#include <petscsys.h>       /*I "petscsys.h" I*/

/* ---------------------------------------------------------------- */

#if !defined(PETSC_PYTHON_EXE)
#define PETSC_PYTHON_EXE "python"
#endif

#undef __FUNCT__
#define __FUNCT__ "PetscPythonFindExecutable"
static PetscErrorCode PetscPythonFindExecutable(char pythonexe[PETSC_MAX_PATH_LEN])
{
  PetscBool      flag;
  PetscErrorCode ierr;
  PetscFunctionBegin;
  /* get the path for the Python interpreter executable */
  ierr = PetscStrncpy(pythonexe,PETSC_PYTHON_EXE,PETSC_MAX_PATH_LEN);CHKERRQ(ierr);
  ierr = PetscOptionsGetString(PETSC_NULL,"-python",pythonexe,PETSC_MAX_PATH_LEN,&flag);CHKERRQ(ierr);
  if (!flag || pythonexe[0]==0) {
    ierr = PetscStrncpy(pythonexe,PETSC_PYTHON_EXE,PETSC_MAX_PATH_LEN);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "PetscPythonFindLibrary"
static PetscErrorCode PetscPythonFindLibrary(char pythonexe[PETSC_MAX_PATH_LEN],
                                             char pythonlib[PETSC_MAX_PATH_LEN])
{
  const char cmdline[] = "-c 'import sys; print(sys.exec_prefix); print(sys.version[:3])'";
  char command[PETSC_MAX_PATH_LEN+1+sizeof(cmdline)+1];
  char prefix[PETSC_MAX_PATH_LEN],version[8],sep[2]={PETSC_DIR_SEPARATOR, 0},*eol;
  FILE* fp = NULL;
  char path[PETSC_MAX_PATH_LEN+1];
  PetscBool  found = PETSC_FALSE;
  PetscErrorCode ierr;
  PetscFunctionBegin;

#if defined(PETSC_PYTHON_LIB)
  ierr = PetscStrcpy(pythonlib,PETSC_PYTHON_LIB);CHKERRQ(ierr);
  PetscFunctionReturn(0);
#endif

  /* call Python to find out the name of the Python dynamic library */
  ierr = PetscStrncpy(command,pythonexe,PETSC_MAX_PATH_LEN);CHKERRQ(ierr);
  ierr = PetscStrcat(command," ");CHKERRQ(ierr);
  ierr = PetscStrcat(command,cmdline);CHKERRQ(ierr);
#if defined(PETSC_HAVE_POPEN)
  ierr = PetscPOpen(PETSC_COMM_SELF,PETSC_NULL,command,"r",&fp);CHKERRQ(ierr);
  if (!fgets(prefix,sizeof(prefix),fp))
    { SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Python: bad output from executable: %s",pythonexe); }
  if (!fgets(version,sizeof(version),fp))
    { SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Python: bad output from executable: %s",pythonexe); }
  ierr = PetscPClose(PETSC_COMM_SELF,fp);CHKERRQ(ierr);
#else
  SETERRQ(PETSC_COMM_SELF,1,"Python: Aborted due to missing popen()");
#endif
  /* remove newlines */
  ierr = PetscStrchr(prefix,'\n',&eol);CHKERRQ(ierr);
  if (eol) eol[0] = 0;
  ierr = PetscStrchr(version,'\n',&eol);CHKERRQ(ierr);
  if (eol) eol[0] = 0;

  /* test for $prefix/lib64/libpythonX.X[.so]*/
  ierr = PetscStrcpy(pythonlib,prefix);CHKERRQ(ierr);
  ierr = PetscStrcat(pythonlib,sep);CHKERRQ(ierr);
  ierr = PetscStrcat(pythonlib,"lib64");CHKERRQ(ierr);
  ierr = PetscTestDirectory(pythonlib,'r',&found);CHKERRQ(ierr);
  if (found) {
    ierr = PetscStrcat(pythonlib,sep);CHKERRQ(ierr);
    ierr = PetscStrcat(pythonlib,"libpython");CHKERRQ(ierr);
    ierr = PetscStrcat(pythonlib,version);CHKERRQ(ierr);
    ierr = PetscDLLibraryRetrieve(PETSC_COMM_SELF,pythonlib,path,PETSC_MAX_PATH_LEN,&found);CHKERRQ(ierr);
    if (found) PetscFunctionReturn(0);
  }

