"""This utility helps you migrate from PyTables 2.x APIs to 3.x APIs, which
are PEP 8 compliant.

"""
import re
import sys
import argparse
from pathlib import Path

old2newnames = dict([
    # from __init__.py
    ('hdf5Version', 'hdf5_version'),                    # data
    # from array.py
    ('parentNode', 'parentnode'),                       # kwarg
    ('getEnum', 'get_enum'),
    ('_initLoop', '_init_loop'),
    ('_fancySelection', '_fancy_selection'),
    ('_checkShape', '_check_shape'),
    ('_readSlice', '_read_slice'),
    ('_readCoords', '_read_coords'),
    ('_readSelection', '_read_selection'),
    ('_writeSlice', '_write_slice'),
    ('_writeCoords', '_write_coords'),
    ('_writeSelection', '_write_selection'),
    ('_g_copyWithStats', '_g_copy_with_stats'),
    ('_c_classId', '_c_classid'),                       # attr
    # from atom.py
    ('_checkBase', '_checkbase'),
    # from attributeset.py
    ('newSet', 'newset'),                               # kwarg
    ('copyClass', 'copyclass'),                         # kwarg
    ('_g_updateNodeLocation', '_g_update_node_location'),
    ('_g_logAdd', '_g_log_add'),
    ('_g_delAndLog', '_g_del_and_log'),
    ('_v__nodeFile', '_v__nodefile'),                   # attr (private)
    ('_v__nodePath', '_v__nodepath'),                   # attr (private)
    # from carray.py
    # ('parentNode', 'parentnode'),                       # kwarg
    # from description.py
    ('_g_setNestedNamesDescr', '_g_set_nested_names_descr'),
    ('_g_setPathNames', '_g_set_path_names'),
    ('_v_colObjects', '_v_colobjects'),                 # attr
    ('_v_nestedFormats', '_v_nested_formats'),          # attr
    ('_v_nestedNames', '_v_nested_names'),              # attr
    ('_v_nestedDescr', '_v_nested_descr'),              # attr
    ('getColsInOrder', 'get_cols_in_order'),
    ('joinPaths', 'join_paths'),
    ('metaIsDescription', 'MetaIsDescription'),
    # from earray.py
    # ('parentNode', 'parentnode'),                       # kwarg
    ('_checkShapeAppend', '_check_shape_append'),
    # from expression.py
    ('_exprvarsCache', '_exprvars_cache'),              # attr (private)
    ('_requiredExprVars', '_required_expr_vars'),
    ('setInputsRange', 'set_inputs_range'),
    ('setOutput', 'set_output'),
    ('setOutputRange', 'set_output_range'),
    # from file.py
    ('_opToCode', '_op_to_code'),                       # data (private)
    ('_codeToOp', '_code_to_op'),                       # data (private)
    ('_transVersion', '_trans_version'),                # data (private)
    ('_transGroupParent', '_trans_group_parent'),       # data (private)
    ('_transGroupName', '_trans_group_name'),           # data (private)
    ('_transGroupPath', '_trans_group_path'),           # data (private)
    ('_actionLogParent', '_action_log_parent'),         # data (private)
    ('_actionLogName', '_action_log_name'),             # data (private)
    ('_actionLogPath', '_action_log_path'),             # data (private)
    ('_transParent', '_trans_parent'),                  # data (private)
    ('_transName', '_trans_name'),                      # data (private)
    ('_transPath', '_trans_path'),                      # data (private)
    ('_shadowParent', '_shadow_parent'),                # data (private)
    ('_shadowName', '_shadow_name'),                    # data (private)
    ('_shadowPath', '_shadow_path'),                    # data (private)
    ('copyFile', 'copy_file'),
    ('openFile', 'open_file'),
    ('_getValueFromContainer', '_get_value_from_container'),
    ('__getRootGroup', '__get_root_group'),
    ('rootUEP', 'root_uep'),                            # attr
    ('_getOrCreatePath', '_get_or_create_path'),
    ('_createPath', '_create_path'),
    ('createGroup', 'create_group'),
    ('createTable', 'create_table'),
    ('createArray', 'create_array'),
    ('createCArray', 'create_carray'),
    ('createEArray', 'create_earray'),
    ('createVLArray', 'create_vlarray'),
    ('createHardLink', 'create_hard_link'),
    ('createSoftLink', 'create_soft_link'),
    ('createExternalLink', 'create_external_link'),
    ('_getNode', '_get_node'),
    ('getNode', 'get_node'),
