package cat

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

	"hamlog/internal/cat/civ"

	"go.bug.st/serial"
)

// IcomSerial controls an Icom transceiver over its USB/serial CI-V port (local
// control). It speaks the shared civ protocol, so when the network backend
// (icomnet) is added it will reuse the same encode/decode — only the transport
// changes. Implements Backend; all methods run on the Manager's CAT goroutine,
// so the port is accessed single-threaded (no locking needed).
type IcomSerial struct {
	portName string
	baud     int
	rigAddr  byte   // rig's CI-V address (IC-7610 default 0x98)
	digital  string // mode to command for DATA (FT8/RTTY/…)

	port  serial.Port
	rx    []byte // accumulated bytes awaiting a complete frame
	model string

	curFreq       int64 // last frequency read (for sideband choice)
	curModeByte   byte  // last raw Icom mode byte (for filter re-send)
	lastSetFreq   int64 // last frequency commanded (spot click: freq then mode)
	lastSetFreqAt time.Time

	// dsp caches the receive-DSP state for the Icom control tab. Read off the
	// CAT goroutine via IcomState(), written on the CAT goroutine (RefreshIcom
	// / setters) — hence the mutex.
	dspMu sync.Mutex
	dsp   IcomTXState
}

const (
	icomReadTimeout = 350 * time.Millisecond // wait for a poll response
	icomCmdTimeout  = 400 * time.Millisecond // wait for a set ack (FB/FA)
)

// NewIcomSerial builds an (unconnected) Icom serial backend. baud defaults to
// 115200, rig address to the IC-7610's 0x98 when out of range.
func NewIcomSerial(portName string, baud, civAddr int, digitalDefault string) *IcomSerial {
	if baud <= 0 {
		baud = 115200
	}
	if civAddr <= 0 || civAddr > 0xFF {
		civAddr = 0x98 // IC-7610
	}
	if digitalDefault == "" {
		digitalDefault = "FT8"
	}
	return &IcomSerial{
		portName: portName,
		baud:     baud,
		rigAddr:  byte(civAddr),
		digital:  strings.ToUpper(digitalDefault),
		model:    "Icom",
	}
}

func (b *IcomSerial) Name() string { return "icom" }

func (b *IcomSerial) Connect() error {
	if b.portName == "" {
		return fmt.Errorf("no serial port configured")
	}
	port, err := serial.Open(b.portName, &serial.Mode{BaudRate: b.baud})
	if err != nil {
		return fmt.Errorf("open %s @ %d baud: %w", b.portName, b.baud, err)
	}
	// Short read timeout so recv() polls in a tight loop without blocking the
	// CAT goroutine when the rig is silent.
	_ = port.SetReadTimeout(60 * time.Millisecond)
	b.port = port
	b.rx = b.rx[:0]
	b.model = civ.ModelName(b.rigAddr)

	// Best-effort model identification: ask the rig for its own CI-V address.
	if err := b.write(civ.CmdReadID, civ.SubPTT); err == nil {
		if f, err := b.recv(icomReadTimeout, func(d civ.Decoded) bool {
			return d.Cmd == civ.CmdReadID && len(d.Data) >= 2 && d.Data[0] == 0x00
		}); err == nil {
			b.model = civ.ModelName(f.Data[1])
		}
	}
	b.readDSP() // best-effort initial snapshot for the control tab
	return nil
}

func (b *IcomSerial) Disconnect() {
	if b.port != nil {
		_ = b.port.Close()
		b.port = nil
	}
}

// ReadState polls the rig for frequency and mode. A failed frequency read is
// treated as "lost the rig" so the Manager reconnects.
func (b *IcomSerial) ReadState() (RigState, error) {
	if b.port == nil {
		return RigState{}, fmt.Errorf("not connected")
	}
	s := RigState{Backend: b.Name(), Connected: true, Rig: b.model}

	hz, err := b.readFreq()
	if err != nil {
		return RigState{}, err
	}
	s.FreqHz = hz
	b.curFreq = hz

	if m, ok := b.readMode(); ok {
		b.curModeByte = m
		data := b.readDataMode() // best-effort; ignored on failure
		s.Mode = civ.ModeToADIF(m, data)
		if s.Mode == "DATA" {
			s.Mode = b.digital
		}
		b.dspMu.Lock()
		b.dsp.Mode = s.Mode
		b.dspMu.Unlock()
	}
	return s, nil
}

