# -*- coding: utf-8 -*-
# Copyright (C) 2012 Anaconda, Inc
# SPDX-License-Identifier: BSD-3-Clause
from __future__ import absolute_import, division, print_function, unicode_literals

import itertools
from collections import defaultdict, namedtuple
from logging import getLogger
import os
from os.path import basename, dirname, isdir, join
import sys
from pathlib import Path
from traceback import format_exception_only
from textwrap import indent
import warnings

from .package_cache_data import PackageCacheData
from .path_actions import (CompileMultiPycAction, CreateNonadminAction, CreatePrefixRecordAction,
                           CreatePythonEntryPointAction, LinkPathAction, MakeMenuAction,
                           RegisterEnvironmentLocationAction, RemoveLinkedPackageRecordAction,
                           RemoveMenuAction, UnlinkPathAction, UnregisterEnvironmentLocationAction,
                           UpdateHistoryAction, AggregateCompileMultiPycAction)
from .prefix_data import PrefixData, get_python_version_for_prefix
from .. import CondaError, CondaMultiError, conda_signal_handler
from ..auxlib.collection import first
from ..auxlib.ish import dals
from .._vendor.toolz import concat, concatv, interleave
from ..base.constants import DEFAULTS_CHANNEL_NAME, PREFIX_MAGIC_FILE, SafetyChecks
from ..base.context import context
from ..cli.common import confirm_yn
from ..common.compat import ensure_text_type, iteritems, itervalues, odict, on_win, text_type
from ..common.io import Spinner, dashlist, time_recorder
from ..common.io import DummyExecutor, ThreadLimitedThreadPoolExecutor
from ..common.path import (explode_directories, get_all_directories, get_major_minor_version,
                           get_python_site_packages_short_path)
from ..common.signals import signal_handler
from ..exceptions import (DisallowedPackageError, EnvironmentNotWritableError,
                          KnownPackageClobberError, LinkError, RemoveError,
                          SharedLinkPathClobberError, UnknownPackageClobberError, maybe_raise,
                          CondaSystemExit)
from ..gateways.disk import mkdir_p
from ..gateways.disk.delete import rm_rf
from ..gateways.disk.read import isfile, lexists, read_package_info
from ..gateways.disk.test import hardlink_supported, is_conda_environment, softlink_supported
from ..gateways.subprocess import subprocess_call
from ..models.enums import LinkType
from ..models.enums import MetadataSignatureStatus
from ..models.version import VersionOrder
from ..resolve import MatchSpec
from ..utils import get_comspec, human_bytes, wrap_subprocess_call

log = getLogger(__name__)


def determine_link_type(extracted_package_dir, target_prefix):
    source_test_file = join(extracted_package_dir, 'info', 'index.json')
    if context.always_copy:
        return LinkType.copy
    if context.always_softlink:
        return LinkType.softlink
    if hardlink_supported(source_test_file, target_prefix):
        return LinkType.hardlink
    if context.allow_softlinks and softlink_supported(source_test_file, target_prefix):
        return LinkType.softlink
    return LinkType.copy


def make_unlink_actions(transaction_context, target_prefix, prefix_record):
    # no side effects in this function!
    unlink_path_actions = tuple(UnlinkPathAction(transaction_context, prefix_record,
                                                 target_prefix, trgt)
                                for trgt in prefix_record.files)

    try:
        extracted_package_dir = basename(prefix_record.extracted_package_dir)
    except AttributeError:
        try:
            extracted_package_dir = basename(prefix_record.link.source)
        except AttributeError:
            # for backward compatibility only
            extracted_package_dir = '%s-%s-%s' % (prefix_record.name, prefix_record.version,
                                                  prefix_record.build)

    meta_short_path = '%s/%s' % ('conda-meta', extracted_package_dir + '.json')
    remove_conda_meta_actions = (RemoveLinkedPackageRecordAction(transaction_context,
                                                                 prefix_record,
                                                                 target_prefix, meta_short_path),)