    ('isVisibleNode', 'is_visible_node'),
    ('renameNode', 'rename_node'),
    ('moveNode', 'move_node'),
    ('copyNode', 'copy_node'),
    ('removeNode', 'remove_node'),
    ('getNodeAttr', 'get_node_attr'),
    ('setNodeAttr', 'set_node_attr'),
    ('delNodeAttr', 'del_node_attr'),
    ('copyNodeAttrs', 'copy_node_attrs'),
    ('copyChildren', 'copy_children'),
    ('listNodes', 'list_nodes'),
    ('iterNodes', 'iter_nodes'),
    ('walkNodes', 'walk_nodes'),
    ('walkGroups', 'walk_groups'),
    ('_checkOpen', '_check_open'),
    ('_isWritable', '_iswritable'),
    ('_checkWritable', '_check_writable'),
    ('_checkGroup', '_check_group'),
    ('isUndoEnabled', 'is_undo_enabled'),
    ('_checkUndoEnabled', '_check_undo_enabled'),
    ('_createTransactionGroup', '_create_transaction_group'),
    ('_createTransaction', '_create_transaction'),
    ('_createMark', '_create_mark'),
    ('enableUndo', 'enable_undo'),
    ('disableUndo', 'disable_undo'),
    ('_getMarkID', '_get_mark_id'),
    ('_getFinalAction', '_get_final_action'),
    ('getCurrentMark', 'get_current_mark'),
    ('_updateNodeLocations', '_update_node_locations'),
    # from group.py
    # ('parentNode', 'parentnode'),                       # kwarg
    # ('ptFile', 'ptfile'),                               # kwarg
    ('_getValueFromContainer', '_get_value_from_container'),
    ('_g_postInitHook', '_g_post_init_hook'),
    ('_g_getChildGroupClass', '_g_get_child_group_class'),
    ('_g_getChildLeafClass', '_g_get_child_leaf_class'),
    ('_g_addChildrenNames', '_g_add_children_names'),
    ('_g_checkHasChild', '_g_check_has_child'),
    ('_f_walkNodes', '_f_walknodes'),
    ('_g_widthWarning', '_g_width_warning'),
    ('_g_refNode', '_g_refnode'),
    ('_g_unrefNode', '_g_unrefnode'),
    ('_g_copyChildren', '_g_copy_children'),
    ('_f_getChild', '_f_get_child'),
    ('_f_listNodes', '_f_list_nodes'),
    ('_f_iterNodes', '_f_iter_nodes'),
    ('_f_walkGroups', '_f_walk_groups'),
    ('_g_closeDescendents', '_g_close_descendents'),
    ('_f_copyChildren', '_f_copy_children'),
    ('_v_maxGroupWidth', '_v_max_group_width'),         # attr
    ('_v_objectID', '_v_objectid'),                     # attr
    ('_g_loadChild', '_g_load_child'),
    ('childName', 'childname'),                         # ???
    ('_c_shadowNameRE', '_c_shadow_name_re'),           # attr (private)
    # from hdf5extension.p{yx,xd}
    ('hdf5Extension', 'hdf5extension'),
    ('_getFileId', '_get_file_id'),
    ('_flushFile', '_flush_file'),
    ('_closeFile', '_close_file'),
    ('_g_listAttr', '_g_list_attr'),
    ('_g_setAttr', '_g_setattr'),
    ('_g_getAttr', '_g_getattr'),
    ('_g_listGroup', '_g_list_group'),
    ('_g_getGChildAttr', '_g_get_gchild_attr'),
    ('_g_getLChildAttr', '_g_get_lchild_attr'),
    ('_g_flushGroup', '_g_flush_group'),
    ('_g_closeGroup', '_g_close_group'),
    ('_g_moveNode', '_g_move_node'),
    ('_convertTime64', '_convert_time64'),
    ('_createArray', '_create_array'),
    ('_createCArray', '_create_carray'),
    ('_openArray', '_open_array'),
    ('_readArray', '_read_array'),
    ('_g_readSlice', '_g_read_slice'),
    ('_g_readCoords', '_g_read_coords'),
    ('_g_readSelection', '_g_read_selection'),
    ('_g_writeSlice', '_g_write_slice'),
    ('_g_writeCoords', '_g_write_coords'),
    ('_g_writeSelection', '_g_write_selection'),
    # from idxutils.py
    ('calcChunksize', 'calc_chunksize'),
    ('infinityF', 'infinityf'),                         # data
    ('infinityMap', 'infinitymap'),                     # data
    ('infType', 'inftype'),
    ('StringNextAfter', 'string_next_after'),
    ('IntTypeNextAfter', 'int_type_next_after'),
    ('BoolTypeNextAfter', 'bool_type_next_after'),
    # from index.py
    # ('parentNode', 'parentnode'),                       # kwarg
    ('defaultAutoIndex', 'default_auto_index'),         # data
    ('defaultIndexFilters', 'default_index_filters'),   # data
    ('_tableColumnPathnameOfIndex', '_table_column_pathname_of_index'),
    ('_is_CSI', '_is_csi'),
    ('is_CSI', 'is_csi'),                               # property
    ('appendLastRow', 'append_last_row'),