func (b *IcomSerial) SetFrequency(hz int64) error {
	if hz <= 0 {
		return fmt.Errorf("invalid frequency")
	}
	b.lastSetFreq, b.lastSetFreqAt = hz, time.Now()
	return b.exec(append([]byte{civ.CmdSetFreq}, civ.FreqToBCD(hz)...)...)
}

func (b *IcomSerial) SetMode(mode string) error {
	code, data, err := b.modeCode(mode)
	if err != nil {
		return err
	}
	// Set the base mode (keeping the rig's current filter by sending only the
	// mode byte), then set the data-mode flag for digital modes.
	if err := b.exec(civ.CmdSetMode, code); err != nil {
		return err
	}
	dataByte := byte(0)
	if data {
		dataByte = 1
	}
	// Filter 0x01 (FIL1) is the conventional default for the data-mode set.
	_ = b.exec(civ.CmdExtra, civ.SubDataMode, dataByte, 0x01)
	return nil
}

func (b *IcomSerial) SetPTT(on bool) error {
	state := byte(0)
	if on {
		state = 1
	}
	return b.exec(civ.CmdPTT, civ.SubPTT, state)
}

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

func (b *IcomSerial) write(payload ...byte) error {
	_, err := b.port.Write(civ.Frame(b.rigAddr, civ.AddrController, payload...))
	return err
}

// recv reads from the port until a frame from the rig satisfies match or the
// timeout elapses. Frames that are our own echo (from == controller) or don't
// match are discarded.
func (b *IcomSerial) recv(timeout time.Duration, match func(civ.Decoded) bool) (civ.Decoded, error) {
	deadline := time.Now().Add(timeout)
	tmp := make([]byte, 256)
	for time.Now().Before(deadline) {
		n, err := b.port.Read(tmp)
		if err != nil {
			return civ.Decoded{}, err
		}
		if n == 0 {
			continue
		}
		b.rx = append(b.rx, tmp[:n]...)
		frames, consumed := civ.Scan(b.rx)
		if consumed > 0 {
			b.rx = append(b.rx[:0], b.rx[consumed:]...)
		}
		for _, f := range frames {
			if f.From != b.rigAddr {
				continue // skip echo of our own commands
			}
			if match(f) {
				return f, nil
			}
		}
	}
	return civ.Decoded{}, fmt.Errorf("icom: timeout waiting for response")
}

// exec sends a set command and waits for the rig's OK (FB) / NG (FA) ack.
func (b *IcomSerial) exec(payload ...byte) error {
	if err := b.write(payload...); err != nil {
		return err
	}
	f, err := b.recv(icomCmdTimeout, func(d civ.Decoded) bool {
		return d.Cmd == civ.OK || d.Cmd == civ.NG
	})
	if err != nil {
		return err
	}
	if f.Cmd == civ.NG {
		return fmt.Errorf("icom: rig rejected command 0x%02X", payload[0])
	}
	return nil
}

func (b *IcomSerial) readFreq() (int64, error) {
	if err := b.write(civ.CmdReadFreq); err != nil {
		return 0, err
	}
	f, err := b.recv(icomReadTimeout, func(d civ.Decoded) bool {
		return d.Cmd == civ.CmdReadFreq || d.Cmd == civ.CmdTransceiveFreq
	})
	if err != nil {
		return 0, err
	}
	return civ.BCDToFreq(f.Data), nil
}

func (b *IcomSerial) readMode() (byte, bool) {
	if err := b.write(civ.CmdReadMode); err != nil {
		return 0, false
	}
	f, err := b.recv(icomReadTimeout, func(d civ.Decoded) bool {
		return (d.Cmd == civ.CmdReadMode || d.Cmd == civ.CmdTransceiveMode) && len(d.Data) >= 1
	})
	if err != nil {
		return 0, false
	}
	return f.Data[0], true
}

func (b *IcomSerial) readDataMode() bool {
	if err := b.write(civ.CmdExtra, civ.SubDataMode); err != nil {
		return false
	}
	f, err := b.recv(icomReadTimeout, func(d civ.Decoded) bool {
		return d.Cmd == civ.CmdExtra && len(d.Data) >= 2 && d.Data[0] == civ.SubDataMode
	})
	if err != nil {
		return false
	}
	return f.Data[1] != 0
}

