package peer

import (
	"net"
	"net/netip"
	"slices"
	"sort"
	"time"
)

// Peer represents a machine connected to the network.
// The Peer is a WireGuard peer identified by a public key
type Peer struct {
	// ID is an internal ID of the peer
	ID string `gorm:"primaryKey"`
	// AccountID is a reference to Account that this object belongs
	AccountID string `json:"-" gorm:"index"`
	// WireGuard public key
	Key string `gorm:"index"`
	// IP address of the Peer
	IP net.IP `gorm:"serializer:json"`
	// Meta is a Peer system meta data
	Meta PeerSystemMeta `gorm:"embedded;embeddedPrefix:meta_"`
	// Name is peer's name (machine name)
	Name string
	// DNSLabel is the parsed peer name for domain resolution. It is used to form an FQDN by appending the account's
	// domain to the peer label. e.g. peer-dns-label.netbird.cloud
	DNSLabel string
	// Status peer's management connection status
	Status *PeerStatus `gorm:"embedded;embeddedPrefix:peer_status_"`
	// The user ID that registered the peer
	UserID string
	// SSHKey is a public SSH key of the peer
	SSHKey string
	// SSHEnabled indicates whether SSH server is enabled on the peer
	SSHEnabled bool
	// LoginExpirationEnabled indicates whether peer's login expiration is enabled and once expired the peer has to re-login.
	// Works with LastLogin
	LoginExpirationEnabled bool

	InactivityExpirationEnabled bool
	// LastLogin the time when peer performed last login operation
	LastLogin time.Time
	// CreatedAt records the time the peer was created
	CreatedAt time.Time
	// Indicate ephemeral peer attribute
	Ephemeral bool
	// Geo location based on connection IP
	Location Location `gorm:"embedded;embeddedPrefix:location_"`
}

type PeerStatus struct { //nolint:revive
	// LastSeen is the last time peer was connected to the management service
	LastSeen time.Time
	// Connected indicates whether peer is connected to the management service or not
	Connected bool
	// LoginExpired
	LoginExpired bool
	// RequiresApproval indicates whether peer requires approval or not
	RequiresApproval bool
}

// Location is a geo location information of a Peer based on public connection IP
type Location struct {
	ConnectionIP net.IP `gorm:"serializer:json"` // from grpc peer or reverse proxy headers depends on setup
	CountryCode  string
	CityName     string
	GeoNameID    uint // city level geoname id
}

// NetworkAddress is the IP address with network and MAC address of a network interface
type NetworkAddress struct {
	NetIP netip.Prefix `gorm:"serializer:json"`
	Mac   string
}

// Environment is a system environment information
type Environment struct {
	Cloud    string
	Platform string
}

// File is a file on the system.
type File struct {
	Path             string
	Exist            bool
	ProcessIsRunning bool
}

// PeerSystemMeta is a metadata of a Peer machine system
type PeerSystemMeta struct { //nolint:revive
	Hostname           string
	GoOS               string
	Kernel             string
	Core               string
	Platform           string
	OS                 string
	OSVersion          string
	WtVersion          string
	UIVersion          string
	KernelVersion      string
	NetworkAddresses   []NetworkAddress `gorm:"serializer:json"`
	SystemSerialNumber string
	SystemProductName  string
	SystemManufacturer string
	Environment        Environment `gorm:"serializer:json"`
	Files              []File      `gorm:"serializer:json"`
}

func (p PeerSystemMeta) isEqual(other PeerSystemMeta) bool {
	sort.Slice(p.NetworkAddresses, func(i, j int) bool {
		return p.NetworkAddresses[i].Mac < p.NetworkAddresses[j].Mac
	})
	sort.Slice(other.NetworkAddresses, func(i, j int) bool {
		return other.NetworkAddresses[i].Mac < other.NetworkAddresses[j].Mac
	})
	equalNetworkAddresses := slices.EqualFunc(p.NetworkAddresses, other.NetworkAddresses, func(addr NetworkAddress, oAddr NetworkAddress) bool {
		return addr.Mac == oAddr.Mac && addr.NetIP == oAddr.NetIP
	})
	if !equalNetworkAddresses {
		return false
	}

	sort.Slice(p.Files, func(i, j int) bool {
		return p.Files[i].Path < p.Files[j].Path
	})
	sort.Slice(other.Files, func(i, j int) bool {
		return other.Files[i].Path < other.Files[j].Path
	})
	equalFiles := slices.EqualFunc(p.Files, other.Files, func(file File, oFile File) bool {
		return file.Path == oFile.Path && file.Exist == oFile.Exist && file.ProcessIsRunning == oFile.ProcessIsRunning
	})
	if !equalFiles {
		return false
	}

	return p.Hostname == other.Hostname &&
		p.GoOS == other.GoOS &&
		p.Kernel == other.Kernel &&
		p.KernelVersion == other.KernelVersion &&
		p.Core == other.Core &&
		p.Platform == other.Platform &&
		p.OS == other.OS &&
		p.OSVersion == other.OSVersion &&
		p.WtVersion == other.WtVersion &&
		p.UIVersion == other.UIVersion &&
		p.SystemSerialNumber == other.SystemSerialNumber &&
		p.SystemProductName == other.SystemProductName &&
		p.SystemManufacturer == other.SystemManufacturer &&
		p.Environment.Cloud == other.Environment.Cloud &&
		p.Environment.Platform == other.Environment.Platform
}

func (p PeerSystemMeta) isEmpty() bool {
	return p.Hostname == "" &&
		p.GoOS == "" &&
		p.Kernel == "" &&
		p.Core == "" &&
		p.Platform == "" &&
		p.OS == "" &&
		p.OSVersion == "" &&
		p.WtVersion == "" &&
		p.UIVersion == "" &&
		p.KernelVersion == "" &&
		len(p.NetworkAddresses) == 0 &&
		p.SystemSerialNumber == "" &&
		p.SystemProductName == "" &&
		p.SystemManufacturer == "" &&
		p.Environment.Cloud == "" &&
		p.Environment.Platform == "" &&
		len(p.Files) == 0
}

