package cat

// Native Yaesu CAT over the rig's serial/USB port — no OmniRig.
//
// Why this exists: OmniRig sits between OpsLog and the radio and adds its own
// rig-description files, its own VFO/split interpretation and its own polling.
// Every Yaesu problem reported so far came from that layer disagreeing with the
// radio — a .ini that never exposes the VFO, a Freq property that means A on one
// model and B on another, a split flag that alternates. Talking to the rig
// directly removes the disagreement: what the radio answers is what we show.
//
// ── The protocol ──────────────────────────────────────────────────────────
// Modern Yaesu CAT is plain ASCII: a command, its arguments, and a ';'
// terminator. A query is the command with no argument; the rig echoes the same
// command with the value. It is the same shape as Kenwood's, which is why an
// FTDX10 answers a Kenwood-speaking logger for the basics.
//
//	FA;            → FA014074000;   VFO A frequency, 9 digits, Hz
//	FB;            → FB014100000;   VFO B frequency
//	MD0;           → MD02;          operating mode of the main receiver
//	VS;            → VS0;           which VFO is selected (0=A, 1=B)
//	ST;            → ST1;           split (FTDX10/FTDX101)
//	FT;            → FT1;           TX VFO (FT-991A/FT-710/FT-891 family)
//	TX1; / TX0;                     key / unkey
//	ID;            → ID0761;        model identifier
//
// Two of these are genuinely uncertain across the family and are treated as
// such rather than guessed at: SPLIT is read through ST and, if the rig does not
// answer that, through FT — whichever replies wins, and the choice is
// remembered. Every unrecognised reply is logged raw, because that log is the
// only way to learn a model's real behaviour from an operator's shack.
//
// Verified on: FTDX10, 2026-07-29 — frequency, mode, VFO and split all correct
// against the radio. The other models are still inference from the same CAT
// reference; anything this file asserts about a rig it has not met should be
// read as a hypothesis with a log line attached.

import (
	"fmt"
	"strconv"
	"strings"
	"sync"
	"time"

	"go.bug.st/serial"
)

// yaesuModels maps the ID reply to a display name. An unknown id is shown as
// itself rather than guessed — a wrong model name would be worse than a number,
// because it silently implies capabilities the rig may not have.
var yaesuModels = map[string]string{
	"0761": "FTDX10",
	"0681": "FTDX101D",
	"0682": "FTDX101MP",
	"0800": "FT-710",
	"0570": "FT-991A",
	"0650": "FT-891",
	"0670": "FT-DX3000",
	"0460": "FT-450D",
}

// yaesuModeToADIF maps the MD digit to an ADIF mode. The DATA and RTTY variants
// differ only by sideband, which ADIF does not record — they collapse to the
// operator's configured digital mode and to RTTY respectively.
var yaesuModeToADIF = map[byte]string{
	'1': "LSB",
	'2': "USB",
	'3': "CW",
	'4': "FM",
	'5': "AM",
	'6': "RTTY",
	'7': "CW",
	'8': "DATA",
	'9': "RTTY",
	'A': "FM",
	'B': "FM",
	'C': "DATA",
	'D': "AM",
	'E': "FM", // C4FM — digital voice, closest ADIF sense is FM
}

type Yaesu struct {
	portName string
	baud     int
	digital  string // ADIF mode reported for DATA (FT8, RTTY…)

	mu   sync.Mutex
	port serial.Port

	model string
	// splitCmd is learned at connect: "ST" or "FT" depending on which the rig
	// answers. Empty means the rig answered neither, and split is reported as
	// off rather than invented.
	splitCmd string

	curFreq int64
	curVFO  string // "A" or "B"
}

func NewYaesu(portName string, baud int, digital string) *Yaesu {
	if baud <= 0 {
		baud = 38400 // FTDX10/FTDX101 factory default
	}
	if strings.TrimSpace(digital) == "" {
		digital = "FT8"
	}
	return &Yaesu{portName: strings.TrimSpace(portName), baud: baud, digital: digital, curVFO: "A"}
}

func (y *Yaesu) Name() string { return "yaesu" }

func (y *Yaesu) Connect() error {
	y.mu.Lock()
	defer y.mu.Unlock()
	if y.portName == "" {
		return fmt.Errorf("yaesu: no serial port configured")
	}
	p, err := serial.Open(y.portName, &serial.Mode{BaudRate: y.baud})
	if err != nil {
		return fmt.Errorf("yaesu: open %s @ %d baud: %w", y.portName, y.baud, err)
	}
	p.SetReadTimeout(300 * time.Millisecond)
	y.port = p

