package session

import (
	"encoding/json"
	"fmt"
	"net"
	"strconv"
	"sync"

	omd "git.loafle.net/overflow/model/discovery"
	ounc "git.loafle.net/overflow/util-go/net/cidr"
	"git.loafle.net/overflow_scanner/probe/discovery/types"
	"git.loafle.net/overflow_scanner/probe/internal/pcap"
)

type DiscoverySession interface {
	InitWithRequest(request types.DiscoveryRequest) error

	DiscoveryRequest() types.DiscoveryRequest

	PCapScanner() pcap.PCapScanner

	Zone() *omd.Zone
	Host() *omd.Host
	Port() *omd.Port

	DiscoveryConfig() *omd.DiscoveryConfig

	DiscoverHost() *omd.DiscoverHost
	DiscoverPort() *omd.DiscoverPort
	DiscoverService() *omd.DiscoverService

	TargetHosts() []net.IP

	SetDiscoveryDelegator(chan<- interface{})

	AddHost(host *omd.Host) *omd.Host
	AddPort(port *omd.Port) *omd.Port
	AddService(service *omd.Service) *omd.Service

	DiscoveredHost(address string) *omd.Host
	DiscoveredAllHosts(includeMac bool) map[string]*omd.Host
	DiscoveredPort(host *omd.Host, portNumber int) map[string]*omd.Port
	DiscoveredAllPorts() map[*omd.Host]map[json.Number]map[string]*omd.Port
	DiscoveredService(port *omd.Port, name string) map[string]*omd.Service
	DiscoveredAllServices() map[*omd.Port]map[string]map[string]*omd.Service

	StopChan() <-chan struct{}
}

type ofDiscoverySession struct {
	discoveryRequest types.DiscoveryRequest
	pCapScanner      pcap.PCapScanner

	zone *omd.Zone
	host *omd.Host
	port *omd.Port

	discoveryConfig *omd.DiscoveryConfig

	discoverHost    *omd.DiscoverHost
	discoverPort    *omd.DiscoverPort
	discoverService *omd.DiscoverService

	targetHosts []net.IP

	discoveryDelegator chan<- interface{}

	discoveredMtx   sync.RWMutex
	hosts           map[string]*omd.Host
	includeMachosts map[string]*omd.Host
	ports           map[*omd.Host]map[json.Number]map[string]*omd.Port
	services        map[*omd.Port]map[string]map[string]*omd.Service

	stopChan chan struct{}
}

func (ds *ofDiscoverySession) init(request types.DiscoveryRequest) {
	ds.discoveryRequest = request
	ds.zone = nil
	ds.host = nil
	ds.port = nil
	ds.discoverHost = nil
	ds.discoverPort = nil
	ds.discoverService = nil
	ds.pCapScanner = nil

	ds.hosts = make(map[string]*omd.Host)
	ds.includeMachosts = make(map[string]*omd.Host)
	ds.ports = make(map[*omd.Host]map[json.Number]map[string]*omd.Port)
	ds.services = make(map[*omd.Port]map[string]map[string]*omd.Service)

	ds.stopChan = make(chan struct{})
}

func (ds *ofDiscoverySession) InitWithRequest(request types.DiscoveryRequest) error {
	ds.init(request)

	params := request.Params()

	switch request.RequestType() {
	case types.DiscoveryRequestTypeHost:
		if nil == params || 2 != len(params) {
			return fmt.Errorf("Parameter is not valid")
		}

		zone, ok := params[0].(*omd.Zone)
		if !ok {
			return fmt.Errorf("Zone of parameter is not valid")
		}

		discoverHost, ok := params[1].(*omd.DiscoverHost)
		if !ok {
			return fmt.Errorf("DiscoverHost of parameter is not valid")
		}

		if nil == discoverHost.DiscoveryConfig {
			return fmt.Errorf("DiscoveryConfig of parameter is not valid")
		}

		if ts, err := ds.getTargetHosts(zone, discoverHost); nil != err {
			return err
		} else {
			ds.targetHosts = ts
		}

		ds.discoveryConfig = discoverHost.DiscoveryConfig
		ds.setZone(zone)
		ds.setDiscoverHost(discoverHost)
	case types.DiscoveryRequestTypePort:
		if nil == params || 2 != len(params) {
			return fmt.Errorf("Parameter is not valid")
		}

