using System.Collections.Concurrent;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Xunit;
using YarpGateway.Data;
using YarpGateway.DynamicProxy;
using YarpGateway.Services;
using Fengling.Platform.Domain.AggregatesModel.GatewayAggregate;

namespace YarpGateway.Tests.Integration;

/// <summary>
/// 网关配置热重载集成测试
/// </summary>
[Collection("Integration Tests")]
public class ConfigReloadTests : IDisposable
{
    private readonly TestFixture _fixture;
    private readonly GatewayDbContext _dbContext;

    public ConfigReloadTests(TestFixture fixture)
    {
        _fixture = fixture;
        _dbContext = _fixture.CreateDbContext();
    }

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

    #region 配置重载测试

    [Fact]
    public async Task WhenConfigChanged_ReloadAsync_ShouldUpdateRouteCache()
    {
        // Arrange: 获取初始路由数量
        var routeCache = _fixture.GetRouteCache();
        var initialRoute = routeCache.GetRoute("test-tenant", "reload-test");
        initialRoute.Should().BeNull(); // 初始时不存在

        // 添加新路由
        var newRoute = new GwTenantRoute
        {
            Id = Guid.CreateVersion7().ToString("N"),
            TenantCode = "test-tenant",
            ServiceName = "reload-test",
            ClusterId = "member-cluster",
            Match = new GwRouteMatch { Path = "/api/reload-test/**" },
            Priority = 1,
            Status = 1,
            IsGlobal = false,
            CreatedTime = DateTime.UtcNow
        };

        _dbContext.GwTenantRoutes.Add(newRoute);
        await _dbContext.SaveChangesAsync();

        // Act: 重新加载配置
        await routeCache.ReloadAsync();

        // Assert: 应该能找到新路由
        var reloadedRoute = routeCache.GetRoute("test-tenant", "reload-test");
        reloadedRoute.Should().NotBeNull();
        reloadedRoute!.ClusterId.Should().Be("member-cluster");

        // 清理
        _dbContext.GwTenantRoutes.Remove(newRoute);
        await _dbContext.SaveChangesAsync();
    }

    [Fact]
    public async Task WhenConfigChanged_ReloadAsync_ShouldUpdateProxyConfig()
    {
        // Arrange
        var configProvider = _fixture.GetConfigProvider();
        var initialConfig = configProvider.GetConfig();
        var initialRouteCount = initialConfig.Routes.Count;

        // 添加新路由
        var newRoute = new GwTenantRoute
        {
            Id = Guid.CreateVersion7().ToString("N"),
            TenantCode = "",
            ServiceName = "proxy-reload-test",
            ClusterId = "member-cluster",
            Match = new GwRouteMatch { Path = "/api/proxy-reload/**" },
            Priority = 1,
            Status = 1,
            IsGlobal = true,
            CreatedTime = DateTime.UtcNow
        };

        _dbContext.GwTenantRoutes.Add(newRoute);
        await _dbContext.SaveChangesAsync();

        // 重新加载 RouteCache
        var routeCache = _fixture.GetRouteCache();
        await routeCache.ReloadAsync();

        // Act: 更新代理配置
        configProvider.UpdateConfig();

        // Assert
        var newConfig = configProvider.GetConfig();
        newConfig.Routes.Count.Should().BeGreaterThanOrEqualTo(initialRouteCount);

        // 验证可以通过服务名找到路由
        var route = newConfig.Routes.FirstOrDefault(r => 
            r.Metadata?.ContainsKey("ServiceName") == true &&
            r.Metadata["ServiceName"] == "proxy-reload-test");
        route.Should().NotBeNull();

        // 清理
        _dbContext.GwTenantRoutes.Remove(newRoute);
        await _dbContext.SaveChangesAsync();
    }

    [Fact]
    public async Task WhenRouteDisabled_Reload_ShouldRemoveFromCache()
    {
        // Arrange: 添加并确认路由存在
        var routeId = Guid.CreateVersion7().ToString("N");
        var newRoute = new GwTenantRoute
        {
            Id = routeId,
            TenantCode = "disable-test",
            ServiceName = "disable-test-service",
            ClusterId = "member-cluster",
            Match = new GwRouteMatch { Path = "/api/disable/**" },
            Priority = 1,
            Status = 1,
            IsGlobal = false,
            CreatedTime = DateTime.UtcNow
        };

        _dbContext.GwTenantRoutes.Add(newRoute);
        await _dbContext.SaveChangesAsync();

        var routeCache = _fixture.GetRouteCache();
        await routeCache.ReloadAsync();

        // 确认路由存在
        var routeBefore = routeCache.GetRoute("disable-test", "disable-test-service");
        routeBefore.Should().NotBeNull();

        // Act: 禁用路由
        newRoute.Status = 0;
        _dbContext.GwTenantRoutes.Update(newRoute);
        await _dbContext.SaveChangesAsync();

        await routeCache.ReloadAsync();

