// Runs XMMT.ocx under Wine so that Nonemm, which is a Linux program, can drive
// MMTTY or 2Tone. Everything arrives on standard input and leaves on standard
// output, one protocol line at a time. Wine's own diagnostics go to standard
// error, which keeps them out of the protocol.
//
// The startup is N1MM's, in N1MM's order: title, PTT port and command line on
// the control, then bActive, then the host window handle to the engine.

#include <windows.h>

#include <cstdio>
#include <iostream>
#include <string>
#include <thread>

#include "Protocol.h"
#include "XmmrControl.h"

namespace {

// One protocol line, handed from the reader thread to the thread the control
// lives on. COM calls have to stay on the one thread.
constexpr UINT WM_BRIDGE_LINE = WM_APP + 1;

constexpr long MessageHostWindow = 0;
constexpr long MessageShutdown = 2;

constexpr UINT_PTR QuitTimer = 1;
constexpr UINT QuitPatience = 5000;

void killEngine();

XmmrControl* control = nullptr;
HWND bridgeWindow = nullptr;
DWORD enginePid = 0;
bool quitting = false;

// Dispatch arguments arrive last one first; `position` counts them the way the
// event declares them.
long argument(DISPPARAMS* arguments, unsigned position) {
    if (arguments == nullptr || position >= arguments->cArgs) {
        return 0;
    }
    VARIANT wanted;
    VariantInit(&wanted);
    if (FAILED(VariantChangeType(&wanted, &arguments->rgvarg[arguments->cArgs - 1 - position], 0,
                                 VT_I4))) {
        return 0;
    }
    long value = wanted.lVal;
    VariantClear(&wanted);
    return value;
}

// The control turns each message MMTTY sends it into an event of its own. Only
// the messages it has no event for reach OnTranslateMessage, and every message
// the logger needs has one, so that event is not listened to.
void onEvent(const std::wstring& name, DISPPARAMS* arguments) {
    if (name == L"OnConnected") {
        protocol::write("connected", {control->getString(L"verMMTTY")});
    } else if (name == L"OnDisconnected") {
        protocol::write("disconnected", argument(arguments, 0));
        if (quitting) {
            killEngine();
            PostQuitMessage(0);
        }
    } else if (name == L"OnCharRcvd") {
        protocol::write("rx", argument(arguments, 0));
    } else if (name == L"OnPttEvent") {
        protocol::write("tx", argument(arguments, 0));
    } else if (name == L"OnFreqChanged") {
        protocol::write("mark", argument(arguments, 0));
        protocol::write("space", argument(arguments, 1));
    } else if (name == L"OnSwitchChanged") {
        protocol::write("switch", argument(arguments, 0));
    } else if (name == L"OnViewChanged") {
        protocol::write("view", argument(arguments, 0));
    }
}

// The bridge started the engine, so the bridge stops it. MMTTY is asked first
// and killed only if it is still there when the wait runs out; the control's
// own shutdown call blocks forever under Wine, waiting for a message loop that
// is by then no longer pumping.
BOOL CALLBACK closeWindow(HWND window, LPARAM wanted) {
    DWORD owner = 0;
    GetWindowThreadProcessId(window, &owner);
    if (owner == static_cast<DWORD>(wanted)) {
        PostMessageW(window, WM_CLOSE, 0, 0);
    }
    return TRUE;
}

void stopEngine() {
    control->callLong(L"PostMmttyMessage", MessageShutdown, 0);
    HWND engine = reinterpret_cast<HWND>(static_cast<uintptr_t>(control->getLong(L"hWndMmtty")));
    if (engine == nullptr) {
        return;
    }
    GetWindowThreadProcessId(engine, &enginePid);
    EnumWindows(closeWindow, static_cast<LPARAM>(enginePid));
}

void killEngine() {
    if (enginePid == 0) {
        return;
    }
    HANDLE engine = OpenProcess(PROCESS_TERMINATE | SYNCHRONIZE, FALSE, enginePid);
    if (engine == nullptr) {
        return;
    }
    if (WaitForSingleObject(engine, 0) != WAIT_OBJECT_0) {
        TerminateProcess(engine, 0);
    }
    CloseHandle(engine);
    enginePid = 0;
}

void report(const char* what, HRESULT result) {
    if (FAILED(result)) {
        char message[128];
        std::snprintf(message, sizeof(message), "%s failed: 0x%08lx", what,
                      static_cast<unsigned long>(result));
        protocol::write("error", {message});
    }
}

void open(const protocol::Line& line) {
    report("Visible", control->putBool(L"Visible", true));
    report("VisibleMmtty", control->putBool(L"VisibleMmtty", true));
    report("InvokeCommand", control->putString(L"InvokeCommand", line.field(2)));
    report("ComName", control->putString(L"ComName", line.field(1)));
    report("Title", control->putString(L"Title", line.field(0)));
    report("bActive", control->putBool(L"bActive", true));
    report("PostMmttyMessage",
           control->callLong(L"PostMmttyMessage", MessageHostWindow, control->getLong(L"hwnd")));
}

void send(const std::string& text) {
    VARIANT argument;
    VariantInit(&argument);
    argument.vt = VT_BSTR;
    argument.bstrVal = SysAllocString(toWide(text).c_str());
    control->call(L"SendString", &argument, 1);
    VariantClear(&argument);
}

