// Package main is the waste-go terminal UI.
// It connects to a running daemon's IPC port, joins a named network, and
// renders a three-pane layout: rooms (left), messages (centre), peers (right).
package main

import (
	"bufio"
	"encoding/json"
	"flag"
	"fmt"
	"net"
	"os"
	"strings"
	"time"

	"github.com/charmbracelet/bubbles/textinput"
	"github.com/charmbracelet/bubbles/viewport"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"

	"github.com/waste-go/internal/invite"
	"github.com/waste-go/internal/proto"
)

// ── styles ────────────────────────────────────────────────────────────────────

var (
	styleHeader  = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("33"))
	styleActive  = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("86"))
	styleRoom    = lipgloss.NewStyle().Foreground(lipgloss.Color("250"))
	stylePeer    = lipgloss.NewStyle().Foreground(lipgloss.Color("72"))
	styleSelf    = lipgloss.NewStyle().Foreground(lipgloss.Color("86"))
	styleMsgFrom = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("33"))
	styleMsgMe   = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("86"))
	styleMsgTime = lipgloss.NewStyle().Foreground(lipgloss.Color("238"))
	styleTitle   = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("33"))
	styleBorder  = lipgloss.Color("238")
	styleStatus  = lipgloss.NewStyle().Foreground(lipgloss.Color("238"))
	styleErr     = lipgloss.NewStyle().Foreground(lipgloss.Color("196")).Bold(true)
)

const sideW = 22 // total width of each sidebar box (inner = sideW-2)

// ── tea messages ──────────────────────────────────────────────────────────────

type connectedMsg struct {
	conn   net.Conn
	reader *lineReader
}
type ipcLineMsg struct{ line []byte }
type connectErrMsg struct{ err error }
type readErrMsg struct{ err error }

// lineReader pumps a TCP connection through a channel so a single bufio.Scanner
// is alive for the lifetime of the connection (avoids read-ahead data loss when
// a new scanner is created on each call).
type lineReader struct {
	ch chan []byte
}

func newLineReader(conn net.Conn) *lineReader {
	lr := &lineReader{ch: make(chan []byte, 64)}
	go func() {
		scanner := bufio.NewScanner(conn)
		for scanner.Scan() {
			b := make([]byte, len(scanner.Bytes()))
			copy(b, scanner.Bytes())
			lr.ch <- b
		}
		close(lr.ch)
	}()
	return lr
}

func (lr *lineReader) next() tea.Cmd {
	return func() tea.Msg {
		b, ok := <-lr.ch
		if !ok {
			return readErrMsg{fmt.Errorf("daemon closed connection")}
		}
		return ipcLineMsg{b}
	}
}

// ── model ─────────────────────────────────────────────────────────────────────

type entry struct {
	from   string
	body   string
	at     time.Time
	fromMe bool
}

type model struct {
	ipcPort     int
	networkName string

	width, height int

	conn   net.Conn
	enc    *json.Encoder
	reader *lineReader

	localID    proto.PeerID
	localAlias string

	rooms      []string // "general" always first; DM rooms appended
	activeRoom int
	messages   map[string][]entry

	peers     map[proto.PeerID]string // connected peers: id → alias
	peerOrder []proto.PeerID

	input    textinput.Model
	viewport viewport.Model
	vpReady  bool

	status      string
	errMsg      string
	invitePopup string // non-empty = show invite overlay
}

func newModel(ipcPort int, network string) model {
	ti := textinput.New()
	ti.Placeholder = "Type a message…"
	ti.Focus()
	ti.CharLimit = 2000

	return model{
		ipcPort:     ipcPort,
		networkName: network,
		rooms:       []string{"general"},
		messages:    make(map[string][]entry),
		peers:       make(map[proto.PeerID]string),
		input:       ti,
		status:      "connecting…",
	}
}

func (m model) Init() tea.Cmd {
	return tea.Batch(connectCmd(m.ipcPort), textinput.Blink)
}

