// Copyright (c) 2017 Shivaram Lingamneni <slingamn@cs.stanford.edu>
// released under the MIT license

package irc

import (
	"net"
	"sync/atomic"
	"time"
	"unsafe"

	"github.com/ergochat/ergo/irc/caps"
	"github.com/ergochat/ergo/irc/languages"
	"github.com/ergochat/ergo/irc/modes"
	"github.com/ergochat/ergo/irc/utils"
)

func (server *Server) Config() (config *Config) {
	return (*Config)(atomic.LoadPointer(&server.config))
}

func (server *Server) SetConfig(config *Config) {
	atomic.StorePointer(&server.config, unsafe.Pointer(config))
}

func (server *Server) ChannelRegistrationEnabled() bool {
	return server.Config().Channels.Registration.Enabled
}

func (server *Server) GetOperator(name string) (oper *Oper) {
	name, err := CasefoldName(name)
	if err != nil {
		return
	}
	return server.Config().operators[name]
}

func (server *Server) Languages() (lm *languages.Manager) {
	return server.Config().languageManager
}

func (server *Server) Defcon() uint32 {
	return atomic.LoadUint32(&server.defcon)
}

func (server *Server) SetDefcon(defcon uint32) {
	atomic.StoreUint32(&server.defcon, defcon)
}

func (client *Client) Sessions() (sessions []*Session) {
	client.stateMutex.RLock()
	sessions = client.sessions
	client.stateMutex.RUnlock()
	return
}

type SessionData struct {
	ctime        time.Time
	atime        time.Time
	ip           net.IP
	hostname     string
	certfp       string
	deviceID     string
	connInfo     string
	sessionID    int64
	caps         []string
	bytesRead    uint64
	bytesWritten uint64
}

func (client *Client) AllSessionData(currentSession *Session, hasPrivs bool) (data []SessionData, currentIndex int) {
	currentIndex = -1
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()

	data = make([]SessionData, len(client.sessions))
	for i, session := range client.sessions {
		if session == currentSession {
			currentIndex = i
		}
		bytesRead, bytesWritten := session.socket.Stats()
		data[i] = SessionData{
			atime:        session.lastActive,
			ctime:        session.ctime,
			hostname:     session.rawHostname,
			certfp:       session.certfp,
			deviceID:     session.deviceID,
			sessionID:    session.sessionID,
			bytesRead:    bytesRead,
			bytesWritten: bytesWritten,
		}
		if session.proxiedIP != nil {
			data[i].ip = session.proxiedIP
		} else {
			data[i].ip = session.realIP
		}
		if hasPrivs {
			data[i].connInfo = utils.DescribeConn(session.socket.conn.UnderlyingConn().Conn)
		}
		data[i].caps = session.capabilities.Strings(caps.Cap302, nil, 300)
	}
	return
}

func (client *Client) AddSession(session *Session) (success bool, numSessions int, lastSeen time.Time, back bool) {
	config := client.server.Config()
	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()

	// client may be dying and ineligible to receive another session
	if client.destroyed {
		return
	}
	// success, attach the new session to the client
	session.client = client
	session.sessionID = client.nextSessionID
	client.nextSessionID++
	newSessions := make([]*Session, len(client.sessions)+1)
	copy(newSessions, client.sessions)
	newSessions[len(newSessions)-1] = session
	if client.accountSettings.AutoreplayMissed || session.deviceID != "" {
		lastSeen = client.lastSeen[session.deviceID]
		client.setLastSeen(time.Now().UTC(), session.deviceID)
	}
	client.sessions = newSessions
	// TODO(#1551) there should be a cap to opt out of this behavior on a session
	if persistenceEnabled(config.Accounts.Multiclient.AutoAway, client.accountSettings.AutoAway) {
		client.awayMessage = ""
		if len(client.sessions) == 1 {
			back = true
		}
	}
	return true, len(client.sessions), lastSeen, back
}

func (client *Client) removeSession(session *Session) (success bool, length int) {
	if len(client.sessions) == 0 {
		return
	}
	sessions := make([]*Session, 0, len(client.sessions)-1)
	for _, currentSession := range client.sessions {
		if session == currentSession {
			success = true
		} else {
			sessions = append(sessions, currentSession)
		}
	}
	client.sessions = sessions
	length = len(sessions)
	return
}

func (client *Client) Nick() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.nick
}

func (client *Client) NickMaskString() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.nickMaskString
}

func (client *Client) NickCasefolded() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.nickCasefolded
}

func (client *Client) NickMaskCasefolded() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.nickMaskCasefolded
}

func (client *Client) Username() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.username
}

func (client *Client) Hostname() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.hostname
}

func (client *Client) Away() (result bool, message string) {
	client.stateMutex.Lock()
	message = client.awayMessage
	client.stateMutex.Unlock()
	result = client.awayMessage != ""
	return
}

func (session *Session) SetAway(awayMessage string) {
	client := session.client
	config := client.server.Config()