    _all_d = get_all_directories(axn.target_short_path for axn in unlink_path_actions)
    all_directories = sorted(explode_directories(_all_d, already_split=True), reverse=True)
    directory_remove_actions = tuple(UnlinkPathAction(transaction_context, prefix_record,
                                                      target_prefix, d, LinkType.directory)
                                     for d in all_directories)

    # unregister_private_package_actions = UnregisterPrivateEnvAction.create_actions(
    #     transaction_context, package_cache_record, target_prefix
    # )

    return tuple(concatv(
        unlink_path_actions,
        directory_remove_actions,
        # unregister_private_package_actions,
        remove_conda_meta_actions,
    ))


def match_specs_to_dists(packages_info_to_link, specs):
    matched_specs = [None for _ in range(len(packages_info_to_link))]
    for spec in specs or ():
        spec = MatchSpec(spec)
        idx = next((q for q, pkg_info in enumerate(packages_info_to_link)
                    if pkg_info.repodata_record.name == spec.name),
                   None)
        if idx is not None:
            matched_specs[idx] = spec
    return tuple(matched_specs)


PrefixSetup = namedtuple('PrefixSetup', (
    'target_prefix',
    'unlink_precs',
    'link_precs',
    'remove_specs',
    'update_specs',
    'neutered_specs'
))

PrefixActionGroup = namedtuple('PrefixActionGroup', (
    'remove_menu_action_groups',
    'unlink_action_groups',
    'unregister_action_groups',
    'link_action_groups',
    'register_action_groups',
    'compile_action_groups',
    'make_menu_action_groups',
    'entry_point_action_groups',
    'prefix_record_groups',
))

# each PrefixGroup item is a sequence of ActionGroups
ActionGroup = namedtuple('ActionGroup', (
    'type',
    'pkg_data',
    'actions',
    'target_prefix',
))

ChangeReport = namedtuple("ChangeReport", (
    "prefix",
    "specs_to_remove",
    "specs_to_add",
    "removed_precs",
    "new_precs",
    "updated_precs",
    "downgraded_precs",
    "superseded_precs",
    "fetch_precs",
))


class UnlinkLinkTransaction(object):

    def __init__(self, *setups):
        self.prefix_setups = odict((stp.target_prefix, stp) for stp in setups)
        self.prefix_action_groups = odict()

        for stp in itervalues(self.prefix_setups):
            log.info("initializing UnlinkLinkTransaction with\n"
                     "  target_prefix: %s\n"
                     "  unlink_precs:\n"
                     "    %s\n"
                     "  link_precs:\n"
                     "    %s\n",
                     stp.target_prefix,
                     '\n    '.join(prec.dist_str() for prec in stp.unlink_precs),
                     '\n    '.join(prec.dist_str() for prec in stp.link_precs))

        self._pfe = None
        self._prepared = False
        self._verified = False
        # this can be CPU-bound.  Use ProcessPoolExecutor.
        self.verify_executor = (DummyExecutor() if context.debug or context.verify_threads == 1
                                else ThreadLimitedThreadPoolExecutor(context.verify_threads))
        # this is more I/O bound.  Use ThreadPoolExecutor.
        self.execute_executor = (DummyExecutor() if context.debug or context.execute_threads == 1
                                 else ThreadLimitedThreadPoolExecutor(context.execute_threads))

    @property
    def nothing_to_do(self):
        return (
            not any((stp.unlink_precs or stp.link_precs) for stp in itervalues(self.prefix_setups))
            and all(is_conda_environment(stp.target_prefix)
                    for stp in itervalues(self.prefix_setups))
        )

    def download_and_extract(self):
        if self._pfe is None:
            self._get_pfe()
        if not self._pfe._executed:
            self._pfe.execute()

    def prepare(self):
        if self._pfe is None:
            self._get_pfe()
        if not self._pfe._executed:
            self._pfe.execute()

        if self._prepared:
            return

        self.transaction_context = {}

        with Spinner("Preparing transaction", not context.verbosity and not context.quiet,
                     context.json):
            for stp in itervalues(self.prefix_setups):
                grps = self._prepare(self.transaction_context, stp.target_prefix,
                                     stp.unlink_precs, stp.link_precs,
                                     stp.remove_specs, stp.update_specs,
                                     stp.neutered_specs)
                self.prefix_action_groups[stp.target_prefix] = PrefixActionGroup(*grps)

