/*
  Exception code, data and macros

  See the accompanying LICENSE file.
*/

/* EXCEPTION TYPES */

static PyObject *ExcThreadingViolation;  /* thread misuse */
static PyObject *ExcIncomplete;          /* didn't finish previous query */
static PyObject *ExcBindings;            /* wrong number of bindings */
static PyObject *ExcComplete;            /* query is finished */
static PyObject *ExcTraceAbort;          /* aborted by exectrace */
static PyObject *ExcExtensionLoading;    /* error loading extension */
static PyObject *ExcConnectionNotClosed; /* connection wasn't closed when destructor called */
static PyObject *ExcCursorClosed;        /* cursor object was closed when function called */
static PyObject *ExcConnectionClosed;    /* connection was closed when function called */
static PyObject *ExcVFSNotImplemented;   /* base vfs doesn't implement function */
static PyObject *ExcVFSFileClosed;       /* attempted operation on closed file */
static PyObject *ExcForkingViolation;    /* used object across a fork */

static void make_exception(int res, sqlite3 *db);

/* If res indicates an SQLite error then do all the exception creation
 work.  We don't overwrite earlier exceptions hence the PyErr_Occurred
 check */
#define SET_EXC(res, db)                       \
  do                                           \
  {                                            \
    if (res != SQLITE_OK && !PyErr_Occurred()) \
      make_exception(res, db);                 \
  } while (0)

/* A dictionary we store the last error from each thread in.  Used
   thread local storage previously. The key is a PyLong of the thread
   id and the value is a PyBytes. */
static PyObject *tls_errmsg;

/* This method is called with the database mutex held but the GIL
   released.  Previous code used thread local storage which is a bit
   too OS dependent (eg required a DllMain under Windows) but it
   didn't need any Python code.  It is safe to acquire the GIL since
   the db mutex has been acquired first so we are no different than a
   user defined function. */
static void
apsw_set_errmsg(const char *msg)
{
  PyObject *key = NULL, *value = NULL;
  PyObject *etype, *eval, *etb;

  PyGILState_STATE gilstate = PyGILState_Ensure();
  /* dictionary operations whine if there is an outstanding error */
  PyErr_Fetch(&etype, &eval, &etb);

  assert(tls_errmsg);

  key = PyLong_FromLong(PyThread_get_thread_ident());
  if (key)
    value = PyBytes_FromStringAndSize(msg, strlen(msg));

  if (key && value && 0 == PyDict_SetItem(tls_errmsg, key, value))
    ;
  else
    apsw_write_unraisable(NULL);

  Py_XDECREF(key);
  Py_XDECREF(value);
  PyErr_Restore(etype, eval, etb);
  PyGILState_Release(gilstate);
}

static const char *
apsw_get_errmsg(void)
{
  const char *retval = NULL;
  PyObject *key = NULL, *value;

  /* set should always have been called first */
  assert(tls_errmsg);

  key = PyLong_FromLong(PyThread_get_thread_ident());
  if (key)
  {
    value = PyDict_GetItem(tls_errmsg, key);
    if (value)
      retval = PyBytes_AsString(value);
  }

  Py_XDECREF(key);
  /* value is borrowed */
  return retval;
}

static struct
{
  int code;
  const char *name;
  PyObject *cls;
  const char *doc;
} exc_descriptors[] =
    {
        /* Generic Errors */
        {SQLITE_ERROR, "SQL", NULL, SQLError_exc_DOC},
        {SQLITE_MISMATCH, "Mismatch", NULL, MismatchError_exc_DOC},
        {SQLITE_NOTFOUND, "NotFound", NULL, NotFoundError_exc_DOC},

        /* Internal Errors */
        {SQLITE_INTERNAL, "Internal", NULL, InternalError_exc_DOC}, /* NOT USED */
        {SQLITE_PROTOCOL, "Protocol", NULL, ProtocolError_exc_DOC},
        {SQLITE_MISUSE, "Misuse", NULL, MisuseError_exc_DOC},
        {SQLITE_RANGE, "Range", NULL, RangeError_exc_DOC},

        /* permissions etc */
        {SQLITE_PERM, "Permissions", NULL, PermissionsError_exc_DOC},
        {SQLITE_READONLY, "ReadOnly", NULL, ReadOnlyError_exc_DOC},
        {SQLITE_CANTOPEN, "CantOpen", NULL, CantOpenError_exc_DOC},
        {SQLITE_AUTH, "Auth", NULL, AuthError_exc_DOC},

