"""utilities for instances migration

"""

__docformat__ = "restructuredtext en"

import sys

import os

import logging

import tempfile

from os.path import exists, join, basename, splitext

from logilab.common.decorators import cached

from logilab.common.configuration import REQUIRED, read_old_config

from logilab.common.shellutils import ASK

from cubicweb import ConfigurationError

def filter_scripts(config, directory, fromversion, toversion, quiet=True):

    """return a list of paths of migration files to consider to upgrade

    from a version to a greater one

    """

    from logilab.common.changelog import Version # doesn't work with appengine

    assert fromversion

    assert toversion

    assert isinstance(fromversion, tuple), fromversion.__class__

    assert isinstance(toversion, tuple), toversion.__class__

    assert fromversion <= toversion, (fromversion, toversion)

    if not exists(directory):

        if not quiet:

            print directory, "doesn't exists, no migration path"

        return []

    if fromversion == toversion:

        return []

    result = []

    for fname in os.listdir(directory):

        if fname.endswith('.pyc') or fname.endswith('.pyo') \

               or fname.endswith('~'):

            continue

        fpath = join(directory, fname)

        try:

            tver, mode = fname.split('_', 1)

        except ValueError:

            continue

        mode = mode.split('.', 1)[0]

        if not config.accept_mode(mode):

            continue

        try:

            tver = Version(tver)

        except ValueError:

            continue

        if tver <= fromversion:

            continue

        if tver > toversion:

            continue

        result.append((tver, fpath))

    # be sure scripts are executed in order

    return sorted(result)

IGNORED_EXTENSIONS = ('.swp', '~')

def execscript_confirm(scriptpath):

    """asks for confirmation before executing a script and provides the

    ability to show the script's content

    """

    while True:

        answer = ASK.ask('Execute %r ?' % scriptpath,

                         ('Y','n','show','abort'), 'Y')

        if answer == 'abort':

            raise SystemExit(1)

        elif answer == 'n':

            return False

        elif answer == 'show':

            stream = open(scriptpath)

            scriptcontent = stream.read()

            stream.close()

            print

            print scriptcontent

            print

        else:

            return True

def yes(*args, **kwargs):

    return True

class MigrationHelper(object):

    """class holding CubicWeb Migration Actions used by migration scripts"""

    def __init__(self, config, interactive=True, verbosity=1):

        self.config = config

        if config:

            # no config on shell to a remote instance

            self.config.init_log(logthreshold=logging.ERROR, debug=True)

        # 0: no confirmation, 1: only main commands confirmed, 2 ask for everything

        self.verbosity = verbosity

        self.need_wrap = True

        if not interactive or not verbosity:

            self.confirm = yes

            self.execscript_confirm = yes

        else:

            self.execscript_confirm = execscript_confirm

        self._option_changes = []

        self.__context = {'confirm': self.confirm,

                          'config': self.config,

                          'interactive_mode': interactive,

                          }

    def __getattribute__(self, name):

        try:

            return object.__getattribute__(self, name)

        except AttributeError:

            cmd = 'cmd_%s' % name

            if hasattr(self, cmd):

                meth = getattr(self, cmd)

                return lambda *args, **kwargs: self.interact(args, kwargs,

                                                             meth=meth)

            raise

        raise AttributeError(name)

    def repo_connect(self):

        return self.config.repository()

    def migrate(self, vcconf, toupgrade, options):

        """upgrade the given set of cubes

        `cubes` is an ordered list of 3-uple:

        (cube, fromversion, toversion)

        """

        if options.fs_only:

