BotBuilder-Samples/CSharp/Blog-LUISActionBinding/Microsoft.Cognitive.LUIS.ActionBinding/LuisActionResolver.cs

namespace Microsoft.Cognitive.LUIS.ActionBinding
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Reflection;
    using System.Threading;
    using System.Threading.Tasks;
    using Microsoft.Bot.Builder.Dialogs.Internals;
    using Microsoft.Bot.Builder.Luis;
    using Microsoft.Bot.Builder.Luis.Models;

    [Serializable]
    public class LuisActionResolver
    {
        private readonly IDictionary<string, Type> luisActions;

        public LuisActionResolver(params Assembly[] lookupAssemblies)
        {
            this.luisActions = new Dictionary<string, Type>();

            if (lookupAssemblies == null)
            {
                throw new ArgumentNullException(nameof(lookupAssemblies));
            }

            foreach (var lookupAssembly in lookupAssemblies)
            {
                foreach (var info in lookupAssembly.GetTypes().Select(t => new { Type = t, Attribs = t.GetCustomAttributes<LuisActionBindingAttribute>(true) }).Where(o => o.Attribs.Any()))
                {
                    foreach (var intentAttrib in info.Attribs)
                    {
                        this.luisActions.Add(intentAttrib.IntentName, info.Type);
                    }
                }
            }
        }

        public static bool AssignValue(ILuisAction action, string paramName, object paramValue)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (string.IsNullOrWhiteSpace(paramName))
            {
                throw new ArgumentNullException(nameof(paramName));
            }

            if (paramValue == null)
            {
                throw new ArgumentNullException(nameof(paramValue));
            }

            return AssignValue(action, action.GetType().GetProperty(paramName, BindingFlags.Public | BindingFlags.Instance), paramValue);
        }

        public static async Task<QueryValueResult> QueryValueFromLuisAsync(
            ILuisService service,
            ILuisAction action,
            string paramName,
            object paramValue,
            CancellationToken token,
            Func<PropertyInfo, IEnumerable<EntityRecommendation>, EntityRecommendation> entityExtractor = null)
        {
            var originalValue = paramValue;

            if (service == null)
            {
                throw new ArgumentNullException(nameof(service));
            }

            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (string.IsNullOrWhiteSpace(paramName))
            {
                throw new ArgumentNullException(nameof(paramName));
            }

            if (paramValue == null)
            {
                throw new ArgumentNullException(nameof(paramValue));
            }

            var result = await service.QueryAsync(paramValue.ToString(), token);
            var queryIntent = result.Intents.FirstOrDefault();
            if (!Intents.None.Equals(queryIntent.Intent, StringComparison.InvariantCultureIgnoreCase))
            {
                var newIntentName = default(string);
                var newAction = new LuisActionResolver(action.GetType().Assembly).ResolveActionFromLuisIntent(result, out newIntentName);
                if (newAction != null)
                {
                    return new QueryValueResult(false)
                    {
                        NewAction = newAction,
                        NewIntent = newIntentName
                    };
                }
            }

            var properties = new List<PropertyInfo> { action.GetType().GetProperty(paramName, BindingFlags.Public | BindingFlags.Instance) };
            if (!LuisActionResolver.AssignEntitiesToMembers(action, properties, result.Entities, entityExtractor))
            {
                return new QueryValueResult(AssignValue(action, properties.First(), originalValue));
            }

            return new QueryValueResult(true);
        }

        public static LuisActionBindingAttribute GetActionDefinition(ILuisAction action)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            return action.GetType().GetCustomAttributes<LuisActionBindingAttribute>(true).FirstOrDefault();
        }

        public static LuisActionBindingParamAttribute GetParameterDefinition(ILuisAction action, string paramName)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (string.IsNullOrWhiteSpace(paramName))
            {
                throw new ArgumentNullException(nameof(paramName));
            }

            var prop = action.GetType().GetProperty(paramName, BindingFlags.Public | BindingFlags.Instance);

