# chainsaw.py

#

# Copyright 2022 Georges Racinet <georges.racinet@octobus.net>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

"""chainsaw is a collection of single-minded and dangerous tools. (EXPERIMENTAL)

  "Don't use a chainsaw to cut your food!"

The chainsaw is a collection of commands that are so much geared towards a

specific use case in a specific context or environment that they are totally

inappropriate and **really dangerous** in other contexts.

The help text of each command explicitly summarizes its context of application

and the wanted end result.

It is recommended to run these commands with the ``HGPLAIN`` environment

variable (see :hg:`help scripting`).

"""

import shutil

from ..i18n import _

from .. import (

    cmdutil,

    commands,

    error,

    localrepo,

    registrar,

)

from ..utils import (

    urlutil,

)

cmdtable = {}

command = registrar.command(cmdtable)

@command(

    b'admin::chainsaw-update',

    [

        (

            b'',

            b'purge-unknown',

            True,

            _(

                b'Remove unversioned files before update. Disabling this can '

                b'in some cases interfere with the update.'

                b'See also :hg:`purge`.'

            ),

        ),

        (

            b'',

            b'purge-ignored',

            True,

            _(

                b'Remove ignored files before update. Disable this for '

                b'instance to reuse previous compiler object files. '

                b'See also :hg:`purge`.'

            ),

        ),

        (

            b'',

            b'rev',

            b'',

            _(b'revision to update to'),

        ),

        (

            b'',

            b'source',

            b'',

            _(b'repository to clone from'),

        ),

        (

            b'',

            b'dest',

            b'',

            _(b'repository to update to REV (possibly cloning)'),

        ),

        (

            b'',

            b'initial-clone-minimal',

            False,

            _(

                b'Pull only the prescribed revision upon initial cloning. '

                b'This has the side effect of ignoring clone-bundles, '

                b'which if often slower on the client side and stressful '

                b'to the server than applying available clone bundles.'

            ),

        ),

    ],

    _(

        b'hg admin::chainsaw-update [OPTION] --rev REV --source SOURCE --dest DEST'

    ),

    helpbasic=True,

    norepo=True,

)

def update(ui, **opts):

    """pull and update to a given revision, no matter what, (EXPERIMENTAL)

    Context of application: *some* Continuous Integration (CI) systems,

    packaging or deployment tools.

    Wanted end result: local repository at the given REPO_PATH, having the

    latest changes to the given revision and with a clean working directory

    updated at the given revision.

    chainsaw-update pulls from one source, then updates the working directory

    to the given revision, overcoming anything that would stand in the way.

    By default, it will:

    - clone if the local repo does not exist yet, **removing any directory

      at the given path** that would not be a Mercurial repository.

      The initial clone is full by default, so that clonebundles can be

      applied. Use the --initial-clone-minimal flag to avoid this.

    - break locks if needed, leading to possible corruption if there

      is a concurrent write access.

    - perform recovery actions if needed

    - revert any local modification.

    - purge unknown and ignored files.

    - go as far as to reclone if everything else failed (not implemented yet).

    DO NOT use it for anything else than performing a series

    of unattended updates, with full exclusive repository access each time

    and without any other local work than running build scripts.

    In case the local repository is a share (see :hg:`help share`), exclusive

    write access to the share source is also mandatory.

    It is recommended to run these commands with the ``HGPLAIN`` environment

    variable (see :hg:`scripting`).

    Motivation: in Continuous Integration and Delivery systems (CI/CD), the

    occasional remnant or bogus lock are common sources of waste of time (both

    working time and calendar time). CI/CD scripts tend to grow with counter-

    measures, often done in urgency. Also, whilst it is neat to keep

    repositories from one job to the next (especially with large

    repositories), an exceptional recloning is better than missing a release

    deadline.

    """

    rev = opts['rev']

    source = opts['source']

    repo_path = opts['dest']

    if not rev:

        raise error.InputError(_(b'specify a target revision with --rev'))

    if not source:

        raise error.InputError(_(b'specify a pull path with --source'))

    if not repo_path:

        raise error.InputError(_(b'specify a repo path with --dest'))

    repo_path = urlutil.urllocalpath(repo_path)

    try:

        repo = localrepo.instance(ui, repo_path, create=False)

        repo_created = False

        ui.status(_(b'loaded repository at "%s"\n' % repo_path))

    except error.RepoError:

        try:

            shutil.rmtree(repo_path)

        except FileNotFoundError:

            ui.status(_(b'no such directory: "%s"\n' % repo_path))

        else:

            ui.status(

                _(

                    b'removed non-repository file or directory '

                    b'at "%s"' % repo_path

                )

            )

        ui.status(_(b'creating repository at "%s"\n' % repo_path))

        repo = localrepo.instance(ui, repo_path, create=True)

        repo_created = True

    if repo.svfs.tryunlink(b'lock'):

        ui.status(_(b'had to break store lock\n'))

    if repo.vfs.tryunlink(b'wlock'):

        ui.status(_(b'had to break working copy lock\n'))

    # If another process relock after the breacking above, the next locking

    # will have to wait.

    with repo.wlock(), repo.lock():

        ui.status(_(b'recovering after interrupted transaction, if any\n'))

        repo.recover()

        ui.status(_(b'pulling from %s\n') % source)

        if repo_created and not opts.get('initial_clone_minimal'):

            pull_revs = []

        else:

            pull_revs = [rev]

        overrides = {(b'ui', b'quiet'): True}

        with repo.ui.configoverride(overrides, b'chainsaw-update'):

            pull = cmdutil.findcmd(b'pull', commands.table)[1][0]

            ret = pull(

                repo.ui,

                repo,

                source,

                rev=pull_revs,

                remote_hidden=False,

            )

            if ret:

                return ret

        purge = cmdutil.findcmd(b'purge', commands.table)[1][0]

        ret = purge(

            ui,

            repo,

            dirs=True,

            all=opts.get('purge_ignored'),

            files=opts.get('purge_unknown'),

            confirm=False,

        )

        if ret:

            return ret

        ui.status(_(b'updating to revision \'%s\'\n') % rev)

        update = cmdutil.findcmd(b'update', commands.table)[1][0]

        ret = update(ui, repo, rev=rev, clean=True)

        if ret:

            return ret

        ui.status(

            _(

                b'chainsaw-update to revision \'%s\' '

                b'for repository at \'%s\' done\n'

            )

            % (rev, repo.root)

        )