// N1MM's {TX}: the control's own PTT property, which is what starts a
// transmission. SetMmttyPTT is the other direction, and only that.
void key(bool on) {
    report("PTT", control->putBool(L"PTT", on));
}

// 1 stops when the buffer is empty, which is N1MM's XmitOff; 0 stops now,
// which is its AbortXmit.
void setPtt(long on) {
    VARIANT argument;
    VariantInit(&argument);
    argument.vt = VT_I4;
    argument.lVal = on;
    control->call(L"SetMmttyPTT", &argument, 1);
}

// How many characters MMTTY still has to transmit. It is asked for rather than
// reported: the control has no event for it.
void askBuffer(const std::string& name) {
    const std::wstring wanted = toWide(name.empty() ? "TxBufLen" : name);
    long left = 0;
    HRESULT result = control->tryGetLong(wanted.c_str(), &left);
    if (FAILED(result)) {
        char message[128];
        std::snprintf(message, sizeof(message), "%s failed: 0x%08lx", wanted.empty() ? "" : name.c_str(),
                      static_cast<unsigned long>(result));
        // not an "error": a property the control will not answer stops nothing
        protocol::write("log", {message});
        protocol::write("buffer", -1);
        return;
    }
    protocol::write("buffer", left);
}

void act(const std::string& text) {
    protocol::Line line = protocol::read(text);
    if (line.verb == "open") {
        open(line);
    } else if (line.verb == "send") {
        send(line.field(0));
    } else if (line.verb == "key") {
        key(line.number(0) != 0);
    } else if (line.verb == "ptt") {
        setPtt(line.number(0));
    } else if (line.verb == "buffer") {
        askBuffer(line.field(0));
    } else if (line.verb == "post") {
        control->callLong(L"PostMmttyMessage", line.number(0), line.number(1));
    } else if (line.verb == "close") {
        stopEngine();
    } else if (line.verb == "quit") {
        quitting = true;
        stopEngine();
        SetTimer(bridgeWindow, QuitTimer, QuitPatience, nullptr);
    } else {
        protocol::write("error", {"unknown verb: " + line.verb});
    }
}

LRESULT CALLBACK onMessage(HWND window, UINT message, WPARAM first, LPARAM second) {
    // The engine did not report itself gone, so stop waiting for it.
    if (message == WM_TIMER && first == QuitTimer) {
        killEngine();
        PostQuitMessage(0);
        return 0;
    }
    if (message == WM_BRIDGE_LINE) {
        std::string* line = reinterpret_cast<std::string*>(second);
        act(*line);
        delete line;
        return 0;
    }
    return DefWindowProcW(window, message, first, second);
}

HWND createWindow(bool show) {
    WNDCLASSEXW description = {};
    description.cbSize = sizeof(description);
    description.lpfnWndProc = onMessage;
    description.hInstance = GetModuleHandleW(nullptr);
    description.lpszClassName = L"NonemmMmttyBridge";
    RegisterClassExW(&description);
    HWND window = CreateWindowExW(0, description.lpszClassName, L"Nonemm MMTTY bridge",
                                  WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 320, 200,
                                  nullptr, nullptr, description.hInstance, nullptr);
    if (window != nullptr && show) {
        ShowWindow(window, SW_SHOW);
    }
    return window;
}

void readLines(HWND window) {
    std::string line;
    while (std::getline(std::cin, line)) {
        if (!line.empty() && line.back() == '\r') {
            line.pop_back();
        }
        PostMessageW(window, WM_BRIDGE_LINE, 0, reinterpret_cast<LPARAM>(new std::string(line)));
    }
    PostMessageW(window, WM_QUIT, 0, 0);
}

}  // namespace

int main(int count, char** arguments) {
    bool show = count > 1 && std::string(arguments[1]) == "--show";
    HRESULT started = CoInitialize(nullptr);
    if (FAILED(started)) {
        protocol::write("error", {"COM would not start"});
        return 1;
    }
    OleInitialize(nullptr);
    HWND window = createWindow(show);
    bridgeWindow = window;
    if (window == nullptr) {
        protocol::write("error", {"the bridge window would not open"});
        return 1;
    }
    XmmrControl xmmr(onEvent);
    control = &xmmr;
    std::string error;
    if (!xmmr.create(window, &error)) {
        protocol::write("error", {error});
        return 1;
    }
    protocol::write("ready");
    std::thread reader(readLines, window);
    reader.detach();
    MSG message;
    while (GetMessageW(&message, nullptr, 0, 0) > 0) {
        TranslateMessage(&message);
        DispatchMessageW(&message);
    }
    // The control's own teardown waits for an engine that has already been told
    // to shut down, and never returns. The bridge has nothing left to do here,
    // so it leaves and lets Wine reclaim what it held.
    protocol::write("closed");
    ExitProcess(0);
}