    ('read_sliceLR', 'read_slice_lr'),
    ('readSorted', 'read_sorted'),
    ('readIndices', 'read_indices'),
    ('_processRange', '_process_range'),
    ('searchLastRow', 'search_last_row'),
    ('getLookupRange', 'get_lookup_range'),
    ('_g_checkName', '_g_check_name'),
    # from indexes.py
    # ('parentNode', 'parentnode'),                       # kwarg
    ('_searchBin', '_search_bin'),
    # from indexesextension
    ('indexesExtension', 'indexesextension'),
    ('initRead', 'initread'),
    ('readSlice', 'read_slice'),
    ('_readIndexSlice', '_read_index_slice'),
    ('_initSortedSlice', '_init_sorted_slice'),
    ('_g_readSortedSlice', '_g_read_sorted_slice'),
    ('_readSortedSlice', '_read_sorted_slice'),
    ('getLRUbounds', 'get_lru_bounds'),
    ('getLRUsorted', 'get_lru_sorted'),
    ('_searchBinNA_b', '_search_bin_na_b'),
    ('_searchBinNA_ub', '_search_bin_na_ub'),
    ('_searchBinNA_s', '_search_bin_na_s'),
    ('_searchBinNA_us', '_search_bin_na_us'),
    ('_searchBinNA_i', '_search_bin_na_i'),
    ('_searchBinNA_ui', '_search_bin_na_ui'),
    ('_searchBinNA_ll', '_search_bin_na_ll'),
    ('_searchBinNA_ull', '_search_bin_na_ull'),
    ('_searchBinNA_e', '_search_bin_na_e'),
    ('_searchBinNA_f', '_search_bin_na_f'),
    ('_searchBinNA_d', '_search_bin_na_d'),
    ('_searchBinNA_g', '_search_bin_na_g'),
    # from leaf.py
    # ('parentNode', 'parentnode'),                       # kwarg
    ('objectID', 'object_id'),                          # property
    ('_processRangeRead', '_process_range_read'),
    ('_pointSelection', '_point_selection'),
    ('isVisible', 'isvisible'),
    ('getAttr', 'get_attr'),
    ('setAttr', 'set_attr'),
    ('delAttr', 'del_attr'),
    # from link.py
    # ('parentNode', 'parentnode'),                       # kwarg
    ('_g_getLinkClass', '_g_get_link_class'),
    # from linkextension
    ('linkExtension', 'linkextension'),
    ('_getLinkClass', '_get_link_class'),
    ('_g_createHardLink', '_g_create_hard_link'),
    # from lrucacheextension
    ('lrucacheExtension', 'lrucacheextension'),
    # from misc/enum.py
    ('_checkAndSetPair', '_check_and_set_pair'),
    ('_getContainer', '_get_container'),
    # from misc/proxydict.py
    ('containerRef', 'containerref'),                   # attr
    # from node.py
    # ('parentNode', 'parentnode'),                       # kwarg
    ('_g_logCreate', '_g_log_create'),
    ('_g_preKillHook', '_g_pre_kill_hook'),
    ('_g_checkOpen', '_g_check_open'),
    ('_g_setLocation', '_g_set_location'),
    ('_g_updateLocation', '_g_update_location'),
    ('_g_delLocation', '_g_del_location'),
    ('_g_updateDependent', '_g_update_dependent'),
    ('_g_removeAndLog', '_g_remove_and_log'),
    ('_g_logMove', '_g_log_move'),
    ('oldPathname', 'oldpathname'),                     # ??
    ('_g_copyAsChild', '_g_copy_as_child'),
    ('_f_isVisible', '_f_isvisible'),
    ('_g_checkGroup', '_g_check_group'),
    ('_g_checkNotContains', '_g_check_not_contains'),
    ('_g_maybeRemove', '_g_maybe_remove'),
    ('_f_getAttr', '_f_getattr'),
    ('_f_setAttr', '_f_setattr'),
    ('_f_delAttr', '_f_delattr'),
    ('_v_maxTreeDepth', '_v_maxtreedepth'),             # attr
    # from nodes/filenode.py
    ('newNode', 'new_node'),
    ('openNode', 'open_node'),
    ('_lineChunkSize', '_line_chunksize'),              # attr (private)
    ('_lineSeparator', '_line_separator'),              # attr (private)
    # ('getLineSeparator', 'get_line_separator'),        # dropped
    # ('setLineSeparator', 'set_line_separator'),        # dropped
    # ('delLineSeparator', 'del_line_separator'),        # dropped
    # ('lineSeparator', 'line_separator'),                # property -- dropped
    ('_notReadableError', '_not_readable_error'),
    ('_appendZeros', '_append_zeros'),
    ('getAttrs', '_get_attrs'),
    ('setAttrs', '_set_attrs'),
    ('delAttrs', '_del_attrs'),
    ('_setAttributes', '_set_attributes'),
    ('_checkAttributes', '_check_attributes'),
    ('_checkNotClosed', '_check_not_closed'),
    ('__allowedInitKwArgs', '__allowed_init_kwargs'),   # attr (private)
    ('_byteShape', '_byte_shape'),                      # attr (private)