// modeCode maps an ADIF mode to an Icom mode byte plus whether the data-mode
// flag should be set. SSB sideband follows the usual convention (LSB below
// 10 MHz, USB above); the frequency just commanded is preferred over the last
// poll so a clicked spot (freq then mode) picks the right sideband immediately.
func (b *IcomSerial) modeCode(mode string) (code byte, data bool, err error) {
	freq := b.curFreq
	if b.lastSetFreq > 0 && time.Since(b.lastSetFreqAt) < 5*time.Second {
		freq = b.lastSetFreq
	}
	usb := byte(civ.ModeUSB)
	if freq > 0 && freq < 10_000_000 {
		usb = civ.ModeLSB
	}
	switch strings.ToUpper(strings.TrimSpace(mode)) {
	case "CW":
		return civ.ModeCW, false, nil
	case "SSB":
		return usb, false, nil
	case "AM":
		return civ.ModeAM, false, nil
	case "FM":
		return civ.ModeFM, false, nil
	case "RTTY", "FSK":
		return civ.ModeRTTY, false, nil
	case "FT8", "FT4", "PSK31", "MFSK", "JS8", "JT65", "JT9", "OLIVIA", "DATA", "DIGITALVOICE":
		// Digital data modes ride on USB with the data flag set (FT8 etc.).
		return civ.ModeUSB, true, nil
	}
	return 0, false, fmt.Errorf("icom: unsupported mode %q", mode)
}

// ── IcomController: receive-DSP controls for the Icom tab ───────────────────

func (b *IcomSerial) IcomState() IcomTXState {
	b.dspMu.Lock()
	defer b.dspMu.Unlock()
	return b.dsp
}

// RefreshIcom re-reads the whole DSP snapshot from the rig. Runs on the CAT
// goroutine (dispatched via IcomDo).
func (b *IcomSerial) RefreshIcom() error {
	if b.port == nil {
		return fmt.Errorf("not connected")
	}
	b.readDSP()
	return nil
}

// readDSP polls every DSP value once and replaces the cache. Best-effort: a
// value the rig doesn't answer keeps its previous cached value rather than
// stalling (each read has a short timeout).
func (b *IcomSerial) readDSP() {
	st := IcomTXState{Available: true, Model: b.model}
	b.dspMu.Lock()
	st.Mode = b.dsp.Mode // preserve mode (set by ReadState)
	b.dspMu.Unlock()

	if v, ok := b.readLevel(civ.SubLevelAF); ok {
		st.AFGain = from255(v)
	}
	if v, ok := b.readLevel(civ.SubLevelRF); ok {
		st.RFGain = from255(v)
	}
	if v, ok := b.readLevel(civ.SubLevelNR); ok {
		st.NRLevel = from255(v)
	}
	if v, ok := b.readLevel(civ.SubLevelNB); ok {
		st.NBLevel = from255(v)
	}
	if v, ok := b.readSwitch(civ.SubSwNB); ok {
		st.NB = v != 0
	}
	if v, ok := b.readSwitch(civ.SubSwNR); ok {
		st.NR = v != 0
	}
	if v, ok := b.readSwitch(civ.SubSwANF); ok {
		st.ANF = v != 0
	}
	if v, ok := b.readSwitch(civ.SubSwAGC); ok {
		st.AGC = agcName(v)
	}
	if v, ok := b.readSwitch(civ.SubSwPreamp); ok {
		st.Preamp = int(v)
	}
	if v, ok := b.readAtt(); ok {
		st.Att = v
	}
	if _, f, ok := b.readModeFilter(); ok {
		st.Filter = int(f)
	}

	b.dspMu.Lock()
	b.dsp = st
	b.dspMu.Unlock()
}

const icomDSPTimeout = 150 * time.Millisecond // shorter: unsupported reads mustn't stall the poll

func (b *IcomSerial) readLevel(sub byte) (int, bool) {
	if err := b.write(civ.CmdLevel, sub); err != nil {
		return 0, false
	}
	f, err := b.recv(icomDSPTimeout, func(d civ.Decoded) bool {
		return d.Cmd == civ.CmdLevel && len(d.Data) >= 3 && d.Data[0] == sub
	})
	if err != nil {
		return 0, false
	}
	return civ.BCDToLevel(f.Data[1:3]), true
}

func (b *IcomSerial) readSwitch(sub byte) (byte, bool) {
	if err := b.write(civ.CmdSwitch, sub); err != nil {
		return 0, false
	}
	f, err := b.recv(icomDSPTimeout, func(d civ.Decoded) bool {
		return d.Cmd == civ.CmdSwitch && len(d.Data) >= 2 && d.Data[0] == sub
	})
	if err != nil {
		return 0, false
	}
	return f.Data[1], true
}

func (b *IcomSerial) readAtt() (int, bool) {
	if err := b.write(civ.CmdAtt); err != nil {
		return 0, false
	}
	f, err := b.recv(icomDSPTimeout, func(d civ.Decoded) bool {
		return d.Cmd == civ.CmdAtt && len(d.Data) >= 1
	})
	if err != nil {
		return 0, false
	}
	return civ.BCDToByte(f.Data[0]), true
}

