//go:build windows

package cat

import (
	"bufio"
	"fmt"
	"math"
	"net"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"
)

// Flex is a native FlexRadio (SmartSDR) CAT backend. It speaks the radio's TCP
// API on port 4992 — a line-based text protocol — and tracks slice state pushed
// by the radio in REAL TIME, so frequency/mode/split are always current (unlike
// the polled, lagging OmniRig path that needed a second click to fix a mode).
// Pure Go, no CGO, and no OmniRig install required for Flex users.
type Flex struct {
	host string
	port int

	mu        sync.Mutex
	conn      net.Conn
	wmu       sync.Mutex // serialises writes to conn
	seq       int
	handle    string
	model     string
	gotHandle bool

	slices       map[int]*flexSlice
	lastStateSig string // last logged derived-state signature (log only on change)

	spotsEnabled bool           // push cluster spots + manage the panadapter overlay
	spotIdx      map[int]bool   // panadapter spot indices currently known to the radio
	pendingSpot  map[int]string // seq → callsign, awaiting the spot index in the R response
	spotCall     map[int]string // spot index → callsign (to fill the call on a panadapter click)

	// OnSpotClick is called (off the reader goroutine's hot path) when the user
	// clicks one of our spots on the panadapter, with the spot's callsign and
	// frequency. The host wires this to fill the entry form. Set before Connect.
	OnSpotClick func(callsign string, freqHz int64)
}

type flexSlice struct {
	freqHz int64
	mode   string // raw Flex mode (USB/LSB/CW/DIGU/…)
	active bool
	tx     bool
	inUse  bool
}

// flexTriggerRe matches the radio's "spot <index> triggered" notification, sent
// when the user clicks one of our spots on the panadapter.
var flexTriggerRe = regexp.MustCompile(`spot (\d+) triggered`)

// NewFlex builds a Flex backend for the given radio IP (host) and port (4992).
// spotsEnabled turns on the panadapter spot overlay (subscribe + clear leftovers
// on connect + accept SendSpot).
func NewFlex(host string, port int, spotsEnabled bool) *Flex {
	if port == 0 {
		port = 4992
	}
	return &Flex{
		host: strings.TrimSpace(host), port: port,
		slices: map[int]*flexSlice{}, spotsEnabled: spotsEnabled,
		spotIdx: map[int]bool{}, pendingSpot: map[int]string{}, spotCall: map[int]string{},
	}
}

func (f *Flex) Name() string { return "flex" }

// Connect dials the radio and subscribes to slice/radio status. The reader
// goroutine then keeps our cached state current from the radio's push messages.
func (f *Flex) Connect() error {
	f.mu.Lock()
	already := f.conn != nil
	host := f.host
	port := f.port
	f.mu.Unlock()
	if already {
		return nil
	}
	if host == "" {
		return fmt.Errorf("flex: no radio IP configured")
	}
	conn, err := net.DialTimeout("tcp", net.JoinHostPort(host, strconv.Itoa(port)), 5*time.Second)
	if err != nil {
		return fmt.Errorf("flex: connect %s:%d: %w", host, port, err)
	}
	f.mu.Lock()
	f.conn = conn
	f.gotHandle = false
	f.slices = map[int]*flexSlice{}
	f.mu.Unlock()
	debugLog.Printf("Flex: connected to %s:%d", host, port)

	go f.reader(conn)
	// Identify ourselves in SmartSDR's client list, then stream slice + transmit
	// (TX/split) status. Command names per the SmartSDR TCP/IP API docs.
	f.send("client program=OpsLog")
	f.send("sub slice all")
	f.send("sub transmit all")
	f.send("sub radio all")
	if f.spotsEnabled {
		// Subscribe so the radio pushes existing spots (we learn their indices),
		// then wipe the panadapter so stale spots from a previous session or
		// another logger are cleared before we start adding our own.
		f.send("sub spot all")
		go f.clearSpotsOnConnect(conn)
	}
	return nil
}

func (f *Flex) Disconnect() {
	f.mu.Lock()
	c := f.conn
	f.conn = nil
	f.gotHandle = false
	f.mu.Unlock()
	if c != nil {
		_ = c.Close()
		debugLog.Printf("Flex: disconnected")
	}
}