        /* abort/busy/etc */
        {SQLITE_ABORT, "Abort", NULL, AbortError_exc_DOC},
        {SQLITE_BUSY, "Busy", NULL, BusyError_exc_DOC},
        {SQLITE_LOCKED, "Locked", NULL, LockedError_exc_DOC},
        {SQLITE_INTERRUPT, "Interrupt", NULL, InterruptError_exc_DOC},
        {SQLITE_SCHEMA, "SchemaChange", NULL, SchemaChangeError_exc_DOC},
        {SQLITE_CONSTRAINT, "Constraint", NULL, ConstraintError_exc_DOC},

        /* memory/disk/corrupt etc */
        {SQLITE_NOMEM, "NoMem", NULL, NoMemError_exc_DOC},
        {SQLITE_IOERR, "IO", NULL, IOError_exc_DOC},
        {SQLITE_CORRUPT, "Corrupt", NULL, CorruptError_exc_DOC},
        {SQLITE_FULL, "Full", NULL, FullError_exc_DOC},
        {SQLITE_TOOBIG, "TooBig", NULL, TooBigError_exc_DOC},
        {SQLITE_NOLFS, "NoLFS", NULL, NoLFSError_exc_DOC},
        {SQLITE_EMPTY, "Empty", NULL, EmptyError_exc_DOC},
        {SQLITE_FORMAT, "Format", NULL, FormatError_exc_DOC},
        {SQLITE_NOTADB, "NotADB", NULL, NotADBError_exc_DOC},

        {-1, 0, 0}};

/* EXCEPTION CODE */

typedef struct
{
  PyObject **var;
  const char *name;
  const char *doc;
} APSWExceptionMapping;

static int init_exceptions(PyObject *m)
{
  char buffy[100]; /* more than enough for anyone :-) */
  unsigned int i;
  PyObject *obj;

  APSWExceptionMapping apswexceptions[] = {
      {&ExcThreadingViolation, "ThreadingViolationError", ThreadingViolationError_exc_DOC},
      {&ExcIncomplete, "IncompleteExecutionError", IncompleteExecutionError_exc_DOC},
      {&ExcBindings, "BindingsError", BindingsError_exc_DOC},
      {&ExcComplete, "ExecutionCompleteError", ExecutionCompleteError_exc_DOC},
      {&ExcTraceAbort, "ExecTraceAbort", ExecTraceAbort_exc_DOC},
      {&ExcExtensionLoading, "ExtensionLoadingError", ExtensionLoadingError_exc_DOC},
      {&ExcConnectionNotClosed, "ConnectionNotClosedError", ConnectionNotClosedError_exc_DOC},
      {&ExcConnectionClosed, "ConnectionClosedError", ConnectionClosedError_exc_DOC},
      {&ExcCursorClosed, "CursorClosedError", CursorClosedError_exc_DOC},
      {&ExcVFSNotImplemented, "VFSNotImplementedError", VFSNotImplementedError_exc_DOC},
      {&ExcVFSFileClosed, "VFSFileClosedError", VFSFileClosedError_exc_DOC},
      {&ExcForkingViolation, "ForkingViolationError", ForkingViolationError_exc_DOC}};

  /* PyModule_AddObject uses borrowed reference so we incref whatever
     we give to it, so we still have a copy to use */

  /* custom ones first */

  APSWException = PyErr_NewExceptionWithDoc("apsw.Error", Error_exc_DOC, NULL, NULL);
  if (!APSWException)
    return -1;
  if (PyModule_AddObject(m, "Error", Py_NewRef((PyObject *)APSWException)))
    return -1;

  for (i = 0; i < sizeof(apswexceptions) / sizeof(apswexceptions[0]); i++)
  {
    PyOS_snprintf(buffy, sizeof(buffy), "apsw.%s", apswexceptions[i].name);
    *apswexceptions[i].var = PyErr_NewExceptionWithDoc(buffy, apswexceptions[i].doc, APSWException, NULL);
    if (!*apswexceptions[i].var)
      return -1;
    /* PyModule_AddObject steals the ref, but we don't add a ref for
      ourselves because it leaks on module unload when we couldn't use
      these anyway */
    if (PyModule_AddObject(m, apswexceptions[i].name, *apswexceptions[i].var))
      return -1;
  }

