# -*- coding: utf-8 -*-
# Copyright (C) 2012 Anaconda, Inc
# SPDX-License-Identifier: BSD-3-Clause
from __future__ import absolute_import, division, print_function, unicode_literals

import logging
from os.path import dirname
import re
import sys

from .auxlib.decorators import memoize
from .auxlib.compat import shlex_split_unicode, string_types, Utf8NamedTemporaryFile
from .common.compat import on_win, isiterable

from .common.path import win_path_to_unix, which
from .common.url import path_to_url
from os.path import abspath, join, isfile, basename
from os import environ

log = logging.getLogger(__name__)

# in conda/exports.py
memoized = memoize


def path_identity(path):
    """Used as a dummy path converter where no conversion necessary"""
    return path


def unix_path_to_win(path, root_prefix=""):
    """Convert a path or :-separated string of paths into a Windows representation

    Does not add cygdrive.  If you need that, set root_prefix to "/cygdrive"
    """
    if len(path) > 1 and (";" in path or (path[1] == ":" and path.count(":") == 1)):
        # already a windows path
        return path.replace("/", "\\")
    path_re = root_prefix + r'(/[a-zA-Z]/(?:(?![:\s]/)[^:*?"<>])*)'

    def _translation(found_path):
        group = found_path.group(0)
        return "{0}:{1}".format(group[len(root_prefix)+1],
                                group[len(root_prefix)+2:].replace("/", "\\"))
    translation = re.sub(path_re, _translation, path)
    translation = re.sub(":([a-zA-Z]):\\\\",
                         lambda match: ";" + match.group(0)[1] + ":\\",
                         translation)
    return translation


# curry cygwin functions
def win_path_to_cygwin(path):
    return win_path_to_unix(path, "/cygdrive")


def cygwin_path_to_win(path):
    return unix_path_to_win(path, "/cygdrive")


def translate_stream(stream, translator):
    return "\n".join(translator(line) for line in stream.split("\n"))


def human_bytes(n):
    """
    Return the number of bytes n in more human readable form.

    Examples:
        >>> human_bytes(42)
        '42 B'
        >>> human_bytes(1042)
        '1 KB'
        >>> human_bytes(10004242)
        '9.5 MB'
        >>> human_bytes(100000004242)
        '93.13 GB'
    """
    if n < 1024:
        return '%d B' % n
    k = n/1024
    if k < 1024:
        return '%d KB' % round(k)
    m = k/1024
    if m < 1024:
        return '%.1f MB' % m
    g = m/1024
    return '%.2f GB' % g


# TODO: this should be done in a more extensible way
#     (like files for each shell, with some registration mechanism.)

# defaults for unix shells.  Note: missing "exe" entry, which should be set to
#    either an executable on PATH, or a full path to an executable for a shell
unix_shell_base = dict(
                       binpath="/bin/",  # mind the trailing slash.
                       echo="echo",
                       env_script_suffix=".sh",
                       nul='2>/dev/null',
                       path_from=path_identity,
                       path_to=path_identity,
                       pathsep=":",
                       printdefaultenv='echo $CONDA_DEFAULT_ENV',
                       printpath="echo $PATH",
                       printps1='echo $CONDA_PROMPT_MODIFIER',
                       promptvar='PS1',
                       sep="/",
                       set_var='export ',
                       shell_args=["-l", "-c"],
                       shell_suffix="",
                       slash_convert=("\\", "/"),
                       source_setup="source",
                       test_echo_extra="",
                       var_format="${}",
)

msys2_shell_base = dict(
                        unix_shell_base,
                        path_from=unix_path_to_win,
                        path_to=win_path_to_unix,
                        binpath="/bin/",  # mind the trailing slash.
                        printpath="python -c \"import os; print(';'.join(os.environ['PATH'].split(';')[1:]))\" | cygpath --path -f -",  # NOQA
)

