﻿/*
 * 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.
 */

namespace DotPulsar.Schemas
{
    using DotPulsar.Abstractions;
    using DotPulsar.Exceptions;
    using System;
    using System.Buffers;
    using System.Collections.Immutable;

    /// <summary>
    /// Schema definition for Timestamp (DateTime) messages.
    /// </summary>
    public sealed class TimestampSchema : ISchema<DateTime>
    {
        static TimestampSchema()
        {
            Timestamp = new TimestampSchema(new SchemaInfo("Timestamp", Array.Empty<byte>(), SchemaType.Timestamp, ImmutableDictionary<string, string>.Empty));
            Date = new TimestampSchema(new SchemaInfo("Date", Array.Empty<byte>(), SchemaType.Date, ImmutableDictionary<string, string>.Empty));
        }

        public static TimestampSchema Timestamp { get; }
        public static TimestampSchema Date { get; }

        public TimestampSchema(SchemaInfo schemaInfo)
            => SchemaInfo = schemaInfo;

        public SchemaInfo SchemaInfo { get; }

        public DateTime Decode(ReadOnlySequence<byte> bytes, byte[]? schemaVersion = null)
        {
            if (bytes.Length != 8)
                throw new SchemaSerializationException($"{nameof(TimestampSchema)} expected to decode 8 bytes, but received {bytes} bytes");

            var milliseconds = Schema.Int64.Decode(bytes);

            if (milliseconds < -62135596800000)
                return DateTime.MinValue;

            if (milliseconds > 253402300799999)
                return DateTime.MaxValue;

            return DateTimeOffset.FromUnixTimeMilliseconds(milliseconds).DateTime;
        }

        public ReadOnlySequence<byte> Encode(DateTime message)
        {
            var milliseconds = new DateTimeOffset(message).ToUnixTimeMilliseconds();
            return Schema.Int64.Encode(milliseconds);
        }
    }
}