		host, ok := params[0].(*omd.Host)
		if !ok {
			return fmt.Errorf("Host of parameter is not valid")
		}

		discoverPort, ok := params[1].(*omd.DiscoverPort)
		if !ok {
			return fmt.Errorf("DiscoverPort of parameter is not valid")
		}

		if nil == discoverPort.DiscoveryConfig {
			return fmt.Errorf("DiscoveryConfig of parameter is not valid")
		}

		ds.discoveryConfig = discoverPort.DiscoveryConfig
		ds.setHost(host)
		ds.setDiscoverPort(discoverPort)
	case types.DiscoveryRequestTypeService:
		if nil == params || 2 != len(params) {
			return fmt.Errorf("Parameter is not valid")
		}

		port, ok := params[0].(*omd.Port)
		if !ok {
			return fmt.Errorf("Port of parameter is not valid")
		}

		discoverService, ok := params[1].(*omd.DiscoverService)
		if !ok {
			return fmt.Errorf("DiscoverService of parameter is not valid")
		}

		if nil == discoverService.DiscoveryConfig {
			return fmt.Errorf("DiscoveryConfig of parameter is not valid")
		}

		ds.discoveryConfig = discoverService.DiscoveryConfig
		ds.setPort(port)
		ds.setDiscoverService(discoverService)
	}

	_pCapScanner := pcap.NewPCapScanner(ds.zone)
	if err := _pCapScanner.Start(); nil == err {
		ds.pCapScanner = _pCapScanner
	}

	return nil
}

func (ds *ofDiscoverySession) PCapScanner() pcap.PCapScanner {
	return ds.pCapScanner
}

func (ds *ofDiscoverySession) SetDiscoveryDelegator(discoveryDelegator chan<- interface{}) {
	ds.discoveryDelegator = discoveryDelegator
}

func (ds *ofDiscoverySession) DiscoveryRequest() types.DiscoveryRequest {
	return ds.discoveryRequest
}

func (ds *ofDiscoverySession) Zone() *omd.Zone {
	return ds.zone
}
func (ds *ofDiscoverySession) Host() *omd.Host {
	return ds.host
}
func (ds *ofDiscoverySession) Port() *omd.Port {
	return ds.port
}

func (ds *ofDiscoverySession) DiscoveryConfig() *omd.DiscoveryConfig {
	return ds.discoveryConfig
}

func (ds *ofDiscoverySession) DiscoverHost() *omd.DiscoverHost {
	return ds.discoverHost
}
func (ds *ofDiscoverySession) DiscoverPort() *omd.DiscoverPort {
	return ds.discoverPort
}
func (ds *ofDiscoverySession) DiscoverService() *omd.DiscoverService {
	return ds.discoverService
}

func (ds *ofDiscoverySession) TargetHosts() []net.IP {
	return ds.targetHosts
}

func (ds *ofDiscoverySession) AddHost(host *omd.Host) *omd.Host {
	ds.discoveredMtx.Lock()
	defer ds.discoveredMtx.Unlock()

	h, modified := ds.findHost(host)

	if "" == h.Mac && "" != host.Mac {
		h.Mac = host.Mac
		modified = true
	}

	meta, metaModified := ds.appendMeta(h.Meta, host.Meta)
	if metaModified {
		h.Meta = meta
		modified = metaModified
	}

	if modified && nil != ds.discoveryDelegator {
		ds.discoveryDelegator <- h
	}

	return h
}

func (ds *ofDiscoverySession) AddPort(port *omd.Port) *omd.Port {
	ds.discoveredMtx.Lock()
	defer ds.discoveredMtx.Unlock()

	p, modified := ds.findPort(port)

	meta, metaModified := ds.appendMeta(p.Meta, port.Meta)
	if metaModified {
		p.Meta = meta
		modified = metaModified
	}

	if modified && nil != ds.discoveryDelegator {
		ds.discoveryDelegator <- p
	}

	return p
}

func (ds *ofDiscoverySession) AddService(service *omd.Service) *omd.Service {
	ds.discoveredMtx.Lock()
	defer ds.discoveredMtx.Unlock()

	s, modified := ds.findService(service)