        // Assert: 路由应该从缓存中移除
        var routeAfter = routeCache.GetRoute("disable-test", "disable-test-service");
        routeAfter.Should().BeNull();

        // 清理
        _dbContext.GwTenantRoutes.Remove(newRoute);
        await _dbContext.SaveChangesAsync();
    }

    [Fact]
    public async Task WhenRouteDeleted_Reload_ShouldRemoveFromCache()
    {
        // Arrange
        var routeId = Guid.CreateVersion7().ToString("N");
        var newRoute = new GwTenantRoute
        {
            Id = routeId,
            TenantCode = "delete-test",
            ServiceName = "delete-test-service",
            ClusterId = "member-cluster",
            Match = new GwRouteMatch { Path = "/api/delete/**" },
            Priority = 1,
            Status = 1,
            IsGlobal = false,
            IsDeleted = false,
            CreatedTime = DateTime.UtcNow
        };

        _dbContext.GwTenantRoutes.Add(newRoute);
        await _dbContext.SaveChangesAsync();

        var routeCache = _fixture.GetRouteCache();
        await routeCache.ReloadAsync();

        // 确认路由存在
        var routeBefore = routeCache.GetRoute("delete-test", "delete-test-service");
        routeBefore.Should().NotBeNull();

        // Act: 软删除路由
        newRoute.IsDeleted = true;
        _dbContext.GwTenantRoutes.Update(newRoute);
        await _dbContext.SaveChangesAsync();

        await routeCache.ReloadAsync();

        // Assert: 路由应该从缓存中移除
        var routeAfter = routeCache.GetRoute("delete-test", "delete-test-service");
        routeAfter.Should().BeNull();

        // 清理
        _dbContext.GwTenantRoutes.Remove(newRoute);
        await _dbContext.SaveChangesAsync();
    }

    [Fact]
    public async Task WhenClusterChanged_Reload_ShouldUpdateClusterConfig()
    {
        // Arrange
        var configProvider = _fixture.GetConfigProvider();
        
        // 添加新集群
        var newCluster = new GwCluster
        {
            Id = Guid.CreateVersion7().ToString("N"),
            ClusterId = "reload-test-cluster",
            Name = "Reload Test Cluster",
            Status = 1,
            CreatedTime = DateTime.UtcNow,
            LoadBalancingPolicy = GwLoadBalancingPolicy.RoundRobin,
            Destinations = new List<GwDestination>
            {
                new()
                {
                    DestinationId = "dest-1",
                    Address = "http://reload-test:8080",
                    Weight = 1,
                    Status = 1
                }
            }
        };

        _dbContext.GwClusters.Add(newCluster);
        await _dbContext.SaveChangesAsync();

        // Act
        await _fixture.ReloadConfigurationAsync();

        // Assert
        var config = configProvider.GetConfig();
        var cluster = config.Clusters.FirstOrDefault(c => c.ClusterId == "reload-test-cluster");
        cluster.Should().NotBeNull();
        cluster!.Destinations.Should().ContainKey("dest-1");

        // 清理
        _dbContext.GwClusters.Remove(newCluster);
        await _dbContext.SaveChangesAsync();
    }

    [Fact]
    public async Task WhenDestinationAdded_Reload_ShouldIncludeNewDestination()
    {
        // Arrange: 获取现有集群
        var cluster = await _dbContext.GwClusters
            .Include(c => c.Destinations)
            .FirstOrDefaultAsync(c => c.ClusterId == "member-cluster");

        cluster.Should().NotBeNull();
        var initialDestCount = cluster!.Destinations.Count;

        // 添加新目标
        var newDest = new GwDestination
        {
            DestinationId = "new-dest",
            Address = "http://new-destination:8080",
            Weight = 1,
            Status = 1
        };
        cluster.Destinations.Add(newDest);

        await _dbContext.SaveChangesAsync();

        // Act
        await _fixture.ReloadConfigurationAsync();

        // Assert
        var configProvider = _fixture.GetConfigProvider();
        var config = configProvider.GetConfig();
        var updatedCluster = config.Clusters.FirstOrDefault(c => c.ClusterId == "member-cluster");
        updatedCluster.Should().NotBeNull();
        updatedCluster!.Destinations.Should().ContainKey("new-dest");

        // 清理
        cluster.Destinations.Remove(newDest);
        await _dbContext.SaveChangesAsync();
    }

    #endregion

    #region 并发重载测试

    [Fact]
    public async Task ConcurrentReload_ShouldBeThreadSafe()
    {
        // Arrange
        var routeCache = _fixture.GetRouteCache();
        var configProvider = _fixture.GetConfigProvider();

        // Act: 并发执行多次重载
        var tasks = Enumerable.Range(0, 10)
            .Select(_ => Task.Run(async () =>
            {
                await routeCache.ReloadAsync();
                configProvider.UpdateConfig();
            }))
            .ToList();

        // 不应该抛出异常
        await Task.WhenAll(tasks);

