/*
 * 86Box    A hypervisor and IBM PC system emulator that specializes in
 *          running old operating systems and software designed for IBM
 *          PC systems and compatibles from 1981 through fairly recent
 *          system designs based on the PCI bus.
 *
 *          This file is part of the 86Box distribution.
 *
 *          Definitions for platform specific serial to host passthrough
 *
 * Authors: Andreas J. Reichel <webmaster@6th-dimension.com>,
 *          Jasmine Iwanek <jasmine@iwanek.co.uk>
 *
 *          Copyright 2021      Andreas J. Reichel
 *          Copyright 2021-2025 Jasmine Iwanek
 */

#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <wchar.h>

#include <86box/86box.h>
#include <86box/log.h>
#include <86box/timer.h>
#include <86box/plat.h>
#include <86box/device.h>
#include <86box/serial_passthrough.h>
#include <86box/plat_serial_passthrough.h>
#include <86box/ui.h>

#include <windows.h>

#define LOG_PREFIX "serial_passthrough: "

void
plat_serpt_close(void *priv)
{
    serial_passthrough_t *dev = (serial_passthrough_t *) priv;

#if 0
    fclose(dev->master_fd);
#endif
    FlushFileBuffers((HANDLE) dev->master_fd);
    if (dev->mode == SERPT_MODE_NPIPE_SRV)
        DisconnectNamedPipe((HANDLE) dev->master_fd);
    else if (dev->mode == SERPT_MODE_HOSTSER) {
        SetCommState((HANDLE) dev->master_fd, (DCB *) dev->backend_priv);
        free(dev->backend_priv);
    }
    CloseHandle((HANDLE) dev->master_fd);
}

static void
plat_serpt_write_vcon(serial_passthrough_t *dev, uint8_t data)
{
#if 0
    fd_set wrfds;
    int res;
#endif

    /* We cannot use select here, this would block the hypervisor! */
#if 0
    FD_ZERO(&wrfds);
    FD_SET(ctx->master_fd, &wrfds);

    res = select(ctx->master_fd + 1, NULL, &wrfds, NULL, NULL);

    if (res <= 0)
        return;
#endif

    /* just write it out */
#if 0
    fwrite(dev->master_fd, &data, 1);
#endif
    DWORD bytesWritten = 0;
    WriteFile((HANDLE) dev->master_fd, &data, 1, &bytesWritten, NULL);
}

void
plat_serpt_set_line_state(void *priv)
{
    const serial_passthrough_t *dev = (serial_passthrough_t *) priv;

    if (dev->mode == SERPT_MODE_HOSTSER) {
        DWORD msrstate;
        EscapeCommFunction((HANDLE) dev->master_fd, (dev->serial->mctrl & 1) ? SETDTR : CLRDTR);
        EscapeCommFunction((HANDLE) dev->master_fd, (dev->serial->mctrl & 2) ? SETRTS : CLRRTS);
        EscapeCommFunction((HANDLE) dev->master_fd, (dev->serial->lcr & (1 << 6) ? SETBREAK : CLRBREAK));

        if (GetCommModemStatus((HANDLE) dev->master_fd, &msrstate)) {
            serial_set_dcd(dev->serial, !!(msrstate & MS_RLSD_ON));
            serial_set_dsr(dev->serial, !!(msrstate & MS_DSR_ON));
            serial_set_cts(dev->serial, !!(msrstate & MS_CTS_ON));
            serial_set_ri(dev->serial, !!(msrstate & MS_RING_ON));
        }
    }
}

void
plat_serpt_set_params(void *priv)
{
    const serial_passthrough_t *dev = (serial_passthrough_t *) priv;

    if (dev->mode == SERPT_MODE_HOSTSER) {
        DCB serialattr = { 0 };
        GetCommState((HANDLE) dev->master_fd, &serialattr);
#define BAUDRATE_RANGE(baud_rate, min, max)    \
    if (baud_rate >= min && baud_rate < max) { \
        serialattr.BaudRate = min;             \
    }