// send writes a sequenced command (C<seq>|<cmd>) to the radio and returns the
// sequence number (so the caller can match the R<seq> response, e.g. to learn a
// new spot's index). Returns 0 when not connected. Best effort.
func (f *Flex) send(cmd string) int {
	f.mu.Lock()
	c := f.conn
	f.seq++
	seq := f.seq
	f.mu.Unlock()
	if c == nil {
		return 0
	}
	f.wmu.Lock()
	_, err := fmt.Fprintf(c, "C%d|%s\n", seq, cmd)
	f.wmu.Unlock()
	if err != nil {
		debugLog.Printf("Flex: send %q failed: %v", cmd, err)
		return 0
	}
	debugLog.Printf("Flex: → %s", cmd)
	return seq
}

// reader consumes the radio's line stream until the connection drops.
func (f *Flex) reader(conn net.Conn) {
	sc := bufio.NewScanner(conn)
	sc.Buffer(make([]byte, 0, 64*1024), 1<<20)
	for sc.Scan() {
		line := strings.TrimRight(sc.Text(), "\r\n")
		if line == "" {
			continue
		}
		// Panadapter spot click → "…spot <index> triggered…". Resolve the index
		// back to the callsign we stored at spot-add time and notify the host.
		if mm := flexTriggerRe.FindStringSubmatch(line); mm != nil {
			if idx, err := strconv.Atoi(mm[1]); err == nil {
				f.mu.Lock()
				call := f.spotCall[idx]
				handler := f.OnSpotClick
				f.mu.Unlock()
				if call != "" && handler != nil {
					debugLog.Printf("Flex: spot %d triggered → %s", idx, call)
					go handler(call, 0)
				}
			}
		}
		switch line[0] {
		case 'V': // version banner, e.g. "V1.4.0.0"
			debugLog.Printf("Flex: radio %s", line)
		case 'H': // our client handle
			f.mu.Lock()
			f.handle = line[1:]
			f.gotHandle = true
			f.mu.Unlock()
			debugLog.Printf("Flex: handshake ok, handle=%s", line[1:])
		case 'S': // status push: S<handle>|<object ...>
			if i := strings.IndexByte(line, '|'); i >= 0 {
				f.handleStatus(line[i+1:])
			}
		case 'M': // message
			debugLog.Printf("Flex: msg %s", line)
		case 'R': // command response: R<seq>|<hex>|<message>
			parts := strings.SplitN(line[1:], "|", 3)
			if len(parts) < 2 {
				break
			}
			seq, _ := strconv.Atoi(parts[0])
			ok := parts[1] == "0" || parts[1] == "00000000"
			if !ok {
				debugLog.Printf("Flex: cmd error %s", line)
			}
			// A successful "spot add" returns the new spot's index in the message;
			// pair it with the callsign we stashed under this seq.
			f.mu.Lock()
			call, pending := f.pendingSpot[seq]
			if pending {
				delete(f.pendingSpot, seq)
			}
			if pending && ok && len(parts) >= 3 {
				if idx, e := strconv.Atoi(strings.TrimSpace(parts[2])); e == nil {
					f.spotCall[idx] = call
					f.spotIdx[idx] = true
				}
			}
			f.mu.Unlock()
		}
	}
	// Connection ended.
	f.mu.Lock()
	if f.conn == conn {
		f.conn = nil
		f.gotHandle = false
	}
	f.mu.Unlock()
}