            // search binding attrib
            return prop.GetCustomAttributes<LuisActionBindingParamAttribute>(true).FirstOrDefault();
        }

        public static bool IsValidContextualAction(ILuisAction action, ILuisAction context, out bool isContextual)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (context == null)
            {
                throw new ArgumentNullException(nameof(context));
            }

            isContextual = LuisActionResolver.IsContextualAction(action);

            if (!isContextual)
            {
                return false;
            }

            var validContextualType = typeof(ILuisContextualAction<>).MakeGenericType(context.GetType());
            if (validContextualType.IsAssignableFrom(action.GetType()))
            {
                var prop = validContextualType.GetProperty("Context", BindingFlags.Public | BindingFlags.Instance);
                prop.SetValue(action, context);

                return true;
            }

            return false;
        }

        public static bool IsContextualAction(ILuisAction action)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            return action
                .GetType()
                .GetInterfaces()
                .Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(ILuisContextualAction<>));
        }

        public static bool UpdateIfValidContextualAction(ILuisAction action, ILuisAction context, out bool isContextual)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (context == null)
            {
                throw new ArgumentNullException(nameof(context));
            }

            isContextual = false;

            if (!LuisActionResolver.IsContextualAction(context))
            {
                return true;
            }

            var prop = context.GetType().GetProperty("Context", BindingFlags.Public | BindingFlags.Instance);
            var actionContext = prop.GetValue(context) as ILuisAction;

            return LuisActionResolver.IsValidContextualAction(action, actionContext, out isContextual);
        }

        public static bool CanStartWithNoContextAction(ILuisAction action, out LuisActionBindingAttribute actionDefinition)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (!LuisActionResolver.IsContextualAction(action))
            {
                actionDefinition = null;
                return true;
            }

            actionDefinition = LuisActionResolver.GetActionDefinition(action);

            return actionDefinition.CanExecuteWithNoContext;
        }

        public static ILuisAction BuildContextForContextualAction(ILuisAction action, out string intentName)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (!LuisActionResolver.IsContextualAction(action))
            {
                intentName = null;
                return null;
            }

            var contextType = action
                .GetType()
                .GetInterfaces()
                .First(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(ILuisContextualAction<>))
                .GetGenericArguments()[0];

            var result = Activator.CreateInstance(contextType) as ILuisAction;
            intentName = LuisActionResolver.GetActionDefinition(result).IntentName;

            var isContextual = false;
            LuisActionResolver.IsValidContextualAction(action, result, out isContextual);

            return result;
        }

        public ILuisAction ResolveActionFromLuisIntent(LuisResult luisResult)
        {
            if (luisResult == null)
            {
                throw new ArgumentNullException(nameof(luisResult));
            }

            var intentName = default(string);
            var unassigned = default(IList<EntityRecommendation>);

            return this.ResolveActionFromLuisIntent(luisResult, out intentName, out unassigned);
        }

        public ILuisAction ResolveActionFromLuisIntent(
            LuisResult luisResult,
            out string intentName,
            out IList<EntityRecommendation> intentEntities,
            Func<PropertyInfo, IEnumerable<EntityRecommendation>, EntityRecommendation> entityExtractor = null)
        {
            intentEntities = default(IList<EntityRecommendation>);

            if (luisResult == null)
            {
                throw new ArgumentNullException(nameof(luisResult));
            }

            // Has Intent?
            intentName = (luisResult.TopScoringIntent ?? luisResult.Intents?.MaxBy(i => i.Score ?? 0d)).Intent;
            if (string.IsNullOrWhiteSpace(intentName))
            {
                return null;
            }

            // Set out intent entities reference
            intentEntities = luisResult.Entities;

            // Get Actions that map to this intent
            var actionType = default(Type);
            if (!this.luisActions.TryGetValue(intentName, out actionType))
            {
                return null;
            }

            // Get the action instance and check if it implements ILuisAction
            var luisAction = Activator.CreateInstance(actionType) as ILuisAction;
            if (luisAction == null)
            {
                return null;
            }

