//keyHook.c
//Copyright (c) 2007-2008 Michael Curran <mick@kulgan.net>
//This file is covered by the GNU General Public Licence
//See the file copying.txt for details.

#define UNICODE
#include <stdio.h>
#include <windows.h>
#include "keyHook.h"

keyCallback_t keyDownCallback=(keyCallback_t)NULL;
keyCallback_t keyUpCallback=(keyCallback_t)NULL;
HINSTANCE moduleHandle;
HHOOK keyHookID=0;

#pragma comment(linker,"/entry:_DllMainCRTStartup@12")
BOOL DllMain(HINSTANCE hModule,DWORD reason,LPVOID lpReserved) {
	if((reason==DLL_PROCESS_ATTACH)&&(moduleHandle==NULL)) {
		moduleHandle=hModule;
	}
	return TRUE;
}

LRESULT CALLBACK keyHook(int code, WPARAM wParam, LPARAM lParam) {
	int vkCode, scanCode, extended, injected; 
	int res;
	PKBDLLHOOKSTRUCT kbd=(PKBDLLHOOKSTRUCT)lParam;
	if(code!=HC_ACTION) {
		return CallNextHookEx(keyHookID,code,wParam,lParam);
	}
	vkCode=kbd->vkCode;
	scanCode=kbd->scanCode;
	extended=(kbd->flags)&LLKHF_EXTENDED;
	injected=(kbd->flags)&LLKHF_INJECTED;
	if(kbd->flags&LLKHF_UP) {
		res=keyUpCallback(vkCode,scanCode,extended,injected);
	} else {
		res=keyDownCallback(vkCode,scanCode,extended,injected);
	}
	if(res==TRUE) {
		return CallNextHookEx(keyHookID,code,wParam,lParam);
	} else {
		return 1;
	}
}

int initialize(keyCallback_t downCallback, keyCallback_t upCallback) {
	if(keyHookID) {
		fprintf(stderr,"Already initialized\n");
		return -1;
	}
	keyDownCallback=downCallback;
	keyUpCallback=upCallback;
	if(!(keyHookID=SetWindowsHookEx(WH_KEYBOARD_LL,(HOOKPROC)keyHook,moduleHandle,0))) {
		fprintf(stderr,"Error registering key hook\n");
		return -1;
	}
	return 0;
}

int terminate() {
	if(keyHookID) {
		if(UnhookWindowsHookEx(keyHookID)) {
			keyHookID=0;
			return 0;
		}
	}
	return -1;
}