            # monkey path configuration.accept_mode so database mode (e.g. Any)

            # won't be accepted

            orig_accept_mode = self.config.accept_mode

            def accept_mode(mode):

                if mode == 'Any':

                    return False

                return orig_accept_mode(mode)

            self.config.accept_mode = accept_mode

        # may be an iterator

        toupgrade = tuple(toupgrade)

        vmap = dict( (cube, (fromver, tover)) for cube, fromver, tover in toupgrade)

        ctx = self.__context

        ctx['versions_map'] = vmap

        if self.config.accept_mode('Any') and 'cubicweb' in vmap:

            migrdir = self.config.migration_scripts_dir()

            self.cmd_process_script(join(migrdir, 'bootstrapmigration_repository.py'))

        for cube, fromversion, toversion in toupgrade:

            if cube == 'cubicweb':

                migrdir = self.config.migration_scripts_dir()

            else:

                migrdir = self.config.cube_migration_scripts_dir(cube)

            scripts = filter_scripts(self.config, migrdir, fromversion, toversion)

            if scripts:

                prevversion = None

                for version, script in scripts:

                    # take care to X.Y.Z_Any.py / X.Y.Z_common.py: we've to call

                    # cube_upgraded once all script of X.Y.Z have been executed

                    if prevversion is not None and version != prevversion:

                        self.cube_upgraded(cube, prevversion)

                    prevversion = version

                    self.cmd_process_script(script)

                self.cube_upgraded(cube, toversion)

            else:

                self.cube_upgraded(cube, toversion)

    def cube_upgraded(self, cube, version):

        pass

    def shutdown(self):

        pass

    def interact(self, args, kwargs, meth):

        """execute the given method according to user's confirmation"""

        msg = 'Execute command: %s(%s) ?' % (

            meth.__name__[4:],

            ', '.join([repr(arg) for arg in args] +

                      ['%s=%r' % (n,v) for n,v in kwargs.items()]))

        if 'ask_confirm' in kwargs:

            ask_confirm = kwargs.pop('ask_confirm')

        else:

            ask_confirm = True

        if not ask_confirm or self.confirm(msg):

            return meth(*args, **kwargs)

    def confirm(self, question, shell=True, abort=True, retry=False, default='y'):

        """ask for confirmation and return true on positive answer

        if `retry` is true the r[etry] answer may return 2

        """

        possibleanswers = ['y', 'n']

        if abort:

            possibleanswers.append('abort')

        if shell:

            possibleanswers.append('shell')

        if retry:

            possibleanswers.append('retry')

        try:

            answer = ASK.ask(question, possibleanswers, default)

        except (EOFError, KeyboardInterrupt):

            answer = 'abort'

        if answer == 'n':

            return False

        if answer == 'retry':

            return 2

        if answer == 'abort':

            raise SystemExit(1)

        if shell and answer == 'shell':

            self.interactive_shell()

            return self.confirm(question)

        return True

    def interactive_shell(self):

        self.confirm = yes

        self.need_wrap = False

        # avoid '_' to be added to builtins by sys.display_hook

        def do_not_add___to_builtins(obj):

            if obj is not None:

                print repr(obj)

        sys.displayhook = do_not_add___to_builtins

        local_ctx = self._create_context()

        try:

            import readline

            from rlcompleter import Completer

        except ImportError:

            # readline not available

            pass

        else:

            readline.set_completer(Completer(local_ctx).complete)

            readline.parse_and_bind('tab: complete')

            home_key = 'HOME'

            if sys.platform == 'win32':

                home_key = 'USERPROFILE'

            histfile = os.path.join(os.environ[home_key], ".eshellhist")

            try:

                readline.read_history_file(histfile)

            except IOError:

                pass

        from code import interact

        banner = """entering the migration python shell

just type migration commands or arbitrary python code and type ENTER to execute it

type "exit" or Ctrl-D to quit the shell and resume operation"""

        # give custom readfunc to avoid http://bugs.python.org/issue1288615

        def unicode_raw_input(prompt):

            return unicode(raw_input(prompt), sys.stdin.encoding)

        interact(banner, readfunc=unicode_raw_input, local=local_ctx)

        readline.write_history_file(histfile)

        # delete instance's confirm attribute to avoid questions

        del self.confirm

        self.need_wrap = True

    @cached

    def _create_context(self):

        """return a dictionary to use as migration script execution context"""

        context = self.__context

        for attr in dir(self):

            if attr.startswith('cmd_'):

                if self.need_wrap:

                    context[attr[4:]] = getattr(self, attr[4:])

                else:

                    context[attr[4:]] = getattr(self, attr)

        return context

    def cmd_process_script(self, migrscript, funcname=None, *args, **kwargs):