        // Assert: 配置应该保持一致
        var config = configProvider.GetConfig();
        config.Should().NotBeNull();
        config.Routes.Should().NotBeNull();
        config.Clusters.Should().NotBeNull();
    }

    #endregion

    #region 配置变更通知测试（模拟）

    [Fact]
    public async Task SimulateNotify_ShouldTriggerReload()
    {
        // Arrange
        var routeCache = _fixture.GetRouteCache();
        var configProvider = _fixture.GetConfigProvider();

        // 添加新路由
        var newRoute = new GwTenantRoute
        {
            Id = Guid.CreateVersion7().ToString("N"),
            TenantCode = "",
            ServiceName = "notify-test",
            ClusterId = "member-cluster",
            Match = new GwRouteMatch { Path = "/api/notify/**" },
            Priority = 1,
            Status = 1,
            IsGlobal = true,
            CreatedTime = DateTime.UtcNow
        };

        _dbContext.GwTenantRoutes.Add(newRoute);
        await _dbContext.SaveChangesAsync();

        // Act: 模拟接收到 NOTIFY 事件后手动触发重载
        // 在真实环境中，这是由 PgSqlConfigChangeListener 自动处理的
        await routeCache.ReloadAsync();
        configProvider.UpdateConfig();

        // Assert
        var route = routeCache.GetRoute("any-tenant", "notify-test");
        route.Should().NotBeNull();
        route!.ClusterId.Should().Be("test-cluster");

        // 清理
        _dbContext.GwTenantRoutes.Remove(newRoute);
        await _dbContext.SaveChangesAsync();
    }

    [Fact]
    public async Task ConfigChangeToken_ShouldSignalChange()
    {
        // Arrange
        var configProvider = _fixture.GetConfigProvider();
        var config = configProvider.GetConfig();

        // 获取变更令牌
        var changeToken = config.ChangeToken;
        var changeDetected = false;

        // 注册变更回调
        using var registration = changeToken.RegisterChangeCallback(_ =>
        {
            changeDetected = true;
        }, null);

        // Act: 添加新路由并更新配置
        var newRoute = new GwTenantRoute
        {
            Id = Guid.CreateVersion7().ToString("N"),
            TenantCode = "",
            ServiceName = "token-test",
            ClusterId = "member-cluster",
            Match = new GwRouteMatch { Path = "/api/token/**" },
            Priority = 1,
            Status = 1,
            IsGlobal = true,
            CreatedTime = DateTime.UtcNow
        };

        _dbContext.GwTenantRoutes.Add(newRoute);
        await _dbContext.SaveChangesAsync();

        await _fixture.ReloadConfigurationAsync();

        // 获取新配置
        var newConfig = configProvider.GetConfig();

        // Assert: 新配置的 ChangeToken 应该与老配置不同
        newConfig.ChangeToken.Should().NotBeSameAs(changeToken);

        // 清理
        _dbContext.GwTenantRoutes.Remove(newRoute);
        await _dbContext.SaveChangesAsync();
    }

    #endregion

    #region 性能测试

    [Fact]
    public async Task ReloadPerformance_ShouldBeFast()
    {
        // Arrange
        var routeCache = _fixture.GetRouteCache();
        var stopwatch = System.Diagnostics.Stopwatch.StartNew();

        // Act: 执行多次重载
        for (int i = 0; i < 10; i++)
        {
            await routeCache.ReloadAsync();
        }

        stopwatch.Stop();

        // Assert: 10 次重载应该在合理时间内完成
        stopwatch.ElapsedMilliseconds.Should().BeLessThan(5000);
    }

    [Fact]
    public async Task LargeConfigReload_ShouldHandleGracefully()
    {
        // Arrange: 批量添加路由
        var routes = new List<GwTenantRoute>();
        for (int i = 0; i < 100; i++)
        {
            routes.Add(new GwTenantRoute
            {
                Id = Guid.CreateVersion7().ToString("N"),
                TenantCode = $"perf-tenant-{i % 10}",
                ServiceName = $"perf-service-{i}",
                ClusterId = "member-cluster",
                Match = new GwRouteMatch { Path = $"/api/perf-{i}/**" },
                Priority = 1,
                Status = 1,
                IsGlobal = i % 10 == 0,
                CreatedTime = DateTime.UtcNow
            });
        }

        _dbContext.GwTenantRoutes.AddRange(routes);
        await _dbContext.SaveChangesAsync();

        var routeCache = _fixture.GetRouteCache();
        var stopwatch = System.Diagnostics.Stopwatch.StartNew();

        // Act
        await routeCache.ReloadAsync();

        stopwatch.Stop();

        // Assert: 100 条路由的重载应该在合理时间内完成
        stopwatch.ElapsedMilliseconds.Should().BeLessThan(5000);

        // 验证路由已加载
        var route = routeCache.GetRoute("perf-tenant-0", "perf-service-0");
        route.Should().NotBeNull();

        // 清理
        _dbContext.GwTenantRoutes.RemoveRange(routes);
        await _dbContext.SaveChangesAsync();
    }

    #endregion
}