// ── commands ──────────────────────────────────────────────────────────────────

func connectCmd(port int) tea.Cmd {
	return func() tea.Msg {
		conn, err := net.Dial("tcp", fmt.Sprintf("127.0.0.1:%d", port))
		if err != nil {
			return connectErrMsg{err}
		}
		return connectedMsg{conn: conn, reader: newLineReader(conn)}
	}
}

func sendIPC(enc *json.Encoder, msg proto.IpcMessage) tea.Cmd {
	return func() tea.Msg {
		enc.Encode(msg) //nolint:errcheck
		return nil
	}
}

// ── update ────────────────────────────────────────────────────────────────────

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmds []tea.Cmd

	switch msg := msg.(type) {

	case tea.WindowSizeMsg:
		m.width, m.height = msg.Width, msg.Height
		m = m.resizeViewport()

	case connectErrMsg:
		m.errMsg = fmt.Sprintf("cannot connect to daemon on :%d — is it running?", m.ipcPort)
		m.status = "disconnected"

	case connectedMsg:
		m.conn = msg.conn
		m.enc = json.NewEncoder(msg.conn)
		m.reader = msg.reader
		m.status = "joining " + m.networkName + "…"
		cmds = append(cmds,
			sendIPC(m.enc, proto.IpcMessage{Type: proto.CmdJoinNetwork, NetworkName: m.networkName}),
			sendIPC(m.enc, proto.IpcMessage{Type: proto.CmdGetState}),
			m.reader.next(),
		)

	case ipcLineMsg:
		var evt proto.IpcMessage
		if json.Unmarshal(msg.line, &evt) == nil {
			m = m.applyEvent(evt)
		}
		cmds = append(cmds, m.reader.next())

	case readErrMsg:
		m.errMsg = "IPC disconnected: " + msg.err.Error()
		m.status = "disconnected"

	case tea.KeyMsg:
		switch {
		case msg.Type == tea.KeyCtrlC:
			return m, tea.Quit
		case msg.Type == tea.KeyEsc:
			if m.invitePopup != "" {
				m.invitePopup = ""
				return m, nil
			}
			return m, tea.Quit
		case msg.String() == "ctrl+i":
			if m.enc != nil {
				cmds = append(cmds, sendIPC(m.enc, proto.IpcMessage{Type: proto.CmdGenerateInvite}))
			}
		case msg.Type == tea.KeyEnter:
			m, cmds = m.doSend(cmds)
		case msg.Type == tea.KeyTab:
			m.activeRoom = (m.activeRoom + 1) % len(m.rooms)
			m = m.refreshViewport()
		case msg.Type == tea.KeyShiftTab:
			m.activeRoom = (m.activeRoom - 1 + len(m.rooms)) % len(m.rooms)
			m = m.refreshViewport()
		default:
			var tiCmd tea.Cmd
			m.input, tiCmd = m.input.Update(msg)
			cmds = append(cmds, tiCmd)
		}

	default:
		// Let viewport handle scroll events.
		if m.vpReady {
			var vpCmd tea.Cmd
			m.viewport, vpCmd = m.viewport.Update(msg)
			cmds = append(cmds, vpCmd)
		}
	}

	return m, tea.Batch(cmds...)
}

func (m model) applyEvent(evt proto.IpcMessage) model {
	switch evt.Type {

	case proto.EvtStateSnapshot:
		if evt.LocalPeer != nil {
			m.localID = evt.LocalPeer.ID
			m.localAlias = evt.LocalPeer.Alias
		}
		m.peers = make(map[proto.PeerID]string)
		m.peerOrder = nil
		for _, p := range evt.ConnectedPeers {
			m.peers[p.ID] = p.Alias
			m.peerOrder = append(m.peerOrder, p.ID)
		}
		m.status = fmt.Sprintf("● %s  ·  %s", m.localAlias, m.networkName)

