using System;
using System.Collections.Generic;
using NewLife.NovaDb.Cluster;
using NewLife.NovaDb.Core;
using NewLife.NovaDb.WAL;
using Xunit;

namespace XUnitTest.Cluster;

public class ReplicationManagerTests : IDisposable
{
    private readonly ReplicationManager _manager;
    private readonly NodeInfo _masterInfo;

    public ReplicationManagerTests()
    {
        _masterInfo = new NodeInfo
        {
            NodeId = "master-1",
            Endpoint = "127.0.0.1:9000",
            Role = NodeRole.Master
        };
        _manager = new ReplicationManager("/tmp/test.wal", _masterInfo);
    }

    public void Dispose()
    {
        _manager.Dispose();
    }

    [Fact(DisplayName = "测试创建复制管理器")]
    public void TestCreateReplicationManager()
    {
        Assert.NotNull(_manager);
        Assert.Equal("master-1", _manager.MasterInfo.NodeId);
        Assert.Equal(NodeRole.Master, _manager.MasterInfo.Role);
        Assert.Equal(NodeState.Online, _manager.MasterInfo.State);
        Assert.Equal(0, _manager.SlaveCount);
        Assert.Equal(0UL, _manager.MasterLsn);
    }

    [Fact(DisplayName = "测试注册从节点")]
    public void TestRegisterSlave()
    {
        var slave = new NodeInfo
        {
            NodeId = "slave-1",
            Endpoint = "127.0.0.1:9001",
            Role = NodeRole.Slave
        };

        _manager.RegisterSlave(slave);

        Assert.Equal(1, _manager.SlaveCount);
        var retrieved = _manager.GetSlave("slave-1");
        Assert.NotNull(retrieved);
        Assert.Equal("slave-1", retrieved!.NodeId);
        Assert.Equal(NodeState.Syncing, retrieved.State);
    }

    [Fact(DisplayName = "测试移除从节点")]
    public void TestRemoveSlave()
    {
        var slave = new NodeInfo
        {
            NodeId = "slave-1",
            Endpoint = "127.0.0.1:9001",
            Role = NodeRole.Slave
        };

        _manager.RegisterSlave(slave);
        Assert.Equal(1, _manager.SlaveCount);

        var removed = _manager.RemoveSlave("slave-1");
        Assert.True(removed);
        Assert.Equal(0, _manager.SlaveCount);
        Assert.Null(_manager.GetSlave("slave-1"));

        // 移除不存在的节点
        Assert.False(_manager.RemoveSlave("slave-nonexistent"));
    }

    [Fact(DisplayName = "测试追加复制记录")]
    public void TestAppendRecord()
    {
        var record1 = new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 1, Data = new Byte[] { 1, 2, 3 } };
        var record2 = new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 2, Data = new Byte[] { 4, 5, 6 } };

        _manager.AppendRecord(record1);
        Assert.Equal(1UL, _manager.MasterLsn);
        Assert.Equal(1UL, record1.Lsn);

        _manager.AppendRecord(record2);
        Assert.Equal(2UL, _manager.MasterLsn);
        Assert.Equal(2UL, record2.Lsn);
    }

    [Fact(DisplayName = "测试获取待复制记录")]
    public void TestGetPendingRecords()
    {
        var slave = new NodeInfo { NodeId = "slave-1", Endpoint = "127.0.0.1:9001", Role = NodeRole.Slave };
        _manager.RegisterSlave(slave);

        // 追加 3 条记录
        for (var i = 0; i < 3; i++)
        {
            _manager.AppendRecord(new WalRecord
            {
                RecordType = WalRecordType.UpdatePage,
                PageId = (UInt64)i,
                Data = new Byte[] { (Byte)i }
            });
        }

        // 获取全部待复制记录
        var pending = _manager.GetPendingRecords("slave-1");
        Assert.Equal(3, pending.Count);
        Assert.Equal(1UL, pending[0].Lsn);
        Assert.Equal(3UL, pending[2].Lsn);

        // 使用 maxCount 限制
        var limited = _manager.GetPendingRecords("slave-1", 2);
        Assert.Equal(2, limited.Count);
    }

    [Fact(DisplayName = "测试确认复制")]
    public void TestAcknowledgeReplication()
    {
        var slave = new NodeInfo { NodeId = "slave-1", Endpoint = "127.0.0.1:9001", Role = NodeRole.Slave };
        _manager.RegisterSlave(slave);

        _manager.AppendRecord(new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 1, Data = Array.Empty<Byte>() });
        _manager.AppendRecord(new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 2, Data = Array.Empty<Byte>() });

        // 确认第一条
        _manager.AcknowledgeReplication("slave-1", 1);
        var pending = _manager.GetPendingRecords("slave-1");
        Assert.Single(pending);
        Assert.Equal(2UL, pending[0].Lsn);
        Assert.Equal(NodeState.Syncing, slave.State);

        // 确认全部
        _manager.AcknowledgeReplication("slave-1", 2);
        pending = _manager.GetPendingRecords("slave-1");
        Assert.Empty(pending);
        Assert.Equal(NodeState.Online, slave.State);
    }

