# Copyright (C) 2016  Codethink Limited
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program.  If not, see <http://www.gnu.org/licenses/>.


import cliapp
import contextlib
import glob
import logging
import os
import shutil

import morphlib


class FixRefPlugin(cliapp.Plugin):
   '''Add subcommands for handling workspaces and system branches.'''

    def enable(self):
        self.app.add_subcommand(
            'fix', self.petrify, arg_synopsis='')
        self.app.add_subcommand(
            'unfix', self.unpetrify, arg_synopsis='')

    def petrify(self, args):
        '''Convert all chunk refs in a system branch to be fixed SHA1s.

        This modifies all git commit references in system and stratum
        morphologies, in the current system branch, to be fixed SHA
        commit identifiers, rather than symbolic branch or tag names.
        This is useful for making sure none of the components in a system
        branch change accidentally.

        Consider the following scenario:

        * The `master` system branch refers to `gcc` using the
          `baserock/morph` ref. This is appropriate, since the main line
          of development should use the latest curated code.

        * You create a system branch to prepare for a release, called
          `TROVE_ID/release/2.0`. The reference to `gcc` is still
          `baserock/morph`.

        * You test everything, and make a release. You deploy the release
          images onto devices, which get shipped to your customers.

        * A new version GCC is committed to the `baserock/morph` branch.

        * Your release branch suddenly uses a new compiler, which may
          or may not work for your particular system at that release.

        To avoid this, you need to _petrify_ all git references
        so that they do not change accidentally. If you've tested
        your release with the GCC release that is stored in commit
        `94c50665324a7aeb32f3096393ec54b2e63bfb28`, then you should
        continue to use that version of GCC, regardless of what might
        happen in the master system branch. If, and only if, you decide
        that a new compiler would be good for your release should you
        include it in your release branch. This way, only the things
        that you change intentionally change in your release branch.

        '''

        if args:
            raise cliapp.AppException('morph petrify takes no arguments')

        ws = morphlib.workspace.open('.')
        sb = morphlib.sysbranchdir.open_from_within('.')
        loader = morphlib.morphloader.MorphologyLoader()
        lrc, rrc = morphlib.util.new_repo_caches(self.app)
        update_repos = not self.app.settings['no-git-update']

        morphs = self._load_all_sysbranch_morphologies(sb, loader)

        #TODO: Stop using app.resolve_ref
        def resolve_refs(morphs):
            for repo, ref in morphs.list_refs():
                # You can't resolve null refs, so don't attempt to.
                if repo is None or ref is None:
                    continue
                # TODO: Handle refs that are only in workspace in general
                if (repo == sb.root_repository_url
                    and ref == sb.system_branch_name):
                    continue
                commit_sha1, tree_sha1 = self.app.resolve_ref(
                    lrc, rrc, repo, ref, update=update_repos)
                yield ((repo, ref), commit_sha1)

        morphs.repoint_refs(sb.root_repository_url,
                            sb.system_branch_name)

        morphs.petrify_chunks(dict(resolve_refs(morphs)))

        # Write morphologies back out again.
        self._save_dirty_morphologies(loader, sb, morphs.morphologies)

    def unpetrify(self, args):
        '''Reverse the process of petrification.

        This undoes the changes `morph petrify` did.

        '''

        if args:
            raise cliapp.AppException('morph petrify takes no arguments')

        ws = morphlib.workspace.open('.')
        sb = morphlib.sysbranchdir.open_from_within('.')
        loader = morphlib.morphloader.MorphologyLoader()

        morphs = self._load_all_sysbranch_morphologies(sb, loader)

        # Restore the ref for each stratum and chunk
        morphs.unpetrify_all()

        # Write morphologies back out again.
        self._save_dirty_morphologies(loader, sb, morphs.morphologies)