using System;

using System.Collections.Generic;

using System.Linq;

using System.Reflection;

using System.Runtime.CompilerServices;

using System.Text;

using Android.App;

using Android.Views;

using Java.Interop;

namespace ReactiveUI

{

/// <summary>

/// ControlFetcherMixin helps you automatically wire-up Activities and

/// Fragments via property names, similar to Butter Knife, as well as allows

/// you to fetch controls manually.

/// </summary>

public static class ControlFetcherMixin

{

static readonly Dictionary<string, int> controlIds;

static readonly ConditionalWeakTable<object, Dictionary<string, View>> viewCache =

new ConditionalWeakTable<object, Dictionary<string, View>>();

static readonly MethodInfo getControlActivity;

static readonly MethodInfo getControlView;

static ControlFetcherMixin()

{

// NB: This is some hacky shit, but on Xamarin.Android at the moment,

// this is always the entry assembly.

var assm = AppDomain.CurrentDomain.GetAssemblies()[1];

var resources = assm.GetModules().SelectMany(x => x.GetTypes()).First(x => x.Name == "Resource");

controlIds = resources.GetNestedType("Id").GetFields()

.Where(x => x.FieldType == typeof(int))

.ToDictionary(k => k.Name.ToLowerInvariant(), v => (int)v.GetRawConstantValue());

var type = typeof(ControlFetcherMixin);

getControlActivity = type.GetMethod("GetControl", new[] { typeof(Activity), typeof(string) });

getControlView = type.GetMethod("GetControl", new[] { typeof(View), typeof(string) });

}

/// <summary>

///

/// </summary>

/// <returns></returns>

public static T GetControl<T>(this Activity This, [CallerMemberName]string propertyName = null)

where T : View

{

return (T)getCachedControl(propertyName, This,

() => This.FindViewById(controlIds[propertyName.ToLowerInvariant()]).JavaCast<T>());

}

/// <summary>

///

/// </summary>

/// <returns></returns>

public static T GetControl<T>(this View This, [CallerMemberName]string propertyName = null)

where T : View

{

return (T)getCachedControl(propertyName, This,

() => This.FindViewById(controlIds[propertyName.ToLowerInvariant()]).JavaCast<T>());

}

/// <summary>

///

/// </summary>

/// <returns></returns>

public static T GetControl<T>(this Fragment This, [CallerMemberName]string propertyName = null)

where T : View

{

return GetControl<T>(This.View, propertyName);

}

/// <summary>

///

/// </summary>

public static void WireUpControls(this ILayoutViewHost This)

{

var members = This.GetType().GetRuntimeProperties()

.Where(m => m.PropertyType.IsSubclassOf(typeof(View)));

members.ToList().ForEach(m => {

try {

// Find the android control with the same name

var view = This.View.getControlInternal(m.PropertyType, m.Name);

// Set the activity field's value to the view with that identifier

m.SetValue(This, view);

} catch (Exception ex) {

throw new MissingFieldException("Failed to wire up the Property "

+ m.Name + " to a View in your layout with a corresponding identifier", ex);

}

});

}

/// <summary>

///

/// </summary>

public static void WireUpControls(this View This)

{

var members = This.GetType().GetRuntimeProperties()

.Where(m => m.PropertyType.IsSubclassOf(typeof(View)));

members.ToList().ForEach(m => {

try {

// Find the android control with the same name

var view = This.getControlInternal(m.PropertyType, m.Name);

// Set the activity field's value to the view with that identifier

m.SetValue(This, view);

} catch (Exception ex) {

throw new MissingFieldException("Failed to wire up the Property "

+ m.Name + " to a View in your layout with a corresponding identifier", ex);

}

});

}

/// <summary>

/// This should be called in the Fragement's OnCreateView, with the newly inflated layout

/// </summary>

/// <param name="This"></param>

/// <param name="inflatedView"></param>

public static void WireUpControls(this Fragment This, View inflatedView)

{

var members = This.GetType().GetRuntimeProperties()

.Where(m => m.PropertyType.IsSubclassOf(typeof(View)));

members.ToList().ForEach(m => {

try {

// Find the android control with the same name from the view

var view = inflatedView.getControlInternal(m.PropertyType, m.Name);

// Set the activity field's value to the view with that identifier

m.SetValue(This, view);

} catch (Exception ex) {

throw new MissingFieldException("Failed to wire up the Property "

+ m.Name + " to a View in your layout with a corresponding identifier", ex);

}

});

}

/// <summary>

///

/// </summary>

public static void WireUpControls(this Activity This)

{

var members = This.GetType().GetRuntimeProperties()

.Where(m => m.PropertyType.IsSubclassOf(typeof(View)));

members.ToList().ForEach(m => {

try {

// Find the android control with the same name

var view = This.getControlInternal(m.PropertyType, m.Name);

// Set the activity field's value to the view with that identifier

m.SetValue(This, view);

} catch (Exception ex) {

throw new MissingFieldException("Failed to wire up the Property "

+ m.Name + " to a View in your layout with a corresponding identifier", ex);

}

});

}

static View getControlInternal(this View parent, Type viewType, string name)

{

var mi = getControlView.MakeGenericMethod(new[] { viewType });

return (View)mi.Invoke(null, new object[] { parent, name });

}

static View getControlInternal(this Activity parent, Type viewType, string name)

{

var mi = getControlActivity.MakeGenericMethod(new[] { viewType });

return (View)mi.Invoke(null, new object[] { parent, name });

}

static View getCachedControl(string propertyName, object rootView, Func<View> fetchControlFromView)

{

var ret = default(View);

var ourViewCache = viewCache.GetOrCreateValue(rootView);

if (ourViewCache.TryGetValue(propertyName, out ret)) {

return ret;

}

ret = fetchControlFromView();

ourViewCache.Add(propertyName, ret);

return ret;

}

}

}