using System.Collections.Concurrent;
using YarpGateway.Models;
using YarpGateway.Data;
using Microsoft.Extensions.Logging;
using Microsoft.EntityFrameworkCore;

namespace YarpGateway.Services;

public class RouteInfo
{
    public long Id { get; set; }
    public string ClusterId { get; set; } = string.Empty;
    public string PathPattern { get; set; } = string.Empty;
    public int Priority { get; set; }
    public bool IsGlobal { get; set; }
}

public interface IRouteCache
{
    Task InitializeAsync();
    Task ReloadAsync();
    RouteInfo? GetRoute(string tenantCode, string serviceName);
    RouteInfo? GetRouteByPath(string path);
}

public class RouteCache : IRouteCache
{
    private readonly IDbContextFactory<GatewayDbContext> _dbContextFactory;
    private readonly ILogger<RouteCache> _logger;

    private readonly ConcurrentDictionary<string, RouteInfo> _globalRoutes = new();
    private readonly ConcurrentDictionary<string, ConcurrentDictionary<string, RouteInfo>> _tenantRoutes = new();
    private readonly ConcurrentDictionary<string, RouteInfo> _pathRoutes = new();
    private readonly ReaderWriterLockSlim _lock = new();

    public RouteCache(IDbContextFactory<GatewayDbContext> dbContextFactory, ILogger<RouteCache> logger)
    {
        _dbContextFactory = dbContextFactory;
        _logger = logger;
    }

    public async Task InitializeAsync()
    {
        _logger.LogInformation("Initializing route cache from database...");
        await LoadFromDatabaseAsync();
        _logger.LogInformation("Route cache initialized: {GlobalCount} global routes, {TenantCount} tenant routes",
            _globalRoutes.Count, _tenantRoutes.Count);
    }

    public async Task ReloadAsync()
    {
        _logger.LogInformation("Reloading route cache...");
        await LoadFromDatabaseAsync();
        _logger.LogInformation("Route cache reloaded");
    }

    public RouteInfo? GetRoute(string tenantCode, string serviceName)
    {
        _lock.EnterUpgradeableReadLock();
        try
        {
            // 1. 优先查找租户专用路由
            if (_tenantRoutes.TryGetValue(tenantCode, out var tenantRouteMap) &&
                tenantRouteMap.TryGetValue(serviceName, out var tenantRoute))
            {
                _logger.LogDebug("Found tenant-specific route: {Tenant}/{Service} -> {Cluster}",
                    tenantCode, serviceName, tenantRoute.ClusterId);
                return tenantRoute;
            }

            // 2. 查找全局路由
            if (_globalRoutes.TryGetValue(serviceName, out var globalRoute))
            {
                _logger.LogDebug("Found global route: {Service} -> {Cluster} for tenant {Tenant}",
                    serviceName, globalRoute.ClusterId, tenantCode);
                return globalRoute;
            }

            // 3. 没找到
            _logger.LogWarning("No route found for: {Tenant}/{Service}", tenantCode, serviceName);
            return null;
        }
        finally
        {
            _lock.ExitUpgradeableReadLock();
        }
    }

    public RouteInfo? GetRouteByPath(string path)
    {
        return _pathRoutes.TryGetValue(path, out var route) ? route : null;
    }

    private async Task LoadFromDatabaseAsync()
    {
        using var db = _dbContextFactory.CreateDbContext();

        var routes = await db.TenantRoutes
            .Where(r => r.Status == 1 && !r.IsDeleted)
            .ToListAsync();

        _lock.EnterWriteLock();
        try
        {
            _globalRoutes.Clear();
            _tenantRoutes.Clear();
            _pathRoutes.Clear();

            foreach (var route in routes)
            {
                var routeInfo = new RouteInfo
                {
                    Id = route.Id,
                    ClusterId = route.ClusterId,
                    PathPattern = route.PathPattern,
                    Priority = route.Priority,
                    IsGlobal = route.IsGlobal
                };

                if (route.IsGlobal)
                {
                    _globalRoutes[route.ServiceName] = routeInfo;
                    _pathRoutes[route.PathPattern] = routeInfo;
                }
                else if (!string.IsNullOrEmpty(route.TenantCode))
                {
                    _tenantRoutes.GetOrAdd(route.TenantCode, _ => new())
                        [route.ServiceName] = routeInfo;
                    _pathRoutes[route.PathPattern] = routeInfo;
                }
            }
        }
        finally
        {
            _lock.ExitWriteLock();
        }
    }
}