/*
 *  VWE fork: in-fork cockpit plasma display (serial<n>=plasma). See
 *  serialplasma.h. Graphics-only (ESC P) transcription of vPLASMA's device;
 *  receive-only, single emulator thread except the framebuffer snapshot which
 *  the VPX render thread reads under a lock.
 */

#include "dosbox.h"

#include "logging.h"
#include "pic.h"
#include "serialport.h"
#include "serialplasma.h"

#include <cstdarg>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#define PLASMA_ESC 0x1B

static CSerialPlasma* plasma_instance = nullptr;

bool PLASMA_GetFrame(uint8_t out[512]) {
	if (!plasma_instance) return false;
	plasma_instance->getFrame(out);
	return true;
}

CSerialPlasma::CSerialPlasma(Bitu id, CommandLine* cmd) : CSerial(id, cmd) {
	(void)cmd;
	InstallationSuccessful = false;
	logv = (getenv("VWE_PLASMA_LOG") != nullptr);

	LOG_MSG("Serial%d: in-fork plasma display (128x32, ESC P graphics)", (int)COMNUMBER);

	CSerial::Init_Registers();
	// the display is always present -- assert the modem-in lines the game reads
	setRI(false);
	setCD(true);
	setDSR(true);
	setCTS(true);

	if (plasma_instance == nullptr) plasma_instance = this;
	else LOG_MSG("Serial%d: another plasma port already owns the display window", (int)COMNUMBER);

	InstallationSuccessful = true;
}

CSerialPlasma::~CSerialPlasma() {
	if (plasma_instance == this) plasma_instance = nullptr;
}

void CSerialPlasma::logf(const char* fmt, ...) {
	if (!logv) return;
	va_list ap; va_start(ap, fmt);
	fprintf(stderr, "[plasma] ");
	vfprintf(stderr, fmt, ap);
	fprintf(stderr, "\n");
	va_end(ap);
}

void CSerialPlasma::getFrame(uint8_t out[512]) {
	std::lock_guard<std::mutex> lk(fbMx);
	memcpy(out, fb, 512);
}

// ---- ESC command parser (VPlasmaDevice.Step, graphics path) ------------------
void CSerialPlasma::feed(uint8_t b) {
	switch (st) {
	case P_TEXT:
		// The game is graphics-only; a printable/control byte in text mode is
		// not something it sends, so swallow it (text mode isn't rendered).
		if (b == PLASMA_ESC) st = P_ESC;
		return;

	case P_ESC:
		st = P_TEXT;
		switch (b) {
		case '@':                       // clear screen
			{ std::lock_guard<std::mutex> lk(fbMx); memset(fb, 0, 512); }
			logf("clear (ESC @)");
			break;
		case 'L':                       // home cursor -- no-op for graphics
			break;
		case 'G': case 'K': case 'H':   // cursor mode / font / attributes
		case 'Q': case 'R':             // set row / column
		case 'I': case 'i':             // draw / display page
			st = P_OPERAND;             // consume 1 operand, unused (text mode)
			break;
		case 'P':                       // graphics write
			hdrFill = 0;
			st = P_GHDR;
			break;
		default:
			logf("unknown ESC 0x%02X ('%c')", b, (b >= 0x20 && b < 0x7F) ? (char)b : '?');
			break;
		}
		return;

	case P_OPERAND:
		st = P_TEXT;                    // operand read + discarded
		return;

	case P_GHDR:
		hdr[hdrFill++] = b;
		if (hdrFill == 5) {             // screen, y, xbyte, w, h
			int w = hdr[3], h = hdr[4];
			dataLen = w * h;
			dataIdx = 0;
			logf("ESC P y=%u xbyte=%u %ux%u", hdr[1], hdr[2], (unsigned)w, (unsigned)h);
			st = dataLen > 0 ? P_GDATA : P_TEXT;
		}
		return;

	case P_GDATA:
		{
			int w = hdr[3];
			int rowOfBlock = w > 0 ? dataIdx / w : 0;
			int byteOfRow  = w > 0 ? dataIdx % w : 0;
			int y = hdr[1] + rowOfBlock;         // 0..31
			int xByte = hdr[2] + byteOfRow;       // 0..15
			// MSB = leftmost pixel; the game packs whole rows (xbyte=0, w=16).
			if (y >= 0 && y < 32 && xByte >= 0 && xByte < 16) {
				std::lock_guard<std::mutex> lk(fbMx);
				fb[y * 16 + xByte] = b;
			}
			if (byteOfRow == w - 1 && y >= 0 && y < 32) graphicsRows++;
			if (++dataIdx >= dataLen) {
				st = P_TEXT;
				if ((graphicsRows % 200) == 0) logf("rows drawn: %ld", graphicsRows);
			}
		}
		return;
	}
}

// ---- UART plumbing (receive-only; drain the game's TX like the pipe) ---------
void CSerialPlasma::transmitByte(uint8_t val, bool first) {
	if (first) setEvent(SERIAL_THR_EVENT, bytetime / 10);
	else setEvent(SERIAL_TX_EVENT, bytetime);
	feed(val);
}

void CSerialPlasma::handleUpperEvent(uint16_t type) {
	if (type == SERIAL_THR_EVENT) {
		ByteTransmitting();
		setEvent(SERIAL_TX_EVENT, bytetime * 1.1f);
	} else if (type == SERIAL_TX_EVENT) {
		ByteTransmitted();
	}
}

void CSerialPlasma::updatePortConfig(uint16_t divider, uint8_t lcr) { (void)divider; (void)lcr; }
void CSerialPlasma::updateMSR() {}
void CSerialPlasma::setBreak(bool value) { (void)value; }
void CSerialPlasma::setRTSDTR(bool rts, bool dtr) { (void)rts; (void)dtr; }
void CSerialPlasma::setRTS(bool val) { (void)val; }
void CSerialPlasma::setDTR(bool val) { (void)val; }