if on_win:
    shells = {
        # "powershell.exe": dict(
        #    echo="echo",
        #    test_echo_extra=" .",
        #    var_format="${var}",
        #    binpath="/bin/",  # mind the trailing slash.
        #    source_setup="source",
        #    nul='2>/dev/null',
        #    set_var='export ',
        #    shell_suffix=".ps",
        #    env_script_suffix=".ps",
        #    printps1='echo $PS1',
        #    printdefaultenv='echo $CONDA_DEFAULT_ENV',
        #    printpath="echo %PATH%",
        #    exe="powershell.exe",
        #    path_from=path_identity,
        #    path_to=path_identity,
        #    slash_convert = ("/", "\\"),
        # ),
        "cmd.exe": dict(
            echo="@echo",
            var_format="%{}%",
            binpath="\\Scripts\\",  # mind the trailing slash.
            source_setup="call",
            test_echo_extra="",
            nul='1>NUL 2>&1',
            set_var='set ',
            shell_suffix=".bat",
            env_script_suffix=".bat",
            printps1="@echo %PROMPT%",
            promptvar="PROMPT",
            # parens mismatched intentionally.  See http://stackoverflow.com/questions/20691060/how-do-i-echo-a-blank-empty-line-to-the-console-from-a-windows-batch-file # NOQA
            printdefaultenv='IF NOT "%CONDA_DEFAULT_ENV%" == "" (\n'
                            'echo %CONDA_DEFAULT_ENV% ) ELSE (\n'
                            'echo()',
            printpath="@echo %PATH%",
            exe="cmd.exe",
            shell_args=["/d", "/c"],
            path_from=path_identity,
            path_to=path_identity,
            slash_convert=("/", "\\"),
            sep="\\",
            pathsep=";",
        ),
        "cygwin": dict(
            unix_shell_base,
            exe="bash.exe",
            binpath="/Scripts/",  # mind the trailing slash.
            path_from=cygwin_path_to_win,
            path_to=win_path_to_cygwin
        ),
        # bash is whichever bash is on PATH.  If using Cygwin, you should use the cygwin
        #    entry instead.  The only major difference is that it handle's cygwin's /cygdrive
        #    filesystem root.
        "bash.exe": dict(
            msys2_shell_base, exe="bash.exe",
        ),
        "bash": dict(
            msys2_shell_base, exe="bash",
        ),
        "sh.exe": dict(
            msys2_shell_base, exe="sh.exe",
        ),
        "zsh.exe": dict(
            msys2_shell_base, exe="zsh.exe",
        ),
        "zsh": dict(
            msys2_shell_base, exe="zsh",
        ),
    }

else:
    shells = {
        "bash": dict(
            unix_shell_base, exe="bash",
        ),
        "dash": dict(
            unix_shell_base, exe="dash",
            source_setup=".",
        ),
        "zsh": dict(
            unix_shell_base, exe="zsh",
        ),
        "fish": dict(
            unix_shell_base, exe="fish",
            pathsep=" ",
        ),
    }


# ##########################################
# put back because of conda build
# ##########################################

urlpath = url_path = path_to_url


def md5_file(path):  # pragma: no cover
    from .gateways.disk.read import compute_md5sum
    return compute_md5sum(path)


def hashsum_file(path, mode='md5'):  # pragma: no cover
    import hashlib
    h = hashlib.new(mode)
    with open(path, 'rb') as fi:
        while True:
            chunk = fi.read(262144)  # process chunks of 256KB
            if not chunk:
                break
            h.update(chunk)
    return h.hexdigest()


@memoize
def sys_prefix_unfollowed():
    """Since conda is installed into non-root environments as a symlink only
    and because sys.prefix follows symlinks, this function can be used to
    get the 'unfollowed' sys.prefix.

    This value is usually the same as the prefix of the environment into
    which conda has been symlinked. An example of when this is necessary
    is when conda looks for external sub-commands in find_commands.py
    """
    try:
        frame = next(iter(sys._current_frames().values()))
        while frame.f_back:
            frame = frame.f_back
        code = frame.f_code
        filename = code.co_filename
        unfollowed = dirname(dirname(filename))
    except Exception:
        return sys.prefix
    return unfollowed


def quote_for_shell(*arguments):
    """Properly quote arguments for command line passing.

    For POSIX uses `shlex.join`, for Windows uses a custom implementation to properly escape
    metacharacters.

