/*
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 engine

import (
	"fmt"
	"strings"
	"sync"

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

// NewConnManager returns the Connection Manager
func NewConnManager(cfg *config.CGRConfig, rpcInternal map[string]chan birpc.ClientConnector) (cM *ConnManager) {
	cM = &ConnManager{
		cfg:         cfg,
		rpcInternal: rpcInternal,
		connCache:   ltcache.NewCache(-1, 0, true, false, nil),
		connLks:     make(map[string]*sync.Mutex),
	}
	for connID := range cfg.RPCConns() {
		cM.connLks[connID] = new(sync.Mutex)
	}
	SetConnManager(cM)
	return
}

// ConnManager handle the RPC connections
type ConnManager struct {
	cfg         *config.CGRConfig
	rpcInternal map[string]chan birpc.ClientConnector
	connCache   *ltcache.Cache
	connLks     map[string]*sync.Mutex // control connection initialization and caching
}

// lkConn will lock a connection if preconfigured
func (cM *ConnManager) lkConn(connID string) {
	if lk, hasConn := cM.connLks[connID]; hasConn {
		lk.Lock()
	}
}

// unlkConn will unlock a connection if preconfigured
func (cM *ConnManager) unlkConn(connID string) {
	if lk, hasConn := cM.connLks[connID]; hasConn {
		lk.Unlock()
	}
}

// getConn is used to retrieve a connection from cache
// in case this doesn't exist create it and cache it
func (cM *ConnManager) getConn(ctx *context.Context, connID string) (conn birpc.ClientConnector, err error) {
	//try to get the connection from cache
	if x, ok := Cache.Get(utils.CacheRPCConnections, connID); ok {
		if x == nil {
			return nil, utils.ErrNotFound
		}
		return x.(birpc.ClientConnector), nil
	}
	// in case we don't find in cache create the connection and add this in cache
	var intChan chan birpc.ClientConnector
	var isInternalRPC bool
	var connCfg *config.RPCConn
	if intChan, isInternalRPC = cM.rpcInternal[connID]; isInternalRPC {
		connCfg = cM.cfg.RPCConns()[rpcclient.InternalRPC]
		if strings.HasPrefix(connID, rpcclient.BiRPCInternal) {
			connCfg = cM.cfg.RPCConns()[rpcclient.BiRPCInternal]
		}
	} else {
		connCfg = cM.cfg.RPCConns()[connID]
		for _, rpcConn := range connCfg.Conns {
			if rpcConn.Address == utils.MetaInternal {
				intChan = IntRPC.GetInternalChanel()
				break
			}
		}
	}
	if conn, err = cM.getConnWithConfig(ctx, connID, connCfg, intChan); err != nil {
		return
	}
	err = Cache.Set(utils.CacheRPCConnections, connID, conn, nil,
		true, utils.NonTransactional)
	return
}