    ('_sizeToShape', '_size_to_shape'),                 # attr (private)
    ('_vType', '_vtype'),                               # attr (private)
    ('_vShape', '_vshape'),                             # attr (private)
    # from path.py
    ('parentPath', 'parentpath'),                       # kwarg
    ('_pythonIdRE', '_python_id_re'),                   # attr (private)
    ('_reservedIdRE', '_reserved_id_re'),               # attr (private)
    ('_hiddenNameRE', '_hidden_name_re'),               # attr (private)
    ('_hiddenPathRE', '_hidden_path_re'),               # attr (private)
    ('checkNameValidity', 'check_name_validity'),
    ('joinPath', 'join_path'),
    ('splitPath', 'split_path'),
    ('isVisibleName', 'isvisiblename'),
    ('isVisiblePath', 'isvisiblepath'),
    # from registry.py
    ('className', 'classname'),                         # kwarg
    ('classNameDict', 'class_name_dict'),               # data
    ('classIdDict', 'class_id_dict'),                   # data
    ('getClassByName', 'get_class_by_name'),
    # from scripts/ptdump.py
    ('dumpLeaf', 'dump_leaf'),
    ('dumpGroup', 'dump_group'),
    # from scripts/ptrepack.py
    ('newdstGroup', 'newdst_group'),
    ('recreateIndexes', 'recreate_indexes'),
    ('copyLeaf', 'copy_leaf'),
    # from table.py
    # ('parentNode', 'parentnode'),                       # kwarg
    ('_nxTypeFromNPType', '_nxtype_from_nptype'),       # data (private)
    ('_npSizeType', '_npsizetype'),                     # data (private)
    ('_indexNameOf', '_index_name_of'),
    ('_indexPathnameOf', '_index_pathname_of'),
    ('_indexPathnameOfColumn', '_index_pathname_of_column'),
    ('_indexNameOf_', '_index_name_of_'),
    ('_indexPathnameOf_', '_index_pathname_of_'),
    ('_indexPathnameOfColumn_', '_index_pathname_of_column_'),
    ('_table__setautoIndex', '_table__setautoindex'),
    ('_table__getautoIndex', '_table__getautoindex'),
    ('_table__autoIndex', '_table__autoindex'),         # data (private)
    ('_table__whereIndexed', '_table__where_indexed'),
    ('createIndexesTable', 'create_indexes_table'),
    ('createIndexesDescr', 'create_indexes_descr'),
    ('_column__createIndex', '_column__create_index'),
    ('_autoIndex', '_autoindex'),                       # attr
    ('autoIndex', 'autoindex'),                         # attr
    ('_useIndex', '_use_index'),
    ('_whereCondition', '_where_condition'),            # attr (private)
    ('_conditionCache', '_condition_cache'),            # attr (private)
    # ('_exprvarsCache', '_exprvars_cache'),
    ('_enabledIndexingInQueries',
     '_enabled_indexing_in_queries'),  # attr (private)
    ('_emptyArrayCache', '_empty_array_cache'),         # attr (private)
    ('_getTypeColNames', '_get_type_col_names'),
    ('_getEnumMap', '_get_enum_map'),
    ('_cacheDescriptionData', '_cache_description_data'),
    ('_getColumnInstance', '_get_column_instance'),
    ('_checkColumn', '_check_column'),
    ('_disableIndexingInQueries', '_disable_indexing_in_queries'),
    ('_enableIndexingInQueries', '_enable_indexing_in_queries'),
    # ('_requiredExprVars', '_required_expr_vars'),
    ('_getConditionKey', '_get_condition_key'),
    ('_compileCondition', '_compile_condition'),
    ('willQueryUseIndexing', 'will_query_use_indexing'),
    ('readWhere', 'read_where'),
    ('whereAppend', 'append_where'),
    ('getWhereList', 'get_where_list'),
    ('_check_sortby_CSI', '_check_sortby_csi'),
    ('_readCoordinates', '_read_coordinates'),
    ('readCoordinates', 'read_coordinates'),
    ('_saveBufferedRows', '_save_buffered_rows'),
    ('modifyCoordinates', 'modify_coordinates'),
    ('modifyRows', 'modify_rows'),
    ('modifyColumn', 'modify_column'),
    ('modifyColumns', 'modify_columns'),
    ('flushRowsToIndex', 'flush_rows_to_index'),
    ('_addRowsToIndex', '_add_rows_to_index'),
    ('removeRows', 'remove_rows'),
    ('_setColumnIndexing', '_set_column_indexing'),
    ('_markColumnsAsDirty', '_mark_columns_as_dirty'),
    ('_reIndex', '_reindex'),
    ('_doReIndex', '_do_reindex'),
    ('reIndex', 'reindex'),
    ('reIndexDirty', 'reindex_dirty'),
    ('_g_copyRows', '_g_copy_rows'),
