#
# Copyright (c) 2001 Bizar Software Pty Ltd (http://www.bizarsoftware.com.au/)
# This module is free software, and you may redistribute it and/or modify
# under the same terms as Python, so long as this copyright message and
# disclaimer are retained in their original form.
#
# IN NO EVENT SHALL BIZAR SOFTWARE PTY LTD BE LIABLE TO ANY PARTY FOR
# DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING
# OUT OF THE USE OF THIS CODE, EVEN IF THE AUTHOR HAS BEEN ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# BIZAR SOFTWARE PTY LTD SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
# BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE.  THE CODE PROVIDED HEREUNDER IS ON AN "AS IS"
# BASIS, AND THERE IS NO OBLIGATION WHATSOEVER TO PROVIDE MAINTENANCE,
# SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
#

"""Top-level tracker interface.

Open a tracker with:

    >>> from roundup import instance
    >>> db = instance.open('path to tracker home')

The "db" handle you get back is the tracker's hyperdb which has the interface
described in `roundup.hyperdb.Database`.
"""
__docformat__ = 'restructuredtext'

try:
    import builtins
except ImportError:
    import __builtin__ as builtins

try:
    from collections.abc import Callable
except ImportError:
    from collections import Callable

import os
import sys

from roundup import configuration, mailgw
from roundup import hyperdb, backends, actions
from roundup.cgi import client, templating
from roundup.cgi import actions as cgi_actions
from roundup.exceptions import RoundupException


class Tracker:
    def __init__(self, tracker_home, optimize=0):
        """New-style tracker instance constructor

        Parameters:
            tracker_home:
                tracker home directory
            optimize:
                if set, precompile html templates

        """
        self.tracker_home = tracker_home
        self.optimize = optimize
        # if set, call schema_hook after executing schema.py will get
        # same variables (in particular db) as schema.py main purpose is
        # for regression tests
        self.schema_hook = None
        self.config = configuration.CoreConfig(tracker_home)
        self.actions = {}
        self.cgi_actions = {}
        self.templating_utils = {}

        libdir = os.path.join(self.tracker_home, 'lib')
        self.libdir = os.path.isdir(libdir) and libdir or ''

        self.load_interfaces()
        self.templates = templating.get_loader(self.config["TEMPLATES"],
                                               self.config["TEMPLATE_ENGINE"])

        rdbms_backend = self.config.RDBMS_BACKEND

        self.backend = backends.get_backend(rdbms_backend)

        if self.optimize:
            self.templates.precompile()
            # initialize tracker extensions
            for extension in self.get_extensions('extensions'):
                extension(self)
            # load database schema
            self.schema = self._compile('schema.py')
            # load database detectors
            self.detectors = self.get_extensions('detectors')
            # db_open is set to True after first open()
            self.db_open = 0

    def open(self, name=None):
        # load the database schema
        # we cannot skip this part even if self.optimize is set
        # because the schema has security settings that must be
        # applied to each database instance
        backend = self.backend
        env = {
            'Class': backend.Class,
            'FileClass': backend.FileClass,
            'IssueClass': backend.IssueClass,
            'String': hyperdb.String,
            'Password': hyperdb.Password,
            'Date': hyperdb.Date,
            'Link': hyperdb.Link,
            'Multilink': hyperdb.Multilink,
            'Interval': hyperdb.Interval,
            'Boolean': hyperdb.Boolean,
            'Number': hyperdb.Number,
            'Integer': hyperdb.Integer,
            'db': backend.Database(self.config, name)
        }

        if self.optimize:
            # execute preloaded schema object
            self._exec(self.schema, env)
            if isinstance(self.schema_hook, Callable):
                self.schema_hook(**env)
            # use preloaded detectors
            detectors = self.detectors
        else:
            # execute the schema file
            self._execfile('schema.py', env)
            if isinstance(self.schema_hook, Callable):
                self.schema_hook(**env)
            # reload extensions and detectors
            for extension in self.get_extensions('extensions'):
                extension(self)
            detectors = self.get_extensions('detectors')
        db = env['db']
        db.tx_Source = None
        # Useful for script when multiple open calls happen. Scripts have
        # to inject the i18n object, there is currently no support for this
        if hasattr(self, 'i18n'):
            db.i18n = self.i18n

