package jogamp.common.os;

import com.jogamp.common.os.DynamicLinker;
import com.jogamp.common.util.SecurityUtil;

public class WindowsDynamicLinkerImpl implements DynamicLinker {

  /** Interface to C language function: <br> <code> BOOL FreeLibrary(HANDLE hLibModule); </code>    */
  private static native int FreeLibrary(long hLibModule);

  /** Interface to C language function: <br> <code> DWORD GetLastError(void); </code>    */
  private static native int GetLastError();

  /** Interface to C language function: <br> <code> PROC GetProcAddressA(HANDLE hModule, LPCSTR lpProcName); </code>    */
  private static native long GetProcAddressA(long hModule, java.lang.String lpProcName);

  /** Interface to C language function: <br> <code> HANDLE LoadLibraryW(LPCWSTR lpLibFileName); </code>    */
  private static native long LoadLibraryW(java.lang.String lpLibFileName);


  // --- Begin CustomJavaCode .cfg declarations
  public long openLibraryLocal(String libraryName, boolean debug) throws SecurityException {
    // How does that work under Windows ?
    // Don't know .. so it's an alias for the time being
    return openLibraryGlobal(libraryName, debug);
  }
  
  public long openLibraryGlobal(String libraryName, boolean debug) throws SecurityException {
    SecurityUtil.checkLinkPermission(libraryName);
    long handle = LoadLibraryW(libraryName);
    if(0==handle && debug) {
        int err = GetLastError();
        System.err.println("LoadLibraryW \""+libraryName+"\" failed, error code: 0x"+Integer.toHexString(err)+", "+err);
    }
    return handle;
  }
  
  public long lookupSymbol(long libraryHandle, String symbolName) {
    String _symbolName = symbolName;
    long addr = GetProcAddressA(libraryHandle, _symbolName);
    if(0==addr) {
        // __stdcall hack: try some @nn decorations,
        //                 the leading '_' must not be added (same with cdecl)
        final int argAlignment=4;  // 4 byte alignment of each argument
        final int maxArguments=12; // experience ..
        for(int arg=0; 0==addr && arg<=maxArguments; arg++) {
            _symbolName = symbolName+"@"+(arg*argAlignment);
            addr = GetProcAddressA(libraryHandle, _symbolName);
        }
    }
    if(DEBUG_LOOKUP) {
        System.err.println("DynamicLinkerImpl.lookupSymbol(0x"+Long.toHexString(libraryHandle)+", "+symbolName+") -> "+_symbolName+", 0x"+Long.toHexString(addr));
    }
    return addr;
  }
  
  public long lookupSymbolGlobal(String symbolName) {
    if(DEBUG_LOOKUP) {
        System.err.println("lookupSymbolGlobal: Not supported on Windows");
    }
    // allow DynamicLibraryBundle to continue w/ local libs
    return 0;
  }

  public void closeLibrary(long libraryHandle) {
    FreeLibrary(libraryHandle);
  }

}