    ('_g_copyRows_optim', '_g_copy_rows_optim'),
    ('_g_propIndexes', '_g_prop_indexes'),
    ('_g_updateTableLocation', '_g_update_table_location'),
    ('_tableFile', '_table_file'),                      # attr (private)
    ('_tablePath', '_table_path'),                      # attr (private)
    ('createIndex', 'create_index'),
    ('createCSIndex', 'create_csindex'),
    ('removeIndex', 'remove_index'),
    # from tableextension
    ('tableExtension', 'tableextension'),
    ('getNestedFieldCache', 'get_nested_field_cache'),
    ('getNestedType', 'get_nested_type'),
    ('_createTable', '_create_table'),
    ('_getInfo', '_get_info'),
    ('indexChunk', 'indexchunk'),                       # attr
    ('indexValid', 'indexvalid'),                       # attr
    ('indexValues', 'indexvalues'),                     # attr
    ('bufcoordsData', 'bufcoords_data'),                # attr
    ('indexValuesData', 'index_values_data'),           # attr
    ('chunkmapData', 'chunkmap_data'),                  # attr
    ('indexValidData', 'index_valid_data'),             # attr
    ('whereCond', 'wherecond'),                         # attr
    ('iterseqMaxElements', 'iterseq_max_elements'),     # attr
    ('IObuf', 'iobuf'),                                 # attr
    ('IObufcpy', 'iobufcpy'),                           # attr
    ('_convertTime64_', '_convert_time64_'),
    ('_convertTypes', '_convert_types'),
    ('_newBuffer', '_new_buffer'),
    ('__next__inKernel', '__next__inkernel'),
    ('_fillCol', '_fill_col'),
    ('_flushBufferedRows', '_flush_buffered_rows'),
    ('_getUnsavedNrows', '_get_unsaved_nrows'),
    ('_flushModRows', '_flush_mod_rows'),
    # from undoredo.py
    ('moveToShadow', 'move_to_shadow'),
    ('moveFromShadow', 'move_from_shadow'),
    ('undoCreate', 'undo_create'),
    ('redoCreate', 'redo_create'),
    ('undoRemove', 'undo_remove'),
    ('redoRemove', 'redo_remove'),
    ('undoMove', 'undo_move'),
    ('redoMove', 'redo_move'),
    ('attrToShadow', 'attr_to_shadow'),
    ('attrFromShadow', 'attr_from_shadow'),
    ('undoAddAttr', 'undo_add_attr'),
    ('redoAddAttr', 'redo_add_attr'),
    ('undoDelAttr', 'undo_del_attr'),
    ('redoDelAttr', 'redo_del_attr'),
    # from utils.py
    ('convertToNPAtom', 'convert_to_np_atom'),
    ('convertToNPAtom2', 'convert_to_np_atom2'),
    ('checkFileAccess', 'check_file_access'),
    ('logInstanceCreation', 'log_instance_creation'),
    ('fetchLoggedInstances', 'fetch_logged_instances'),
    ('countLoggedInstances', 'count_logged_instances'),
    ('listLoggedInstances', 'list_logged_instances'),
    ('dumpLoggedInstances', 'dump_logged_instances'),
    ('detectNumberOfCores', 'detect_number_of_cores'),
    # from utilsextension
    ('utilsExtension', 'utilsextension'),
    ('PTTypeToHDF5', 'pttype_to_hdf5'),                 # data
    ('PTSpecialKinds', 'pt_special_kinds'),             # data
    ('NPExtPrefixesToPTKinds', 'npext_prefixes_to_ptkinds'),    # data
    ('HDF5ClassToString', 'hdf5_class_to_string'),      # data
    ('setBloscMaxThreads', 'set_blosc_max_threads'),
    ('silenceHDF5Messages', 'silence_hdf5_messages'),
    ('isHDF5File', 'is_hdf5_file'),
    ('isPyTablesFile', 'is_pytables_file'),
    ('getHDF5Version', 'get_hdf5_version'),
    ('getPyTablesVersion', 'get_pytables_version'),
    ('whichLibVersion', 'which_lib_version'),
    ('whichClass', 'which_class'),
    ('getNestedField', 'get_nested_field'),
    ('getFilters', 'get_filters'),
    ('getTypeEnum', 'get_type_enum'),
    ('enumFromHDF5', 'enum_from_hdf5'),
    ('enumToHDF5', 'enum_to_hdf5'),
    ('AtomToHDF5Type', 'atom_to_hdf5_type'),
    ('loadEnum', 'load_enum'),
    ('HDF5ToNPNestedType', 'hdf5_to_np_nested_type'),
    ('HDF5ToNPExtType', 'hdf5_to_np_ext_type'),
    ('AtomFromHDF5Type', 'atom_from_hdf5_type'),
    ('createNestedType', 'create_nested_type'),
    # from unimlemented.py
    ('_openUnImplemented', '_open_unimplemented'),
    # from vlarray.py
    # ('parentNode', 'parentnode'),                       # kwarg
    # ('expectedsizeinMB', 'expected_mb'),                # --> expectedrows
    # ('_v_expectedsizeinMB', '_v_expected_mb'),          # --> expectedrows
])

