Signum Framework Tutorials Part 3 - Southwind Load

#region usings
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Mvc;
using System.Linq.Expressions;
using Signum.Utilities;
using System.Web.Mvc.Html;
using Signum.Entities;
using System.Reflection;
using Signum.Entities.Reflection;
using Signum.Engine;
using System.Configuration;
using Signum.Web.Properties;
using System.Web;
using Signum.Engine.DynamicQuery;
#endregion

namespace Signum.Web
{
    public static class EntityComboHelper
    {
        internal static MvcHtmlString InternalEntityCombo(this HtmlHelper helper, EntityCombo entityCombo)
        {
            if (!entityCombo.Visible || entityCombo.HideIfNull && entityCombo.UntypedValue == null)
                return MvcHtmlString.Empty;

            if (!entityCombo.Type.IsIIdentifiable() && !entityCombo.Type.IsLite())
                throw new InvalidOperationException("EntityCombo can only be done for an identifiable or a lite, not for {0}".Formato(entityCombo.Type.CleanType()));

            HtmlStringBuilder sb = new HtmlStringBuilder();

            using (entityCombo.ShowFieldDiv && !entityCombo.OnlyValue ? sb.Surround(new HtmlTag("div").Class("sf-field")): null)
            using (entityCombo.ValueFirst ? sb.Surround(new HtmlTag("div").Class("sf-value-first")) : null)
            {
                if (!entityCombo.ValueFirst)
                    sb.AddLine(EntityBaseHelper.BaseLineLabel(helper, entityCombo, entityCombo.ControlID));

                using (!entityCombo.OnlyValue ? sb.Surround(new HtmlTag("div").Class("sf-value-container")) : null)
                {
                    sb.AddLine(helper.HiddenEntityInfo(entityCombo));

                    if (EntityBaseHelper.RequiresLoadAll(helper, entityCombo))
                        sb.AddLine(EntityBaseHelper.RenderTypeContext(helper, (TypeContext)entityCombo.Parent, RenderMode.PopupInDiv, entityCombo));
                    else if (entityCombo.UntypedValue != null)
                        sb.AddLine(helper.Div(entityCombo.Compose(EntityBaseKeys.Entity), null, "", new Dictionary<string, object> { { "style", "display:none" } }));

                    if (entityCombo.ReadOnly)
                        sb.AddLine(helper.Span(entityCombo.ControlID, entityCombo.UntypedValue.TryToString(), "sf-value-line"));
                    else
                    {
                        List<SelectListItem> items = new List<SelectListItem>();
                        items.Add(new SelectListItem() { Text = "-", Value = "" });
                        if (entityCombo.Preload)
                        {
                            int? id = entityCombo.IdOrNull;

                            List<Lite> data = entityCombo.Data ?? AutoCompleteUtils.RetriveAllLite(entityCombo.Type.CleanType(), entityCombo.Implementations);

                            items.AddRange(
                                data.Select(lite => new SelectListItem()
                                    {
                                        Text = lite.ToString(),
                                        Value = entityCombo.Implementations != null ? lite.Key() : lite.Id.ToString(),
                                        Selected = lite.IdOrNull == entityCombo.IdOrNull
                                    })
                                );
                        }

                        entityCombo.ComboHtmlProperties.AddCssClass("sf-value-line");

                        if (entityCombo.ComboHtmlProperties.ContainsKey("onchange"))
                            throw new InvalidOperationException("EntityCombo cannot have onchange html property, use onEntityChanged instead");

                        entityCombo.ComboHtmlProperties.Add("onchange", "{0}.setSelected();".Formato(entityCombo.ToJS()));

                        if (entityCombo.Size > 0)
                        {
                            entityCombo.ComboHtmlProperties.AddCssClass("sf-entity-list");
                            entityCombo.ComboHtmlProperties.Add("size", Math.Min(entityCombo.Size, items.Count - 1));
                        }

                        sb.AddLine(helper.DropDownList(
                                entityCombo.ControlID,
                                items,
                                entityCombo.ComboHtmlProperties));
                    }

                    sb.AddLine(EntityBaseHelper.ViewButton(helper, entityCombo));
                    sb.AddLine(EntityBaseHelper.CreateButton(helper, entityCombo));

                    if (entityCombo.ShowValidationMessage)
                    {
                        sb.AddLine(helper.ValidationMessage(entityCombo.ControlID));
                    }

                }

                if (entityCombo.ValueFirst)
                    sb.AddLine(EntityBaseHelper.BaseLineLabel(helper, entityCombo, entityCombo.ControlID));
            }

            return sb.ToHtml();
        }

        public static MvcHtmlString EntityCombo<T,S>(this HtmlHelper helper, TypeContext<T> tc, Expression<Func<T, S>> property) 
        {
            return helper.EntityCombo<T, S>(tc, property, null);
        }

        public static MvcHtmlString EntityCombo<T, S>(this HtmlHelper helper, TypeContext<T> tc, Expression<Func<T, S>> property, Action<EntityCombo> settingsModifier)
        {
            TypeContext<S> context = Common.WalkExpression(tc, property);

            EntityCombo ec = new EntityCombo(typeof(S), context.Value, context, null, context.PropertyRoute);

            EntityBaseHelper.ConfigureEntityBase(ec, ec.CleanRuntimeType ?? ec.Type.CleanType());

            Common.FireCommonTasks(ec);

            if (settingsModifier != null)
                settingsModifier(ec);

            return helper.InternalEntityCombo(ec);
        }

        public static MvcHtmlString RenderOption(this SelectListItem item)
        {
            HtmlTag builder = new HtmlTag("option").SetInnerText(item.Text);

            if (item.Value != null)
                builder.Attr("value", item.Value);

            if (item.Selected)
                builder.Attr("selected", "selected");

            return builder.ToHtml();
        }

        public static SelectListItem ToSelectListItem(this Lite lite, bool selected)
        {
            return new SelectListItem { Text = lite.ToStr, Value = lite.Id.ToString(), Selected = selected };
        }

        public static MvcHtmlString ToOptions<T>(this IEnumerable<Lite<T>> lites, Lite<T> selectedElement) where T : class, IIdentifiable
        {
            List<SelectListItem> list = new List<SelectListItem>();

            if (selectedElement == null || !lites.Contains(selectedElement))
                list.Add(new SelectListItem { Text = "-", Value = "" });

            list.AddRange(lites.Select(l => l.ToSelectListItem(l.Is(selectedElement))));

            return new HtmlStringBuilder( list.Select(RenderOption)).ToHtml();
        }
    }
}