/* Copyright 2016-present MongoDB Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

using System;
using MongoDB.Bson.IO;
using MongoDB.Bson.Serialization.Options;

namespace MongoDB.Bson.Serialization.Serializers
{
    /// <summary>
    /// Represents a serializer for Decimals.
    /// </summary>
    public class DecimalSerializer : StructSerializerBase<decimal>, IRepresentationConfigurable<DecimalSerializer>, IRepresentationConverterConfigurable<DecimalSerializer>
    {
        // private fields
        private readonly BsonType _representation;
        private readonly RepresentationConverter _converter;

        // constructors
        /// <summary>
        /// Initializes a new instance of the <see cref="DecimalSerializer"/> class.
        /// </summary>
        public DecimalSerializer()
            : this(BsonType.String)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DecimalSerializer"/> class.
        /// </summary>
        /// <param name="representation">The representation.</param>
        public DecimalSerializer(BsonType representation)
            : this(representation, new RepresentationConverter(false, false))
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DecimalSerializer"/> class.
        /// </summary>
        /// <param name="representation">The representation.</param>
        /// <param name="converter">The converter.</param>
        public DecimalSerializer(BsonType representation, RepresentationConverter converter)
        {
            switch (representation)
            {
                case BsonType.Array:
                case BsonType.Decimal128:
                case BsonType.Double:
                case BsonType.Int32:
                case BsonType.Int64:
                case BsonType.String:
                    break;

                default:
                    var message = string.Format("{0} is not a valid representation for a DecimalSerializer.", representation);
                    throw new ArgumentException(message);
            }

            _representation = representation;
            _converter = converter;
        }

        // public properties
        /// <summary>
        /// Gets the converter.
        /// </summary>
        /// <value>
        /// The converter.
        /// </value>
        public RepresentationConverter Converter
        {
            get { return _converter; }
        }

        /// <summary>
        /// Gets the representation.
        /// </summary>
        /// <value>
        /// The representation.
        /// </value>
        public BsonType Representation
        {
            get { return _representation; }
        }

        // public methods
        /// <summary>
        /// Deserializes a value.
        /// </summary>
        /// <param name="context">The deserialization context.</param>
        /// <param name="args">The deserialization args.</param>
        /// <returns>A deserialized value.</returns>
        public override decimal Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
        {
            var bsonReader = context.Reader;

            var bsonType = bsonReader.GetCurrentBsonType();
            switch (bsonType)
            {
                case BsonType.Array:
                    var array = BsonArraySerializer.Instance.Deserialize(context);
                    var bits = new int[4];
                    bits[0] = array[0].AsInt32;
                    bits[1] = array[1].AsInt32;
                    bits[2] = array[2].AsInt32;
                    bits[3] = array[3].AsInt32;
                    return new decimal(bits);

                case BsonType.Decimal128:
                    return _converter.ToDecimal(bsonReader.ReadDecimal128());

                case BsonType.Double:
                    return _converter.ToDecimal(bsonReader.ReadDouble());

                case BsonType.Int32:
                    return _converter.ToDecimal(bsonReader.ReadInt32());

                case BsonType.Int64:
                    return _converter.ToDecimal(bsonReader.ReadInt64());

                case BsonType.String:
                    return JsonConvert.ToDecimal(bsonReader.ReadString());

                default:
                    throw CreateCannotDeserializeFromBsonTypeException(bsonType);
            }
        }

        /// <summary>
        /// Serializes a value.
        /// </summary>
        /// <param name="context">The serialization context.</param>
        /// <param name="args">The serialization args.</param>
        /// <param name="value">The object.</param>
        public override void Serialize(BsonSerializationContext context, BsonSerializationArgs args, decimal value)
        {
            var bsonWriter = context.Writer;

            switch (_representation)
            {
                case BsonType.Array:
                    bsonWriter.WriteStartArray();
                    var bits = Decimal.GetBits(value);
                    bsonWriter.WriteInt32(bits[0]);
                    bsonWriter.WriteInt32(bits[1]);
                    bsonWriter.WriteInt32(bits[2]);
                    bsonWriter.WriteInt32(bits[3]);
                    bsonWriter.WriteEndArray();
                    break;

                case BsonType.Decimal128:
                    bsonWriter.WriteDecimal128(_converter.ToDecimal128(value));
                    break;

                case BsonType.Double:
                    bsonWriter.WriteDouble(_converter.ToDouble(value));
                    break;

                case BsonType.Int32:
                    bsonWriter.WriteInt32(_converter.ToInt32(value));
                    break;

                case BsonType.Int64:
                    bsonWriter.WriteInt64(_converter.ToInt64(value));
                    break;

                case BsonType.String:
                    bsonWriter.WriteString(JsonConvert.ToString(value));
                    break;

                default:
                    var message = string.Format("'{0}' is not a valid Decimal representation.", _representation);
                    throw new BsonSerializationException(message);
            }
        }

        /// <summary>
        /// Returns a serializer that has been reconfigured with the specified item serializer.
        /// </summary>
        /// <param name="converter">The converter.</param>
        /// <returns>The reconfigured serializer.</returns>
        public DecimalSerializer WithConverter(RepresentationConverter converter)
        {
            if (converter == _converter)
            {
                return this;
            }
            else
            {
                return new DecimalSerializer(_representation, converter);
            }
        }

        /// <summary>
        /// Returns a serializer that has been reconfigured with the specified representation.
        /// </summary>
        /// <param name="representation">The representation.</param>
        /// <returns>The reconfigured serializer.</returns>
        public DecimalSerializer WithRepresentation(BsonType representation)
        {
            if (representation == _representation)
            {
                return this;
            }
            else
            {
                return new DecimalSerializer(representation, _converter);
            }
        }

        // explicit interface implementations
        IBsonSerializer IRepresentationConverterConfigurable.WithConverter(RepresentationConverter converter)
        {
            return WithConverter(converter);
        }

        IBsonSerializer IRepresentationConfigurable.WithRepresentation(BsonType representation)
        {
            return WithRepresentation(representation);
        }
    }
}