  /* test for $prefix/lib/libpythonX.X[.so]*/
  ierr = PetscStrcpy(pythonlib,prefix);CHKERRQ(ierr);
  ierr = PetscStrcat(pythonlib,sep);CHKERRQ(ierr);
  ierr = PetscStrcat(pythonlib,"lib");CHKERRQ(ierr);
  ierr = PetscTestDirectory(pythonlib,'r',&found);CHKERRQ(ierr);
  if (found) {
    ierr = PetscStrcat(pythonlib,sep);CHKERRQ(ierr);
    ierr = PetscStrcat(pythonlib,"libpython");CHKERRQ(ierr);
    ierr = PetscStrcat(pythonlib,version);CHKERRQ(ierr);
    ierr = PetscDLLibraryRetrieve(PETSC_COMM_SELF,pythonlib,path,PETSC_MAX_PATH_LEN,&found);CHKERRQ(ierr);
    if (found) PetscFunctionReturn(0);
  }

  /* nothing good found */
  ierr = PetscMemzero(pythonlib,PETSC_MAX_PATH_LEN);CHKERRQ(ierr);
  ierr = PetscInfo(0,"Python dynamic library not found\n");CHKERRQ(ierr);

  PetscFunctionReturn(0);
}

/* ---------------------------------------------------------------- */

typedef struct _Py_object_t PyObject; /* fake definition */

static PyObject* Py_None = 0;

static const char* (*Py_GetVersion)(void);

static int       (*Py_IsInitialized)(void);
static void      (*Py_InitializeEx)(int);
static void      (*Py_Finalize)(void);

static void      (*PySys_SetArgv)(int, char **);
static PyObject* (*PySys_GetObject)(const char *);
static PyObject* (*PyObject_CallMethod)(PyObject *, const char *, const char *, ...);
static PyObject* (*PyImport_ImportModule)(const char *);

static void      (*Py_IncRef)(PyObject *);
static void      (*Py_DecRef)(PyObject *);

static void      (*PyErr_Clear)(void);
static PyObject* (*PyErr_Occurred)(void);
static void      (*PyErr_Fetch)(PyObject **, PyObject **, PyObject **);
static void      (*PyErr_NormalizeException)(PyObject **, PyObject **, PyObject **);
static void      (*PyErr_Display)(PyObject *, PyObject *, PyObject *);
static void      (*PyErr_Restore)(PyObject *, PyObject *, PyObject *);


#define PetscDLPyLibOpen(libname) \
  PetscDLLibraryAppend(PETSC_COMM_SELF,&DLLibrariesLoaded,libname)
#define PetscDLPyLibSym(symbol, value) \
  PetscDLLibrarySym(PETSC_COMM_SELF,&DLLibrariesLoaded,PETSC_NULL,symbol,(void**)value)
#define PetscDLPyLibClose(comm) \
  do { } while(0)

#undef __FUNCT__
#define __FUNCT__ "PetscPythonLoadLibrary"
static PetscErrorCode PetscPythonLoadLibrary(const char pythonlib[])
{
  PetscErrorCode ierr;
  PetscFunctionBegin;

