BindingContext.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using Android.Widget;

namespace Android.Dialog
{
    public class BindingContext : IDisposable
    {
        public RootElement Root;
        Dictionary<Element, MemberAndInstance> _mappings;

        class MemberAndInstance
        {
            public MemberAndInstance(MemberInfo mi, object o)
            {
                Member = mi;
                Obj = o;
            }
            public MemberInfo Member;
            public object Obj;
        }

        static object GetValue(MemberInfo mi, object o)
        {
            var fi = mi as FieldInfo;
            if (fi != null)
                return fi.GetValue(o);
            var pi = mi as PropertyInfo;
            if (pi == null)
                return null;
            var getMethod = pi.GetGetMethod();
            return getMethod.Invoke(o, new object[0]);
        }

        static void SetValue(MemberInfo mi, object o, object val)
        {
            var fi = mi as FieldInfo;
            if (fi != null)
            {
                fi.SetValue(o, val);
                return;
            }
            var pi = mi as PropertyInfo;
            if (pi == null)
                return;
            var setMethod = pi.GetSetMethod();
            setMethod.Invoke(o, new[] { val });
        }

        static string MakeCaption(string name)
        {
            var sb = new StringBuilder(name.Length);
            bool nextUp = true;

            foreach (char c in name)
            {
                if (nextUp)
                {
                    sb.Append(Char.ToUpper(c));
                    nextUp = false;
                }
                else
                {
                    if (c == '_')
                    {
                        sb.Append(' ');
                        continue;
                    }
                    if (Char.IsUpper(c))
                        sb.Append(' ');
                    sb.Append(c);
                }
            }
            return sb.ToString();
        }

        // Returns the type for fields and properties and null for everything else
        static Type GetTypeForMember(MemberInfo mi)
        {
            if (mi is FieldInfo)
                return ((FieldInfo)mi).FieldType;
            if (mi is PropertyInfo)
                return ((PropertyInfo)mi).PropertyType;
            return null;
        }

        public BindingContext(object callbacks, object o, string title)
        {
            if (o == null)
                throw new ArgumentNullException("o");

            _mappings = new Dictionary<Element, MemberAndInstance>();

            Root = new RootElement(title);
            Populate(callbacks, o, Root);
        }

        void Populate(object callbacks, object o, RootElement root)
        {
            MemberInfo last_radio_index = null;
            var members = o.GetType().GetMembers(BindingFlags.DeclaredOnly | BindingFlags.Public |
                                                 BindingFlags.NonPublic | BindingFlags.Instance);

            Section section = null;

            foreach (var mi in members)
            {
                Type mType = GetTypeForMember(mi);

                if (mType == null)
                    continue;

                string caption = null;
                object[] attrs = mi.GetCustomAttributes(false);
                bool skip = false;
                foreach (var attr in attrs)
                {
                    if (attr is SkipAttribute)
                        skip = true;
                    if (attr is CaptionAttribute)
                        caption = ((CaptionAttribute)attr).Caption;
                    else if (attr is SectionAttribute)
                    {
                        if (section != null)
                            root.Add(section);
                        var sa = attr as SectionAttribute;
                        section = new Section(sa.Caption, sa.Footer);
                    }
                }
                if (skip)
                    continue;

                if (caption == null)
                    caption = MakeCaption(mi.Name);

                if (section == null)
                    section = new Section();

                Element element = null;
                if (mType == typeof(string))
                {
                    PasswordAttribute pa = null;
                    AlignmentAttribute align = null;
                    EntryAttribute ea = null;
                    object html = null;
                    EventHandler invoke = null;
                    bool multi = false;

                    foreach (object attr in attrs)
                    {
                        if (attr is PasswordAttribute)
                            pa = attr as PasswordAttribute;
                        else if (attr is EntryAttribute)
                            ea = attr as EntryAttribute;
                        else if (attr is MultilineAttribute)
                            multi = true;
                        else if (attr is HtmlAttribute)
                            html = attr;
                        else if (attr is AlignmentAttribute)
                            align = attr as AlignmentAttribute;

                        if (attr is OnTapAttribute)
                        {
                            string mname = ((OnTapAttribute)attr).Method;

                            if (callbacks == null)
                            {
                                throw new Exception("Your class contains [OnTap] attributes, but you passed a null object for `context' in the constructor");
                            }

                            var method = callbacks.GetType().GetMethod(mname);
                            if (method == null)
                                throw new Exception("Did not find method " + mname);
                            invoke = delegate
                            {
                                method.Invoke(method.IsStatic ? null : callbacks, new object[0]);
                            };
                        }
                    }

                    var value = (string)GetValue(mi, o);
                    if (pa != null)
                        element = new EntryElement(caption, value) { Hint = pa.Placeholder, Password = true };
                    else if (ea != null)
                        element = new EntryElement(caption, value) { Hint = ea.Placeholder };
                    else if (multi)
                        element = new MultilineEntryElement(caption, value);
                    else if (html != null)
                        element = new HtmlElement(caption, value);
                    else
                    {
                        var selement = new StringElement(caption, value);
                        element = selement;

