"""Notebook related utilities"""

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

import asyncio
import errno
import inspect
import os
import sys
from distutils.version import LooseVersion

from urllib.parse import quote, unquote, urlparse, urljoin
from urllib.request import pathname2url

from ipython_genutils import py3compat


def url_path_join(*pieces):
    """Join components of url into a relative url

    Use to prevent double slash when joining subpath. This will leave the
    initial and final / in place
    """
    initial = pieces[0].startswith('/')
    final = pieces[-1].endswith('/')
    stripped = [s.strip('/') for s in pieces]
    result = '/'.join(s for s in stripped if s)
    if initial: result = '/' + result
    if final: result = result + '/'
    if result == '//': result = '/'
    return result


def url_is_absolute(url):
    """Determine whether a given URL is absolute"""
    return urlparse(url).path.startswith("/")


def path2url(path):
    """Convert a local file path to a URL"""
    pieces = [ quote(p) for p in path.split(os.sep) ]
    # preserve trailing /
    if pieces[-1] == '':
        pieces[-1] = '/'
    url = url_path_join(*pieces)
    return url


def url2path(url):
    """Convert a URL to a local file path"""
    pieces = [ unquote(p) for p in url.split('/') ]
    path = os.path.join(*pieces)
    return path


def url_escape(path):
    """Escape special characters in a URL path

    Turns '/foo bar/' into '/foo%20bar/'
    """
    parts = py3compat.unicode_to_str(path, encoding='utf8').split('/')
    return u'/'.join([quote(p) for p in parts])


def url_unescape(path):
    """Unescape special characters in a URL path

    Turns '/foo%20bar/' into '/foo bar/'
    """
    return u'/'.join([
        py3compat.str_to_unicode(unquote(p), encoding='utf8')
        for p in py3compat.unicode_to_str(path, encoding='utf8').split('/')
    ])


def samefile_simple(path, other_path):
    """
    Fill in for os.path.samefile when it is unavailable (Windows+py2).

    Do a case-insensitive string comparison in this case
    plus comparing the full stat result (including times)
    because Windows + py2 doesn't support the stat fields
    needed for identifying if it's the same file (st_ino, st_dev).

    Only to be used if os.path.samefile is not available.

    Parameters
    -----------
    path:       String representing a path to a file
    other_path: String representing a path to another file

    Returns
    -----------
    same:   Boolean that is True if both path and other path are the same
    """
    path_stat = os.stat(path)
    other_path_stat = os.stat(other_path)
    return (path.lower() == other_path.lower()
        and path_stat == other_path_stat)


def to_os_path(path, root=''):
    """Convert an API path to a filesystem path

    If given, root will be prepended to the path.
    root must be a filesystem path already.
    """
    parts = path.strip('/').split('/')
    parts = [p for p in parts if p != ''] # remove duplicate splits
    path = os.path.join(root, *parts)
    return path


def to_api_path(os_path, root=''):
    """Convert a filesystem path to an API path

    If given, root will be removed from the path.
    root must be a filesystem path already.
    """
    if os_path.startswith(root):
        os_path = os_path[len(root):]
    parts = os_path.strip(os.path.sep).split(os.path.sep)
    parts = [p for p in parts if p != ''] # remove duplicate splits
    path = '/'.join(parts)
    return path


def check_version(v, check):
    """check version string v >= check

    If dev/prerelease tags result in TypeError for string-number comparison,
    it is assumed that the dependency is satisfied.
    Users on dev branches are responsible for keeping their own packages up to date.
    """
    try:
        return LooseVersion(v) >= LooseVersion(check)
    except TypeError:
        return True


# Copy of IPython.utils.process.check_pid:

def _check_pid_win32(pid):
    import ctypes
    # OpenProcess returns 0 if no such process (of ours) exists
    # positive int otherwise
    return bool(ctypes.windll.kernel32.OpenProcess(1,0,pid))

def _check_pid_posix(pid):
    """Copy of IPython.utils.process.check_pid"""
    try:
        os.kill(pid, 0)
    except OSError as err:
        if err.errno == errno.ESRCH:
            return False
        elif err.errno == errno.EPERM:
            # Don't have permission to signal the process - probably means it exists
            return True
        raise
    else:
        return True

if sys.platform == 'win32':
    check_pid = _check_pid_win32
else:
    check_pid = _check_pid_posix


async def ensure_async(obj):
    """Convert a non-awaitable object to a coroutine if needed,
    and await it if it was not already awaited.
    """
    if inspect.isawaitable(obj):
        try:
            result = await obj
        except RuntimeError as e:
            if str(e) == 'cannot reuse already awaited coroutine':
                # obj is already the coroutine's result
                return obj
            raise
        return result
    # obj doesn't need to be awaited
    return obj


def run_sync(maybe_async):
    """If async, runs maybe_async and blocks until it has executed,
    possibly creating an event loop.
    If not async, just returns maybe_async as it is the result of something
    that has already executed.

    Parameters
    ----------
    maybe_async : async or non-async object
        The object to be executed, if it is async.

    Returns
    -------
    result :
        Whatever the async object returns, or the object itself.
    """
    if not inspect.isawaitable(maybe_async):
        # that was not something async, just return it
        return maybe_async
    # it is async, we need to run it in an event loop
    def wrapped():
        create_new_event_loop = False
        try:
            loop = asyncio.get_event_loop()
        except RuntimeError:
            create_new_event_loop = True
        else:
            if loop.is_closed():
                create_new_event_loop = True
        if create_new_event_loop:
            loop = asyncio.new_event_loop()
            asyncio.set_event_loop(loop)
        try:
            result = loop.run_until_complete(maybe_async)
        except RuntimeError as e:
            if str(e) == 'This event loop is already running':
                # just return a Future, hoping that it will be awaited
                result = asyncio.ensure_future(maybe_async)
            else:
                raise e
        return result
    return wrapped()