  /* open the Python dynamic library */
  ierr = PetscDLPyLibOpen(pythonlib);CHKERRQ(ierr);
  ierr = PetscInfo1(0,"Python: loaded dynamic library %s\n", pythonlib);CHKERRQ(ierr);
  /* look required symbols from the Python C-API */
  ierr = PetscDLPyLibSym("_Py_NoneStruct"        , &Py_None               );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("Py_GetVersion"         , &Py_GetVersion         );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("Py_IsInitialized"      , &Py_IsInitialized      );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("Py_InitializeEx"       , &Py_InitializeEx       );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("Py_Finalize"           , &Py_Finalize           );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PySys_GetObject"       , &PySys_GetObject       );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PySys_SetArgv"         , &PySys_SetArgv         );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyObject_CallMethod"   , &PyObject_CallMethod   );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyImport_ImportModule" , &PyImport_ImportModule );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("Py_IncRef"             , &Py_IncRef             );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("Py_DecRef"             , &Py_DecRef             );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyErr_Clear"           , &PyErr_Clear           );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyErr_Occurred"        , &PyErr_Occurred        );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyErr_Fetch"             , &PyErr_Fetch             );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyErr_NormalizeException", &PyErr_NormalizeException);CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyErr_Display",            &PyErr_Display           );CHKERRQ(ierr);
  ierr = PetscDLPyLibSym("PyErr_Restore",            &PyErr_Restore           );CHKERRQ(ierr);
  /* XXX TODO: check that ALL symbols were there !!! */
  if (!Py_None)          SETERRQ(PETSC_COMM_SELF,1,"Python: failed to load symbols from dynamic library");
  if (!Py_GetVersion)    SETERRQ(PETSC_COMM_SELF,1,"Python: failed to load symbols from dynamic library");
  if (!Py_IsInitialized) SETERRQ(PETSC_COMM_SELF,1,"Python: failed to load symbols from dynamic library");
  if (!Py_InitializeEx)  SETERRQ(PETSC_COMM_SELF,1,"Python: failed to load symbols from dynamic library");
  if (!Py_Finalize)      SETERRQ(PETSC_COMM_SELF,1,"Python: failed to load symbols from dynamic library");
  ierr = PetscInfo(0,"Python: all required symbols loaded from Python dynamic library\n");CHKERRQ(ierr);

  PetscFunctionReturn(0);
}

/* ---------------------------------------------------------------- */

static char       PetscPythonExe[PETSC_MAX_PATH_LEN] = { 0 };
static char       PetscPythonLib[PETSC_MAX_PATH_LEN] = { 0 };
static PetscBool  PetscBeganPython = PETSC_FALSE;

#undef __FUNCT__
#define __FUNCT__ "PetscPythonFinalize"
/*@C
  PetscPythonFinalize - Finalize Python.

  Level: intermediate

.keywords: Python
@*/
PetscErrorCode  PetscPythonFinalize(void)
{
  PetscFunctionBegin;
  if (PetscBeganPython) { if (Py_IsInitialized()) Py_Finalize(); }
  PetscBeganPython = PETSC_FALSE;
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "PetscPythonInitialize"
/*@C
  PetscPythonInitialize - Initialize Python and import petsc4py.

   Input Parameter:
+  pyexe - path to the Python interpreter executable, or PETSC_NULL.
-  pylib - full path to the Python dynamic library, or PETSC_NULL.