new2oldnames = {v: k for k, v in old2newnames.items()}

# Note that it is tempting to use the ast module here, but then this
# breaks transforming cython files.  So instead we are going to do the
# dumb thing with replace.


def make_subs(ns):
    names = new2oldnames if ns.reverse else old2newnames
    s = r'(?<=\W)({})(?=\W)'.format('|'.join(list(names)))
    if ns.ignore_previous:
        s += r'(?!\s*?=\s*?previous_api(_property)?\()'
        s += r'(?!\* to \*\w+\*)'
        s += r'(?!\* parameter has been renamed into \*\w+\*\.)'
        s += r'(?! is pending deprecation, import \w+ instead\.)'
    subs = re.compile(s, flags=re.MULTILINE)

    def repl(m):
        return names.get(m.group(1), m.group(0))
    return subs, repl


def main():
    desc = ('PyTables 2.x -> 3.x API transition tool\n\n'
            'This tool displays to standard out, so it is \n'
            'common to pipe this to another file:\n\n'
            '$ pt2to3 oldfile.py > newfile.py')
    parser = argparse.ArgumentParser(description=desc)
    parser.add_argument('-r', '--reverse', action='store_true', default=False,
                        dest='reverse',
                        help="reverts changes, going from 3.x -> 2.x.")
    parser.add_argument('-p', '--no-ignore-previous', action='store_false',
                        default=True, dest='ignore_previous',
                        help="ignores previous_api() calls.")
    parser.add_argument('-o', default=None, dest='output',
                        help="output file to write to.")
    parser.add_argument('-i', '--inplace', action='store_true', default=False,
                        dest='inplace', help="overwrites the file in-place.")
    parser.add_argument('filename', help='path to input file.')
    ns = parser.parse_args()

    if not Path(ns.filename).is_file():
        sys.exit(f'file {ns.filename!r} not found')
    src = Path(ns.filename).read_text()

    subs, repl = make_subs(ns)
    targ = subs.sub(repl, src)

    ns.output = ns.filename if ns.inplace else ns.output
    if ns.output is None:
        sys.stdout.write(targ)
    else:
        Path(ns.output).write_text(targ)


if __name__ == '__main__':
    main()