	// Silence unsolicited status reports. The rig can push them on every knob
	// movement (AI1), which interleaves with our request/response pairs and makes
	// a reply impossible to attribute — we poll instead, so the traffic is ours.
	_ = y.write("AI0;")

	if id, err := y.ask("ID;"); err == nil {
		code := strings.TrimSuffix(strings.TrimPrefix(id, "ID"), ";")
		if name, ok := yaesuModels[code]; ok {
			y.model = name
		} else {
			y.model = "Yaesu (" + code + ")"
			debugLog.Printf("yaesu: unknown model id %q — add it to yaesuModels", code)
		}
	} else {
		debugLog.Printf("yaesu: ID query failed (%v) — continuing, the model name is cosmetic", err)
	}

	// Which command carries split on THIS rig. Asking once at connect and
	// remembering the answer keeps the poll loop from paying for two round trips
	// per cycle, and makes "neither answered" an explicit, logged state instead
	// of a silent assumption that split is off.
	for _, c := range []string{"ST", "FT"} {
		if r, err := y.ask(c + ";"); err == nil && strings.HasPrefix(r, c) {
			y.splitCmd = c
			debugLog.Printf("yaesu: split is read through %s (answered %q)", c, r)
			break
		}
	}
	if y.splitCmd == "" {
		debugLog.Printf("yaesu: neither ST; nor FT; answered — split will be reported as OFF. Send this log if the rig does have split.")
	}
	debugLog.Printf("yaesu: connected on %s @ %d baud, model=%q", y.portName, y.baud, y.model)
	return nil
}

func (y *Yaesu) Disconnect() {
	y.mu.Lock()
	defer y.mu.Unlock()
	if y.port != nil {
		_ = y.port.Close()
		y.port = nil
	}
}

func (y *Yaesu) ReadState() (RigState, error) {
	y.mu.Lock()
	defer y.mu.Unlock()
	if y.port == nil {
		return RigState{}, fmt.Errorf("yaesu: not connected")
	}
	s := RigState{Backend: y.Name(), Connected: true, Rig: y.model}

	faRaw, err := y.ask("FA;")
	if err != nil {
		return RigState{}, err // the rig stopped answering — let the Manager reconnect
	}
	freqA, ok := parseYaesuFreq(faRaw, "FA")
	if !ok {
		return RigState{}, fmt.Errorf("yaesu: unparsable FA reply %q", faRaw)
	}
	freqB := int64(0)
	if r, err := y.ask("FB;"); err == nil {
		freqB, _ = parseYaesuFreq(r, "FB")
	}

	// Which VFO the operator is listening on. Unlike OmniRig there is no
	// interpretation to do: VS answers 0 or 1.
	vfo := "A"
	if r, err := y.ask("VS;"); err == nil && len(r) >= 3 && r[2] == '1' {
		vfo = "B"
	}
	y.curVFO = vfo

	split := false
	if y.splitCmd != "" {
		if r, err := y.ask(y.splitCmd + ";"); err == nil {
			split = yaesuSplitOn(r, y.splitCmd)
		}
	}

	s.Vfo = vfo
	s.FreqHz, s.RxFreqHz, s.Split = resolveYaesuVFOs(freqA, freqB, vfo, split)
	y.curFreq = s.FreqHz

	if r, err := y.ask("MD0;"); err == nil && len(r) >= 4 {
		if m, ok := yaesuModeToADIF[r[3]]; ok {
			if m == "DATA" {
				m = y.digital
			}
			s.Mode = m
		} else {
			debugLog.Printf("yaesu: unknown mode reply %q", r)
		}
	}
	return s, nil
}

func (y *Yaesu) SetFrequency(hz int64) error {
	y.mu.Lock()
	defer y.mu.Unlock()
	if y.port == nil {
		return fmt.Errorf("yaesu: not connected")
	}
	if hz <= 0 || hz > 999_999_999 {
		return fmt.Errorf("yaesu: frequency %d out of the 9-digit CAT range", hz)
	}
	// Write to the VFO the operator is ACTUALLY on. Always writing FA is what
	// makes a display disagree with the radio when the operator is on B.
	cmd := "FA"
	if y.curVFO == "B" {
		cmd = "FB"
	}
	return y.write(fmt.Sprintf("%s%09d;", cmd, hz))
}

func (y *Yaesu) SetMode(mode string) error {
	y.mu.Lock()
	defer y.mu.Unlock()
	if y.port == nil {
		return fmt.Errorf("yaesu: not connected")
	}
	d := yaesuModeDigit(mode, y.curFreq)
	if d == 0 {
		return fmt.Errorf("yaesu: no CAT mode for %q", mode)
	}
	return y.write(fmt.Sprintf("MD0%c;", d))
}

func (y *Yaesu) SetPTT(on bool) error {
	y.mu.Lock()
	defer y.mu.Unlock()
	if y.port == nil {
		return fmt.Errorf("yaesu: not connected")
	}
	if on {
		return y.write("TX1;")
	}
	return y.write("TX0;")
}

