/*
Real-time Online/Offline Charging System (OCS) for Telecom & ISP environments
Copyright (C) ITsysCOM GmbH

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>
*/

package servmanager

import (
	"fmt"
	"sync"

	"github.com/cgrates/birpc"
	"github.com/cgrates/birpc/context"
	"github.com/cgrates/cgrates/config"
	"github.com/cgrates/cgrates/engine"
	"github.com/cgrates/cgrates/utils"
	"github.com/cgrates/rpcclient"
)

// NewServiceManager returns a service manager
func NewServiceManager(shdWg *sync.WaitGroup, connMgr *engine.ConnManager,
	cfg *config.CGRConfig, registry *ServiceRegistry, services []Service) (sM *ServiceManager) {
	sM = &ServiceManager{
		cfg:      cfg,
		registry: registry,
		shdWg:    shdWg,
		connMgr:  connMgr,
		rldChan:  cfg.GetReloadChan(),
	}
	sM.AddServices(services...)
	return
}

// ServiceManager handles service management ran by the engine
type ServiceManager struct {
	sync.RWMutex // lock access to any shared data
	cfg          *config.CGRConfig
	registry     *ServiceRegistry // index here the services for accessing them by their IDs
	shdWg        *sync.WaitGroup  // list of shutdown items
	rldChan      <-chan string    // reload signals come over this channelc
	connMgr      *engine.ConnManager
}

// StartServices starts all enabled services
func (m *ServiceManager) StartServices(shutdown chan struct{}) {
	go m.handleReload(shutdown)
	for _, svc := range m.registry.List() {
		// TODO: verify if IsServiceInState check is needed. It should
		// be redundant since ServManager manages all services and this
		// runs only at startup
		if svc.ShouldRun() && !IsServiceInState(svc, utils.StateServiceUP) {
			m.shdWg.Add(1)
			go func() {
				if err := svc.Start(shutdown, m.registry); err != nil &&
					err != utils.ErrServiceAlreadyRunning { // in case the service was started in another gorutine
					utils.Logger.Err(fmt.Sprintf("<%s> failed to start <%s> service: %v", utils.ServiceManager, svc.ServiceName(), err))
					close(shutdown)
				}
				close(svc.StateChan(utils.StateServiceUP))
				utils.Logger.Info(fmt.Sprintf("<%s> started <%s> service", utils.ServiceManager, svc.ServiceName()))
			}()
		}
	}
	// startServer()
}

// AddServices adds given services
func (m *ServiceManager) AddServices(services ...Service) {
	m.Lock()
	for _, svc := range services {
		m.registry.Register(svc)
		if sAPIData, hasAPIData := serviceAPIData[svc.ServiceName()]; hasAPIData { // Add the internal connections
			rpcIntChan := make(chan birpc.ClientConnector, 1)
			m.connMgr.AddInternalConn(sAPIData[1], sAPIData[0], rpcIntChan)
			if len(sAPIData) > 2 { // Add the bidirectional API
				m.connMgr.AddInternalConn(sAPIData[2], sAPIData[0], rpcIntChan)
			}
			go func() { // ToDo: centralize management into one single goroutine
				if utils.StructChanTimeout(
					m.registry.Lookup(svc.ServiceName()).StateChan(utils.StateServiceUP),
					m.cfg.GeneralCfg().ConnectTimeout) {
					utils.Logger.Err(
						fmt.Sprintf("<%s> failed to register internal connection to service %s because of timeout waiting for ServiceUP state",
							utils.ServiceManager, svc.ServiceName()))
					// toDo: shutdown service
				}
				rpcIntChan <- svc.IntRPCConn()
			}()
		}
	}
	m.Unlock()
}

func (m *ServiceManager) handleReload(shutdown chan struct{}) {
	var serviceID string
	for {
		select {
		case <-shutdown:
			m.ShutdownServices()
			return
		case serviceID = <-m.rldChan:
		}
		if serviceID == config.RPCConnsJSON {
			go m.connMgr.Reload()
		} else {
			go m.reloadService(serviceID, shutdown)

