/* -------------------------------------------------------------------------
 *
 * pgevent.c
 *		Defines the entry point for pgevent dll.
 *		The DLL defines event source for backend
 *
 *
 * IDENTIFICATION
 *	  src/bin/pgevent/pgevent.c
 *
 * -------------------------------------------------------------------------
 */

#include <windows.h>
#include <olectl.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

/* Global variables */
HANDLE g_module = NULL; /* hModule of DLL */

/*
 * The event source is stored as a registry key.
 * The maximum length of a registry key is 255 characters.
 * http://msdn.microsoft.com/en-us/library/ms724872(v=vs.85).aspx
 */
char event_source[256] = "PostgreSQL";

/* Prototypes */
HRESULT DllInstall(BOOL bInstall, LPCWSTR pszCmdLine);
STDAPI DllRegisterServer(void);
STDAPI DllUnregisterServer(void);
BOOL WINAPI DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved);

/*
 * DllInstall --- Passes the command line argument to DLL
 */
HRESULT DllInstall(BOOL bInstall, LPCWSTR pszCmdLine)
{
    if (pszCmdLine && *pszCmdLine != '\0') {
        wcstombs(event_source, pszCmdLine, sizeof(event_source));
    }

    /*
     * This is an ugly hack due to the strange behavior of "regsvr32 /i".
     *
     * When installing, regsvr32 calls DllRegisterServer before DllInstall.
     * When uninstalling (i.e. "regsvr32 /u /i"), on the other hand, regsvr32
     * calls DllInstall and then DllUnregisterServer as expected.
     *
     * This strange behavior forces us to specify -n (i.e. "regsvr32 /n /i").
     * Without -n, DllRegisterServer called before DllInstall would mistakenly
     * overwrite the default "PostgreSQL" event source registration.
     */
    if (bInstall)
        DllRegisterServer();
    return S_OK;
}

/*
 * DllRegisterServer --- Instructs DLL to create its registry entries
 */
STDAPI DllRegisterServer(void)
{
    HKEY key;
    DWORD data;
    char buffer[_MAX_PATH];
    char key_name[400];

    /* Set the name of DLL full path name. */
    if (!GetModuleFileName((HMODULE)g_module, buffer, sizeof(buffer))) {
        MessageBox(NULL, "Could not retrieve DLL filename", "PostgreSQL error", MB_OK | MB_ICONSTOP);
        return SELFREG_E_TYPELIB;
    }

    /*
     * Add openGauss source name as a subkey under the Application key in the
     * EventLog registry key.
     */
    _snprintf(
        key_name, sizeof(key_name), "SYSTEM\\CurrentControlSet\\Services\\EventLog\\Application\\%s", event_source);
    if (RegCreateKey(HKEY_LOCAL_MACHINE, key_name, &key)) {
        MessageBox(NULL, "Could not create the registry key.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
        return SELFREG_E_TYPELIB;
    }

    /* Add the name to the EventMessageFile subkey. */
    if (RegSetValueEx(key, "EventMessageFile", 0, REG_EXPAND_SZ, (LPBYTE)buffer, strlen(buffer) + 1)) {
        MessageBox(NULL, "Could not set the event message file.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
        return SELFREG_E_TYPELIB;
    }

    /* Set the supported event types in the TypesSupported subkey. */
    data = EVENTLOG_ERROR_TYPE | EVENTLOG_WARNING_TYPE | EVENTLOG_INFORMATION_TYPE;

    if (RegSetValueEx(key, "TypesSupported", 0, REG_DWORD, (LPBYTE)&data, sizeof(DWORD))) {
        MessageBox(NULL, "Could not set the supported types.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
        return SELFREG_E_TYPELIB;
    }

    RegCloseKey(key);
    return S_OK;
}

/*
 * DllUnregisterServer --- Instructs DLL to remove only those entries created through DllRegisterServer
 */
STDAPI DllUnregisterServer(void)
{
    char key_name[400];

    /*
     * Remove openGauss source name as a subkey under the Application key in
     * the EventLog registry key.
     */

    _snprintf(
        key_name, sizeof(key_name), "SYSTEM\\CurrentControlSet\\Services\\EventLog\\Application\\%s", event_source);
    if (RegDeleteKey(HKEY_LOCAL_MACHINE, key_name)) {
        MessageBox(NULL, "Could not delete the registry key.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
        return SELFREG_E_TYPELIB;
    }
    return S_OK;
}

/*
 * DllMain --- is an optional entry point into a DLL.
 */
BOOL WINAPI DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
    if (ul_reason_for_call == DLL_PROCESS_ATTACH)
        g_module = hModule;
    return TRUE;
}