func (cM *ConnManager) getConnWithConfig(ctx *context.Context, connID string, connCfg *config.RPCConn,
	intChan chan birpc.ClientConnector) (conn birpc.ClientConnector, err error) {
	if connCfg.Strategy == rpcclient.PoolParallel {
		rpcConnCfg := connCfg.Conns[0] // for parallel we need only the first connection
		codec := rpcclient.GOBrpc
		switch {
		case rpcConnCfg.Address == rpcclient.InternalRPC:
			codec = rpcclient.InternalRPC
		case rpcConnCfg.Address == rpcclient.BiRPCInternal:
			codec = rpcclient.BiRPCInternal
		case rpcConnCfg.Transport == utils.EmptyString:
			intChan = nil
		case rpcConnCfg.Transport == rpcclient.GOBrpc,
			rpcConnCfg.Transport == rpcclient.JSONrpc,
			rpcConnCfg.Transport == rpcclient.BiRPCGOB,
			rpcConnCfg.Transport == rpcclient.BiRPCJSON:
			codec = rpcConnCfg.Transport
			intChan = nil
		default:
			err = fmt.Errorf("Unsupported transport: <%s>", rpcConnCfg.Transport)
			return
		}
		if conn, err = rpcclient.NewRPCParallelClientPool(ctx, utils.TCP, rpcConnCfg.Address, rpcConnCfg.TLS,
			utils.FirstNonEmpty(rpcConnCfg.ClientKey, cM.cfg.TLSCfg().ClientKey),
			utils.FirstNonEmpty(rpcConnCfg.ClientCertificate, cM.cfg.TLSCfg().ClientCerificate),
			utils.FirstNonEmpty(rpcConnCfg.CaCertificate, cM.cfg.TLSCfg().CaCertificate),
			utils.FirstIntNonEmpty(rpcConnCfg.ConnectAttempts, cM.cfg.GeneralCfg().ConnectAttempts),
			utils.FirstIntNonEmpty(rpcConnCfg.Reconnects, cM.cfg.GeneralCfg().Reconnects),
			utils.FirstDurationNonEmpty(rpcConnCfg.MaxReconnectInterval, cM.cfg.GeneralCfg().MaxReconnectInterval),
			utils.FibDuration,
			utils.FirstDurationNonEmpty(rpcConnCfg.ConnectTimeout, cM.cfg.GeneralCfg().ConnectTimeout),
			utils.FirstDurationNonEmpty(rpcConnCfg.ReplyTimeout, cM.cfg.GeneralCfg().ReplyTimeout),
			codec, intChan, int64(cM.cfg.GeneralCfg().MaxParallelConns), false, ctx.Client); err != nil {
			return
		}
	} else {
		if conn, err = NewRPCPool(ctx, connCfg.Strategy,
			cM.cfg.TLSCfg().ClientKey,
			cM.cfg.TLSCfg().ClientCerificate,
			cM.cfg.TLSCfg().CaCertificate,
			cM.cfg.GeneralCfg().ConnectAttempts,
			cM.cfg.GeneralCfg().Reconnects,
			cM.cfg.GeneralCfg().MaxReconnectInterval,
			cM.cfg.GeneralCfg().ConnectTimeout,
			cM.cfg.GeneralCfg().ReplyTimeout,
			connCfg.Conns, intChan, false, connID, cM.connCache); err != nil {
			return
		}
	}
	if ctx.Client != nil {
		for _, c := range connCfg.Conns {
			if c.Address == rpcclient.BiRPCInternal { // register only on internal
				var rply string
				if err = conn.Call(ctx, utils.SessionSv1RegisterInternalBiJSONConn,
					connID, &rply); err != nil {
					utils.Logger.Crit(fmt.Sprintf("<%s> Could not register biRPCClient, error: <%s>",
						utils.SessionS, err.Error()))
					return
				}
				break
			}
		}
	}
	return
}

// Call gets the connection calls the method on it
func (cM *ConnManager) Call(ctx *context.Context, connIDs []string, method string, arg, reply any) (err error) {
	if len(connIDs) == 0 {
		return utils.NewErrMandatoryIeMissing("connIDs")
	}
	var conn birpc.ClientConnector
	for _, connID := range connIDs {
		cM.lkConn(connID)
		conn, err = cM.getConn(ctx, connID)
		cM.unlkConn(connID)
		if err != nil {
			continue
		}
		if err = conn.Call(ctx, method, arg, reply); !rpcclient.ShouldFailover(err) {
			return
		}
	}
	return
}

// CallWithConnIDs will call the method only on specified rpcconns
func (cM *ConnManager) CallWithConnIDs(connIDs []string, subsHostIDs utils.StringSet, method string, arg, reply any) (err error) {
	if len(connIDs) == 0 {
		return utils.NewErrMandatoryIeMissing("connIDs")
	}
	// no connection for this id exit here
	if subsHostIDs.Size() == 0 {
		return
	}
	var conn birpc.ClientConnector
	for _, connID := range connIDs {
		// recreate the config with only conns that are needed
		connCfg := cM.cfg.RPCConns()[connID]
		newCfg := &config.RPCConn{
			Strategy: connCfg.Strategy,
			PoolSize: connCfg.PoolSize,
			// alloc for all connection in order to not increase the size later
			Conns: make([]*config.RemoteHost, 0, len(connCfg.Conns)),
		}
		for _, conn := range connCfg.Conns {
			if conn.ID != utils.EmptyString &&
				subsHostIDs.Has(conn.ID) {
				newCfg.Conns = append(newCfg.Conns, conn) // the slice will never grow
			}
		}
		if len(newCfg.Conns) == 0 {
			// skip this pool if no connection matches
			continue
		}
		if conn, err = cM.getConnWithConfig(context.TODO(), connID, newCfg, nil); err != nil {
			continue
		}
		if err = conn.Call(context.TODO(), method, arg, reply); !rpcclient.ShouldFailover(err) {
			return
		}
	}
	return
}

// Reload will clear all RPC related caches
func (cM *ConnManager) Reload() {
	Cache.Clear([]string{utils.CacheRPCConnections})
	Cache.Clear([]string{utils.CacheReplicationHosts})
	cM.connCache.Clear()
}