  /* all the ones corresponding to SQLITE error codes */
  for (i = 0; exc_descriptors[i].name; i++)
  {
    PyOS_snprintf(buffy, sizeof(buffy), "apsw.%sError", exc_descriptors[i].name);
    obj = PyErr_NewExceptionWithDoc(buffy, exc_descriptors[i].doc, APSWException, NULL);
    if (!obj)
      return -1;
    exc_descriptors[i].cls = obj;
    PyOS_snprintf(buffy, sizeof(buffy), "%sError", exc_descriptors[i].name);
    /* PyModule_AddObject steals the ref, but we don't add a ref for
      ourselves because it leaks on module unload when we couldn't use
      these anyway */
    if (PyModule_AddObject(m, buffy, obj))
      return -1;
  }

  return 0;
}

static void make_exception(int res, sqlite3 *db)
{
  int i;
  const char *errmsg = NULL;
  int error_offset = -1;

  if (db)
    errmsg = apsw_get_errmsg();
  if (!errmsg)
    errmsg = "error";

  if (db)
    _PYSQLITE_CALL_V(error_offset = sqlite3_error_offset(db));

  for (i = 0; exc_descriptors[i].name; i++)
    if (exc_descriptors[i].code == (res & 0xff))
    {
      PyObject *etype, *eval, *etb, *tmp;
      assert(exc_descriptors[i].cls);
      PyErr_Format(exc_descriptors[i].cls, "%sError: %s", exc_descriptors[i].name, errmsg);
      PyErr_Fetch(&etype, &eval, &etb);
      PyErr_NormalizeException(&etype, &eval, &etb);

      assert(!PyErr_Occurred());
      tmp = PyLong_FromLongLong(res & 0xff);
      if (!tmp)
        goto error;

      if (PyObject_SetAttrString(eval, "result", tmp))
        goto error;

      Py_DECREF(tmp);
      tmp = PyLong_FromLongLong(res);
      if (!tmp)
        goto error;

      if (PyObject_SetAttrString(eval, "extendedresult", tmp))
        goto error;
      Py_DECREF(tmp);

      tmp = PyLong_FromLong(error_offset);
      if (!tmp)
        goto error;

      PyObject_SetAttrString(eval, "error_offset", tmp);
    error:
      Py_XDECREF(tmp);
      if (PyErr_Occurred())
        apsw_write_unraisable(NULL);
      PyErr_Restore(etype, eval, etb);
      assert(PyErr_Occurred());
      return;
    }

  /* this line should only be reached if SQLite returns an error code not in the main list */
  PyErr_Format(APSWException, "Error %d: %s", res, errmsg);
}

/* Turns the current Python exception into an SQLite error code and
   stores the string in the errmsg field (if not NULL).  The errmsg
   field is expected to belong to sqlite and hence uses sqlite
   semantics/ownership - for example see the pzErr parameter to
   xCreate */

static int
MakeSqliteMsgFromPyException(char **errmsg)
{
  int res = SQLITE_ERROR;
  int i;
  PyObject *str = NULL;
  PyObject *etype = NULL, *evalue = NULL, *etraceback = NULL;

  assert(PyErr_Occurred());

  PyErr_Fetch(&etype, &evalue, &etraceback);

  /* find out if the exception corresponds to an apsw exception descriptor */
  for (i = 0; exc_descriptors[i].code != -1; i++)
    if (PyErr_GivenExceptionMatches(etype, exc_descriptors[i].cls))
    {
      res = exc_descriptors[i].code;
      /* do we have extended information available? */
      if (PyObject_HasAttrString(evalue, "extendedresult"))
      {
        /* extract it */
        PyObject *extended = PyObject_GetAttrString(evalue, "extendedresult");
        if (extended && PyLong_Check(extended))
          res = PyLong_AsInt(extended);
        Py_XDECREF(extended);
        PyErr_Clear();
      }
      /* this can happen with inopportune failures in the above */
      if (res < 1)
        res = SQLITE_ERROR;
      break;
    }

  if (errmsg)
  {
    /* I just want a string of the error! */
    if (!str && evalue)
      str = PyObject_Str(evalue);
    if (!str && etype)
    {
      PyErr_Clear();
      str = PyObject_Str(etype);
    }
    if (!str)
    {
      PyErr_Clear();
      str = PyUnicode_FromString("python exception with no information");
    }
    if (*errmsg && str)
    {
      sqlite3_free(*errmsg);
      *errmsg = sqlite3_mprintf("%s", PyUnicode_AsUTF8(str));
    }

    Py_XDECREF(str);
  }

  PyErr_Restore(etype, evalue, etraceback);
  assert(PyErr_Occurred());
  assert(res != -1);
  assert(res > 0);
  return res;
}
