# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# You can obtain one at http://mozilla.org/MPL/2.0/.

from __future__ import print_function, unicode_literals

import os
import re
import subprocess
import sys

from distutils.version import StrictVersion


NO_MERCURIAL = '''
Could not find Mercurial (hg) in the current shell's path. Try starting a new
shell and running the bootstrapper again.
'''

MERCURIAL_UNABLE_UPGRADE = '''
You are currently running Mercurial %s. Running %s or newer is
recommended for performance and stability reasons.

Unfortunately, this bootstrapper currently does not know how to automatically
upgrade Mercurial on your machine.

You can usually install Mercurial through your package manager or by
downloading a package from http://mercurial.selenic.com/.
'''

MERCURIAL_UPGRADE_FAILED = '''
We attempted to upgrade Mercurial to a modern version (%s or newer).
However, you appear to have version %s still.

It's possible your package manager doesn't support a modern version of
Mercurial. It's also possible Mercurial is not being installed in the search
path for this shell. Try creating a new shell and run this bootstrapper again.

If it continues to fail, consider installing Mercurial by following the
instructions at http://mercurial.selenic.com/.
'''

PYTHON_UNABLE_UPGRADE = '''
You are currently running Python %s. Running %s or newer (but
not 3.x) is required.

Unfortunately, this bootstrapper does not currently know how to automatically
upgrade Python on your machine.

Please search the Internet for how to upgrade your Python and try running this
bootstrapper again to ensure your machine is up to date.
'''

PYTHON_UPGRADE_FAILED = '''
We attempted to upgrade Python to a modern version (%s or newer).
However, you appear to still have version %s.

It's possible your package manager doesn't yet expose a modern version of
Python. It's also possible Python is not being installed in the search path for
this shell. Try creating a new shell and run this bootstrapper again.

If this continues to fail and you are sure you have a modern Python on your
system, ensure it is on the $PATH and try again. If that fails, you'll need to
install Python manually. See http://www.python.org/.
'''


# Upgrade Mercurial older than this.
MODERN_MERCURIAL_VERSION = StrictVersion('2.5')

# Upgrade Python older than this.
MODERN_PYTHON_VERSION = StrictVersion('2.7.3')


class BaseBootstrapper(object):
    """Base class for system bootstrappers."""

    def __init__(self):
        self.package_manager_updated = False

    def install_system_packages(self):
        raise NotImplemented('%s must implement install_system_packages()' %
            __name__)

    def which(self, name):
        """Python implementation of which.

        It returns the path of an executable or None if it couldn't be found.
        """
        for path in os.environ['PATH'].split(os.pathsep):
            test = os.path.join(path, name)
            if os.path.exists(test) and os.access(test, os.X_OK):
                return test

        return None

    def run_as_root(self, command):
        if os.geteuid() != 0:
            command.insert(0, 'sudo')

        print('Executing as root:', subprocess.list2cmdline(command))

        subprocess.check_call(command, stdin=sys.stdin)

    def yum_install(self, *packages):
        command = ['yum', 'install']
        command.extend(packages)

        self.run_as_root(command)

    def yum_groupinstall(self, *packages):
        command = ['yum', 'groupinstall']
        command.extend(packages)

        self.run_as_root(command)

    def yum_update(self, *packages):
        command = ['yum', 'update']
        command.extend(packages)

        self.run_as_root(command)

    def apt_install(self, *packages):
        command = ['apt-get', 'install']
        command.extend(packages)

        self.run_as_root(command)

    def check_output(self, *args, **kwargs):
        """Run subprocess.check_output even if Python doesn't provide it."""
        fn = getattr(subprocess, 'check_output', BaseBootstrapper._check_output)

        return fn(*args, **kwargs)

    @staticmethod
    def _check_output(*args, **kwargs):
        """Python 2.6 compatible implementation of subprocess.check_output."""
        proc = subprocess.Popen(stdout=subprocess.PIPE, *args, **kwargs)
        output, unused_err = proc.communicate()
        retcode = proc.poll()
        if retcode:
            cmd = kwargs.get('args', args[0])
            e = subprocess.CalledProcessError(retcode, cmd)
            e.output = output
            raise e

        return output

    def prompt_int(self, prompt, low, high, limit=5):
        ''' Prompts the user with prompt and requires an integer between low and high. '''
        valid = False
        while not valid and limit > 0:
            try:
                choice = int(raw_input(prompt))
                if not low <= choice <= high:
                    print("ERROR! Please enter a valid option!")
                    limit -= 1
                else:
                    valid = True
            except ValueError:
                print("ERROR! Please enter a valid option!")
                limit -= 1

        if limit > 0:
            return choice
        else:
            raise Exception("Error! Reached max attempts of entering option.")

    def _ensure_package_manager_updated(self):
        if self.package_manager_updated:
            return

        self._update_package_manager()
        self.package_manager_updated = True

    def _update_package_manager(self):
        """Updates the package manager's manifests/package list.

        This should be defined in child classes.
        """

    def is_mercurial_modern(self):
        hg = self.which('hg')
        if not hg:
            print(NO_MERCURIAL)
            return False, False, None

        info = self.check_output([hg, '--version']).splitlines()[0]

        match = re.search('version ([^\)]+)', info)
        if not match:
            print('ERROR: Unable to identify Mercurial version.')
            return True, False, None

        our = StrictVersion(match.group(1))

        return True, our >= MODERN_MERCURIAL_VERSION, our

    def ensure_mercurial_modern(self):
        installed, modern, version = self.is_mercurial_modern()

        if not installed or modern:
            print('Your version of Mercurial (%s) is sufficiently modern.' %
                version)
            return

        self._ensure_package_manager_updated()
        self.upgrade_mercurial(version)

        installed, modern, after = self.is_mercurial_modern()

        if installed and not modern:
            print(MERCURIAL_UPGRADE_FAILED % (MODERN_MERCURIAL_VERSION, after))

    def upgrade_mercurial(self, current):
        """Upgrade Mercurial.

        Child classes should reimplement this.
        """
        print(MERCURIAL_UNABLE_UPGRADE % (current, MODERN_MERCURIAL_VERSION))

    def is_python_modern(self):
        python = None

        for test in ['python2.7', 'python']:
            python = self.which(test)
            if python:
                break

        assert python

        info = self.check_output([python, '--version'],
            stderr=subprocess.STDOUT)
        match = re.search('Python ([a-z0-9\.]+)', info)
        if not match:
            print('ERROR Unable to identify Python version.')
            return False, None

        our = StrictVersion(match.group(1))

        return our >= MODERN_PYTHON_VERSION, our

    def ensure_python_modern(self):
        modern, version = self.is_python_modern()

        if modern:
            print('Your version of Python (%s) is new enough.' % version)
            return

        self._ensure_package_manager_updated()
        self.upgrade_python(version)

        modern, after = self.is_python_modern()

        if not modern:
            print(PYTHON_UPGRADE_FAILED % (MODERN_PYTHON_VERSION, after))

    def upgrade_python(self, current):
        """Upgrade Python.

        Child classes should reimplement this.
        """
        print(PYTHON_UNABLE_UPGRADE % (current, MODERN_PYTHON_VERSION))