        BAUDRATE_RANGE(dev->baudrate, 110, 300);
        BAUDRATE_RANGE(dev->baudrate, 300, 600);
        BAUDRATE_RANGE(dev->baudrate, 600, 1200);
        BAUDRATE_RANGE(dev->baudrate, 1200, 2400);
        BAUDRATE_RANGE(dev->baudrate, 2400, 4800);
        BAUDRATE_RANGE(dev->baudrate, 4800, 9600);
        BAUDRATE_RANGE(dev->baudrate, 9600, 14400);
        BAUDRATE_RANGE(dev->baudrate, 14400, 19200);
        BAUDRATE_RANGE(dev->baudrate, 19200, 38400);
        BAUDRATE_RANGE(dev->baudrate, 38400, 57600);
        BAUDRATE_RANGE(dev->baudrate, 57600, 115200);
        BAUDRATE_RANGE(dev->baudrate, 115200, 0xFFFFFFFF);

        serialattr.fRtsControl     = RTS_CONTROL_ENABLE;
        serialattr.fDtrControl     = DTR_CONTROL_ENABLE;
        serialattr.fDsrSensitivity = FALSE;
        serialattr.fAbortOnError   = FALSE;

        serialattr.fInX     = FALSE;
        serialattr.fOutX    = FALSE;
        serialattr.ByteSize = dev->data_bits;
        serialattr.StopBits = (dev->serial->lcr & 0x04) ? TWOSTOPBITS : ONESTOPBIT;
        if (!(dev->serial->lcr & 0x08)) {
            serialattr.fParity = 0;
            serialattr.Parity  = NOPARITY;
        } else {
            serialattr.fParity = 1;
            if (dev->serial->lcr & 0x20) {
                serialattr.Parity = MARKPARITY + !!(dev->serial->lcr & 0x10);
            } else {
                serialattr.Parity = ODDPARITY + !!(dev->serial->lcr & 0x10);
            }
        }

        (void) SetCommState((HANDLE) dev->master_fd, &serialattr);

        {
            DWORD msrstate;
            EscapeCommFunction((HANDLE) dev->master_fd, (dev->serial->mctrl & 1) ? SETDTR : CLRDTR);
            EscapeCommFunction((HANDLE) dev->master_fd, (dev->serial->mctrl & 2) ? SETRTS : CLRRTS);
            EscapeCommFunction((HANDLE) dev->master_fd, (dev->serial->lcr & (1 << 6) ? SETBREAK : CLRBREAK));

            if (GetCommModemStatus((HANDLE) dev->master_fd, &msrstate)) {
                serial_set_dcd(dev->serial, !!(msrstate & MS_RLSD_ON));
                serial_set_dsr(dev->serial, !!(msrstate & MS_DSR_ON));
                serial_set_cts(dev->serial, !!(msrstate & MS_CTS_ON));
                serial_set_ri(dev->serial, !!(msrstate & MS_RING_ON));
            }
        }
#undef BAUDRATE_RANGE
    }
}

void
plat_serpt_write(void *priv, uint8_t data)
{
    serial_passthrough_t *dev = (serial_passthrough_t *) priv;

    switch (dev->mode) {
        case SERPT_MODE_NPIPE_SRV:
        case SERPT_MODE_NPIPE_CLNT:
        case SERPT_MODE_HOSTSER:
            plat_serpt_write_vcon(dev, data);
            break;
        default:
            break;
    }
}

uint8_t
plat_serpt_read_vcon(serial_passthrough_t *dev, uint8_t *data)
{
    DWORD bytesRead = 0;
    ReadFile((HANDLE) dev->master_fd, data, 1, &bytesRead, NULL);
    return !!bytesRead;
}

int
plat_serpt_read(void *priv, uint8_t *data)
{
    serial_passthrough_t *dev = (serial_passthrough_t *) priv;
    int                   res = 0;

    switch (dev->mode) {
        case SERPT_MODE_NPIPE_SRV:
        case SERPT_MODE_NPIPE_CLNT:
        case SERPT_MODE_HOSTSER:
            res = plat_serpt_read_vcon(dev, data);
            break;
        default:
            break;
    }
    return res;
}

