using System.Text.Json;

using VNLib.Net.Http;
using VNLib.Utils.Logging;
using VNLib.Utils.Extensions;
using VNLib.Plugins.Essentials.Oauth;
using VNLib.Plugins.Essentials.Sessions.OAuth;
using VNLib.Plugins.Essentials.Sessions.OAuth.Endpoints;
using VNLib.Plugins.Extensions.Loading;
using VNLib.Plugins.Extensions.Loading.Sql;
using VNLib.Plugins.Extensions.Loading.Events;
using VNLib.Plugins.Extensions.Loading.Routing;
using VNLib.Plugins.Extensions.Loading.Configuration;

namespace VNLib.Plugins.Essentials.Sessions.Oauth
{
    public sealed class O2SessionProviderEntry : IRuntimeSessionProvider
    {
        const string VNCACHE_CONFIG_KEY = "vncache";
        const string OAUTH2_CONFIG_KEY = "oauth2";

        private OAuth2SessionProvider? _sessions;

        bool IRuntimeSessionProvider.CanProcess(IHttpEvent entity)
        {
            //If authorization header is set try to process as oauth2 session
            return entity.Server.Headers.HeaderSet(System.Net.HttpRequestHeader.Authorization);
        }

        ValueTask<SessionHandle> ISessionProvider.GetSessionAsync(IHttpEvent entity, CancellationToken cancellationToken)
        {
            return _sessions!.GetSessionAsync(entity, cancellationToken);
        }
        

        void IRuntimeSessionProvider.Load(PluginBase plugin, ILogProvider localized)
        {
            //Try get vncache config element
            IReadOnlyDictionary<string, JsonElement> cacheConfig = plugin.GetConfig(VNCACHE_CONFIG_KEY);
            
            IReadOnlyDictionary<string, JsonElement> oauth2Config = plugin.GetConfig(OAUTH2_CONFIG_KEY);

            string tokenEpPath = oauth2Config["token_path"].GetString() ?? throw new KeyNotFoundException($"Missing required 'token_path' in '{OAUTH2_CONFIG_KEY}' config");

            //TODO fix with method that will wait until cache is actually loaded
            Lazy<ITokenManager> lazyTokenMan = new(() => _sessions!, false);

            //Init auth endpoint
            AccessTokenEndpoint authEp = new(tokenEpPath, plugin, lazyTokenMan);

            //route auth endpoint
            plugin.Route(authEp);
            
            //Route revocation endpoint
            plugin.Route<RevocationEndpoint>();

            //Run
            _ = WokerDoWorkAsync(plugin, localized, cacheConfig, oauth2Config);
        }

        /*
         * Starts and monitors the VNCache connection
         */

        private async Task WokerDoWorkAsync(PluginBase plugin, ILogProvider localized, IReadOnlyDictionary<string, JsonElement> cacheConfig, IReadOnlyDictionary<string, JsonElement> oauth2Config)
        {
            //Init cache client
            using VnCacheClient cache = new(plugin.IsDebug() ? plugin.Log : null, Utils.Memory.Memory.Shared);
            
            try
            {
                int cacheLimit = oauth2Config["cache_size"].GetInt32();
                int maxTokensPerApp = oauth2Config["max_tokens_per_app"].GetInt32();
                int sessionIdSize = (int)oauth2Config["access_token_size"].GetUInt32();
                TimeSpan tokenValidFor = oauth2Config["token_valid_for_sec"].GetTimeSpan(TimeParseType.Seconds);
                TimeSpan cleanupInterval = oauth2Config["gc_interval_sec"].GetTimeSpan(TimeParseType.Seconds);
                string sessionIdPrefix = oauth2Config["cache_prefix"].GetString() ?? throw new KeyNotFoundException($"Missing required key 'cache_prefix' in '{OAUTH2_CONFIG_KEY}' config");

                //init the id provider
                OAuth2SessionIdProvider idProv = new(sessionIdPrefix, maxTokensPerApp, sessionIdSize, tokenValidFor);

                //Try loading config
                await cache.LoadConfigAsync(plugin, cacheConfig);

                //Init session provider now that client is loaded
                _sessions = new(cache.Resource!, cacheLimit, idProv, plugin.GetContextOptions());

                //Schedule cleanup interval with the plugin scheduler
                plugin.ScheduleInterval(_sessions, cleanupInterval);


                localized.Information("Session provider loaded");

                //Run and wait for exit
                await cache.RunAsync(localized, plugin.UnloadToken);

            }
            catch (OperationCanceledException)
            {}
            catch (KeyNotFoundException e)
            {
                localized.Error("Missing required configuration variable for VnCache client: {0}", e.Message);
            }
            catch (Exception ex)
            {
                localized.Error(ex, "Cache client error occured in session provider");
            }
            finally
            {
                _sessions = null;
            }

            localized.Information("Cache client exited");
        }
    }
}