            // Try complete parameters from entities
            var properties = luisAction.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);
            LuisActionResolver.AssignEntitiesToMembers(luisAction, properties, luisResult.Entities, entityExtractor);

            return luisAction;
        }

        internal ILuisAction ResolveActionFromLuisIntent(LuisResult luisResult, out string intentName)
        {
            if (luisResult == null)
            {
                throw new ArgumentNullException(nameof(luisResult));
            }

            var unassigned = default(IList<EntityRecommendation>);

            return this.ResolveActionFromLuisIntent(luisResult, out intentName, out unassigned);
        }

        private static bool AssignValue(ILuisAction action, PropertyInfo property, object paramValue)
        {
            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (property == null)
            {
                throw new ArgumentNullException(nameof(property));
            }

            if (paramValue == null)
            {
                throw new ArgumentNullException(nameof(paramValue));
            }

            if (property != null && property.CanWrite)
            {
                // nullable support
                var type = property.PropertyType;
                type = Nullable.GetUnderlyingType(type) ?? type;

                try
                {
                    var value = Convert.ChangeType(paramValue, type);
                    property.SetValue(action, value);
                    return true;
                }
                catch (FormatException)
                {
                    // Handle invalid values (Eg. Try Parse '2017' as a Date will fail)
                }
            }

            return false;
        }

        private static bool AssignEntitiesToMembers(
            ILuisAction action, 
            IEnumerable<PropertyInfo> properties,
            IEnumerable<EntityRecommendation> entities, 
            Func<PropertyInfo, IEnumerable<EntityRecommendation>, EntityRecommendation> entityExtractor = null)
        {
            var result = true;

            if (action == null)
            {
                throw new ArgumentNullException(nameof(action));
            }

            if (properties == null)
            {
                throw new ArgumentNullException(nameof(properties));
            }

            if (entities == null)
            {
                throw new ArgumentNullException(nameof(entities));
            }

            if (!entities.Any())
            {
                return !result;
            }

            // Cross match entities to copy resolution values for custom entities from pairs
            foreach (var group in entities.GroupBy(e => e.Entity))
            {
                if (group.Count() > 1)
                {
                    var entityToUpdate = group.FirstOrDefault(e => !BuiltInTypes.IsBuiltInType(e.Type));
                    var entityWithValue = group.FirstOrDefault(e => e.Resolution != null);
                    if (entityToUpdate != null && entityWithValue != null)
                    {
                        entityToUpdate.Resolution = entityWithValue.Resolution;
                    }
                }
            }

            foreach (var property in properties)
            {
                var matchingEntity = default(EntityRecommendation);
                var matchingEntities = default(IEnumerable<EntityRecommendation>);

                // Find using custom type from attrib if available
                var paramAttrib = property.GetCustomAttributes<LuisActionBindingParamAttribute>(true).FirstOrDefault();
                if (paramAttrib != null)
                {
                    matchingEntities = entities.Where(e => e.Type == paramAttrib.CustomType);
                }

                // Find using property name
                if (matchingEntities == null || !matchingEntities.Any())
                {
                    matchingEntities = entities.Where(e => e.Type == property.Name);
                }

                // Find using builtin type from attrib if available
                if ((matchingEntities == null || !matchingEntities.Any()) && paramAttrib != null)
                {
                    matchingEntities = entities.Where(e => e.Type == paramAttrib.BuiltinType);
                }

                // If callback available then use it
                if (matchingEntities.Count() > 1)
                {
                    if (entityExtractor != null)
                    {
                        matchingEntity = entityExtractor(property, matchingEntities);
                    }
                }
                else
                {
                    matchingEntity = matchingEntities.FirstOrDefault();
                }

                // Prioritize resolution
                if (matchingEntity != null)
                {
                    var paramValue = matchingEntity.Resolution != null && matchingEntity.Resolution.Count > 0
                        ? matchingEntity.Resolution.First().Value
                        : matchingEntity.Entity;

                    result &= AssignValue(action, property, paramValue);
                }
                else
                {
                    result = false;
                }
            }

            return result;
        } 
    }
}