                        if (align != null)
                            selement.Alignment = align.Alignment;
                    }

                    if (invoke != null)
                        element.Click = invoke;
                }
                else if (mType == typeof(float))
                {
                    var floatElement = new FloatElement(null, null, (int)GetValue(mi, o)) { Caption = caption, };
                    element = floatElement;

                    foreach (object attr in attrs)
                    {
                        if (attr is RangeAttribute)
                        {
                            var ra = attr as RangeAttribute;
                            floatElement.MinValue = ra.Low;
                            floatElement.MaxValue = ra.High;
                            floatElement.ShowCaption = ra.ShowCaption;
                        }
                    }
                }
                else if (mType == typeof(bool))
                {
                    bool checkbox = false;
                    foreach (object attr in attrs)
                    {
                        if (attr is CheckboxAttribute)
                            checkbox = true;
                    }

                    if (checkbox)
                        element = new CheckboxElement(caption, (bool)GetValue(mi, o));
                    else
                        element = new BooleanElement(caption, (bool)GetValue(mi, o));
                }
                else if (mType == typeof(DateTime))
                {
                    var dateTime = (DateTime)GetValue(mi, o);
                    bool asDate = false, asTime = false;

                    foreach (object attr in attrs)
                    {
                        if (attr is DateAttribute)
                            asDate = true;
                        else if (attr is TimeAttribute)
                            asTime = true;
                    }

                    if (asDate)
                        element = new DateElement(caption, dateTime);
                    else if (asTime)
                        element = new TimeElement(caption, dateTime);
                    else
                        element = new DateTimeElement(caption, dateTime);
                }
                else if (mType.IsEnum)
                {
                    var csection = new Section();
                    ulong evalue = Convert.ToUInt64(GetValue(mi, o), null);
                    int idx = 0;
                    int selected = 0;

                    foreach (var fi in mType.GetFields(BindingFlags.Public | BindingFlags.Static))
                    {
                        ulong v = Convert.ToUInt64(GetValue(fi, null));

                        if (v == evalue)
                            selected = idx;

                        csection.Add(new RadioElement(MakeCaption(fi.Name)));
                        idx++;
                    }

                    element = new RootElement(caption, new RadioGroup(null, selected)) { csection };
                }
                else if (mType == typeof(ImageView))
                {
                    element = new ImageElement((ImageView)GetValue(mi, o));
                }
                else if (typeof(IEnumerable).IsAssignableFrom(mType))
                {
                    var csection = new Section();
                    int count = 0;

                    if (last_radio_index == null)
                        throw new Exception("IEnumerable found, but no previous int found");
                    foreach (var e in (IEnumerable)GetValue(mi, o))
                    {
                        csection.Add(new RadioElement(e.ToString()));
                        count++;
                    }
                    var selected = (int)GetValue(last_radio_index, o);
                    if (selected >= count || selected < 0)
                        selected = 0;
                    element = new RootElement(caption, new MemberRadioGroup(null, selected, last_radio_index)) { csection };
                    last_radio_index = null;
                }
                else if (typeof(int) == mType)
                {
                    if (attrs.OfType<RadioSelectionAttribute>().Any())
                    {
                        last_radio_index = mi;
                    }
                }
                else
                {
                    var nested = GetValue(mi, o);
                    if (nested != null)
                    {
                        var newRoot = new RootElement(caption);
                        Populate(callbacks, nested, newRoot);
                        element = newRoot;
                    }
                }

                if (element == null)
                    continue;

                section.Add(element);
                _mappings[element] = new MemberAndInstance(mi, o);
            }
            root.Add(section);
        }

        class MemberRadioGroup : RadioGroup
        {
            public MemberInfo mi;

            public MemberRadioGroup(string key, int selected, MemberInfo mi)
                : base(key, selected)
            {
                this.mi = mi;
            }
        }

        public void Dispose()
        {
            Dispose(true);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                foreach (var element in _mappings.Keys)
                {
                    element.Dispose();
                }
                _mappings = null;
            }
        }

        public void Fetch()
        {
            foreach (var dk in _mappings)
            {
                Element element = dk.Key;
                MemberInfo mi = dk.Value.Member;
                object obj = dk.Value.Obj;

                if (element is DateTimeElement)
                    SetValue(mi, obj, ((DateTimeElement)element).DateValue);
                else if (element is FloatElement)
                    SetValue(mi, obj, ((FloatElement)element).Value);
                else if (element is BooleanElement)
                    SetValue(mi, obj, ((BooleanElement)element).Value);
                else if (element is CheckboxElement)
                    SetValue(mi, obj, ((CheckboxElement)element).Value);
                else if (element is EntryElement)
                {
                    var entry = (EntryElement)element;
                    // TODO: entry.FetchValue();
                    SetValue(mi, obj, entry.Value);
                }
                else if (element is ImageElement)
                    SetValue(mi, obj, ((ImageElement)element).Value);
                else if (element is RootElement)
                {
                    var re = element as RootElement;
                    if (re._group as MemberRadioGroup != null)
                    {
                        var group = re._group as MemberRadioGroup;
                        SetValue(group.mi, obj, re.RadioSelected);
                    }
                    else if (re._group as RadioGroup != null)
                    {
                        var mType = GetTypeForMember(mi);
                        var fi = mType.GetFields(BindingFlags.Public | BindingFlags.Static)[re.RadioSelected];

                        SetValue(mi, obj, fi.GetValue(null));
                    }
                }
            }
        }
    }
}