# encoding: utf-8
"""An object for managing IPython profile directories."""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.

import os
import shutil
import errno
from pathlib import Path

from traitlets.config.configurable import LoggingConfigurable
from ..paths import get_ipython_package_dir
from ..utils.path import expand_path, ensure_dir_exists
from traitlets import Unicode, Bool, observe

from typing import Optional

#-----------------------------------------------------------------------------
# Module errors
#-----------------------------------------------------------------------------

class ProfileDirError(Exception):
    pass


#-----------------------------------------------------------------------------
# Class for managing profile directories
#-----------------------------------------------------------------------------

class ProfileDir(LoggingConfigurable):
    """An object to manage the profile directory and its resources.

    The profile directory is used by all IPython applications, to manage
    configuration, logging and security.

    This object knows how to find, create and manage these directories. This
    should be used by any code that wants to handle profiles.
    """

    security_dir_name = Unicode('security')
    log_dir_name = Unicode('log')
    startup_dir_name = Unicode('startup')
    pid_dir_name = Unicode('pid')
    static_dir_name = Unicode('static')
    security_dir = Unicode(u'')
    log_dir = Unicode(u'')
    startup_dir = Unicode(u'')
    pid_dir = Unicode(u'')
    static_dir = Unicode(u'')

    location = Unicode(u'',
        help="""Set the profile location directly. This overrides the logic used by the
        `profile` option.""",
        ).tag(config=True)

    _location_isset = Bool(False) # flag for detecting multiply set location
    @observe('location')
    def _location_changed(self, change):
        if self._location_isset:
            raise RuntimeError("Cannot set profile location more than once.")
        self._location_isset = True
        new = change['new']
        ensure_dir_exists(new)

        # ensure config files exist:
        self.security_dir = os.path.join(new, self.security_dir_name)
        self.log_dir = os.path.join(new, self.log_dir_name)
        self.startup_dir = os.path.join(new, self.startup_dir_name)
        self.pid_dir = os.path.join(new, self.pid_dir_name)
        self.static_dir = os.path.join(new, self.static_dir_name)
        self.check_dirs()

    def _mkdir(self, path: str, mode: Optional[int] = None) -> bool:
        """ensure a directory exists at a given path

        This is a version of os.mkdir, with the following differences:

        - returns whether the directory has been created or not.
        - ignores EEXIST, protecting against race conditions where
          the dir may have been created in between the check and
          the creation
        - sets permissions if requested and the dir already exists

        Parameters
        ----------
        path: str
            path of the dir to create
        mode: int
            see `mode` of `os.mkdir`

        Returns
        -------
        bool:
            returns True if it created the directory, False otherwise
        """

        if os.path.exists(path):
            if mode and os.stat(path).st_mode != mode:
                try:
                    os.chmod(path, mode)
                except OSError:
                    self.log.warning(
                        "Could not set permissions on %s",
                        path
                    )
            return False
        try:
            if mode:
                os.mkdir(path, mode)
            else:
                os.mkdir(path)
        except OSError as e:
            if e.errno == errno.EEXIST:
                return False
            else:
                raise

        return True
    
    @observe('log_dir')
    def check_log_dir(self, change=None):
        self._mkdir(self.log_dir)
    
    @observe('startup_dir')
    def check_startup_dir(self, change=None):
        if self._mkdir(self.startup_dir):
            readme = os.path.join(self.startup_dir, "README")
            src = os.path.join(
                get_ipython_package_dir(), "core", "profile", "README_STARTUP"
            )

            if os.path.exists(src):
                if not os.path.exists(readme):
                    shutil.copy(src, readme)
            else:
                self.log.warning(
                    "Could not copy README_STARTUP to startup dir. Source file %s does not exist.",
                    src,
                )

    @observe('security_dir')
    def check_security_dir(self, change=None):
        self._mkdir(self.security_dir, 0o40700)

    @observe('pid_dir')
    def check_pid_dir(self, change=None):
        self._mkdir(self.pid_dir, 0o40700)

    def check_dirs(self):
        self.check_security_dir()
        self.check_log_dir()
        self.check_pid_dir()
        self.check_startup_dir()

    def copy_config_file(self, config_file: str, path: Path, overwrite=False) -> bool:
        """Copy a default config file into the active profile directory.

        Default configuration files are kept in :mod:`IPython.core.profile`.
        This function moves these from that location to the working profile
        directory.
        """
        dst = Path(os.path.join(self.location, config_file))
        if dst.exists() and not overwrite:
            return False
        if path is None:
            path = os.path.join(get_ipython_package_dir(), u'core', u'profile', u'default')
        assert isinstance(path, Path)
        src = path / config_file
        shutil.copy(src, dst)
        return True

    @classmethod
    def create_profile_dir(cls, profile_dir, config=None):
        """Create a new profile directory given a full path.

        Parameters
        ----------
        profile_dir : str
            The full path to the profile directory.  If it does exist, it will
            be used.  If not, it will be created.
        """
        return cls(location=profile_dir, config=config)

    @classmethod
    def create_profile_dir_by_name(cls, path, name=u'default', config=None):
        """Create a profile dir by profile name and path.

        Parameters
        ----------
        path : unicode
            The path (directory) to put the profile directory in.
        name : unicode
            The name of the profile.  The name of the profile directory will
            be "profile_<profile>".
        """
        if not os.path.isdir(path):
            raise ProfileDirError('Directory not found: %s' % path)
        profile_dir = os.path.join(path, u'profile_' + name)
        return cls(location=profile_dir, config=config)

    @classmethod
    def find_profile_dir_by_name(cls, ipython_dir, name=u'default', config=None):
        """Find an existing profile dir by profile name, return its ProfileDir.

        This searches through a sequence of paths for a profile dir.  If it
        is not found, a :class:`ProfileDirError` exception will be raised.

        The search path algorithm is:
        1. ``os.getcwd()`` # removed for security reason.
        2. ``ipython_dir``

        Parameters
        ----------
        ipython_dir : unicode or str
            The IPython directory to use.
        name : unicode or str
            The name of the profile.  The name of the profile directory
            will be "profile_<profile>".
        """
        dirname = u'profile_' + name
        paths = [ipython_dir]
        for p in paths:
            profile_dir = os.path.join(p, dirname)
            if os.path.isdir(profile_dir):
                return cls(location=profile_dir, config=config)
        else:
            raise ProfileDirError('Profile directory not found in paths: %s' % dirname)

    @classmethod
    def find_profile_dir(cls, profile_dir, config=None):
        """Find/create a profile dir and return its ProfileDir.

        This will create the profile directory if it doesn't exist.

        Parameters
        ----------
        profile_dir : unicode or str
            The path of the profile directory.
        """
        profile_dir = expand_path(profile_dir)
        if not os.path.isdir(profile_dir):
            raise ProfileDirError('Profile directory not found: %s' % profile_dir)
        return cls(location=profile_dir, config=config)