static int
open_pseudo_terminal(serial_passthrough_t *dev)
{
    char ascii_pipe_name[1024] = { 0 };
    strncpy(ascii_pipe_name, dev->named_pipe, sizeof(ascii_pipe_name));
    ascii_pipe_name[1023] = '\0';
    dev->master_fd        = (intptr_t) CreateNamedPipeA(ascii_pipe_name, PIPE_ACCESS_DUPLEX, PIPE_TYPE_BYTE | PIPE_READMODE_BYTE | PIPE_NOWAIT, PIPE_UNLIMITED_INSTANCES, 65536, 65536, NMPWAIT_USE_DEFAULT_WAIT, NULL);
    if (dev->master_fd == (intptr_t) INVALID_HANDLE_VALUE) {
        wchar_t errorMsg[1024] = { 0 };
        wchar_t finalMsg[1024] = { 0 };
        DWORD   error          = GetLastError();
        FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM, NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), errorMsg, 1024, NULL);
        swprintf(finalMsg, 1024, L"Named Pipe (server, named_pipe=\"%hs\", port=COM%d): %ls\n", ascii_pipe_name, dev->port + 1, errorMsg);
        ui_msgbox(MBX_ERROR | MBX_FATAL, finalMsg);
        return 0;
    }
    pclog("Named Pipe @ %s\n", ascii_pipe_name);
    return 1;
}

static int
connect_named_pipe_client(serial_passthrough_t *dev)
{
    char ascii_pipe_name[1024] = { 0 };
    size_t len = strlen(dev->named_pipe);
    if ((len + 1) >= sizeof(ascii_pipe_name))
        memcpy(ascii_pipe_name, dev->named_pipe, sizeof(ascii_pipe_name));
    else
        memcpy(ascii_pipe_name, dev->named_pipe, len + 1);

    HANDLE hPipe = CreateFileA(
        ascii_pipe_name,            // pipe name
        GENERIC_READ | GENERIC_WRITE,
        0,                          // no sharing
        NULL,                       // default security attributes
        OPEN_EXISTING,              // open existing pipe
        0,                          // default attributes
        NULL);                      // no template file

    if (hPipe == INVALID_HANDLE_VALUE) {
        DWORD error = GetLastError();
        wchar_t errorMsg[1024] = { 0 };
        wchar_t finalMsg[1024] = { 0 };
        FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM, NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), errorMsg, 1024, NULL);
        swprintf(finalMsg, 1024, L"Named Pipe (client, named_pipe=\"%hs\", port=COM%d): %ls\n", ascii_pipe_name, dev->port + 1, errorMsg);
        ui_msgbox(MBX_ERROR | MBX_FATAL, finalMsg);
        return 0;
    }

    DWORD mode = PIPE_READMODE_BYTE | PIPE_NOWAIT;
    SetNamedPipeHandleState(hPipe, &mode, NULL, NULL);
    dev->master_fd = (intptr_t) hPipe;
    pclog("Named Pipe client connected to %s\n", ascii_pipe_name);
    return 1;
}

static int
open_host_serial_port(serial_passthrough_t *dev)
{
    COMMTIMEOUTS timeouts = {
        .ReadIntervalTimeout         = MAXDWORD,
        .ReadTotalTimeoutConstant    = 0,
        .ReadTotalTimeoutMultiplier  = 0,
        .WriteTotalTimeoutMultiplier = 0,
        .WriteTotalTimeoutConstant   = 1000
    };
    DCB *serialattr = calloc(1, sizeof(DCB));
    if (!serialattr)
        return 0;
    dev->master_fd = (intptr_t) CreateFileA(dev->host_serial_path, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_WRITE_THROUGH, NULL);
    if (dev->master_fd == (intptr_t) INVALID_HANDLE_VALUE) {
        free(serialattr);
        return 0;
    }
    if (!SetCommTimeouts((HANDLE) dev->master_fd, &timeouts)) {
        pclog(LOG_PREFIX "error setting COM port timeouts.\n");
        CloseHandle((HANDLE) dev->master_fd);
        free(serialattr);
        return 0;
    }
    GetCommState((HANDLE) dev->master_fd, serialattr);
    dev->backend_priv = serialattr;
    return 1;
}

int
plat_serpt_open_device(void *priv)
{
    serial_passthrough_t *dev = (serial_passthrough_t *) priv;

    switch (dev->mode) {
        case SERPT_MODE_NPIPE_SRV:
            if (open_pseudo_terminal(dev))
                return 0;
            break;
        case SERPT_MODE_NPIPE_CLNT:
            if (connect_named_pipe_client(dev))
                return 0;
            break;
        case SERPT_MODE_HOSTSER:
            if (open_host_serial_port(dev))
                return 0;
            break;
        default:
            break;
    }
    return 1;
}
