Files
teachat/internal/model.go
2025-12-28 00:55:33 -07:00

616 lines
13 KiB
Go

package internal
import (
"crypto/rand"
"database/sql"
"encoding/base64"
"fmt"
"io"
"strings"
"time"
"github.com/charmbracelet/bubbles/textinput"
"github.com/charmbracelet/bubbles/viewport"
tea "github.com/charmbracelet/bubbletea"
"github.com/charmbracelet/lipgloss"
"github.com/charmbracelet/ssh"
)
var (
msgStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("252")).PaddingLeft(1)
senderStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("205")).Bold(true)
errStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("196")).Bold(true)
sysStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("117")).Italic(true)
roomStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("86")).Bold(true)
dmStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("141")).Bold(true)
noteStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("228")).Bold(true)
commandStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("39")).Italic(true)
timeStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("246"))
lockedStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("240")).Italic(true)
)
type chatMsg struct {
Timestamp time.Time
Sender string
Content string
}
type model struct {
sshSession ssh.Session
pubkey string
username string
authorized bool
needsRegistration bool
state int
passphrase string
identityKey *IdentityKeyPair
encryptedPrivKey []byte
privKeySalt []byte
privKeyNonce []byte
currentRoomID string
currentRoomEpoch int
// We cache keys: Epoch -> Plaintext Key
roomKeyCache map[int][]byte
rooms []struct {
ID string
Name string
Creator string
IsDM bool
}
err error
input textinput.Model
viewport viewport.Model
messages []chatMsg
updateChan chan bool
}
func initialModel(s ssh.Session) model {
pk := s.PublicKey()
var pubkeyStr string
var auth bool
var user string
var needsRegistration bool
if pk == nil {
auth = false
user = ""
pubkeyStr = ""
} else {
pubkeyStr = fmt.Sprintf("%s %s", pk.Type(), base64.StdEncoding.EncodeToString(pk.Marshal()))
username, err := getUsername(pubkeyStr)
if err == sql.ErrNoRows {
needsRegistration = true
auth = true
user = ""
} else {
auth = true
needsRegistration = false
user = username
}
}
ti := textinput.New()
if needsRegistration {
ti.Placeholder = "Choose a username..."
} else {
ti.Placeholder = "Enter Passphrase..."
ti.EchoMode = textinput.EchoPassword
}
ti.Focus()
ti.CharLimit = 156
ti.Width = 50
vp := viewport.New(80, 20)
return model{
sshSession: s,
pubkey: pubkeyStr,
username: user,
authorized: auth,
needsRegistration: needsRegistration,
state: 0,
input: ti,
viewport: vp,
updateChan: updates.subscribe(),
roomKeyCache: make(map[int][]byte),
}
}
func (m model) Init() tea.Cmd {
return tea.Batch(textinput.Blink, m.waitForUpdate())
}
func (m model) waitForUpdate() tea.Cmd {
return func() tea.Msg {
<-m.updateChan
return struct{}{}
}
}
func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
var cmd tea.Cmd
switch msg := msg.(type) {
case tea.WindowSizeMsg:
m.viewport.Width = msg.Width
m.viewport.Height = msg.Height - 4
return m, tea.ClearScreen
case tea.KeyMsg:
switch msg.Type {
case tea.KeyCtrlC, tea.KeyEsc:
return m, tea.Quit
case tea.KeyEnter:
if !m.authorized {
return m, tea.Quit
}
if m.needsRegistration {
username := m.input.Value()
if len(username) > 0 {
identityKey, err := generateIdentityKeyPair()
if err != nil {
m.err = err
return m, nil
}
prekey, prekeySignature, err := generateSignedPrekey()
if err != nil {
m.err = err
return m, nil
}
if err := authorizeUser(m.pubkey, username, identityKey.PublicKey[:], prekey[:], prekeySignature); err != nil {
m.err = err
} else {
m.username = username
m.identityKey = identityKey
m.needsRegistration = false
m.input.Reset()
m.input.Placeholder = "Enter Passphrase..."
m.input.EchoMode = textinput.EchoPassword
m.viewport.SetContent("")
return m, tea.ClearScreen
}
}
return m, nil
}
if m.state == 0 {
pass := m.input.Value()
if len(pass) > 0 {
if m.identityKey != nil {
ciphertext, nonce, salt, err := encryptUserKey(m.identityKey.PrivateKey, pass)
if err != nil {
m.err = err
return m, nil
}
m.encryptedPrivKey = ciphertext
m.privKeyNonce = nonce
m.privKeySalt = salt
}
m.passphrase = pass
m.state = 1
m.input.Reset()
m.input.EchoMode = textinput.EchoNormal
m.input.Placeholder = "Loading rooms..."
