        }


        /// <internalonly/>
        /// <devdoc>
        /// </devdoc>
        protected virtual void RaisePostBackEvent(string eventArgument) {
            ValidateEvent(UniqueID, eventArgument);

            if (CausesValidation) {
                Page.Validate(ValidationGroup);
            }
            OnServerClick(EventArgs.Empty);
        }
    }
}