# config.py - Reading and writing Git config files
# Copyright (C) 2011-2013 Jelmer Vernooij <jelmer@jelmer.uk>
#
# Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU
# General Public License as public by the Free Software Foundation; version 2.0
# or (at your option) any later version. You can redistribute it and/or
# modify it under the terms of either of these two licenses.
#
# 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.
#
# You should have received a copy of the licenses; if not, see
# <http://www.gnu.org/licenses/> for a copy of the GNU General Public License
# and <http://www.apache.org/licenses/LICENSE-2.0> for a copy of the Apache
# License, Version 2.0.
#

"""Reading and writing Git configuration files.

TODO:
 * preserve formatting when updating configuration files
 * treat subsection names as case-insensitive for [branch.foo] style
   subsections
"""

import errno
import os
import sys

from collections import (
    OrderedDict,
    )
try:
    from collections.abc import (
        Iterable,
        MutableMapping,
        )
except ImportError:  # python < 3.7
    from collections import (
        Iterable,
        MutableMapping,
        )

from dulwich.file import GitFile


SENTINAL = object()


def lower_key(key):
    if isinstance(key, (bytes, str)):
        return key.lower()

    if isinstance(key, Iterable):
        return type(key)(
            map(lower_key, key)
        )

    return key


class CaseInsensitiveDict(OrderedDict):

    @classmethod
    def make(cls, dict_in=None):

        if isinstance(dict_in, cls):
            return dict_in

        out = cls()

        if dict_in is None:
            return out

        if not isinstance(dict_in, MutableMapping):
            raise TypeError

        for key, value in dict_in.items():
            out[key] = value

        return out

    def __setitem__(self, key, value, **kwargs):
        key = lower_key(key)

        super(CaseInsensitiveDict, self).__setitem__(key, value,  **kwargs)

    def __getitem__(self, item):
        key = lower_key(item)

        return super(CaseInsensitiveDict, self).__getitem__(key)

    def get(self, key, default=SENTINAL):
        try:
            return self[key]
        except KeyError:
            pass

        if default is SENTINAL:
            return type(self)()

        return default

    def setdefault(self, key, default=SENTINAL):
        try:
            return self[key]
        except KeyError:
            self[key] = self.get(key, default)

        return self[key]


class Config(object):
    """A Git configuration."""

    def get(self, section, name):
        """Retrieve the contents of a configuration setting.

        :param section: Tuple with section name and optional subsection namee
        :param subsection: Subsection name
        :return: Contents of the setting
        :raise KeyError: if the value is not set
        """
        raise NotImplementedError(self.get)

    def get_boolean(self, section, name, default=None):
        """Retrieve a configuration setting as boolean.

        :param section: Tuple with section name and optional subsection name
        :param name: Name of the setting, including section and possible
            subsection.
        :return: Contents of the setting
        :raise KeyError: if the value is not set
        """
        try:
            value = self.get(section, name)
        except KeyError:
            return default
        if value.lower() == b"true":
            return True
        elif value.lower() == b"false":
            return False
        raise ValueError("not a valid boolean string: %r" % value)

    def set(self, section, name, value):
        """Set a configuration value.

        :param section: Tuple with section name and optional subsection namee
        :param name: Name of the configuration value, including section
            and optional subsection
        :param: Value of the setting
        """
        raise NotImplementedError(self.set)

    def iteritems(self, section):
        """Iterate over the configuration pairs for a specific section.

        :param section: Tuple with section name and optional subsection namee
        :return: Iterator over (name, value) pairs
        """
        raise NotImplementedError(self.iteritems)

    def itersections(self):
        """Iterate over the sections.

        :return: Iterator over section tuples
        """
        raise NotImplementedError(self.itersections)

    def has_section(self, name):
        """Check if a specified section exists.