	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()

	session.awayMessage = awayMessage
	session.awayAt = time.Now().UTC()

	autoAway := client.registered && client.alwaysOn && persistenceEnabled(config.Accounts.Multiclient.AutoAway, client.accountSettings.AutoAway)
	if autoAway {
		client.setAutoAwayNoMutex(config)
	} else {
		client.awayMessage = awayMessage
	}
	return
}

func (client *Client) setAutoAwayNoMutex(config *Config) {
	// aggregate the away statuses of the individual sessions:
	var globalAwayState string
	var awaySetAt time.Time
	for _, cSession := range client.sessions {
		if cSession.awayMessage == "" {
			// a session is active, we are not auto-away
			client.awayMessage = ""
			return
		} else if cSession.awayAt.After(awaySetAt) {
			// choose the latest available away message from any session
			globalAwayState = cSession.awayMessage
			awaySetAt = cSession.awayAt
		}
	}
	if awaySetAt.IsZero() {
		// no sessions, enable auto-away
		client.awayMessage = config.languageManager.Translate(client.languages, `User is currently disconnected`)
	} else {
		client.awayMessage = globalAwayState
	}
}

func (client *Client) AlwaysOn() (alwaysOn bool) {
	client.stateMutex.RLock()
	alwaysOn = client.registered && client.alwaysOn
	client.stateMutex.RUnlock()
	return
}

// uniqueIdentifiers returns the strings for which the server enforces per-client
// uniqueness/ownership; no two clients can have colliding casefolded nicks or
// skeletons.
func (client *Client) uniqueIdentifiers() (nickCasefolded string, skeleton string) {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.nickCasefolded, client.skeleton
}

func (client *Client) Oper() *Oper {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.oper
}

func (client *Client) Registered() (result bool) {
	// `registered` is only written from the client's own goroutine, but may be
	// read from other goroutines; therefore, the client's own goroutine may read
	// the value without synchronization, but must write it with synchronization,
	// and other goroutines must read it with synchronization
	client.stateMutex.RLock()
	result = client.registered
	client.stateMutex.RUnlock()
	return
}

func (client *Client) RawHostname() (result string) {
	client.stateMutex.Lock()
	result = client.rawHostname
	client.stateMutex.Unlock()
	return
}

func (client *Client) AwayMessage() (result string) {
	client.stateMutex.RLock()
	result = client.awayMessage
	client.stateMutex.RUnlock()
	return
}

func (client *Client) Account() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.account
}

func (client *Client) AccountName() string {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.accountName
}

func (client *Client) Login(account ClientAccount) {
	alwaysOn := persistenceEnabled(client.server.Config().Accounts.Multiclient.AlwaysOn, account.Settings.AlwaysOn)
	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()
	client.account = account.NameCasefolded
	client.accountName = account.Name
	client.accountSettings = account.Settings
	// mark always-on here: it will not be respected until the client is registered
	client.alwaysOn = alwaysOn
	client.accountRegDate = account.RegisteredAt
	return
}

func (client *Client) setAccountName(name string) {
	// XXX this assumes validation elsewhere
	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()
	client.accountName = name
}

func (client *Client) setCloakedHostname(cloak string) {
	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()
	client.cloakedHostname = cloak
	client.updateNickMaskNoMutex()
}

func (client *Client) CloakedHostname() string {
	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()
	return client.cloakedHostname
}

func (client *Client) historyCutoff() (cutoff time.Time) {
	client.stateMutex.Lock()
	if client.account != "" {
		cutoff = client.accountRegDate
	} else {
		cutoff = client.ctime
	}
	client.stateMutex.Unlock()
	return
}

func (client *Client) Logout() {
	client.stateMutex.Lock()
	client.account = ""
	client.accountName = "*"
	client.alwaysOn = false
	client.accountRegDate = time.Time{}
	client.accountSettings = AccountSettings{}
	client.stateMutex.Unlock()
}

func (client *Client) AccountSettings() (result AccountSettings) {
	client.stateMutex.RLock()
	result = client.accountSettings
	client.stateMutex.RUnlock()
	return
}

func (client *Client) SetAccountSettings(settings AccountSettings) {
	// we mark dirty if the client is transitioning to always-on
	var becameAlwaysOn bool
	alwaysOn := persistenceEnabled(client.server.Config().Accounts.Multiclient.AlwaysOn, settings.AlwaysOn)
	client.stateMutex.Lock()
	if client.registered {
		// only allow the client to become always-on if their nick equals their account name
		alwaysOn = alwaysOn && client.nick == client.accountName
		becameAlwaysOn = (!client.alwaysOn && alwaysOn)
		client.alwaysOn = alwaysOn
	}
	client.accountSettings = settings
	client.stateMutex.Unlock()
	if becameAlwaysOn {
		client.markDirty(IncludeAllAttrs)
	}
}

func (client *Client) Languages() (languages []string) {
	client.stateMutex.RLock()
	languages = client.languages
	client.stateMutex.RUnlock()
	return languages
}

func (client *Client) SetLanguages(languages []string) {
	client.stateMutex.Lock()
	client.languages = languages
	client.stateMutex.Unlock()
}

func (client *Client) HasMode(mode modes.Mode) bool {
	// client.flags has its own synch
	return client.modes.HasMode(mode)
}

