using System.Collections.Concurrent;
using Microsoft.EntityFrameworkCore;
using Yarp.ReverseProxy.Configuration;
using YarpGateway.Data;
using YarpGateway.Models;

namespace YarpGateway.Config;

public class DatabaseRouteConfigProvider
{
    private readonly IDbContextFactory<GatewayDbContext> _dbContextFactory;
    private readonly ConcurrentDictionary<string, RouteConfig> _routes = new();
    private readonly SemaphoreSlim _lock = new(1, 1);
    private readonly ILogger<DatabaseRouteConfigProvider> _logger;

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

    public IReadOnlyList<RouteConfig> GetRoutes()
    {
        return _routes.Values.ToList().AsReadOnly();
    }

    public async Task ReloadAsync()
    {
        await _lock.WaitAsync();
        try
        {
            await LoadConfigInternalAsync();
        }
        finally
        {
            _lock.Release();
        }
    }

    private async Task LoadConfigAsync()
    {
        await LoadConfigInternalAsync();
    }

    private async Task LoadConfigInternalAsync()
    {
        await using var dbContext = _dbContextFactory.CreateDbContext();

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

        var newRoutes = new ConcurrentDictionary<string, RouteConfig>();

        foreach (var route in routes)
        {
            var config = new RouteConfig
            {
                RouteId = route.Id.ToString(),
                ClusterId = route.ClusterId,
                Match = new RouteMatch { Path = route.PathPattern },
                Metadata = new Dictionary<string, string>
                {
                    ["TenantCode"] = route.TenantCode,
                    ["ServiceName"] = route.ServiceName,
                },
            };
            newRoutes[route.Id.ToString()] = config;
        }

        _routes.Clear();
        foreach (var route in newRoutes)
        {
            _routes[route.Key] = route.Value;
        }

        _logger.LogInformation("Loaded {Count} routes from database", _routes.Count);
    }
}