// handleStatus parses one status payload, e.g.
// "slice 0 in_use=1 RF_frequency=14.150000 mode=USB active=1 tx=1 …"
func (f *Flex) handleStatus(payload string) {
	fields := strings.Fields(payload)
	if len(fields) < 2 || fields[0] != "slice" {
		// radio … model=FLEX-6400 — grab the model when present.
		if len(fields) >= 1 && fields[0] == "radio" {
			for _, kv := range fields[1:] {
				if strings.HasPrefix(kv, "model=") {
					f.mu.Lock()
					f.model = strings.TrimPrefix(kv, "model=")
					f.mu.Unlock()
				}
			}
		}
		if len(fields) >= 1 && fields[0] == "transmit" {
			debugLog.Printf("Flex: status %s", payload)
		}
		// Spot status: "spot <index> …". Track the index so we can clear the
		// panadapter, and log it verbatim — a click on a panadapter spot pushes a
		// spot status, which we'll use to fill the callsign once we see its shape.
		if len(fields) >= 2 && fields[0] == "spot" {
			// The click ("spot N triggered") is handled in the reader; here we
			// just keep the set of live spot indices for ClearSpots.
			if idx, err := strconv.Atoi(fields[1]); err == nil {
				removed := false
				for _, kv := range fields[2:] {
					if kv == "removed" || kv == "in_use=0" {
						removed = true
					}
				}
				f.mu.Lock()
				if removed {
					delete(f.spotIdx, idx)
					delete(f.spotCall, idx)
				} else {
					f.spotIdx[idx] = true
				}
				f.mu.Unlock()
			}
			debugLog.Printf("Flex: status %s", payload)
		}
		return
	}
	// Slice status — log it so split/freq/mode issues are diagnosable.
	debugLog.Printf("Flex: status %s", payload)
	idx, err := strconv.Atoi(fields[1])
	if err != nil {
		return
	}
	f.mu.Lock()
	s := f.slices[idx]
	if s == nil {
		s = &flexSlice{}
		f.slices[idx] = s
	}
	for _, kv := range fields[2:] {
		eq := strings.IndexByte(kv, '=')
		if eq <= 0 {
			continue
		}
		key, val := kv[:eq], kv[eq+1:]
		switch key {
		case "RF_frequency":
			if mhz, e := strconv.ParseFloat(val, 64); e == nil {
				s.freqHz = int64(math.Round(mhz * 1e6))
			}
		case "mode":
			s.mode = val
		case "active":
			s.active = val == "1"
		case "tx":
			s.tx = val == "1"
		case "in_use":
			s.inUse = val == "1"
		}
	}
	f.mu.Unlock()
}

// ReadState returns the cached state derived from the radio's push messages —
// no round-trip, so it's always current.
func (f *Flex) ReadState() (RigState, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.conn == nil {
		return RigState{}, fmt.Errorf("flex: not connected")
	}
	st := RigState{Connected: f.gotHandle, Rig: f.model}
	if !f.gotHandle {
		return st, nil // connected TCP but radio hasn't handshaked yet
	}
	rx, tx := f.pickSlicesLocked()
	if rx == nil && tx == nil {
		return st, nil
	}
	if tx == nil {
		tx = rx
	}
	if rx == nil {
		rx = tx
	}
	st.FreqHz = tx.freqHz
	st.Mode = flexModeToADIF(tx.mode)
	if rx.freqHz != tx.freqHz {
		st.Split = true
		st.RxFreqHz = rx.freqHz
	}
	sig := fmt.Sprintf("%d/%d/%v/%s", st.FreqHz, st.RxFreqHz, st.Split, st.Mode)
	if sig != f.lastStateSig {
		f.lastStateSig = sig
		debugLog.Printf("Flex: state tx=%d rx=%d split=%v mode=%s", st.FreqHz, st.RxFreqHz, st.Split, st.Mode)
	}
	return st, nil
}