m.viewport.SetContent("")
m.loadRooms()
return m, tea.ClearScreen
}
} else if m.state == 1 {
val := m.input.Value()
if len(val) > 0 {
m.handleRoomListInput(val)
m.input.Reset()
if m.state == 2 {
return m, tea.ClearScreen
}
}
} else if m.state == 2 {
val := m.input.Value()
if len(val) > 0 {
if val == "/back" {
m.exitChat()
return m, tea.ClearScreen
}
if val == "/leave" {
leaveRoom(m.currentRoomID, m.username)
m.rotateRoomKey(m.currentRoomID) // Rotate key on leave
m.exitChat()
return m, tea.ClearScreen
}
if val == "/delete" {
isCreator := false
for _, r := range m.rooms {
if r.ID == m.currentRoomID {
if r.Creator == m.username {
isCreator = true
}
break
}
}
if isCreator {
deleteRoom(m.currentRoomID)
m.exitChat()
return m, tea.ClearScreen
} else {
m.saveMessage("System", "Error: Only the creator can delete this room.")
m.input.Reset()
return m, nil
}
}
m.handleChatInput(val)
m.input.Reset()
}
}
}
case struct{}:
if m.state == 2 {
m.loadMessages()
return m, m.waitForUpdate()
}
}
m.input, cmd = m.input.Update(msg)
return m, cmd
}
func (m *model) exitChat() {
m.state = 1
m.currentRoomID = ""
m.currentRoomEpoch = 0
m.messages = nil
m.roomKeyCache = make(map[int][]byte)
m.viewport.SetContent("")
m.loadRooms()
m.input.Reset()
}
func (m *model) loadRooms() {
rooms, err := listUserRooms(m.username)
if err != nil {
m.err = err
return
}
m.rooms = rooms
m.viewport.SetContent("")
m.input.SetValue("")
m.input.Placeholder = "Enter room # or: /join <name>, /dm <username>, /list"
}
func (m *model) handleRoomListInput(text string) {
if text == "/list" {
m.loadRooms()
return
}
if strings.HasPrefix(text, "/join ") {
roomName := strings.TrimPrefix(text, "/join ")
m.handleJoinRoom(roomName)
return
}
if strings.HasPrefix(text, "/new ") {
roomName := strings.TrimPrefix(text, "/new ")
m.handleJoinRoom(roomName)
return
}
if strings.HasPrefix(text, "/dm ") {
targetUser := strings.TrimPrefix(text, "/dm ")
m.handleSelectUserForDM(targetUser)
return
}
if idx := parseInt(text); idx > 0 && idx <= len(m.rooms) {
room := m.rooms[idx-1]
m.enterRoom(room.ID, room.Name)
}
}
func (m *model) handleJoinRoom(roomName string) {
existingID, err := getRoomIDByName(roomName)
if err == nil && existingID != "" {
// Join existing
if err := joinRoomMember(existingID, m.username); err != nil {
m.err = err
return
}
// ROTATE KEY so new user gets a key, but doesn't get old keys
m.rotateRoomKey(existingID)
m.enterRoom(existingID, roomName)
return
}
// Create new
roomID := generateRoomID()
if err := createRoom(roomID, roomName, m.username, false); err != nil {
m.err = err
return
}
if err := joinRoomMember(roomID, m.username); err != nil {
m.err = err
return
}
// Initial Key
m.rotateRoomKey(roomID)
m.enterRoom(roomID, roomName)
}
func (m *model) rotateRoomKey(roomID string) {
newKey := make([]byte, 32)
io.ReadFull(rand.Reader, newKey)
newEpoch, err := incrementRoomEpoch(roomID)
if err != nil {
m.err = err
return
}
members, err := getRoomMembers(roomID)
if err != nil {
m.err = err
return
}
for _, user := range members {
idKey, err := getMemberIdentityKey(user)
if err != nil {
continue
}
encrypted, err := EncryptKeyForUser(idKey, newKey)
if err != nil {
continue
}
storeUserRoomKey(user, roomID, newEpoch, encrypted)
}
}
func (m *model) handleSelectUserForDM(username string) {
if username == "/cancel" {
m.state = 1
m.input.Placeholder = "Enter room # or: /join <name>, /dm <username>, /list"
return
}
if username == m.username {
m.createNoteToSelf()
return
}
roomID := generateRoomID()
roomName := fmt.Sprintf("DM: %s <-> %s", m.username, username)
if err := createRoom(roomID, roomName, m.username, true); err != nil {
m.err = err
return
}
joinRoomMember(roomID, m.username)
joinRoomMember(roomID, username)
m.rotateRoomKey(roomID)
m.enterRoom(roomID, roomName)
}
func (m *model) createNoteToSelf() {
roomID := generateRoomID()
roomName := "[Note to Self]"
if err := createRoom(roomID, roomName, m.username, true); err != nil {
m.err = err
return
}
joinRoomMember(roomID, m.username)
m.rotateRoomKey(roomID)
m.enterRoom(roomID, roomName)