func (client *Client) SetMode(mode modes.Mode, on bool) bool {
	return client.modes.SetMode(mode, on)
}

func (client *Client) SetRealname(realname string) {
	client.stateMutex.Lock()
	client.realname = realname
	alwaysOn := client.registered && client.alwaysOn
	client.stateMutex.Unlock()
	if alwaysOn {
		client.markDirty(IncludeRealname)
	}
}

func (client *Client) Channels() (result []*Channel) {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	length := len(client.channels)
	result = make([]*Channel, length)
	i := 0
	for channel := range client.channels {
		result[i] = channel
		i++
	}
	return
}

func (client *Client) NumChannels() int {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return len(client.channels)
}

func (client *Client) WhoWas() (result WhoWas) {
	return client.Details().WhoWas
}

func (client *Client) Details() (result ClientDetails) {
	client.stateMutex.RLock()
	defer client.stateMutex.RUnlock()
	return client.detailsNoMutex()
}

func (client *Client) detailsNoMutex() (result ClientDetails) {
	result.nick = client.nick
	result.nickCasefolded = client.nickCasefolded
	result.username = client.username
	result.hostname = client.hostname
	result.realname = client.realname
	result.ip = client.getIPNoMutex()
	result.nickMask = client.nickMaskString
	result.nickMaskCasefolded = client.nickMaskCasefolded
	result.account = client.account
	result.accountName = client.accountName
	return
}

func (client *Client) UpdateActive(session *Session) {
	now := time.Now().UTC()
	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()
	client.lastActive = now
	session.lastActive = now
}

func (client *Client) Realname() string {
	client.stateMutex.RLock()
	result := client.realname
	client.stateMutex.RUnlock()
	return result
}

func (client *Client) IsExpiredAlwaysOn(config *Config) (result bool) {
	client.stateMutex.Lock()
	defer client.stateMutex.Unlock()
	return client.checkAlwaysOnExpirationNoMutex(config, false)
}

func (client *Client) checkAlwaysOnExpirationNoMutex(config *Config, ignoreRegistration bool) (result bool) {
	if !((client.registered || ignoreRegistration) && client.alwaysOn) {
		return false
	}
	deadline := time.Duration(config.Accounts.Multiclient.AlwaysOnExpiration)
	if deadline == 0 {
		return false
	}
	now := time.Now()
	for _, ts := range client.lastSeen {
		if now.Sub(ts) < deadline {
			return false
		}
	}
	return true
}

func (channel *Channel) Name() string {
	channel.stateMutex.RLock()
	defer channel.stateMutex.RUnlock()
	return channel.name
}

func (channel *Channel) NameCasefolded() string {
	channel.stateMutex.RLock()
	defer channel.stateMutex.RUnlock()
	return channel.nameCasefolded
}

func (channel *Channel) Rename(name, nameCasefolded string) {
	channel.stateMutex.Lock()
	channel.name = name
	if channel.nameCasefolded != nameCasefolded {
		channel.nameCasefolded = nameCasefolded
		if channel.registeredFounder != "" {
			channel.registeredTime = time.Now().UTC()
		}
	}
	channel.stateMutex.Unlock()
}

func (channel *Channel) Members() (result []*Client) {
	channel.stateMutex.RLock()
	defer channel.stateMutex.RUnlock()
	return channel.membersCache
}

func (channel *Channel) setUserLimit(limit int) {
	channel.stateMutex.Lock()
	channel.userLimit = limit
	channel.stateMutex.Unlock()
}

func (channel *Channel) setKey(key string) {
	channel.stateMutex.Lock()
	defer channel.stateMutex.Unlock()
	channel.key = key
}

func (channel *Channel) Founder() string {
	channel.stateMutex.RLock()
	defer channel.stateMutex.RUnlock()
	return channel.registeredFounder
}

func (channel *Channel) HighestUserMode(client *Client) (result modes.Mode) {
	channel.stateMutex.RLock()
	clientModes := channel.members[client].modes
	channel.stateMutex.RUnlock()
	return clientModes.HighestChannelUserMode()
}

func (channel *Channel) Settings() (result ChannelSettings) {
	channel.stateMutex.RLock()
	result = channel.settings
	channel.stateMutex.RUnlock()
	return result
}

func (channel *Channel) SetSettings(settings ChannelSettings) {
	channel.stateMutex.Lock()
	channel.settings = settings
	channel.stateMutex.Unlock()
	channel.MarkDirty(IncludeSettings)
}

func (channel *Channel) setForward(forward string) {
	channel.stateMutex.Lock()
	channel.forward = forward
	channel.stateMutex.Unlock()
}

func (channel *Channel) Ctime() (ctime time.Time) {
	channel.stateMutex.RLock()
	ctime = channel.createdTime
	channel.stateMutex.RUnlock()
	return
}

func (channel *Channel) getAmode(cfaccount string) (result modes.Mode) {
	channel.stateMutex.RLock()
	defer channel.stateMutex.RUnlock()
	return channel.accountToUMode[cfaccount]
}