// pickSlicesLocked chooses the TX and RX slices among in-use slices. TX is the
// slice flagged tx=1. RX is the slice you actually receive on — the NON-TX slice
// (preferring the active/focused one), NOT simply the active slice: tuning the
// TX slice makes it the active/focused slice, which would otherwise collapse RX
// onto TX and hide the split. Caller holds f.mu.
func (f *Flex) pickSlicesLocked() (rx, tx *flexSlice) {
	idxs := make([]int, 0, len(f.slices))
	for i, s := range f.slices {
		if s.inUse {
			idxs = append(idxs, i)
		}
	}
	sort.Ints(idxs)
	var active, txS, nonTx, first *flexSlice
	for _, i := range idxs {
		s := f.slices[i]
		if first == nil {
			first = s
		}
		if s.active {
			active = s
		}
		if s.tx {
			txS = s
		} else if nonTx == nil {
			nonTx = s
		}
	}
	tx = txS
	if tx == nil {
		if active != nil {
			tx = active
		} else {
			tx = first
		}
	}
	// RX = the receive slice: the active one if it isn't the TX slice, else the
	// first non-TX slice; fall back to TX (simplex) when there's only one slice.
	switch {
	case active != nil && active != tx:
		rx = active
	case nonTx != nil:
		rx = nonTx
	default:
		rx = tx
	}
	return rx, tx
}

// activeSliceIndexLocked returns the slice index to send commands to (the active
// slice, else the lowest in-use index, else 0). Caller holds f.mu.
func (f *Flex) activeSliceIndexLocked() int {
	best, found := 1<<30, false
	for idx, s := range f.slices {
		if !s.inUse {
			continue
		}
		if s.active {
			return idx
		}
		if idx < best {
			best, found = idx, true
		}
	}
	if found {
		return best
	}
	return 0
}

func (f *Flex) SetFrequency(hz int64) error {
	if hz <= 0 {
		return fmt.Errorf("flex: invalid frequency")
	}
	f.mu.Lock()
	idx := f.activeSliceIndexLocked()
	connected := f.conn != nil
	f.mu.Unlock()
	if !connected {
		return fmt.Errorf("flex: not connected")
	}
	// "slice t <rx> <freq_MHz>" — tune command per the SmartSDR API (MHz, 6 dp).
	f.send(fmt.Sprintf("slice t %d %.6f", idx, float64(hz)/1e6))
	return nil
}

func (f *Flex) SetMode(mode string) error {
	f.mu.Lock()
	idx := f.activeSliceIndexLocked()
	var freq int64
	if s := f.slices[idx]; s != nil {
		freq = s.freqHz
	}
	connected := f.conn != nil
	f.mu.Unlock()
	if !connected {
		return fmt.Errorf("flex: not connected")
	}
	fm := adifModeToFlex(mode, freq)
	if fm == "" {
		return fmt.Errorf("flex: unsupported mode %q", mode)
	}
	// "slice s <rx> mode=<m>" — set command per the SmartSDR API.
	f.send(fmt.Sprintf("slice s %d mode=%s", idx, fm))
	return nil
}

// SendSpot renders a cluster spot on the panadapter via "spot add". Spots carry
// a lifetime so the radio expires them on its own (the API has no "spot clear").
// Per the SmartSDR API, spaces inside a field value are encoded as 0x7F.
func (f *Flex) SendSpot(s SpotInfo) error {
	f.mu.Lock()
	connected := f.conn != nil && f.gotHandle
	f.mu.Unlock()
	if !connected {
		return fmt.Errorf("flex: not connected")
	}
	call := flexEncode(s.Callsign)
	if call == "" || s.FreqHz <= 0 {
		return nil
	}
	color := s.Color
	if color == "" {
		color = "#FFFFA500" // opaque orange default
	}
	cmd := fmt.Sprintf("spot add rx_freq=%.6f callsign=%s color=%s source=OpsLog lifetime_seconds=1800 trigger_action=Tune timestamp=%d",
		float64(s.FreqHz)/1e6, call, color, time.Now().Unix())
	if m := flexEncode(s.Mode); m != "" {
		cmd += " mode=" + m
	}
	if c := flexEncode(s.Comment); c != "" {
		cmd += " comment=" + c
	}
	seq := f.send(cmd)
	if seq > 0 {
		// Remember which call this add was for; the R<seq> response carries the
		// radio-assigned spot index, which we map to the call so a later click
		// (trigger) can be resolved back to the callsign.
		f.mu.Lock()
		f.pendingSpot[seq] = s.Callsign
		f.mu.Unlock()
	}
	return nil
}