        """execute a migration script

        in interactive mode,  display the migration script path, ask for

        confirmation and execute it if confirmed

        """

        migrscript = os.path.normpath(migrscript)

        if migrscript.endswith('.py'):

            script_mode = 'python'

        elif migrscript.endswith('.txt') or migrscript.endswith('.rst'):

            script_mode = 'doctest'

        else:

            raise Exception('This is not a valid cubicweb shell input')

        if not self.execscript_confirm(migrscript):

            return

        scriptlocals = self._create_context().copy()

        if script_mode == 'python':

            if funcname is None:

                pyname = '__main__'

            else:

                pyname = splitext(basename(migrscript))[0]

            scriptlocals.update({'__file__': migrscript, '__name__': pyname})

            execfile(migrscript, scriptlocals)

            if funcname is not None:

                try:

                    func = scriptlocals[funcname]

                    self.info('found %s in locals', funcname)

                    assert callable(func), '%s (%s) is not callable' % (func, funcname)

                except KeyError:

                    self.critical('no %s in script %s', funcname, migrscript)

                    return None

                return func(*args, **kwargs)

        else: # script_mode == 'doctest'

            import doctest

            doctest.testfile(migrscript, module_relative=False,

                             optionflags=doctest.ELLIPSIS, globs=scriptlocals)

    def cmd_option_renamed(self, oldname, newname):

        """a configuration option has been renamed"""

        self._option_changes.append(('renamed', oldname, newname))

    def cmd_option_group_change(self, option, oldgroup, newgroup):

        """a configuration option has been moved in another group"""

        self._option_changes.append(('moved', option, oldgroup, newgroup))

    def cmd_option_added(self, optname):

        """a configuration option has been added"""

        self._option_changes.append(('added', optname))

    def cmd_option_removed(self, optname):

        """a configuration option has been removed"""

        # can safely be ignored

        #self._option_changes.append(('removed', optname))

    def cmd_option_type_changed(self, optname, oldtype, newvalue):

        """a configuration option's type has changed"""

        self._option_changes.append(('typechanged', optname, oldtype, newvalue))

    def cmd_add_cubes(self, cubes):

        """modify the list of used cubes in the in-memory config

        returns newly inserted cubes, including dependencies

        """

        if isinstance(cubes, basestring):

            cubes = (cubes,)

        origcubes = self.config.cubes()

        newcubes = [p for p in self.config.expand_cubes(cubes)

                       if not p in origcubes]

        if newcubes:

            for cube in cubes:

                assert cube in newcubes

            self.config.add_cubes(newcubes)

        return newcubes

    def cmd_remove_cube(self, cube, removedeps=False):

        if removedeps:

            toremove = self.config.expand_cubes([cube])

        else:

            toremove = (cube,)

        origcubes = self.config._cubes

        basecubes = [c for c in origcubes if not c in toremove]

        self.config._cubes = tuple(self.config.expand_cubes(basecubes))

        removed = [p for p in origcubes if not p in self.config._cubes]

        if not cube in removed:

            raise ConfigurationError("can't remove cube %s, "

                                     "used as a dependency" % cube)

        return removed

    def rewrite_configuration(self):

        # import locally, show_diffs unavailable in gae environment

        from cubicweb.toolsutils import show_diffs

        configfile = self.config.main_config_file()

        if self._option_changes:

            read_old_config(self.config, self._option_changes, configfile)

        fd, newconfig = tempfile.mkstemp()

        for optdescr in self._option_changes:

            if optdescr[0] == 'added':

                optdict = self.config.get_option_def(optdescr[1])

                if optdict.get('default') is REQUIRED:

                    self.config.input_option(optdescr[1], optdict)

        self.config.generate_config(open(newconfig, 'w'))

        show_diffs(configfile, newconfig)

        os.close(fd)

        if exists(newconfig):

            os.unlink(newconfig)

from logging import getLogger