using System;

using System.Collections.Generic;

using System.Collections.ObjectModel;

using System.Linq;

using System.Linq.Expressions;

using System.Reflection;

namespace JSONAPI.Core

{

/// <summary>

/// Represents a type's registration with a registry

/// </summary>

public class ResourceTypeRegistration : IResourceTypeRegistration

{

private readonly IReadOnlyDictionary<string, ResourceTypeField> _fields;

private readonly Func<ParameterExpression, string, BinaryExpression> _filterByIdExpressionFactory;

private readonly Func<ParameterExpression, Expression> _sortByIdExpressionFactory;

internal ResourceTypeRegistration(Type type, PropertyInfo idProperty, string resourceTypeName,

IDictionary<string, ResourceTypeField> fields,

Func<ParameterExpression, string, BinaryExpression> filterByIdExpressionFactory,

Func<ParameterExpression, Expression> sortByIdExpressionFactory)

{

if (type == null) throw new ArgumentNullException(nameof(type));

if (idProperty == null) throw new ArgumentNullException(nameof(idProperty));

if (resourceTypeName == null) throw new ArgumentNullException(nameof(resourceTypeName));

IdProperty = idProperty;

Type = type;

ResourceTypeName = resourceTypeName;

_filterByIdExpressionFactory = filterByIdExpressionFactory;

_sortByIdExpressionFactory = sortByIdExpressionFactory;

Attributes = fields.Values.OfType<ResourceTypeAttribute>().ToArray();

Relationships = fields.Values.OfType<ResourceTypeRelationship>().ToArray();

_fields = new ReadOnlyDictionary<string, ResourceTypeField>(fields);

}

public Type Type { get; private set; }

public PropertyInfo IdProperty { get; private set; }

public string ResourceTypeName { get; private set; }

public ResourceTypeAttribute[] Attributes { get; private set; }

public ResourceTypeRelationship[] Relationships { get; private set; }

public string GetIdForResource(object resource)

{

if (resource == null) throw new ArgumentNullException(nameof(resource));

var resourceId = IdProperty.GetValue(resource);

if (resourceId == null) throw new ArgumentException($"The ID for the provided `{ResourceTypeName}` resource is null.");

return resourceId.ToString();

}

public void SetIdForResource(object resource, string id)

{

if (resource == null) throw new ArgumentNullException(nameof(resource));

IdProperty.SetValue(resource, id); // TODO: handle classes with non-string ID types

}

public BinaryExpression GetFilterByIdExpression(ParameterExpression parameter, string id)

{

return _filterByIdExpressionFactory(parameter, id);

}

public Expression GetSortByIdExpression(ParameterExpression parameter)

{

return _sortByIdExpressionFactory(parameter);

}

public ResourceTypeField GetFieldByName(string name)

{

return _fields.ContainsKey(name) ? _fields[name] : null;

}

}

}