	meta, metaModified := ds.appendMeta(s.Meta, service.Meta)
	if metaModified {
		s.Meta = meta
		modified = metaModified
	}

	if modified && nil != ds.discoveryDelegator {
		ds.discoveryDelegator <- s
	}

	return s
}

func (ds *ofDiscoverySession) DiscoveredHost(address string) *omd.Host {
	ds.discoveredMtx.RLock()
	defer ds.discoveredMtx.RUnlock()

	h, ok := ds.hosts[address]
	if !ok {
		return nil
	}

	return h
}

func (ds *ofDiscoverySession) DiscoveredAllHosts(includeMac bool) map[string]*omd.Host {
	if includeMac {
		return ds.includeMachosts
	}
	return ds.hosts
}

func (ds *ofDiscoverySession) DiscoveredPort(host *omd.Host, portNumber int) map[string]*omd.Port {
	ds.discoveredMtx.RLock()
	defer ds.discoveredMtx.RUnlock()

	h, _ := ds.findHost(host)
	if nil == h {
		return nil
	}

	hostPorts, ok := ds.ports[h]
	if !ok {
		return nil
	}

	ports, ok := hostPorts[json.Number(strconv.Itoa(portNumber))]
	if !ok {
		return nil
	}

	return ports
}

func (ds *ofDiscoverySession) DiscoveredAllPorts() map[*omd.Host]map[json.Number]map[string]*omd.Port {
	return ds.ports
}

func (ds *ofDiscoverySession) DiscoveredService(port *omd.Port, name string) map[string]*omd.Service {
	ds.discoveredMtx.RLock()
	defer ds.discoveredMtx.RUnlock()

	p, _ := ds.findPort(port)
	if nil == p {
		return nil
	}

	portServices, ok := ds.services[p]
	if !ok {
		return nil
	}

	services, ok := portServices[name]
	if !ok {
		return nil
	}

	return services
}

func (ds *ofDiscoverySession) DiscoveredAllServices() map[*omd.Port]map[string]map[string]*omd.Service {
	return ds.services
}

func (ds *ofDiscoverySession) findHost(host *omd.Host) (h *omd.Host, modified bool) {
	modified = false
	var ok bool

	h, ok = ds.hosts[host.Address]
	if !ok {
		ds.hosts[host.Address] = host
		if "" != host.Mac {
			ds.includeMachosts[host.Address] = host
		}
		h = host
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) StopChan() <-chan struct{} {
	return ds.stopChan
}

func (ds *ofDiscoverySession) findPort(port *omd.Port) (p *omd.Port, modified bool) {
	modified = false
	var ok bool

	h, _ := ds.findHost(port.Host)
	if nil == h {
		return
	}

	hostPorts, ok := ds.ports[h]
	if !ok {
		ds.ports[h] = make(map[json.Number]map[string]*omd.Port)
		hostPorts = ds.ports[h]
	}

	ports, ok := hostPorts[port.PortNumber]
	if !ok {
		hostPorts[port.PortNumber] = make(map[string]*omd.Port)
		ports = hostPorts[port.PortNumber]
	}

	p, ok = ports[port.MetaPortType.Key]
	if !ok {
		ports[port.MetaPortType.Key] = port
		p = ports[port.MetaPortType.Key]
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) findService(service *omd.Service) (s *omd.Service, modified bool) {
	modified = false
	var ok bool

	p, _ := ds.findPort(service.Port)
	if nil == p {
		return
	}

	portServices, ok := ds.services[p]
	if !ok {
		ds.services[p] = make(map[string]map[string]*omd.Service)
		portServices = ds.services[p]
	}

	services, ok := portServices[service.Key]
	if !ok {
		portServices[service.Key] = make(map[string]*omd.Service)
		services = portServices[service.Key]
	}

	s, ok = services[service.MetaCryptoType.Key]
	if !ok {
		services[service.MetaCryptoType.Key] = service
		s = services[service.MetaCryptoType.Key]
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) appendMeta(oriMeta map[string]string, newMeta map[string]string) (resultMap map[string]string, modified bool) {
	modified = false
	if nil == newMeta {
		resultMap = oriMeta
		return
	}
	if nil == oriMeta {
		resultMap = newMeta
		modified = true
		return
	}