		}
		// handle RPC server
	}
}

func (m *ServiceManager) reloadService(id string, shutdown chan struct{}) (err error) {
	svc := m.registry.Lookup(id)
	isUp := IsServiceInState(svc, utils.StateServiceUP)
	if svc.ShouldRun() {
		if isUp {
			// TODO: state channels must be reinitiated for both SERVICE_UP and SERVICE_DOWN.
			if err = svc.Reload(shutdown, m.registry); err != nil {
				utils.Logger.Err(fmt.Sprintf("<%s> failed to reload <%s> service: %v", utils.ServiceManager, svc.ServiceName(), err))
				close(shutdown)
				return // stop if we encounter an error
			}
			utils.Logger.Info(fmt.Sprintf("<%s> reloaded <%s> service", utils.ServiceManager, svc.ServiceName()))
		} else {
			m.shdWg.Add(1)
			if err = svc.Start(shutdown, m.registry); err != nil {
				utils.Logger.Err(fmt.Sprintf("<%s> failed to start <%s> serivce: %v", utils.ServiceManager, svc.ServiceName(), err))
				close(shutdown)
				return // stop if we encounter an error
			}
			close(svc.StateChan(utils.StateServiceUP))
			utils.Logger.Info(fmt.Sprintf("<%s> started <%s> service", utils.ServiceManager, svc.ServiceName()))
		}
	} else if isUp {
		if err = svc.Shutdown(m.registry); err != nil {
			utils.Logger.Err(fmt.Sprintf("<%s> failed to shut down <%s> service: %v", utils.ServiceManager, svc.ServiceName(), err))
			close(shutdown)
		}
		close(svc.StateChan(utils.StateServiceDOWN))
		utils.Logger.Info(fmt.Sprintf("<%s> stopped <%s> service", utils.ServiceManager, svc.ServiceName()))
		m.shdWg.Done()
	}
	return
}

// ShutdownServices will stop all services
func (m *ServiceManager) ShutdownServices() {
	for _, svc := range m.registry.List() {
		if IsServiceInState(svc, utils.StateServiceUP) {
			go func() {
				defer m.shdWg.Done()
				if err := svc.Shutdown(m.registry); err != nil {
					utils.Logger.Err(fmt.Sprintf("<%s> failed to shut down <%s> service: %v",
						utils.ServiceManager, svc.ServiceName(), err))
					return
				}
				close(svc.StateChan(utils.StateServiceDOWN))
				utils.Logger.Info(fmt.Sprintf("<%s> stopped <%s> service", utils.ServiceManager, svc.ServiceName()))
			}()
		}
	}
}

// Service interface that describes what functions should a service implement
type Service interface {
	// Start should handle the service start
	Start(chan struct{}, *ServiceRegistry) error
	// Reload handles the change of config
	Reload(chan struct{}, *ServiceRegistry) error
	// Shutdown stops the service
	Shutdown(*ServiceRegistry) error
	// ShouldRun returns if the service should be running
	ShouldRun() bool
	// ServiceName returns the service name
	ServiceName() string
	// StateChan returns the channel for specific state subscription
	StateChan(stateID string) chan struct{}
	// IntRPCConn returns the connector needed for internal RPC connections
	IntRPCConn() birpc.ClientConnector
}

// ArgsServiceID are passed to Start/Stop/Status RPC methods
type ArgsServiceID struct {
	ServiceID string
	APIOpts   map[string]any
}

// V1StartService starts a service with ID
func (m *ServiceManager) V1StartService(ctx *context.Context, args *ArgsServiceID, reply *string) (err error) {
	err = toggleService(args.ServiceID, true, m)
	if err != nil {
		return
	}
	*reply = utils.OK
	return
}

// V1StopService shuts-down a service with ID
func (m *ServiceManager) V1StopService(ctx *context.Context, args *ArgsServiceID, reply *string) (err error) {
	err = toggleService(args.ServiceID, false, m)
	if err != nil {
		return
	}
	*reply = utils.OK
	return
}

// V1ServiceStatus  returns the service status
func (m *ServiceManager) V1ServiceStatus(ctx *context.Context, args *ArgsServiceID, reply *string) error {
	m.RLock()
	defer m.RUnlock()

	svc := m.registry.Lookup(args.ServiceID)
	if svc == nil {
		return utils.ErrUnsupportedServiceID
	}

	if IsServiceInState(svc, utils.StateServiceUP) {
		*reply = utils.RunningCaps
	} else {
		*reply = utils.StoppedCaps
	}
	return nil
}