// clearSpotsOnConnect waits until the radio handshake completes (we're truly
// connected), then sends "spot clear" so launching OpsLog — or enabling the
// option — starts from a clean panadapter, including spots left by another
// logger or a previous session.
func (f *Flex) clearSpotsOnConnect(conn net.Conn) {
	for i := 0; i < 50; i++ { // up to ~5s for the handshake
		f.mu.Lock()
		ready := f.gotHandle && f.conn == conn
		gone := f.conn != conn
		f.mu.Unlock()
		if gone {
			return // reconnected/closed in the meantime
		}
		if ready {
			f.ClearSpots()
			return
		}
		time.Sleep(100 * time.Millisecond)
	}
}

// ClearSpots wipes ALL panadapter spots in one command ("spot clear") — removes
// stale spots from a previous session or another logger, not just our own.
func (f *Flex) ClearSpots() error {
	f.mu.Lock()
	f.spotIdx = map[int]bool{}
	f.spotCall = map[int]string{}
	connected := f.conn != nil
	f.mu.Unlock()
	if !connected {
		return fmt.Errorf("flex: not connected")
	}
	f.send("spot clear")
	debugLog.Printf("Flex: spot clear sent")
	return nil
}

// flexEncode prepares a value for the Flex command line: trimmed, with any
// internal spaces replaced by 0x7F as the SmartSDR API requires.
func flexEncode(s string) string {
	s = strings.TrimSpace(s)
	if s == "" {
		return ""
	}
	return strings.ReplaceAll(s, " ", "\x7f")
}

func (f *Flex) SetPTT(on bool) error {
	f.mu.Lock()
	connected := f.conn != nil
	f.mu.Unlock()
	if !connected {
		return fmt.Errorf("flex: not connected")
	}
	if on {
		f.send("xmit 1")
	} else {
		f.send("xmit 0")
	}
	return nil
}

// flexModeToADIF maps a Flex slice mode to a generic ADIF mode.
func flexModeToADIF(m string) string {
	switch strings.ToUpper(strings.TrimSpace(m)) {
	case "USB", "LSB":
		return "SSB"
	case "CW":
		return "CW"
	case "AM", "SAM":
		return "AM"
	case "FM", "NFM", "DFM":
		return "FM"
	case "DIGU", "DIGL":
		return "DATA"
	case "RTTY":
		return "RTTY"
	case "FDV":
		return "DIGITALVOICE"
	case "":
		return ""
	default:
		return strings.ToUpper(m)
	}
}

// adifModeToFlex maps an ADIF mode to a Flex slice mode. SSB picks USB/LSB from
// the frequency (LSB below 10 MHz, USB above) — the standard convention.
func adifModeToFlex(mode string, freqHz int64) string {
	switch strings.ToUpper(strings.TrimSpace(mode)) {
	case "SSB":
		if freqHz > 0 && freqHz < 10_000_000 {
			return "LSB"
		}
		return "USB"
	case "USB":
		return "USB"
	case "LSB":
		return "LSB"
	case "CW":
		return "CW"
	case "AM":
		return "AM"
	case "FM":
		return "FM"
	case "RTTY", "FSK":
		return "RTTY"
	case "FT8", "FT4", "PSK31", "MFSK", "JS8", "JT65", "JT9", "OLIVIA", "DATA", "DIGITALVOICE":
		return "DIGU"
	default:
		return ""
	}
}