LOOP:
	for k, v := range newMeta {
		_v, _ok := oriMeta[k]
		if !_ok {
			oriMeta[k] = v
			modified = true
			continue LOOP
		}
		if v == _v {
			continue LOOP
		}
		oriMeta[k] = fmt.Sprintf("%s|||%s", _v, v)
		modified = true
	}

	resultMap = oriMeta

	return
}

func (ds *ofDiscoverySession) setZone(zone *omd.Zone) {
	if nil == zone {
		return
	}
	ds.zone = zone
}

func (ds *ofDiscoverySession) setHost(host *omd.Host) {
	if nil == host {
		return
	}
	ds.setZone(host.Zone)
	ds.host = host
}

func (ds *ofDiscoverySession) setPort(port *omd.Port) {
	if nil == port {
		return
	}
	ds.setHost(port.Host)
	ds.port = port
}

func (ds *ofDiscoverySession) setDiscoverHost(discoverHost *omd.DiscoverHost) {
	if nil == discoverHost {
		return
	}

	ds.discoverHost = discoverHost
	ds.setDiscoverPort(discoverHost.DiscoverPort)
}

func (ds *ofDiscoverySession) setDiscoverPort(discoverPort *omd.DiscoverPort) {
	if nil == discoverPort {
		return
	}

	ds.discoverPort = discoverPort
	ds.setDiscoverService(discoverPort.DiscoverService)
}

func (ds *ofDiscoverySession) setDiscoverService(discoverService *omd.DiscoverService) {
	if nil == discoverService {
		return
	}

	ds.discoverService = discoverService
}

func (ds *ofDiscoverySession) getTargetHosts(zone *omd.Zone, discoverHost *omd.DiscoverHost) ([]net.IP, error) {
	cr, err := ounc.NewCIDRRanger(zone.Network)
	if nil != err {
		return nil, err
	}

	var firstIP net.IP
	if "" != discoverHost.FirstScanRange {
		firstIP = net.ParseIP(discoverHost.FirstScanRange)
		if nil == firstIP {
			return nil, fmt.Errorf("IP(%v) of FirstScanRange host is not valid", firstIP)
		}
	}
	var lastIP net.IP
	if "" != discoverHost.LastScanRange {
		lastIP = net.ParseIP(discoverHost.LastScanRange)
		if nil == lastIP {
			return nil, fmt.Errorf("IP(%v) of LastScanRange host is not valid", lastIP)
		}
	}

	includeIPs := make([]net.IP, 0)
	for _, iHost := range discoverHost.IncludeHosts {
		iIP := net.ParseIP(iHost)
		if nil == iIP {
			return nil, fmt.Errorf("IP(%v) of include host is not valid", iHost)
		}
		includeIPs = append(includeIPs, iIP)
	}

	excludeIPs := make([]net.IP, 0)
	for _, eHost := range discoverHost.ExcludeHosts {
		eIP := net.ParseIP(eHost)
		if nil == eIP {
			return nil, fmt.Errorf("IP(%v) of exclude host is not valid", eHost)
		}
		excludeIPs = append(excludeIPs, eIP)
	}

	ranges, err := cr.Ranges(firstIP, lastIP, includeIPs, excludeIPs)
	if nil != err {
		return nil, err
	}

	return ranges, nil
}

var discoverySessionPool sync.Pool

func RetainDiscoverySession() *ofDiscoverySession {
	v := discoverySessionPool.Get()
	var ds *ofDiscoverySession
	if v == nil {
		ds = &ofDiscoverySession{}
	} else {
		ds = v.(*ofDiscoverySession)
	}

	return ds
}

func ReleaseDiscoverySession(ds *ofDiscoverySession) {
	close(ds.stopChan)

	if nil != ds.pCapScanner {
		ds.pCapScanner.Stop()
	}

	ds.pCapScanner = nil
	ds.discoveryRequest = nil
	ds.zone = nil
	ds.host = nil
	ds.port = nil

	ds.discoveryConfig = nil

	ds.discoverHost = nil
	ds.discoverPort = nil
	ds.discoverService = nil

	ds.targetHosts = nil

	ds.discoveryDelegator = nil

	ds.includeMachosts = nil
	ds.hosts = nil
	ds.ports = nil
	ds.services = nil

	discoverySessionPool.Put(ds)
}