using System.Collections.Concurrent;
using Fengling.Platform.Domain.AggregatesModel.GatewayAggregate;
using YarpGateway.Data;
using Microsoft.Extensions.Logging;
using Microsoft.EntityFrameworkCore;

namespace YarpGateway.Services;

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

public interface IRouteCache
{
    Task InitializeAsync();
    Task ReloadAsync();
    RouteInfo? GetRoute(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> _routes = 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...");
        try
        {
            await LoadFromDatabaseAsync();
            _logger.LogInformation("Route cache initialized: {Count} routes", _routes.Count);
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Failed to load routes from database. This is normal if database is not initialized yet.");
        }
    }

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

    public RouteInfo? GetRoute(string? serviceName)
    {
        if (string.IsNullOrEmpty(serviceName))
        {
            _logger.LogDebug("GetRoute called with null or empty serviceName");
            return null;
        }
        
        _lock.EnterReadLock();
        try
        {
            if (_routes.TryGetValue(serviceName, out var route))
            {
                _logger.LogDebug("Found route: {Service} -> {Cluster}", serviceName, route.ClusterId);
                return route;
            }

            _logger.LogWarning("No route found for: {Service}", serviceName);
            return null;
        }
        finally
        {
            _lock.ExitReadLock();
        }
    }

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

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

        List<GwRoute> routes;
        try
        {
            routes = await db.GwRoutes
                .Where(r => r.Status == 1 && !r.IsDeleted)
                .ToListAsync();
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Database table not found. Returning empty route list.");
            routes = new List<GwRoute>();
        }

        _lock.EnterWriteLock();
        try
        {
            _routes.Clear();
            _pathRoutes.Clear();

            foreach (var route in routes)
            {
                var pathPattern = route.Match?.Path ?? string.Empty;

                var routeInfo = new RouteInfo
                {
                    Id = route.Id,
                    ClusterId = route.ClusterId,
                    PathPattern = pathPattern,
                    Priority = route.Priority
                };

                _routes[route.ServiceName] = routeInfo;
                _pathRoutes[pathPattern] = routeInfo;
                
                _logger.LogDebug("Loaded route: {Service} -> {Cluster}", 
                    route.ServiceName, route.ClusterId);
            }
        }
        finally
        {
            _lock.ExitWriteLock();
        }
    }
}