    :param arguments: Arguments to quote.
    :type arguments: list of str
    :return: Quoted arguments.
    :rtype: str
    """
    # [backport] Support passing in a list of strings or args of string.
    if len(arguments) == 1 and isiterable(arguments[0]):
        arguments = arguments[0]

    return _args_join(arguments)


if on_win:
    # https://ss64.com/nt/syntax-esc.html
    # https://docs.microsoft.com/en-us/archive/blogs/twistylittlepassagesallalike/everyone-quotes-command-line-arguments-the-wrong-way

    _RE_UNSAFE = re.compile(r'["%\s^<>&|]')
    _RE_DBL = re.compile(r'(["%])')

    def _args_join(args):
        """Return a shell-escaped string from *args*."""

        def quote(s):
            # derived from shlex.quote
            if not s:
                return '""'
            # if any unsafe chars are present we must quote
            if not _RE_UNSAFE.search(s):
                return s
            # double escape (" -> "")
            s = _RE_DBL.sub(r"\1\1", s)
            # quote entire string
            return f'"{s}"'

        return " ".join(quote(arg) for arg in args)
else:
    try:
        from shlex import join as _args_join
    except ImportError:
        # [backport] Python <3.8
        def _args_join(args):
            """Return a shell-escaped string from *args*."""
            from shlex import quote

            return " ".join(quote(arg) for arg in args)


# Ensures arguments are a tuple or a list. Strings are converted
# by shlex_split_unicode() which is bad; we warn about it or else
# we assert (and fix the code).
def massage_arguments(arguments, errors='assert'):

    # For reference and in-case anything breaks ..
    # .. one of the places (run_command in conda_env/utils.py) this
    # gets called from used to do this too:
    #
    #    def escape_for_winpath(p):
    #        return p.replace('\\', '\\\\')
    #
    #    if not isinstance(arguments, list):
    #        arguments = list(map(escape_for_winpath, arguments))

    if isinstance(arguments, string_types):
        if errors == 'assert':
            # This should be something like 'conda programming bug', it is an assert
            assert False, 'Please ensure arguments are not strings'
        else:
            arguments = shlex_split_unicode(arguments)
            log.warning("Please ensure arguments is not a string; "
                        "used `shlex_split_unicode()` on it")

    if not isiterable(arguments):
        arguments = (arguments,)

    assert not any([isiterable(arg) for arg in arguments]), "Individual arguments must not be iterable"  # NOQA
    arguments = list(arguments)

    return arguments


def wrap_subprocess_call(
        root_prefix,
        prefix,
        dev_mode,
        debug_wrapper_scripts,
        arguments,
        use_system_tmp_path=False):
    arguments = massage_arguments(arguments)
    if not use_system_tmp_path:
        tmp_prefix = abspath(join(prefix, '.tmp'))
    else:
        tmp_prefix = None
    script_caller = None
    multiline = False
    if len(arguments) == 1 and '\n' in arguments[0]:
        multiline = True
    if on_win:
        comspec = get_comspec()  # fail early with KeyError if undefined
        if dev_mode:
            from conda import CONDA_PACKAGE_ROOT
            conda_bat = join(CONDA_PACKAGE_ROOT, 'shell', 'condabin', 'conda.bat')
        else:
            conda_bat = environ.get("CONDA_BAT",
                                    abspath(join(root_prefix, 'condabin', 'conda.bat')))
        with Utf8NamedTemporaryFile(mode='w', prefix=tmp_prefix,
                                    suffix='.bat', delete=False) as fh:
            silencer = "" if debug_wrapper_scripts else "@"
            fh.write("{}ECHO OFF\n".format(silencer))
            fh.write("{}SET PYTHONIOENCODING=utf-8\n".format(silencer))
            fh.write("{}SET PYTHONUTF8=1\n".format(silencer))
            fh.write('{}FOR /F "tokens=2 delims=:." %%A in (\'chcp\') do for %%B in (%%A) do set "_CONDA_OLD_CHCP=%%B"\n'.format(silencer))  # NOQA
            fh.write("{}chcp 65001 > NUL\n".format(silencer))
            if dev_mode:
                from . import CONDA_SOURCE_ROOT
                fh.write("{}SET CONDA_DEV=1\n".format(silencer))
                # In dev mode, conda is really:
                # 'python -m conda'
                # *with* PYTHONPATH set.
                fh.write("{}SET PYTHONPATH={}\n".format(silencer, CONDA_SOURCE_ROOT))
                fh.write("{}SET CONDA_EXE={}\n".format(silencer, sys.executable))
                fh.write("{}SET _CE_M=-m\n".format(silencer))
                fh.write("{}SET _CE_CONDA=conda\n".format(silencer))
            if debug_wrapper_scripts:
                fh.write('echo *** environment before *** 1>&2\n')
                fh.write('SET 1>&2\n')
            # Not sure there is any point in backing this up, nothing will get called with it reset
            # after all!
            # fh.write("@FOR /F \"tokens=100\" %%F IN ('chcp') DO @SET CONDA_OLD_CHCP=%%F\n")
            # fh.write('@chcp 65001>NUL\n')
            fh.write('{0}CALL \"{1}\" activate \"{2}\"\n'.format(silencer, conda_bat, prefix))
            fh.write("{}IF %ERRORLEVEL% NEQ 0 EXIT /b %ERRORLEVEL%\n".format(silencer))
            if debug_wrapper_scripts:
                fh.write('echo *** environment after *** 1>&2\n')
                fh.write('SET 1>&2\n')
            if multiline:
                # No point silencing the first line. If that's what's wanted then
                # it needs doing for each line and the caller may as well do that.
                fh.write("{0}\n".format(arguments[0]))
            else:
                assert not any("\n" in arg for arg in arguments), (
                    "Support for scripts where arguments contain newlines not implemented.\n"
                    ".. requires writing the script to an external file and knowing how to "
                    "transform the command-line (e.g. `python -c args` => `python file`) "
                    "in a tool dependent way, or attempting something like:\n"
                    ".. https://stackoverflow.com/a/15032476 (adds unacceptable escaping"
                    "requirements)"
                )
                fh.write("{0}{1}\n".format(silencer, quote_for_shell(*arguments)))
            fh.write("{}IF %ERRORLEVEL% NEQ 0 EXIT /b %ERRORLEVEL%\n".format(silencer))
            fh.write("{}chcp %_CONDA_OLD_CHCP%>NUL\n".format(silencer))
            script_caller = fh.name
        command_args = [comspec, '/d', '/c', script_caller]
    else:
        shell_path = which('bash') or which('sh')
        if shell_path is None:
            raise Exception("No compatible shell found!")