        :param name: Name of section to check for
        :return: boolean indicating whether the section exists
        """
        return (name in self.itersections())


class ConfigDict(Config, MutableMapping):
    """Git configuration stored in a dictionary."""

    def __init__(self, values=None, encoding=None):
        """Create a new ConfigDict."""
        if encoding is None:
            encoding = sys.getdefaultencoding()
        self.encoding = encoding
        self._values = CaseInsensitiveDict.make(values)

    def __repr__(self):
        return "%s(%r)" % (self.__class__.__name__, self._values)

    def __eq__(self, other):
        return (
            isinstance(other, self.__class__) and
            other._values == self._values)

    def __getitem__(self, key):
        return self._values.__getitem__(key)

    def __setitem__(self, key, value):
        return self._values.__setitem__(key, value)

    def __delitem__(self, key):
        return self._values.__delitem__(key)

    def __iter__(self):
        return self._values.__iter__()

    def __len__(self):
        return self._values.__len__()

    @classmethod
    def _parse_setting(cls, name):
        parts = name.split(".")
        if len(parts) == 3:
            return (parts[0], parts[1], parts[2])
        else:
            return (parts[0], None, parts[1])

    def _check_section_and_name(self, section, name):
        if not isinstance(section, tuple):
            section = (section, )

        section = tuple([
            subsection.encode(self.encoding)
            if not isinstance(subsection, bytes) else subsection
            for subsection in section
            ])

        if not isinstance(name, bytes):
            name = name.encode(self.encoding)

        return section, name

    def get(self, section, name):
        section, name = self._check_section_and_name(section, name)

        if len(section) > 1:
            try:
                return self._values[section][name]
            except KeyError:
                pass

        return self._values[(section[0],)][name]

    def set(self, section, name, value):
        section, name = self._check_section_and_name(section, name)

        if type(value) not in (bool, bytes):
            value = value.encode(self.encoding)

        self._values.setdefault(section)[name] = value

    def iteritems(self, section):
        return self._values.get(section).items()

    def itersections(self):
        return self._values.keys()


def _format_string(value):
    if (value.startswith(b" ") or
            value.startswith(b"\t") or
            value.endswith(b" ") or
            b'#' in value or
            value.endswith(b"\t")):
        return b'"' + _escape_value(value) + b'"'
    else:
        return _escape_value(value)


_ESCAPE_TABLE = {
    ord(b"\\"): ord(b"\\"),
    ord(b"\""): ord(b"\""),
    ord(b"n"): ord(b"\n"),
    ord(b"t"): ord(b"\t"),
    ord(b"b"): ord(b"\b"),
    }
_COMMENT_CHARS = [ord(b"#"), ord(b";")]
_WHITESPACE_CHARS = [ord(b"\t"), ord(b" ")]


def _parse_string(value):
    value = bytearray(value.strip())
    ret = bytearray()
    whitespace = bytearray()
    in_quotes = False
    i = 0
    while i < len(value):
        c = value[i]
        if c == ord(b"\\"):
            i += 1
            try:
                v = _ESCAPE_TABLE[value[i]]
            except IndexError:
                raise ValueError(
                    "escape character in %r at %d before end of string" %
                    (value, i))
            except KeyError:
                raise ValueError(
                    "escape character followed by unknown character "
                    "%s at %d in %r" % (value[i], i, value))
            if whitespace:
                ret.extend(whitespace)
                whitespace = bytearray()
            ret.append(v)
        elif c == ord(b"\""):
            in_quotes = (not in_quotes)
        elif c in _COMMENT_CHARS and not in_quotes:
            # the rest of the line is a comment
            break
        elif c in _WHITESPACE_CHARS:
            whitespace.append(c)
        else:
            if whitespace:
                ret.extend(whitespace)
                whitespace = bytearray()
            ret.append(c)
        i += 1

    if in_quotes:
        raise ValueError("missing end quote")

    return bytes(ret)


def _escape_value(value):
    """Escape a value."""
    value = value.replace(b"\\", b"\\\\")
    value = value.replace(b"\n", b"\\n")
    value = value.replace(b"\t", b"\\t")
    value = value.replace(b"\"", b"\\\"")
    return value


def _check_variable_name(name):
    for i in range(len(name)):
        c = name[i:i+1]
        if not c.isalnum() and c != b'-':
            return False
    return True