# Copyright 2020 Canonical, Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
import os
import shutil
import logging
import re
from typing import Optional, Tuple, List

from subiquity.common.errorreport import ErrorReportKind
from subiquity.common.types import ApplicationState
from subiquity.common.resources import get_users_and_groups
from subiquity.server.controller import SubiquityController
from subiquitycore.context import with_context
from subiquitycore.utils import arun_command
from system_setup.common.wsl_conf import wsl_config_update

log = logging.getLogger("system_setup.server.controllers.configure")


class ConfigureController(SubiquityController):
    default_uid = 0

    def __init__(self, app):
        super().__init__(app)
        self.app = app
        self.model = app.base_model

    def start(self):
        self.install_task = self.app.aio_loop.create_task(self.configure())

    def __locale_gen_cmd(self) -> Tuple[str, bool]:
        """ Return a tuple of the locale-gen command path and True for
        validity. In dry-run, copy the locale-gen script, altering the
        localedef command line to output into a specified directory.
        """
        cmd = "usr/sbin/locale-gen"
        if self.app.opts.dry_run is False or self.app.opts.dry_run is None:
            return (os.path.join("/", cmd), True)

        outDir = os.path.join(self.model.root, "usr/lib/locale")
        usrSbinDir = os.path.join(self.model.root, "usr/sbin")
        os.makedirs(outDir, exist_ok=True)
        os.makedirs(usrSbinDir, exist_ok=True)
        cmdFile = os.path.join(self.model.root, cmd)
        shutil.copy(os.path.join("/", cmd), cmdFile)
        # Supply LC_* definition files to avoid complains from localedef.
        candidateSourceDirs = ["/usr/lib/locale/C.UTF-8/",
                               "/usr/lib/locale/C.utf8/"]
        sourceDirs = [d for d in candidateSourceDirs if os.path.exists(d)]
        if len(sourceDirs) == 0:
            log.error("No available LC_* definitions found in this system")
            return ("", False)

        shutil.copytree(sourceDirs[0], outDir, dirs_exist_ok=True)
        try:
            # Altering locale-gen script to output to the desired folder.
            with open(cmdFile, "r+") as f:
                script = f.read()
                pattern = r'(localedef .+) (\|\| :; \\)'
                localeDefRe = re.compile(pattern)
                replacement = r'\1 "{}/" \2'.format(outDir)
                (fileContents, n) = localeDefRe.subn(replacement, script,
                                                     count=1)
                if n != 1:
                    log.error("locale-gen script contents were unexpected."
                              " Aborting mock creation")
                    return ("", False)

                f.seek(0)
                f.write(fileContents)

            return (cmdFile, True)

        except IOError as err:
            log.error("Failed to modify %s file. %s", cmdFile, err)
            return ("", False)

    def __update_locale_cmd(self, lang) -> List[str]:
        """ Add mocking cli to update-locale if in dry-run."""
        updateLocCmd = ["update-locale", "LANG={}".format(lang),
                        "--no-checks"]
        if not self.app.opts.dry_run:
            return updateLocCmd

        defaultLocDir = os.path.join(self.model.root,
                                     "etc/default/")
        os.makedirs(defaultLocDir, exist_ok=True)
        updateLocCmd += ["--locale-file",
                         os.path.join(defaultLocDir, "locale")]
        return updateLocCmd

    async def _activate_locale(self, lang, env, skipLocGen=False) -> bool:
        """ Return true if succeed in running the last commands
        to set the locale.
        """
        (locGenCmd, ok) = self.__locale_gen_cmd()
        if not ok:
            log.error("Locale generation failed.")
            return False

        updateCmd = self.__update_locale_cmd(lang)
        cmds = [updateCmd] if skipLocGen else [[locGenCmd], updateCmd]
        for cmd in cmds:
            cp = await arun_command(cmd, env=env)
            if cp.returncode != 0:
                log.error('Command "{}" failed with return code {}'
                          .format(cp.args, cp.returncode))
                return False

        return True

    async def __recommended_language_packs(self, lang) \
            -> Optional[List[str]]:
        """ Return a list of package names recommended by
         check-language-support (or a fake list if in dryrun).
         List returned can be empty on success. None for failure.
        """
        clsCommand = "check-language-support"
        # lang code may be separated by @, dot or spaces.
        # clsLang = lang.split('@')[0].split('.')[0].split(' ')[0]
        pattern = re.compile(r'([^.@\s]+)', re.IGNORECASE)
        matches = pattern.match(lang)
        if matches is None:
            log.error("Failed to match expected language format: %s", lang)
            return None

        langCodes = matches.groups()
        if len(langCodes) != 1:
            log.error("Only one match was expected for: %s", lang)
            return None