  Level: intermediate

.keywords: Python

@*/
PetscErrorCode  PetscPythonInitialize(const char pyexe[],const char pylib[])
{
  PyObject          *module    = 0;
  PetscErrorCode    ierr;
  PetscFunctionBegin;
  if (PetscBeganPython) PetscFunctionReturn(0);
  /* Python executable */
  if (pyexe && pyexe[0] != 0) {
    ierr = PetscStrncpy(PetscPythonExe,pyexe,sizeof(PetscPythonExe));CHKERRQ(ierr);
  } else {
    ierr = PetscPythonFindExecutable(PetscPythonExe);CHKERRQ(ierr);
  }
  /* Python dynamic library */
  if (pylib && pylib[0] != 0) {
    ierr = PetscStrncpy(PetscPythonLib,pylib,sizeof(PetscPythonLib));CHKERRQ(ierr);
  } else {
    ierr = PetscPythonFindLibrary(PetscPythonExe,PetscPythonLib);CHKERRQ(ierr);
  }
  /* dynamically load Python library */
  ierr = PetscPythonLoadLibrary(PetscPythonLib);CHKERRQ(ierr);
  /* initialize Python */
  PetscBeganPython = PETSC_FALSE;
  if (!Py_IsInitialized()) {
    static PetscBool registered = PETSC_FALSE;
    const char *py_version;
    PyObject *sys_path;
    char path[PETSC_MAX_PATH_LEN] = { 0 };
    /* initialize Python */
    Py_InitializeEx(0); /* 0: do not install signal handlers */
    /*  build 'sys.argv' list */
    py_version = Py_GetVersion();
    if (py_version[0] == '2') {
      int argc = 0; char **argv = 0;
      ierr = PetscGetArgs(&argc,&argv);CHKERRQ(ierr);
      PySys_SetArgv(argc,argv);
    }
    if (py_version[0] == '3') {
      /* XXX 'argv' is type 'wchar_t**' */
      PySys_SetArgv(0,PETSC_NULL);
    }
    /* add PETSC_LIB_DIR in front of 'sys.path' */
    sys_path = PySys_GetObject("path");
    if (sys_path) {
      ierr = PetscStrreplace(PETSC_COMM_SELF,"${PETSC_LIB_DIR}",path,sizeof(path));CHKERRQ(ierr);
      Py_DecRef(PyObject_CallMethod(sys_path,"insert","is",(int)0,(char*)path));
    }
    /* register finalizer */
    if (!registered) {
      ierr = PetscRegisterFinalize(PetscPythonFinalize);CHKERRQ(ierr);
      registered = PETSC_TRUE;
    }
    PetscBeganPython = PETSC_TRUE;
  }
  /* import 'petsc4py.PETSc' module */
  module = PyImport_ImportModule("petsc4py.PETSc");
  if (module) {
    ierr = PetscInfo(0,"Python: successfully imported  module 'petsc4py.PETSc'\n");CHKERRQ(ierr);
    Py_DecRef(module); module = 0;
  } else {
    PetscPythonPrintError();
    SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Python: could not import module 'petsc4py.PETSc', perhaps your PYTHONPATH does not contain it\n");
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "PetscPythonPrintError"
/*@C
  PetscPythonPrintError - Print Python errors.

  Level: developer

.keywords: Python

@*/
PetscErrorCode  PetscPythonPrintError(void)
{
  PyObject *exc=0, *val=0, *tb=0;
  PetscFunctionBegin;
  if (!PetscBeganPython) PetscFunctionReturn(0);
  if (!PyErr_Occurred()) PetscFunctionReturn(0);
  PyErr_Fetch(&exc,&val,&tb);
  PyErr_NormalizeException(&exc,&val,&tb);
  PyErr_Display(exc ? exc : Py_None,
                val ? val : Py_None,
                tb  ? tb  : Py_None);
  PyErr_Restore(exc,val,tb);
  PetscFunctionReturn(0);
}

/* ---------------------------------------------------------------- */

EXTERN_C_BEGIN
extern PetscErrorCode (*PetscPythonMonitorSet_C)(PetscObject,const char[]);
PetscErrorCode (*PetscPythonMonitorSet_C)(PetscObject,const char[]) = PETSC_NULL;
EXTERN_C_END

#undef __FUNCT__
#define __FUNCT__ "PetscPythonMonitorSet"
/*@C
  PetscPythonMonitorSet - Set Python monitor

  Level: developer

.keywords: Python

@*/
PetscErrorCode PetscPythonMonitorSet(PetscObject obj, const char url[])
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  PetscValidHeader(obj,1);
  PetscValidCharPointer(url,2);
  if(PetscPythonMonitorSet_C == PETSC_NULL) {
    ierr = PetscPythonInitialize(PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
    if(PetscPythonMonitorSet_C == PETSC_NULL)
      SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Couldn't initialize Python support for monitors");
  }
  ierr = PetscPythonMonitorSet_C(obj,url);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/* ---------------------------------------------------------------- */