    [Fact(DisplayName = "测试复制延迟")]
    public void TestReplicationLag()
    {
        var slave = new NodeInfo { NodeId = "slave-1", Endpoint = "127.0.0.1:9001", Role = NodeRole.Slave };
        _manager.RegisterSlave(slave);

        _manager.AppendRecord(new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 1, Data = Array.Empty<Byte>() });
        _manager.AppendRecord(new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 2, Data = Array.Empty<Byte>() });
        _manager.AppendRecord(new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 3, Data = Array.Empty<Byte>() });

        Assert.Equal(3UL, _manager.GetReplicationLag("slave-1"));

        _manager.AcknowledgeReplication("slave-1", 2);
        Assert.Equal(1UL, _manager.GetReplicationLag("slave-1"));

        _manager.AcknowledgeReplication("slave-1", 3);
        Assert.Equal(0UL, _manager.GetReplicationLag("slave-1"));
    }

    [Fact(DisplayName = "测试完全同步检查")]
    public void TestIsFullySynced()
    {
        // 无从节点时认为已同步
        Assert.True(_manager.IsFullySynced(0));

        var slave1 = new NodeInfo { NodeId = "slave-1", Endpoint = "127.0.0.1:9001", Role = NodeRole.Slave };
        var slave2 = new NodeInfo { NodeId = "slave-2", Endpoint = "127.0.0.1:9002", Role = NodeRole.Slave };
        _manager.RegisterSlave(slave1);
        _manager.RegisterSlave(slave2);

        _manager.AppendRecord(new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 1, Data = Array.Empty<Byte>() });
        _manager.AppendRecord(new WalRecord { RecordType = WalRecordType.UpdatePage, PageId = 2, Data = Array.Empty<Byte>() });

        Assert.False(_manager.IsFullySynced(2));

        _manager.AcknowledgeReplication("slave-1", 2);
        Assert.False(_manager.IsFullySynced(2));

        _manager.AcknowledgeReplication("slave-2", 2);
        Assert.True(_manager.IsFullySynced(2));
    }

    [Fact(DisplayName = "测试清理缓冲区")]
    public void TestCleanupBuffer()
    {
        var slave1 = new NodeInfo { NodeId = "slave-1", Endpoint = "127.0.0.1:9001", Role = NodeRole.Slave };
        var slave2 = new NodeInfo { NodeId = "slave-2", Endpoint = "127.0.0.1:9002", Role = NodeRole.Slave };
        _manager.RegisterSlave(slave1);
        _manager.RegisterSlave(slave2);

        for (var i = 0; i < 5; i++)
        {
            _manager.AppendRecord(new WalRecord
            {
                RecordType = WalRecordType.UpdatePage,
                PageId = (UInt64)i,
                Data = Array.Empty<Byte>()
            });
        }

        // slave1 确认到 3，slave2 确认到 2，最小值为 2
        _manager.AcknowledgeReplication("slave-1", 3);
        _manager.AcknowledgeReplication("slave-2", 2);

        var cleaned = _manager.CleanupBuffer();
        Assert.Equal(2, cleaned);

        // 验证 slave-2 的待复制记录从 LSN 3 开始
        var pending = _manager.GetPendingRecords("slave-2");
        Assert.Equal(3, pending.Count);
        Assert.Equal(3UL, pending[0].Lsn);
    }

    [Fact(DisplayName = "测试注册主节点角色抛出异常")]
    public void TestRegisterMasterRoleThrows()
    {
        var masterNode = new NodeInfo { NodeId = "master-2", Endpoint = "127.0.0.1:9010", Role = NodeRole.Master };

        var ex = Assert.Throws<NovaException>(() => _manager.RegisterSlave(masterNode));
        Assert.Equal(ErrorCode.ReplicationError, ex.Code);
    }

    [Fact(DisplayName = "测试重复注册从节点抛出异常")]
    public void TestDuplicateRegistrationThrows()
    {
        var slave = new NodeInfo { NodeId = "slave-1", Endpoint = "127.0.0.1:9001", Role = NodeRole.Slave };
        _manager.RegisterSlave(slave);

        var duplicate = new NodeInfo { NodeId = "slave-1", Endpoint = "127.0.0.1:9002", Role = NodeRole.Slave };
        var ex = Assert.Throws<NovaException>(() => _manager.RegisterSlave(duplicate));
        Assert.Equal(ErrorCode.ReplicationError, ex.Code);
    }

    [Fact(DisplayName = "测试不存在的节点抛出异常")]
    public void TestNonExistentNodeThrows()
    {
        var ex1 = Assert.Throws<NovaException>(() => _manager.GetPendingRecords("nonexistent"));
        Assert.Equal(ErrorCode.NodeNotFound, ex1.Code);

        var ex2 = Assert.Throws<NovaException>(() => _manager.AcknowledgeReplication("nonexistent", 1));
        Assert.Equal(ErrorCode.NodeNotFound, ex2.Code);

        var ex3 = Assert.Throws<NovaException>(() => _manager.GetReplicationLag("nonexistent"));
        Assert.Equal(ErrorCode.NodeNotFound, ex3.Code);
    }
}