﻿/*
 * 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;

using DotPulsar.Internal.Extensions;
using Internal.PulsarApi;
using System;

/// <summary>
/// Unique identifier of a single message.
/// </summary>
public sealed class MessageId : IEquatable<MessageId>, IComparable<MessageId>
{
    static MessageId()
    {
        Earliest = new MessageId(ulong.MaxValue, ulong.MaxValue, -1, -1);
        Latest = new MessageId(long.MaxValue, long.MaxValue, -1, -1);
    }

    /// <summary>
    /// The oldest message available in the topic.
    /// </summary>
    public static MessageId Earliest { get; }

    /// <summary>
    /// The next message published in the topic.
    /// </summary>
    public static MessageId Latest { get; }

    /// <summary>
    /// Initializes a new instance using the specified ledgerId, entryId, partition and batchIndex.
    /// </summary>
    public MessageId(ulong ledgerId, ulong entryId, int partition, int batchIndex)
    {
        LedgerId = ledgerId;
        EntryId = entryId;
        Partition = partition;
        BatchIndex = batchIndex;
    }

    /// <summary>
    /// The id of the ledger.
    /// </summary>
    public ulong LedgerId { get; }

    /// <summary>
    /// The id of the entry.
    /// </summary>
    public ulong EntryId { get; }

    /// <summary>
    /// The partition.
    /// </summary>
    public int Partition { get; }

    /// <summary>
    /// The batch index.
    /// </summary>
    public int BatchIndex { get; }

    public int CompareTo(MessageId? other)
    {
        if (other is null)
            return 1;

        var result = LedgerId.CompareTo(other.LedgerId);
        if (result != 0)
            return result;

        result = EntryId.CompareTo(other.EntryId);
        if (result != 0)
            return result;

        result = Partition.CompareTo(other.Partition);
        if (result != 0)
            return result;

        return BatchIndex.CompareTo(other.BatchIndex);
    }

    public static bool operator >(MessageId x, MessageId y)
        => x is not null && x.CompareTo(y) >= 1;

    public static bool operator <(MessageId x, MessageId y)
        => x is not null ? x.CompareTo(y) <= -1 : y is not null;

    public static bool operator >=(MessageId x, MessageId y)
        => x is not null ? x.CompareTo(y) >= 0 : y is null;

    public static bool operator <=(MessageId x, MessageId y)
        => x is null || x.CompareTo(y) <= 0;

    public override bool Equals(object? o)
        => o is MessageId id && Equals(id);

    public bool Equals(MessageId? other)
        => other is not null && LedgerId == other.LedgerId && EntryId == other.EntryId && Partition == other.Partition && BatchIndex == other.BatchIndex;

    public static bool operator ==(MessageId x, MessageId y)
        => ReferenceEquals(x, y) || (x is not null && x.Equals(y));

    public static bool operator !=(MessageId x, MessageId y)
        => !(x == y);

    public override int GetHashCode()
        => HashCode.Combine(LedgerId, EntryId, Partition, BatchIndex);

    public override string ToString()
        => $"{LedgerId}:{EntryId}:{Partition}:{BatchIndex}";

    internal MessageIdData ToMessageIdData()
    {
        var messageIdData = new MessageIdData();
        messageIdData.MapFrom(this);
        return messageIdData;
    }
}