	case proto.EvtSessionReady:
		if evt.PeerID != nil {
			pid := *evt.PeerID
			if _, ok := m.peers[pid]; !ok {
				m.peerOrder = append(m.peerOrder, pid)
			}
			alias := evt.Nick
			if alias == "" {
				alias = shortID(pid)
			}
			m.peers[pid] = alias
		}

	case proto.EvtPeerConnected:
		if evt.Peer != nil {
			pid := evt.Peer.ID
			if _, ok := m.peers[pid]; !ok {
				m.peerOrder = append(m.peerOrder, pid)
			}
			m.peers[pid] = evt.Peer.Alias
		}

	case proto.EvtPeerDisconnected:
		if evt.PeerID != nil {
			pid := *evt.PeerID
			delete(m.peers, pid)
			m.peerOrder = filterIDs(m.peerOrder, pid)
		}

	case proto.EvtInviteGenerated:
		m.invitePopup = evt.InviteGenerated

	case proto.EvtMessageReceived:
		if evt.Message != nil {
			msg := evt.Message
			e := entry{
				from:   m.aliasOf(msg.From),
				body:   msg.Text,
				at:     time.UnixMilli(msg.Ts),
				fromMe: msg.From == m.localID,
			}
			m.messages[msg.Room] = append(m.messages[msg.Room], e)
			m = m.addRoom(msg.Room)
			m = m.refreshViewport()
		}
	}
	return m
}

func (m model) doSend(cmds []tea.Cmd) (model, []tea.Cmd) {
	body := strings.TrimSpace(m.input.Value())
	if body == "" || m.enc == nil {
		return m, cmds
	}
	m.input.SetValue("")

	room := m.rooms[m.activeRoom]
	ipcMsg := proto.IpcMessage{Type: proto.CmdSendMessage, Room: room, Body: body}
	if strings.HasPrefix(room, "dm:") {
		recipID := proto.PeerID(strings.TrimPrefix(room, "dm:"))
		ipcMsg.To = &recipID
	}
	cmds = append(cmds, sendIPC(m.enc, ipcMsg))
	return m, cmds
}

// ── layout helpers ────────────────────────────────────────────────────────────

// vpContentWidth returns the inner width of the centre pane (available to the viewport).
func (m model) vpContentWidth() int {
	// Two sidebar boxes (sideW total each) + centre box (borders 2 = -2 from inner).
	w := m.width - sideW*2 - 2
	if w < 10 {
		w = 10
	}
	return w
}

// vpHeight returns the viewport height (lines of messages shown).
func (m model) vpHeight() int {
	// Full height minus: top border(1) + title(1) + divider(1) + bottom border(1) +
	// input box (3 lines incl borders) + status bar(1) = 8 total overhead.
	h := m.height - 8
	if h < 1 {
		h = 1
	}
	return h
}

func (m model) resizeViewport() model {
	if !m.vpReady {
		m.viewport = viewport.New(m.vpContentWidth(), m.vpHeight())
		m.vpReady = true
	} else {
		m.viewport.Width = m.vpContentWidth()
		m.viewport.Height = m.vpHeight()
	}
	return m.refreshViewport()
}

func (m model) refreshViewport() model {
	if !m.vpReady {
		return m
	}
	room := m.activeRoomName()
	w := m.vpContentWidth()
	var sb strings.Builder
	for _, e := range m.messages[room] {
		ts := styleMsgTime.Render(e.at.Format("15:04"))
		var from string
		if e.fromMe {
			from = styleMsgMe.Render(e.from)
		} else {
			from = styleMsgFrom.Render(e.from)
		}
		line := fmt.Sprintf("%s %s  %s", ts, from, e.body)
		// Crude wrap: if line > w, just truncate (viewport handles horizontal scroll).
		_ = w
		sb.WriteString(line + "\n")
	}
	m.viewport.SetContent(sb.String())
	m.viewport.GotoBottom()
	return m
}

func (m model) activeRoomName() string {
	if m.activeRoom < len(m.rooms) {
		return m.rooms[m.activeRoom]
	}
	return ""
}

func (m model) addRoom(room string) model {
	for _, r := range m.rooms {
		if r == room {
			return m
		}
	}
	m.rooms = append(m.rooms, room)
	return m
}