// GetConfig returns the Configuration
func (m *ServiceManager) GetConfig() *config.CGRConfig {
	m.RLock()
	defer m.RUnlock()
	return m.cfg
}

func toggleService(id string, status bool, srvMngr *ServiceManager) (err error) {
	srvMngr.Lock()
	defer srvMngr.Unlock()
	switch id {
	case utils.AccountS:
		srvMngr.cfg.AccountSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.ActionS:
		srvMngr.cfg.ActionSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.AdminS:
		srvMngr.cfg.AdminSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.AnalyzerS:
		srvMngr.cfg.AnalyzerSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.AttributeS:
		srvMngr.cfg.AttributeSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.CDRServer:
		srvMngr.cfg.CdrsCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.ChargerS:
		srvMngr.cfg.ChargerSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.DispatcherS:
		srvMngr.cfg.DispatcherSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.EEs:
		srvMngr.cfg.EEsCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.EFs:
		srvMngr.cfg.EFsCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.ERs:
		srvMngr.cfg.ERsCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
		// case utils.LoaderS:
		// 	srvMngr.cfg.LoaderCfg()[0].Enabled = status
		// 	srvMngr.cfg.GetReloadChan() <- serviceID
	case utils.RateS:
		srvMngr.cfg.RateSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.TrendS:
		srvMngr.cfg.TrendSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.RankingS:
		srvMngr.cfg.RankingSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.ResourceS:
		srvMngr.cfg.ResourceSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.RouteS:
		srvMngr.cfg.RouteSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.SessionS:
		srvMngr.cfg.SessionSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.StatS:
		srvMngr.cfg.StatSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.ThresholdS:
		srvMngr.cfg.ThresholdSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.TPeS:
		srvMngr.cfg.TpeSCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.AsteriskAgent:
		srvMngr.cfg.AsteriskAgentCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.DiameterAgent:
		srvMngr.cfg.DiameterAgentCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.DNSAgent:
		srvMngr.cfg.DNSAgentCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.FreeSWITCHAgent:
		srvMngr.cfg.FsAgentCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.KamailioAgent:
		srvMngr.cfg.KamAgentCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.RadiusAgent:
		srvMngr.cfg.RadiusAgentCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	case utils.SIPAgent:
		srvMngr.cfg.SIPAgentCfg().Enabled = status
		srvMngr.cfg.GetReloadChan() <- id
	default:
		err = utils.ErrUnsupportedServiceID
	}
	return
}

var serviceAPIData = map[string][]string{
	utils.AnalyzerS: {
		utils.AnalyzerSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaAnalyzerS)},
	utils.AdminS: {
		utils.AdminSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaAdminS)},
	utils.AttributeS: {
		utils.AttributeSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaAttributes)},
	utils.CacheS: {
		utils.CacheSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaCaches)},
	utils.CDRs: {
		utils.CDRsV1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaCDRs)},
	utils.ChargerS: {
		utils.ChargerSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaChargers)},
	utils.GuardianS: {
		utils.GuardianSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaGuardian)},
	utils.LoaderS: {
		utils.LoaderSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaLoaders)},
	utils.ResourceS: {
		utils.ResourceSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaResources)},
	utils.SessionS: {
		utils.SessionSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaSessionS),
		utils.ConcatenatedKey(rpcclient.BiRPCInternal, utils.MetaSessionS)},
	utils.StatS: {
		utils.StatSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaStats)},
	utils.RankingS: {
		utils.RankingSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaRankings)},
	utils.TrendS: {
		utils.TrendSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaTrends)},
	utils.RouteS: {
		utils.RouteSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaRoutes)},
	utils.ThresholdS: {
		utils.ThresholdSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaThresholds)},
	utils.ServiceManagerS: {
		utils.ServiceManagerV1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaServiceManager)},
	utils.ConfigS: {
		utils.ConfigSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaConfig)},
	utils.CoreS: {
		utils.CoreSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaCore)},
	utils.EEs: {
		utils.EeSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaEEs)},
	utils.RateS: {
		utils.RateSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaRates)},
	utils.DispatcherS: {
		utils.DispatcherSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaDispatchers)},
	utils.AccountS: {
		utils.AccountSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaAccounts)},
	utils.ActionS: {
		utils.ActionSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaActions)},
	utils.TPeS: {
		utils.TPeSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaTpes)},
	utils.EFs: {
		utils.EfSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaEFs)},
	utils.ERs: {
		utils.ErSv1,
		utils.ConcatenatedKey(utils.MetaInternal, utils.MetaERs)},
}

// IsServiceInState performs a non-blocking check to determine if a service is in the specified state.
func IsServiceInState(svc Service, state string) bool {
	select {
	case <-svc.StateChan(state):
		return true
	default:
		return false
	}
}