// AddedWithSSOLogin indicates whether this peer has been added with an SSO login by a user.
func (p *Peer) AddedWithSSOLogin() bool {
	return p.UserID != ""
}

// Copy copies Peer object
func (p *Peer) Copy() *Peer {
	peerStatus := p.Status
	if peerStatus != nil {
		peerStatus = p.Status.Copy()
	}
	return &Peer{
		ID:                          p.ID,
		AccountID:                   p.AccountID,
		Key:                         p.Key,
		IP:                          p.IP,
		Meta:                        p.Meta,
		Name:                        p.Name,
		DNSLabel:                    p.DNSLabel,
		Status:                      peerStatus,
		UserID:                      p.UserID,
		SSHKey:                      p.SSHKey,
		SSHEnabled:                  p.SSHEnabled,
		LoginExpirationEnabled:      p.LoginExpirationEnabled,
		LastLogin:                   p.LastLogin,
		CreatedAt:                   p.CreatedAt,
		Ephemeral:                   p.Ephemeral,
		Location:                    p.Location,
		InactivityExpirationEnabled: p.InactivityExpirationEnabled,
	}
}

// UpdateMetaIfNew updates peer's system metadata if new information is provided
// returns true if meta was updated, false otherwise
func (p *Peer) UpdateMetaIfNew(meta PeerSystemMeta) bool {
	if meta.isEmpty() {
		return false
	}

	// Avoid overwriting UIVersion if the update was triggered sole by the CLI client
	if meta.UIVersion == "" {
		meta.UIVersion = p.Meta.UIVersion
	}

	if p.Meta.isEqual(meta) {
		return false
	}
	p.Meta = meta
	return true
}

// MarkLoginExpired marks peer's status expired or not
func (p *Peer) MarkLoginExpired(expired bool) {
	newStatus := p.Status.Copy()
	newStatus.LoginExpired = expired
	if expired {
		newStatus.Connected = false
	}
	p.Status = newStatus
}

// SessionExpired indicates whether the peer's session has expired or not.
// If Peer.LastLogin plus the expiresIn duration has happened already; then session has expired.
// Return true if a session has expired, false otherwise, and time left to expiration (negative when expired).
// Session expiration can be disabled/enabled on a Peer level via Peer.LoginExpirationEnabled property.
// Session expiration can also be disabled/enabled globally on the Account level via Settings.PeerLoginExpirationEnabled.
// Only peers added by interactive SSO login can be expired.
func (p *Peer) SessionExpired(expiresIn time.Duration) (bool, time.Duration) {
	if !p.AddedWithSSOLogin() || !p.InactivityExpirationEnabled || p.Status.Connected {
		return false, 0
	}
	expiresAt := p.Status.LastSeen.Add(expiresIn)
	now := time.Now()
	timeLeft := expiresAt.Sub(now)
	return timeLeft <= 0, timeLeft
}

// LoginExpired indicates whether the peer's login has expired or not.
// If Peer.LastLogin plus the expiresIn duration has happened already; then login has expired.
// Return true if a login has expired, false otherwise, and time left to expiration (negative when expired).
// Login expiration can be disabled/enabled on a Peer level via Peer.LoginExpirationEnabled property.
// Login expiration can also be disabled/enabled globally on the Account level via Settings.PeerLoginExpirationEnabled.
// Only peers added by interactive SSO login can be expired.
func (p *Peer) LoginExpired(expiresIn time.Duration) (bool, time.Duration) {
	if !p.AddedWithSSOLogin() || !p.LoginExpirationEnabled {
		return false, 0
	}
	expiresAt := p.LastLogin.Add(expiresIn)
	now := time.Now()
	timeLeft := expiresAt.Sub(now)
	return timeLeft <= 0, timeLeft
}

// FQDN returns peers FQDN combined of the peer's DNS label and the system's DNS domain
func (p *Peer) FQDN(dnsDomain string) string {
	if dnsDomain == "" {
		return ""
	}
	return p.DNSLabel + "." + dnsDomain
}

// EventMeta returns activity event meta related to the peer
func (p *Peer) EventMeta(dnsDomain string) map[string]any {
	return map[string]any{"name": p.Name, "fqdn": p.FQDN(dnsDomain), "ip": p.IP, "created_at": p.CreatedAt,
		"location_city_name": p.Location.CityName, "location_country_code": p.Location.CountryCode,
		"location_geo_name_id": p.Location.GeoNameID, "location_connection_ip": p.Location.ConnectionIP}
}

// Copy PeerStatus
func (p *PeerStatus) Copy() *PeerStatus {
	return &PeerStatus{
		LastSeen:         p.LastSeen,
		Connected:        p.Connected,
		LoginExpired:     p.LoginExpired,
		RequiresApproval: p.RequiresApproval,
	}
}

// UpdateLastLogin and set login expired false
func (p *Peer) UpdateLastLogin() *Peer {
	p.LastLogin = time.Now().UTC()
	newStatus := p.Status.Copy()
	newStatus.LoginExpired = false
	p.Status = newStatus
	return p
}