// ── view ──────────────────────────────────────────────────────────────────────

func (m model) View() string {
	if m.width == 0 {
		return "loading…\n"
	}

	innerH := m.height - 3 - 1 // 3 = input box, 1 = status bar
	if innerH < 4 {
		innerH = 4
	}

	// ── left: rooms ───────────────────────────────────────────────────────────
	leftBox := m.renderRooms(innerH)

	// ── right: peers ──────────────────────────────────────────────────────────
	rightBox := m.renderPeers(innerH)

	// ── centre: title + messages ──────────────────────────────────────────────
	centreBox := m.renderCentre(innerH)

	mainRow := lipgloss.JoinHorizontal(lipgloss.Top, leftBox, centreBox, rightBox)

	// ── input ─────────────────────────────────────────────────────────────────
	inputBox := lipgloss.NewStyle().
		Width(m.width - 2).
		Border(lipgloss.RoundedBorder()).
		BorderForeground(styleBorder).
		Render(m.input.View())

	// ── status bar ────────────────────────────────────────────────────────────
	var statusLine string
	if m.errMsg != "" {
		statusLine = styleErr.Render(" ✗ " + m.errMsg)
	} else {
		hint := "  tab: rooms · ctrl+i: invite · ctrl+c: quit"
		statusLine = styleStatus.Width(m.width).Render(" " + m.status + hint)
	}

	view := lipgloss.JoinVertical(lipgloss.Left, mainRow, inputBox, statusLine)

	// ── invite popup (full-screen overlay) ───────────────────────────────────
	if m.invitePopup != "" {
		label := styleActive.Render("Invite — share this with anyone you want to add:")
		code := lipgloss.NewStyle().
			Border(lipgloss.RoundedBorder()).
			BorderForeground(lipgloss.Color("238")).
			Padding(0, 1).
			Width(m.width - 6).
			Render(m.invitePopup)
		hint := styleStatus.Render("Esc to close  ·  ctrl+c to quit")
		popup := lipgloss.NewStyle().
			Width(m.width).
			Height(m.height).
			Align(lipgloss.Center, lipgloss.Center).
			Render(lipgloss.JoinVertical(lipgloss.Left, label, "", code, "", hint))
		return popup
	}

	return view
}

func (m model) renderRooms(boxH int) string {
	innerW := sideW - 2
	contentH := boxH - 2 // subtract top+bottom border
	var lines []string
	lines = append(lines, styleHeader.Width(innerW).Render("Rooms"))
	lines = append(lines, lipgloss.NewStyle().Foreground(styleBorder).Render(strings.Repeat("─", innerW)))
	for i, room := range m.rooms {
		label := roomLabel(room, m.peers)
		if i == m.activeRoom {
			lines = append(lines, styleActive.Width(innerW).Render("▶ "+label))
		} else {
			lines = append(lines, styleRoom.Width(innerW).Render("  "+label))
		}
	}
	for len(lines) < contentH {
		lines = append(lines, strings.Repeat(" ", innerW))
	}
	content := strings.Join(lines[:min(len(lines), contentH)], "\n")
	return lipgloss.NewStyle().
		Width(sideW - 2).Height(boxH - 2).
		Border(lipgloss.RoundedBorder()).BorderForeground(styleBorder).
		Render(content)
}

