# Copyright 2021 The gRPC Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Follows convention set in objectivec_helpers.cc in the protobuf ObjC compiler.

"""
Contains generic helper utilities.
"""

_upper_segments_list = ["url", "http", "https"]

def strip_extension(str):
    return str.rpartition(".")[0]

def capitalize(word):
    if word in _upper_segments_list:
        return word.upper()
    else:
        return word.capitalize()

def lower_underscore_to_upper_camel(str):
    """Converts from lower underscore case to upper camel case.

    Args:
      str: The snake case string to convert.

    Returns:
      The title case version of str.
    """
    str = strip_extension(str)
    camel_case_str = ""
    word = ""
    for c in str.elems():  # NB: assumes ASCII!
        if c.isalpha():
            word += c.lower()
        else:
            # Last word is finished.
            if len(word):
                camel_case_str += capitalize(word)
                word = ""
            if c.isdigit():
                camel_case_str += c

            # Otherwise, drop the character. See UnderscoresToCamelCase in:
            # third_party/protobuf/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc

    if len(word):
        camel_case_str += capitalize(word)
    return camel_case_str

def file_to_upper_camel(src):
    elements = src.rpartition("/")
    upper_camel = lower_underscore_to_upper_camel(elements[-1])
    return "".join(list(elements[:-1]) + [upper_camel])

def file_with_extension(src, ext):
    elements = src.rpartition("/")
    return "".join(list(elements[:-1]) + [elements[-1], "." + ext])

def to_upper_camel_with_extension(src, ext):
    src = file_to_upper_camel(src)
    return file_with_extension(src, ext)