        clsLang = langCodes[0]
        packages = []
        # Running that command doesn't require root.
        snap_dir = os.getenv("SNAP", default="/")
        # UDI sets the SNAP env var to '.' for development purposes.
        # See:
        # https://github.com/canonical/ubuntu-desktop-installer/commit/9eb6f04
        # It is unlikely that under test or production that env var will
        # ever by just '.'. On the other hand in dry-run we want it pointing to
        # '/' if not properly set.
        snap_dir = snap_dir if snap_dir != '.' else '/'
        data_dir = os.path.join(snap_dir, "usr/share/language-selector")
        if not os.path.exists(data_dir):
            log.error("Misconfigured snap environment pointed L-S-C data dir"
                      " to %s", data_dir)
            return None

        cp = await arun_command([clsCommand, "-d", data_dir, "-l", clsLang])
        if cp.returncode != 0:
            log.error('Command "%s" failed with return code %d',
                      cp.args, cp.returncode)
            if not self.app.opts.dry_run:
                return None

        else:
            packages += [pkg for pkg in cp.stdout.strip().split(' ') if pkg]

        # We will always have language-pack-{baseLang}-base in dryrun.
        if len(packages) == 0 and self.app.opts.dry_run:
            baseLang = clsLang.split('_')[0]
            packages += ["language-pack-{}-base".format(baseLang)]

        return packages

    async def _install_check_lang_support_packages(self, lang, env) -> bool:
        """ Install recommended packages.
        lang is expected to be one single language/locale.
        """
        packages = await self.__recommended_language_packs(lang)
        # Hardcoded path is necessary to ensure escaping out of the snap env.
        aptCommand = "/usr/bin/apt"
        if packages is None:
            log.error('Failed to detect recommended language packs.')
            return False

        if not self.app.opts.dry_run:
            cp = await arun_command([aptCommand, "update"], env=env)
            if cp.returncode != 0:
                log.debug("Failed to update apt cache.\n%s", cp.stderr)

        if self.app.opts.dry_run:  # only empty in dry-run on failure.
            if len(packages) == 0:
                log.error("Packages list in dry-run should never be empty.")
                return False

            packs_dir = os.path.join(self.model.root,
                                     "var/cache/apt/archives/")
            os.makedirs(packs_dir, exist_ok=True)
            try:
                for package in packages:
                    # Just write the apt simulation log if succeeds.
                    lcp = await arun_command([aptCommand, "install", package,
                                              "--simulate"], env=env)
                    archive = os.path.join(packs_dir, package+".log")
                    with open(archive, "wt") as f:
                        if lcp.returncode == 0:
                            f.write(lcp.stdout)
                        # otherwise file will be empty.

                return True

            except IOError as e:
                log.error("Failed to write file.", e)
                return False

        if len(packages) == 0:
            log.info("No missing recommended packages. Nothing to do.")
            return True

        cmd = [aptCommand, "install", "-y"] + packages
        acp = await arun_command(cmd, env=env)

        return acp.returncode == 0

    def _update_locale_gen_file(self, localeGenPath, lang) -> bool:
        """ Uncomment the line in locale.gen file matching lang,
        if found commented. A fully qualified language is expected,
        since that would have passed thru the Locale controller
        validation. e.g. en_UK.UTF-8. Return True for success.
        """
        fileContents: str
        try:
            with open(localeGenPath, "r+") as f:
                fileContents = f.read()
                lineFound = fileContents.find(lang)
                if lineFound == -1:
                    # An unsupported locale coming from our UI is a bug
                    log.error("Selected language %s not supported.", lang)
                    return False

                pattern = r'[# ]*({}.*)'.format(lang)
                commented = re.compile(pattern)
                (fileContents, n) = commented.subn(r'\1', fileContents,
                                                   count=1)
                if n != 1:
                    log.error("Unexpected locale.gen file contents. Aborting.")
                    return False

                f.seek(0)
                f.write(fileContents)
                return True

        except IOError as err:
            log.error("Failed to modify %s file. %s", localeGenPath, err)
            return False

    def _locale_gen_file_path(self):
        """ Return the proper locale.gen path for dry or live-run."""
        localeGenPath = "/etc/locale.gen"
        if self.app.opts.dry_run is False or self.app.opts.dry_run is None:
            return localeGenPath

        # For testing purposes.
        etc_dir = os.path.join(self.model.root, "etc")
        testLocGenPath = os.path.join(etc_dir,
                                      os.path.basename(localeGenPath))
        shutil.copy(localeGenPath, testLocGenPath)
        shutil.copy(localeGenPath, "{}.test".format(testLocGenPath))
        return testLocGenPath

    async def apply_locale(self, lang, env):
        """ Effectively apply the locale setup to the new system."""
        localeGenPath = self._locale_gen_file_path()
        if self._update_locale_gen_file(localeGenPath, lang) is False:
            log.error("Failed to update locale.gen")
            return

        ok = await self._install_check_lang_support_packages(lang, env)
        if not ok:
            log.error("Failed to install recommended language packs.")
            return

