# -*- coding: utf-8 -*-
# Part of Odoo, Flectra. See LICENSE file for full copyright and licensing details.

""" Modules migration handling. """

from collections import defaultdict
import glob
import logging
import os
from os.path import join as opj

from flectra.modules.module import get_resource_path
import flectra.release as release
import flectra.tools as tools
from flectra.tools.parse_version import parse_version
from flectra.tools import pycompat

if pycompat.PY2:
    import imp
    def load_script(path, module_name):
        fp, fname = tools.file_open(path, pathinfo=True)
        fp2 = None

        # pylint: disable=file-builtin,undefined-variable
        if not isinstance(fp, file):
            # imp.load_source need a real file object, so we create
            # one from the file-like object we get from file_open
            fp2 = os.tmpfile()
            fp2.write(fp.read())
            fp2.seek(0)

        try:
            return imp.load_source(module_name, fname, fp2 or fp)
        finally:
            if fp:
                fp.close()
            if fp2:
                fp2.close()

else:
    import importlib.util
    def load_script(path, module_name):
        full_path = get_resource_path(*path.split(os.path.sep))
        spec = importlib.util.spec_from_file_location(module_name, full_path)
        module = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(module)
        return module


_logger = logging.getLogger(__name__)

class MigrationManager(object):
    """
        This class manage the migration of modules
        Migrations files must be python files containing a `migrate(cr, installed_version)`
        function. Theses files must respect a directory tree structure: A 'migrations' folder
        which containt a folder by version. Version can be 'module' version or 'server.module'
        version (in this case, the files will only be processed by this version of the server).
        Python file names must start by `pre` or `post` and will be executed, respectively,
        before and after the module initialisation. `end` scripts are run after all modules have
        been updated.
        Example:
            <moduledir>
            `-- migrations
                |-- 1.0
                |   |-- pre-update_table_x.py
                |   |-- pre-update_table_y.py
                |   |-- post-create_plop_records.py
                |   |-- end-cleanup.py
                |   `-- README.txt                      # not processed
                |-- 9.0.1.1                             # processed only on a 9.0 server
                |   |-- pre-delete_table_z.py
                |   `-- post-clean-data.py
                `-- foo.py                              # not processed
    """

    def __init__(self, cr, graph):
        self.cr = cr
        self.graph = graph
        self.migrations = defaultdict(dict)
        self._get_files()

    def _get_files(self):
        def get_scripts(path):
            if not path:
                return {}
            return {
                version: glob.glob1(opj(path, version), '*.py')
                for version in os.listdir(path)
                if os.path.isdir(opj(path, version))
            }

        for pkg in self.graph:
            if not (hasattr(pkg, 'update') or pkg.state == 'to upgrade' or
                    getattr(pkg, 'load_state', None) == 'to upgrade'):
                continue

            self.migrations[pkg.name] = {
                'module': get_scripts(get_resource_path(pkg.name, 'migrations')),
                'maintenance': get_scripts(get_resource_path('base', 'maintenance', 'migrations', pkg.name)),
            }

    def migrate_module(self, pkg, stage):
        assert stage in ('pre', 'post', 'end')
        stageformat = {
            'pre': '[>%s]',
            'post': '[%s>]',
            'end': '[$%s]',
        }
        state = pkg.state if stage in ('pre', 'post') else getattr(pkg, 'load_state', None)

        if not (hasattr(pkg, 'update') or state == 'to upgrade') or state == 'to install':
            return

        def convert_version(version):
            if version.count('.') >= 2:
                return version  # the version number already containt the server version
            return "%s.%s" % (release.major_version, version)

        def _get_migration_versions(pkg):
            versions = sorted({
                ver
                for lv in self.migrations[pkg.name].values()
                for ver, lf in lv.items()
                if lf
            }, key=lambda k: parse_version(convert_version(k)))
            return versions

        def _get_migration_files(pkg, version, stage):
            """ return a list of migration script files
            """
            m = self.migrations[pkg.name]
            lst = []

            mapping = {
                'module': opj(pkg.name, 'migrations'),
                'maintenance': opj('base', 'maintenance', 'migrations', pkg.name),
            }

            for x in mapping:
                if version in m.get(x):
                    for f in m[x][version]:
                        if not f.startswith(stage + '-'):
                            continue
                        lst.append(opj(mapping[x], version, f))
            lst.sort()
            return lst

        installed_version = getattr(pkg, 'load_version', pkg.installed_version) or ''
        parsed_installed_version = parse_version(installed_version)
        current_version = parse_version(convert_version(pkg.data['version']))

        versions = _get_migration_versions(pkg)

        for version in versions:
            if parsed_installed_version < parse_version(convert_version(version)) <= current_version:

                strfmt = {'addon': pkg.name,
                          'stage': stage,
                          'version': stageformat[stage] % version,
                          }

                for pyfile in _get_migration_files(pkg, version, stage):
                    name, ext = os.path.splitext(os.path.basename(pyfile))
                    if ext.lower() != '.py':
                        continue
                    mod = None
                    try:
                        mod = load_script(pyfile, name)
                        _logger.info('module %(addon)s: Running migration %(version)s %(name)s' % dict(strfmt, name=mod.__name__))
                        migrate = mod.migrate
                    except ImportError:
                        _logger.exception('module %(addon)s: Unable to load %(stage)s-migration file %(file)s' % dict(strfmt, file=pyfile))
                        raise
                    except AttributeError:
                        _logger.error('module %(addon)s: Each %(stage)s-migration file must have a "migrate(cr, installed_version)" function' % strfmt)
                    else:
                        migrate(self.cr, installed_version)
                    finally:
                        if mod:
                            del mod