}
func (m *model) enterRoom(roomID, roomName string) {
epoch, _ := getRoomCurrentEpoch(roomID)
m.currentRoomID = roomID
m.currentRoomEpoch = epoch
m.state = 2
m.input.Placeholder = fmt.Sprintf("[%s] /back, /leave, /delete", roomName)
m.loadMessages()
}
func (m *model) handleChatInput(text string) {
m.saveMessage(m.username, text)
}
func parseInt(s string) int {
var num int
fmt.Sscanf(s, "%d", &num)
return num
}
func generateRoomID() string {
b := make([]byte, 16)
io.ReadFull(rand.Reader, b)
return base64.URLEncoding.EncodeToString(b)
}
func (m *model) getEpochKey(epoch int) []byte {
// Check cache
if key, ok := m.roomKeyCache[epoch]; ok {
return key
}
encKey, err := getUserRoomKey(m.username, m.currentRoomID, epoch)
if err != nil || encKey == nil {
return nil
}
key, err := DecryptKeyForUser(m.identityKey.PrivateKey, encKey)
if err != nil {
return nil
}
m.roomKeyCache[epoch] = key
return key
}
func (m *model) saveMessage(sender, text string) {
m.currentRoomEpoch, _ = getRoomCurrentEpoch(m.currentRoomID)
key := m.getEpochKey(m.currentRoomEpoch)
if key == nil {
m.err = fmt.Errorf("no key for current epoch")
return
}
ct, nonce, err := encryptMsg(text, key)
if err != nil {
m.err = err
return
}
err = saveMessage(m.currentRoomID, sender, m.currentRoomEpoch, ct, nonce)
if err != nil {
m.err = err
return
}
go updates.broadcast()
}
func (m *model) loadMessages() {
if m.currentRoomID == "" {
return
}
dbMessages, err := loadMessages(m.currentRoomID)
if err != nil {
m.err = err
return
}
var msgs []chatMsg
for _, dbMsg := range dbMessages {
key := m.getEpochKey(dbMsg.Epoch)
var plain string
if key == nil {
plain = "[Unreadable: Old History or Key Rotated]"
} else {
p, err := decryptMsg(dbMsg.Ciphertext, dbMsg.Nonce, key)
if err != nil {
plain = "[Decryption Failed]"
} else {
plain = p
}
}
msgs = append(msgs, chatMsg{
Timestamp: dbMsg.Timestamp,
Sender: dbMsg.Sender,
Content: plain,
})
}
m.messages = msgs
m.updateViewport()
}
func (m *model) updateViewport() {
var b strings.Builder
for _, msg := range m.messages {
dateStr := msg.Timestamp.Format("Jan 2 15:04")
if strings.Contains(msg.Content, "[Unreadable") {
b.WriteString(fmt.Sprintf("%s %s\n",
timeStyle.Render(dateStr),
lockedStyle.Render(msg.Content),
))
} else {
b.WriteString(fmt.Sprintf("%s %s: %s\n",
timeStyle.Render(dateStr),
senderStyle.Render(msg.Sender),
msgStyle.Render(msg.Content),
))
}
}
m.viewport.SetContent(b.String())
m.viewport.GotoBottom()
}
func (m model) View() string {
if !m.authorized {
return fmt.Sprintf(`
%s
ACCESS DENIED
No public key authentication provided.
(Press Ctrl+C to quit)
`, errStyle.Render("SECURITY ALERT"))
}
if m.needsRegistration {
return fmt.Sprintf(`
%s
Welcome! You're a new user.
Please choose a username to register.
%s
`, sysStyle.Render("SECURE TUI CHAT - REGISTRATION"), m.input.View())
}
if m.state == 0 {
return fmt.Sprintf(`
%s
Welcome back, %s.
This environment is encrypted at rest.
Please enter your passphrase to unlock your keys.
%s
`, sysStyle.Render("SECURE TUI CHAT"), senderStyle.Render(m.username), m.input.View())
}
if m.state == 1 {
var b strings.Builder
b.WriteString(sysStyle.Render("=== YOUR ROOMS ===") + "\n\n")
if len(m.rooms) == 0 {
b.WriteString(sysStyle.Render("No rooms yet.") + "\n")
b.WriteString(commandStyle.Render(" /join <name>") + " - Join/Create room\n")
b.WriteString(commandStyle.Render(" /dm <user>") + " - Start a DM\n")
} else {
for i, room := range m.rooms {
var style lipgloss.Style
var prefix string
if strings.Contains(room.Name, "Note to Self") {
style = noteStyle
prefix = "[*]"
} else if room.IsDM {
style = dmStyle
prefix = "[DM]"
} else {
style = roomStyle
prefix = "[#]"
}
b.WriteString(fmt.Sprintf("%s %s %s\n",
senderStyle.Render(fmt.Sprintf("%d.", i+1)),
prefix,
style.Render(room.Name)))
}
b.WriteString("\n" + sysStyle.Render("Commands: ") + commandStyle.Render("/join /dm /list") + "\n")
}
b.WriteString("\n" + m.input.View())
return b.String()
}
if m.state == 2 {
return fmt.Sprintf("%s\n%s", m.viewport.View(), m.input.View())
}
return m.input.View()
}