        # We want to run locale-gen if apt fails to install language packs,
        # so the other locale definitions match the user expectation.
        ok = await self._activate_locale(lang, env, skipLocGen=ok)
        if not ok:
            log.error("Failed to run locale activation commands.")
            return

    def __query_uid(self, etc_dir, username):
        """ Finds the UID of username in etc_dir/passwd file. """
        uid = None
        with open(os.path.join(etc_dir, "passwd")) as f:
            for line in f:
                tokens = line.split(":")
                if username == tokens[0]:
                    if len(tokens) != 7:
                        raise Exception("Invalid passwd entry")

                    uid = int(tokens[2])
                    break

        return uid

    async def create_user(self, root_dir, env):
        """ Helper method to create the user from the identity model
            and store it's UID. """
        wsl_id = self.model.identity.user
        username = wsl_id.username
        create_user_base = []
        assign_grp_base = []
        usergroups_list = get_users_and_groups()
        etc_dir = "/etc"  # default if not dryrun.
        if self.app.opts.dry_run:
            log.debug("creating a mock-up env for user %s", username)
            # creating folders and files for dryrun
            etc_dir = os.path.join(root_dir, "etc")
            os.makedirs(etc_dir, exist_ok=True)
            home_dir = os.path.join(root_dir, "home")
            os.makedirs(home_dir, exist_ok=True)
            pseudo_files = ["passwd", "shadow", "gshadow", "group",
                            "subgid", "subuid"]
            for file in pseudo_files:
                filepath = os.path.join(etc_dir, file)
                open(filepath, "a").close()

            # mimic groupadd
            group_id = 1000
            for group in usergroups_list:
                group_filepath = os.path.join(etc_dir, "group")
                gshadow_filepath = os.path.join(etc_dir, "gshadow")
                shutil.copy(group_filepath,
                            "{}-".format(group_filepath))
                with open(group_filepath, "a") as group_file:
                    group_file.write("{}:x:{}:\n".format(group, group_id))
                group_id += 1
                shutil.copy(gshadow_filepath,
                            "{}-".format(gshadow_filepath))
                with open(gshadow_filepath, "a") as gshadow_file:
                    gshadow_file.write("{}:!::\n".format(group))

            create_user_base = ["-P", root_dir]
            assign_grp_base = ["-P", root_dir]

        create_user_cmd = ["/usr/sbin/useradd"] + create_user_base + \
                          ["-m", "-s", "/bin/bash", "-c", wsl_id.realname,
                           "-p", wsl_id.password, username]
        assign_grp_cmd = ["/usr/sbin/usermod"] + assign_grp_base + \
                         ["-a", "-G", ",".join(usergroups_list), username]

        create_user_proc = await arun_command(create_user_cmd, env=env)
        if create_user_proc.returncode != 0:
            raise Exception("Failed to create user %s: %s"
                            % (username, create_user_proc.stderr))
        log.debug("created user %s", username)

        self.default_uid = self.__query_uid(etc_dir, username)
        if self.default_uid is None:
            log.error("Could not retrieve %s UID", username)

        assign_grp_proc = await arun_command(assign_grp_cmd, env=env)
        if assign_grp_proc.returncode != 0:
            raise Exception(("Failed to assign group to user %s: %s")
                            % (username, assign_grp_proc.stderr))

    @with_context(
        description="final system configuration", level="INFO",
        childlevel="DEBUG")
    async def configure(self, *, context):
        """ Apply the installation steps submitted by the user."""
        context.set('is-install-context', True)
        try:

            self.app.update_state(ApplicationState.WAITING)

            await self.model.wait_install()

            self.app.update_state(ApplicationState.NEEDS_CONFIRMATION)

            self.app.update_state(ApplicationState.RUNNING)

            await self.model.wait_postinstall()

            self.app.update_state(ApplicationState.POST_WAIT)

            self.app.update_state(ApplicationState.POST_RUNNING)

            variant = self.app.variant
            root_dir = self.model.root

            if variant == "wsl_setup":
                lang = self.model.locale.selected_language
                envcp = os.environ.copy()
                # Ensures a safe escape out of the snap environment for WSL.
                if not self.app.opts.dry_run:
                    envcp['LD_LIBRARY_PATH'] = ''
                    envcp['LD_PRELOAD'] = ''
                await self.create_user(root_dir, envcp)
                await self.apply_locale(lang, envcp)

            else:
                wsl_config_update(self.model.wslconfadvanced.wslconfadvanced,
                                  root_dir)

            # update advanced config when it is in autoinstall mode
            if self.app.opts.autoinstall is not None and \
               self.model.wslconfadvanced.wslconfadvanced is not None:
                wsl_config_update(self.model.wslconfadvanced.wslconfadvanced,
                                  root_dir)

            wsl_config_update(self.model.wslconfbase.wslconfbase, root_dir)

            self.app.update_state(ApplicationState.DONE)

        except Exception:
            kw = {}
            self.app.make_apport_report(
                ErrorReportKind.INSTALL_FAIL, "configuration failed", **kw)
            raise

    def stop_uu(self):
        # This is a no-op to allow Shutdown controller to depend on this one
        pass

    # Allows passing the recently created user UID to the Shutdown controller.
    def get_default_uid(self):
        return self.default_uid