# Source code for canlib.canlib.txe

    """ Support for accessing information within compiled t program (.txe) files. """

    import ctypes as ct
    from collections import namedtuple
    from datetime import datetime

    from canlib.canlib import TxeDataItem, TxeFileIsEncrypted
    from .wrapper import dll
    from ..versionnumber import VersionNumber

    SourceElement = namedtuple('SourceElement', 'name contents')

    class Txe(object):
        """ The Txe class provides an interface to compiled t programs (.txe) files.

        .. versionadded:: 1.6

        """

        def __init__(self, path):
            """ Create a Txe object for the file found at path.

            Args:
                path (str): Path of the compiled t (.txe) file.
            """
            self._c_path = ct.c_char_p(path.encode('utf-8'))

        def _size_of_item_data(self, item):
            """ If buffer argument is None, then kvScriptTxeGetData stores the required buffer size in buffer_size. """
            buffer_size = ct.c_uint(0)
            dll.kvScriptTxeGetData(self._c_path, item, None, buffer_size)  # pylint: disable=maybe-no-member
            return buffer_size.value

        def _read_item(self, item, expected_buffer_type):
            data = expected_buffer_type()
            # ctypes refuses to cast python int to LP_c_ulong
            buffer_size = ct.c_uint(ct.sizeof(data))
            dll.kvScriptTxeGetData(self._c_path, item, data, buffer_size)  # pylint: disable=maybe-no-member
            assert buffer_size.value == ct.sizeof(data)
            return data

        def _read_variable_size_item(self, item):
            size = self._size_of_item_data(item)
            if size != 0:
                # Return raw to preserve any potentially embedded '\x00' within data.
                # For example TxeDataItem.SOURCE returns data containing multiple strings separated by '\x00'.
                item = self._read_item(item, ct.c_char * size).raw
            else:
                item = b''
            return item

        @property
        def path(self):
            """str: Path of compiled t program (.txe) file. """
            return self._c_path.value.decode('utf-8')

        @property
        def file_version(self):
            """`~canlib.versionnumber.VersionNumber`: .txe binary format version number."""
            values = self._read_item(TxeDataItem.FILE_VERSION, ct.c_uint32 * 3)
            return VersionNumber(*values)

        @property
        def compiler_version(self):
            """`~canlib.versionnumber.VersionNumber`: t compiler version number."""
            values = self._read_item(TxeDataItem.COMPILER_VERSION, ct.c_uint32 * 3)
            return VersionNumber(*values)

        @property
        def date(self):
            """`datetime.datetime`: Compilation date and time."""
            values = self._read_item(TxeDataItem.DATE, ct.c_uint32 * 6)
            return datetime(*values)

        @property
        def description(self):
            """str: t program description."""

            return self._read_variable_size_item(TxeDataItem.DESCRIPTION).rstrip(b'\x00').decode('utf-8')

        @property
        def source(self):
            """Yields name and content of the source files used to create the .txe binary file.

            If the t source files used to create the .txe binary was included at
            compilation time, then this attribute will yield `SourceElement` tuples
            containing the name and content of the individual source files.

            Sample usage::

              for name, contents in txe.source:
                print('file name:{} contents:{}'.format(name, contents))

            If the source and byte-code sections of the .txe binary have been encrypted then it's
            not possible to parse the source list and a `TxeFileIsEncrypted` exception will
            be raised.

            If no source files have been included in the .txe binary then an empty iterator
            is returned.

            Yields:
                `SourceElement`: Name and contents tuple.

            Raises:
                TxeFileIsEncrypted: If the source and byte-code sections of the .txe binary have been encrypted.
            """
            if self.is_encrypted:
                raise TxeFileIsEncrypted('It is not possible to decode an encrypted source code list')

            source_list = self._read_variable_size_item(TxeDataItem.SOURCE).rstrip(b'\x00')
            iterator = (entry.decode('utf-8') for entry in source_list.split(b'\x00'))
            return (SourceElement(name, contents) for name, contents in zip(iterator, iterator))

        @property
        def is_encrypted(self):
            """bool: true if the source and byte-code sections of the .txe binary have been encrypted."""
            values = self._read_item(TxeDataItem.IS_ENCRYPTED, ct.c_uint32 * 1)
            return values[0] != 0

        @property
        def size_of_code(self):
            """int: Size in bytes of byte-code section."""
            values = self._read_item(TxeDataItem.SIZE_OF_CODE, ct.c_uint32 * 1)
            return values[0]