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

// write sends one command. The caller holds the mutex.
func (y *Yaesu) write(cmd string) error {
	if y.port == nil {
		return fmt.Errorf("yaesu: not connected")
	}
	_, err := y.port.Write([]byte(cmd))
	return err
}

// ask sends a query and reads the reply up to its ';'. The caller holds the
// mutex, so a command and its answer are never interleaved with another's.
func (y *Yaesu) ask(cmd string) (string, error) {
	if err := y.write(cmd); err != nil {
		return "", err
	}
	buf := make([]byte, 0, 32)
	tmp := make([]byte, 32)
	deadline := time.Now().Add(600 * time.Millisecond)
	for time.Now().Before(deadline) {
		n, err := y.port.Read(tmp)
		if err != nil {
			return "", err
		}
		if n == 0 {
			continue // read timeout — the rig may still be composing its answer
		}
		buf = append(buf, tmp[:n]...)
		if i := strings.IndexByte(string(buf), ';'); i >= 0 {
			return string(buf[:i+1]), nil
		}
		if len(buf) > 512 {
			return "", fmt.Errorf("yaesu: no ';' in %d bytes answering %q", len(buf), cmd)
		}
	}
	return "", fmt.Errorf("yaesu: timeout answering %q", cmd)
}

// parseYaesuFreq reads "FA014074000;" into Hz.
func parseYaesuFreq(reply, prefix string) (int64, bool) {
	r := strings.TrimSpace(reply)
	if !strings.HasPrefix(r, prefix) {
		return 0, false
	}
	digits := strings.TrimSuffix(strings.TrimPrefix(r, prefix), ";")
	if digits == "" {
		return 0, false
	}
	hz, err := strconv.ParseInt(digits, 10, 64)
	if err != nil || hz <= 0 {
		return 0, false
	}
	return hz, true
}

// yaesuSplitOn reads the split reply for whichever command the rig answers.
//
// ST is a split flag: ST1 means split. FT names the TX VFO: FT1 means transmit
// on VFO B, which IS split when the operator is listening on A. The two are not
// the same statement, which is why the command in use is remembered rather than
// both being tried and merged.
func yaesuSplitOn(reply, cmd string) bool {
	r := strings.TrimSpace(reply)
	if !strings.HasPrefix(r, cmd) || len(r) < len(cmd)+1 {
		return false
	}
	return r[len(cmd)] == '1'
}

// resolveYaesuVFOs turns the two frequencies plus the VFO and split flags into
// the ADIF pair: FreqHz is where we TRANSMIT, RxFreqHz only when split.
//
// Kept pure and separate from ReadState so the rules can be tested without a
// radio — the equivalent OmniRig function is where every Yaesu bug lived.
func resolveYaesuVFOs(freqA, freqB int64, vfo string, split bool) (tx, rx int64, isSplit bool) {
	listening, transmitting := freqA, freqB
	if vfo == "B" {
		listening, transmitting = freqB, freqA
	}
	if !split {
		return listening, 0, false
	}
	// Split with a missing or identical other VFO is not split: reporting it
	// would put a wrong TX frequency in the log, which is worse than ignoring a
	// flag the rig may have left set.
	if transmitting <= 0 || transmitting == listening {
		return listening, 0, false
	}
	return transmitting, listening, true
}

// yaesuModeDigit maps an ADIF mode to the MD digit. SSB has no single digit —
// the sideband follows the worldwide convention (LSB below 10 MHz, USB above),
// which is why the current frequency is part of the decision.
func yaesuModeDigit(mode string, freqHz int64) byte {
	switch strings.ToUpper(strings.TrimSpace(mode)) {
	case "SSB":
		if freqHz > 0 && freqHz < 10_000_000 {
			return '1' // LSB
		}
		return '2' // USB
	case "LSB":
		return '1'
	case "USB":
		return '2'
	case "CW":
		return '3'
	case "FM":
		return '4'
	case "AM":
		return '5'
	case "RTTY":
		return '6'
	case "":
		return 0
	default:
		// Everything else is a digital sub-mode (FT8, FT4, PSK31, JS8…). They all
		// ride on the rig's DATA mode; the sideband follows the same convention.
		if freqHz > 0 && freqHz < 10_000_000 {
			return '8' // DATA-LSB
		}
		return 'C' // DATA-USB
	}
}