// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Web.Mvc.Properties;

namespace System.Web.Mvc
{
    public class ModelBindingContext
    {
        private static readonly Predicate<string> _defaultPropertyFilter = _ => true;

        private string _modelName = String.Empty;
        private ModelStateDictionary _modelState;
        private Predicate<string> _propertyFilter;
        private Dictionary<string, ModelMetadata> _propertyMetadata;

        public ModelBindingContext()
            : this(null)
        {
        }

        // copies certain values that won't change between parent and child objects,
        // e.g. ValueProvider, ModelState
        public ModelBindingContext(ModelBindingContext bindingContext)
        {
            if (bindingContext != null)
            {
                ModelState = bindingContext.ModelState;
                ValueProvider = bindingContext.ValueProvider;
            }
        }

        public bool FallbackToEmptyPrefix { get; set; }

        [SuppressMessage("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "value", Justification = "Cannot remove setter as that's a breaking change")]
        public object Model
        {
            get { return ModelMetadata.Model; }
            set { throw new InvalidOperationException(MvcResources.ModelMetadata_PropertyNotSettable); }
        }

        public ModelMetadata ModelMetadata { get; set; }

        public string ModelName
        {
            get
            {
                return _modelName;
            }
            set 
            {
                _modelName = value ?? String.Empty;
            }
        }

        [SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly", Justification = "The containing type is mutable.")]
        public ModelStateDictionary ModelState
        {
            get
            {
                if (_modelState == null)
                {
                    _modelState = new ModelStateDictionary();
                }
                return _modelState;
            }
            set { _modelState = value; }
        }

        [SuppressMessage("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "value", Justification = "Cannot remove setter as that's a breaking change")]
        public Type ModelType
        {
            get { return ModelMetadata.ModelType; }
            set { throw new InvalidOperationException(MvcResources.ModelMetadata_PropertyNotSettable); }
        }

        public Predicate<string> PropertyFilter
        {
            get
            {
                if (_propertyFilter == null)
                {
                    _propertyFilter = _defaultPropertyFilter;
                }
                return _propertyFilter;
            }
            set { _propertyFilter = value; }
        }

        public IDictionary<string, ModelMetadata> PropertyMetadata
        {
            get
            {
                if (_propertyMetadata == null)
                {
                    _propertyMetadata = ModelMetadata.PropertiesAsArray.ToDictionaryFast(m => m.PropertyName, StringComparer.OrdinalIgnoreCase);
                }

                return _propertyMetadata;
            }
        }

        public IValueProvider ValueProvider { get; set; }

        internal IUnvalidatedValueProvider UnvalidatedValueProvider
        {
            get { return (ValueProvider as IUnvalidatedValueProvider) ?? new UnvalidatedValueProviderWrapper(ValueProvider); }
        }

        // Used to wrap an IValueProvider in an IUnvalidatedValueProvider
        private sealed class UnvalidatedValueProviderWrapper : IValueProvider, IUnvalidatedValueProvider
        {
            private readonly IValueProvider _backingProvider;

            public UnvalidatedValueProviderWrapper(IValueProvider backingProvider)
            {
                _backingProvider = backingProvider;
            }

            public ValueProviderResult GetValue(string key, bool skipValidation)
            {
                // 'skipValidation' isn't understood by the backing provider and can be ignored
                return GetValue(key);
            }

            public bool ContainsPrefix(string prefix)
            {
                return _backingProvider.ContainsPrefix(prefix);
            }

            public ValueProviderResult GetValue(string key)
            {
                return _backingProvider.GetValue(key);
            }
        }
    }
}