        # apply the detectors
        for detector in detectors:
            detector(db)
        # if we are running in debug mode
        # or this is the first time the database is opened,
        # do database upgrade checks
        if not (self.optimize and self.db_open):
            # As a consistency check, ensure that every link property is
            # pointing at a defined class.  Otherwise, the schema is
            # internally inconsistent.  This is an important safety
            # measure as it protects against an accidental schema change
            # dropping a table while there are still links to the table;
            # once the table has been dropped, there is no way to get it
            # back, so it is important to drop it only if we are as sure
            # as possible that it is no longer needed.
            classes = db.getclasses()
            for classname in classes:
                cl = db.getclass(classname)
                for propname, prop in cl.getprops().items():
                    if not isinstance(prop, (hyperdb.Link,
                                             hyperdb.Multilink)):
                        continue
                    linkto = prop.classname
                    if linkto not in classes:
                        raise ValueError("property %s.%s links to "
                                         "non-existent class %s"
                                         % (classname, propname, linkto))

            self.db_open = 1
        # *Must* call post_init! It is not an error if called multiple times.
        db.post_init()
        return db

    def load_interfaces(self):
        """load interfaces.py (if any), initialize Client and MailGW attrs"""
        env = {}
        if os.path.isfile(os.path.join(self.tracker_home, 'interfaces.py')):
            self._execfile('interfaces.py', env)
        self.Client = env.get('Client', client.Client)
        self.MailGW = env.get('MailGW', mailgw.MailGW)
        self.TemplatingUtils = env.get('TemplatingUtils',
                                       templating.TemplatingUtils)

    def get_extensions(self, dirname):
        """Load python extensions

        Parameters:
            dirname:
                extension directory name relative to tracker home

        Return value:
            list of init() functions for each extension

        """
        extensions = []
        dirpath = os.path.join(self.tracker_home, dirname)
        if os.path.isdir(dirpath):
            sys.path.insert(1, dirpath)
            for name in os.listdir(dirpath):
                if not name.endswith('.py'):
                    continue
                env = {}
                self._execfile(os.path.join(dirname, name), env)
                extensions.append(env['init'])
            sys.path.remove(dirpath)
        return extensions

    def init(self, adminpw, tx_Source=None):
        db = self.open('admin')
        db.tx_Source = tx_Source
        self._execfile('initial_data.py',
                       {'db': db, 'adminpw': adminpw,
                        'admin_email': self.config['ADMIN_EMAIL']})
        db.commit()
        db.close()

    def exists(self):
        return self.backend.db_exists(self.config)

    def nuke(self):
        self.backend.db_nuke(self.config)

    def _compile(self, fname):
        fname = os.path.join(self.tracker_home, fname)
        with builtins.open(fname) as fnamed:
            return compile(fnamed.read(), fname, 'exec')

    def _exec(self, obj, env):
        if self.libdir:
            sys.path.insert(1, self.libdir)
        exec(obj, env)
        if self.libdir:
            sys.path.remove(self.libdir)
        return env

    def _execfile(self, fname, env):
        self._exec(self._compile(fname), env)

    def registerAction(self, name, action):

        # The logic here is this:
        # * if `action` derives from actions.Action,
        #   it is executable as a generic action.
        # * if, moreover, it also derives from cgi.actions.Bridge,
        #   it may in addition be called via CGI
        # * in all other cases we register it as a CGI action, without
        #   any check (for backward compatibility).
        if issubclass(action, actions.Action):
            self.actions[name] = action
            if issubclass(action, cgi_actions.Bridge):
                self.cgi_actions[name] = action
        else:
            self.cgi_actions[name] = action

    def registerUtil(self, name, function):
        self.templating_utils[name] = function


class TrackerError(RoundupException):
    pass


def open(tracker_home, optimize=0):
    if os.path.exists(os.path.join(tracker_home, 'dbinit.py')):
        # user should upgrade...
        raise TrackerError("Old style trackers using dbinit.py "
                           "are not supported after release 2.0")

    return Tracker(tracker_home, optimize=optimize)

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