package cat

// CW keying through the Yaesu's own keyer — the KY command.
//
// This is the fifth CW engine, alongside WinKeyer, the DTR/RTS line keyer, the
// Icom CI-V keyer and FlexRadio's CWX. The point is the same in each: no extra
// hardware, no second cable. The radio holds the text and keys it with its own
// timing, which is why the character spacing is perfect where a PC keying a line
// through USB latency is not.
//
//	KY;           → KY0;  buffer has room / KY1; buffer full
//	KY <text>;            queue up to 24 characters
//
// The leading SPACE after KY is part of the command, not padding.
//
// Verified on: nothing yet — the send path follows the FTDX10/FTDX101 CAT
// reference and the way Hamlib drives these rigs. STOP is the uncertain half:
// Yaesu documents no way to clear the buffer, so see StopCW.

import (
	"fmt"
	"strings"
	"time"
)

// yaesuCWChunk is the most characters one KY command accepts. Longer text is
// split and fed as the rig drains its buffer.
const yaesuCWChunk = 24

// cwStatusLogged makes the KY status reply appear in the log once per run: it
// is a line we have no verified sample of, so the first one is worth keeping.
var cwStatusLogged bool

// yaesuCWAllowed is what the rig's keyer can actually send. Anything else is
// dropped rather than passed through: an unsupported byte can abort the whole
// buffer, losing the rest of the message with no error anywhere.
const yaesuCWAllowed = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 /?.,-=+:;()"

// SendCW queues a message on the rig's keyer.
//
// Text is filtered, upper-cased and fed in 24-character pieces, waiting for room
// between pieces. Without that wait a long macro would silently lose its tail:
// the rig drops what does not fit rather than reporting an error.
func (y *Yaesu) SendCW(text string) error {
	msg := filterYaesuCW(text)
	if msg == "" {
		return nil
	}
	for len(msg) > 0 {
		n := yaesuCWChunk
		if len(msg) < n {
			n = len(msg)
		}
		chunk := msg[:n]
		msg = msg[n:]
		if err := y.waitCWBuffer(4 * time.Second); err != nil {
			return err
		}
		y.mu.Lock()
		err := y.write("KY " + chunk + ";")
		y.mu.Unlock()
		if err != nil {
			return err
		}
	}
	return nil
}

// StopCW aborts the message being sent.
//
// Yaesu documents no buffer-clear, so this drops the transmitter instead: TX0
// takes the rig out of transmit, which is what an operator pressing Escape
// actually wants. Anything still queued is not keyed on the air.
//
// It deliberately does NOT send "KY0;" — a plausible-looking clear that the rig
// would read as the CHARACTER zero and dutifully send. A wrong guess here
// transmits, which is worse than an imperfect abort.
func (y *Yaesu) StopCW() error {
	y.mu.Lock()
	defer y.mu.Unlock()
	if y.port == nil {
		return fmt.Errorf("yaesu: not connected")
	}
	return y.write("TX0;")
}

// waitCWBuffer blocks until the keyer reports room, or the deadline passes.
// A rig that never answers the status query is not a reason to refuse to send —
// we go ahead once, and the worst case is the truncation we were avoiding.
func (y *Yaesu) waitCWBuffer(within time.Duration) error {
	deadline := time.Now().Add(within)
	for {
		y.mu.Lock()
		if y.port == nil {
			y.mu.Unlock()
			return fmt.Errorf("yaesu: not connected")
		}
		r, err := y.ask("KY;")
		y.mu.Unlock()
		if err != nil {
			debugLog.Printf("yaesu cw: KY status query failed (%v) — sending anyway", err)
			return nil
		}
		// Only an explicit "full" holds us back.
		//
		// The first version required the reply to be exactly "KY0;" at byte 2, and
		// on a real FTDX10 that refused to send at all: anything the rig phrases
		// differently — a space before the digit, a longer status — read as "still
		// full" and the send died after four seconds having keyed nothing. The rig
		// is the one that knows; when its answer is not a clear "1", the right move
		// is to go ahead rather than to sit and time out.
		// Log the shape once per session: this is a reply we have no verified
		// sample of, and the log is what turns the next surprise into a fact.
		if !cwStatusLogged {
			cwStatusLogged = true
			debugLog.Printf("yaesu cw: KY status reply is %q (full=%v)", r, yaesuCWBufferFull(r))
		}
		if !yaesuCWBufferFull(r) {
			return nil
		}
		if time.Now().After(deadline) {
			return fmt.Errorf("yaesu: the keyer buffer stayed full for %s (last reply %q)", within, r)
		}
		time.Sleep(50 * time.Millisecond)
	}
}

// yaesuCWBufferFull reads the KY status reply.
//
// Deliberately asymmetric: only a clear "1" means full. Anything else — an
// unexpected shape, a reply from another command that arrived first, an empty
// string — is treated as "go ahead". Refusing to send because a status line was
// phrased unexpectedly is the worse failure: the operator gets silence with no
// explanation, where at worst sending early truncates a long message.
func yaesuCWBufferFull(reply string) bool {
	r := strings.TrimSpace(reply)
	if !strings.HasPrefix(strings.ToUpper(r), "KY") {
		return false
	}
	for _, c := range r[2:] {
		switch c {
		case '0':
			return false
		case '1':
			return true
		case ' ', ';':
			continue
		default:
			return false // not a status digit — don't block on it
		}
	}
	return false
}

// filterYaesuCW upper-cases and strips what the keyer cannot send.
func filterYaesuCW(text string) string {
	var b strings.Builder
	for _, r := range strings.ToUpper(text) {
		// Any whitespace becomes a word gap FIRST. Dropping tabs and newlines as
		// "not in the allowed set" glued the words either side together: a macro
		// written on two lines went out as CQCQ.
		if r == '\t' || r == '\n' || r == '\r' {
			b.WriteByte(' ')
			continue
		}
		if strings.ContainsRune(yaesuCWAllowed, r) {
			b.WriteRune(r)
		}
	}
	// Runs of spaces become one: the rig sends each as a word gap, so three in a
	// row is three gaps and the message crawls.
	return strings.Join(strings.Fields(b.String()), " ")
}