        # During tests, we sometimes like to have a temp env with e.g. an old python in it
        # and have it run tests against the very latest development sources. For that to
        # work we need extra smarts here, we want it to be instead:
        if dev_mode:
            conda_exe = [abspath(join(root_prefix, 'bin', 'python')), '-m', 'conda']
            dev_arg = '--dev'
            dev_args = [dev_arg]
        else:
            conda_exe = [environ.get("CONDA_EXE", abspath(join(root_prefix, 'bin', 'conda')))]
            dev_arg = ''
            dev_args = []
        with Utf8NamedTemporaryFile(mode='w', prefix=tmp_prefix, delete=False) as fh:
            if dev_mode:
                from . import CONDA_SOURCE_ROOT

                fh.write(">&2 export PYTHONPATH=" + CONDA_SOURCE_ROOT + "\n")
            hook_quoted = quote_for_shell(*conda_exe, "shell.posix", "hook", *dev_args)
            if debug_wrapper_scripts:
                fh.write(">&2 echo '*** environment before ***'\n" ">&2 env\n")
                fh.write('>&2 echo "$({0})"\n'.format(hook_quoted))
            fh.write('eval "$({0})"\n'.format(hook_quoted))
            fh.write("conda activate {0} {1}\n".format(dev_arg, quote_for_shell(prefix)))
            if debug_wrapper_scripts:
                fh.write(">&2 echo '*** environment after ***'\n" ">&2 env\n")
            if multiline:
                # The ' '.join() is pointless since mutliline is only True when there's 1 arg
                # still, if that were to change this would prevent breakage.
                fh.write("{0}\n".format(" ".join(arguments)))
            else:
                fh.write("{0}\n".format(quote_for_shell(*arguments)))
            script_caller = fh.name
        if debug_wrapper_scripts:
            command_args = [shell_path, "-x", script_caller]
        else:
            command_args = [shell_path, script_caller]

    return script_caller, command_args


def get_comspec():
    """Returns COMSPEC from envvars.

    Ensures COMSPEC envvar is set to cmd.exe, if not attempt to find it.

    :raises KeyError: COMSPEC is undefined and cannot be found.
    :returns: COMSPEC value.
    :rtype: str
    """
    if basename(environ.get("COMSPEC", "")).lower() != "cmd.exe":
        for comspec in (
            # %SystemRoot%\System32\cmd.exe
            environ.get("SystemRoot") and join(environ["SystemRoot"], "System32", "cmd.exe"),
            # %windir%\System32\cmd.exe
            environ.get("windir") and join(environ["windir"], "System32", "cmd.exe"),
        ):
            if comspec and isfile(comspec):
                environ["COMSPEC"] = comspec
                break
        else:
            log.warn("cmd.exe could not be found. Looked in SystemRoot and windir env vars.\n")

    # fails with KeyError if still undefined
    return environ["COMSPEC"]