func (m model) renderPeers(boxH int) string {
	innerW := sideW - 2
	contentH := boxH - 2
	var lines []string
	lines = append(lines, styleHeader.Width(innerW).Render("Peers"))
	lines = append(lines, lipgloss.NewStyle().Foreground(styleBorder).Render(strings.Repeat("─", innerW)))
	// Local peer first
	if m.localAlias != "" {
		lines = append(lines, styleSelf.Width(innerW).Render("◉ "+m.localAlias+" (me)"))
	}
	for _, pid := range m.peerOrder {
		alias := m.peers[pid]
		if alias == "" {
			alias = shortID(pid)
		}
		lines = append(lines, stylePeer.Width(innerW).Render("● "+alias))
	}
	for len(lines) < contentH {
		lines = append(lines, strings.Repeat(" ", innerW))
	}
	content := strings.Join(lines[:min(len(lines), contentH)], "\n")
	return lipgloss.NewStyle().
		Width(sideW - 2).Height(boxH - 2).
		Border(lipgloss.RoundedBorder()).BorderForeground(styleBorder).
		Render(content)
}

func (m model) renderCentre(boxH int) string {
	innerW := m.vpContentWidth()
	room := m.activeRoomName()
	title := styleTitle.Width(innerW).Render(" " + roomTitle(room, m.peers))
	divider := lipgloss.NewStyle().Foreground(styleBorder).Render(strings.Repeat("─", innerW))

	vpView := ""
	if m.vpReady {
		vpView = m.viewport.View()
	}

	content := lipgloss.JoinVertical(lipgloss.Left, title, divider, vpView)

	return lipgloss.NewStyle().
		Width(innerW).Height(boxH - 2).
		Border(lipgloss.RoundedBorder()).BorderForeground(styleBorder).
		Render(content)
}

// ── helpers ───────────────────────────────────────────────────────────────────

func (m model) aliasOf(id proto.PeerID) string {
	if id == m.localID {
		if m.localAlias != "" {
			return m.localAlias
		}
		return "me"
	}
	if a, ok := m.peers[id]; ok && a != "" {
		return a
	}
	return shortID(id)
}

func shortID(id proto.PeerID) string {
	s := string(id)
	if len(s) > 8 {
		return s[:8]
	}
	return s
}

func roomLabel(room string, peers map[proto.PeerID]string) string {
	if room == "general" {
		return "#general"
	}
	if strings.HasPrefix(room, "dm:") {
		pid := proto.PeerID(strings.TrimPrefix(room, "dm:"))
		if a, ok := peers[pid]; ok && a != "" {
			return "@ " + a
		}
		return "@ " + shortID(pid)
	}
	return "#" + room
}

func roomTitle(room string, peers map[proto.PeerID]string) string {
	if room == "general" {
		return "#general"
	}
	if strings.HasPrefix(room, "dm:") {
		pid := proto.PeerID(strings.TrimPrefix(room, "dm:"))
		if a, ok := peers[pid]; ok && a != "" {
			return "@ " + a
		}
		return "@ " + shortID(pid)
	}
	return "#" + room
}

func filterIDs(ids []proto.PeerID, remove proto.PeerID) []proto.PeerID {
	out := ids[:0]
	for _, v := range ids {
		if v != remove {
			out = append(out, v)
		}
	}
	return out
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

// ── main ──────────────────────────────────────────────────────────────────────

func main() {
	ipcPort     := flag.Int("ipc", 17337, "daemon IPC port")
	network     := flag.String("network", "", "network name to join on startup")
	joinInvite  := flag.String("join", "", "waste: invite string — auto-sets the network name")
	flag.Parse()

	// --join overrides --network.
	if *joinInvite != "" {
		inv, err := invite.Decode(*joinInvite)
		if err != nil {
			fmt.Fprintln(os.Stderr, "error: invalid invite:", err)
			os.Exit(1)
		}
		*network = inv.Network
	}

	if *network == "" {
		fmt.Fprintln(os.Stderr, "error: -network or -join is required")
		flag.Usage()
		os.Exit(1)
	}

	p := tea.NewProgram(
		newModel(*ipcPort, *network),
		tea.WithAltScreen(),
		tea.WithMouseCellMotion(),
	)
	if _, err := p.Run(); err != nil {
		fmt.Fprintln(os.Stderr, "tui:", err)
		os.Exit(1)
	}
}