func (b *IcomSerial) readModeFilter() (mode, filter byte, ok bool) {
	if err := b.write(civ.CmdReadMode); err != nil {
		return 0, 0, false
	}
	f, err := b.recv(icomDSPTimeout, func(d civ.Decoded) bool {
		return d.Cmd == civ.CmdReadMode && len(d.Data) >= 2
	})
	if err != nil {
		return 0, 0, false
	}
	return f.Data[0], f.Data[1], true
}

func (b *IcomSerial) SetAFGain(p int) error {
	if err := b.exec(append([]byte{civ.CmdLevel, civ.SubLevelAF}, civ.LevelToBCD(to255(p))...)...); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.AFGain = clampPct(p) })
	return nil
}

func (b *IcomSerial) SetRFGain(p int) error {
	if err := b.exec(append([]byte{civ.CmdLevel, civ.SubLevelRF}, civ.LevelToBCD(to255(p))...)...); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.RFGain = clampPct(p) })
	return nil
}

func (b *IcomSerial) SetNB(on bool) error {
	if err := b.exec(civ.CmdSwitch, civ.SubSwNB, boolByte(on)); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.NB = on })
	return nil
}

func (b *IcomSerial) SetNBLevel(p int) error {
	if err := b.exec(append([]byte{civ.CmdLevel, civ.SubLevelNB}, civ.LevelToBCD(to255(p))...)...); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.NBLevel = clampPct(p) })
	return nil
}

func (b *IcomSerial) SetNR(on bool) error {
	if err := b.exec(civ.CmdSwitch, civ.SubSwNR, boolByte(on)); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.NR = on })
	return nil
}

func (b *IcomSerial) SetNRLevel(p int) error {
	if err := b.exec(append([]byte{civ.CmdLevel, civ.SubLevelNR}, civ.LevelToBCD(to255(p))...)...); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.NRLevel = clampPct(p) })
	return nil
}

func (b *IcomSerial) SetANF(on bool) error {
	if err := b.exec(civ.CmdSwitch, civ.SubSwANF, boolByte(on)); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.ANF = on })
	return nil
}

func (b *IcomSerial) SetAGC(name string) error {
	v := agcValue(name)
	if v == 0 {
		return fmt.Errorf("icom: invalid AGC %q", name)
	}
	if err := b.exec(civ.CmdSwitch, civ.SubSwAGC, v); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.AGC = strings.ToUpper(name) })
	return nil
}

func (b *IcomSerial) SetPreamp(n int) error {
	if n < 0 || n > 2 {
		return fmt.Errorf("icom: invalid preamp %d", n)
	}
	if err := b.exec(civ.CmdSwitch, civ.SubSwPreamp, byte(n)); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.Preamp = n })
	return nil
}

func (b *IcomSerial) SetAtt(db int) error {
	if err := b.exec(civ.CmdAtt, civ.ByteToBCD(db)); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.Att = db })
	return nil
}

func (b *IcomSerial) SetIcomFilter(n int) error {
	if n < 1 || n > 3 {
		return fmt.Errorf("icom: invalid filter %d", n)
	}
	if b.curModeByte == 0 {
		// Need the current mode to re-send with the chosen filter.
		if m, _, ok := b.readModeFilter(); ok {
			b.curModeByte = m
		}
	}
	if err := b.exec(civ.CmdSetMode, b.curModeByte, byte(n)); err != nil {
		return err
	}
	b.setCache(func(s *IcomTXState) { s.Filter = n })
	return nil
}

func (b *IcomSerial) setCache(fn func(*IcomTXState)) {
	b.dspMu.Lock()
	fn(&b.dsp)
	b.dspMu.Unlock()
}

// ── small helpers ──────────────────────────────────────────────────────────

func to255(p int) int    { return clampPct(p) * 255 / 100 }
func from255(v int) int  { return (v*100 + 127) / 255 }
func clampPct(p int) int { return min(100, max(0, p)) }

func boolByte(on bool) byte {
	if on {
		return 1
	}
	return 0
}

func agcName(v byte) string {
	switch v {
	case 1:
		return "FAST"
	case 2:
		return "MID"
	case 3:
		return "SLOW"
	}
	return ""
}

func agcValue(name string) byte {
	switch strings.ToUpper(strings.TrimSpace(name)) {
	case "FAST":
		return 1
	case "MID":
		return 2
	case "SLOW":
		return 3
	}
	return 0
}