        self._prepared = True

    @time_recorder("unlink_link_prepare_and_verify")
    def verify(self):
        if not self._prepared:
            self.prepare()

        assert not context.dry_run

        if context.safety_checks == SafetyChecks.disabled:
            self._verified = True
            return

        with Spinner(
            "Verifying transaction", not context.verbosity and not context.quiet, context.json
        ):
            exceptions = self._verify(self.prefix_setups, self.prefix_action_groups)
            if exceptions:
                try:
                    maybe_raise(CondaMultiError(exceptions), context)
                except:
                    rm_rf(self.transaction_context["temp_dir"])
                    raise
                log.info(exceptions)
        try:
            self._verify_pre_link_message(
                itertools.chain(
                    *(act.link_action_groups for act in self.prefix_action_groups.values())
                )
            )
        except CondaSystemExit:
            rm_rf(self.transaction_context["temp_dir"])
            raise
        self._verified = True

    def _verify_pre_link_message(self, all_link_groups):
        flag_pre_link = False
        for act in all_link_groups:
            prelink_msg_dir = (
                Path(act.pkg_data.extracted_package_dir) / "info" / "prelink_messages"
            )
            all_msg_subdir = list(item for item in prelink_msg_dir.glob("**/*") if item.is_file())
            if prelink_msg_dir.is_dir() and all_msg_subdir:
                print("\n\nThe following PRELINK MESSAGES are INCLUDED:\n\n")
                flag_pre_link = True

                for msg_file in all_msg_subdir:
                    print(f"  File {msg_file.name}:\n")
                    print(indent(msg_file.read_text(), "  "))
                    print("")
        if flag_pre_link:
            confirm_yn()

    def execute(self):
        if not self._verified:
            self.verify()

        assert not context.dry_run
        try:
            self._execute(tuple(concat(interleave(itervalues(self.prefix_action_groups)))))
        finally:
            rm_rf(self.transaction_context['temp_dir'])

    def _get_pfe(self):
        from .package_cache_data import ProgressiveFetchExtract
        if self._pfe is not None:
            pfe = self._pfe
        elif not self.prefix_setups:
            self._pfe = pfe = ProgressiveFetchExtract(())
        else:
            link_precs = set(concat(stp.link_precs for stp in itervalues(self.prefix_setups)))
            self._pfe = pfe = ProgressiveFetchExtract(link_precs)
        return pfe

    @classmethod
    def _prepare(cls, transaction_context, target_prefix, unlink_precs, link_precs,
                 remove_specs, update_specs, neutered_specs):

        # make sure prefix directory exists
        if not isdir(target_prefix):
            try:
                mkdir_p(target_prefix)
            except (IOError, OSError) as e:
                log.debug(repr(e))
                raise CondaError("Unable to create prefix directory '%s'.\n"
                                 "Check that you have sufficient permissions."
                                 "" % target_prefix)

        # gather information from disk and caches
        prefix_data = PrefixData(target_prefix)
        prefix_recs_to_unlink = (prefix_data.get(prec.name) for prec in unlink_precs)
        # NOTE: load_meta can return None
        # TODO: figure out if this filter shouldn't be an assert not None
        prefix_recs_to_unlink = tuple(lpd for lpd in prefix_recs_to_unlink if lpd)
        pkg_cache_recs_to_link = tuple(PackageCacheData.get_entry_to_link(prec)
                                       for prec in link_precs)
        assert all(pkg_cache_recs_to_link)
        packages_info_to_link = tuple(read_package_info(prec, pcrec)
                                      for prec, pcrec in zip(link_precs, pkg_cache_recs_to_link))

        link_types = tuple(determine_link_type(pkg_info.extracted_package_dir, target_prefix)
                           for pkg_info in packages_info_to_link)

        # make all the path actions
        # no side effects allowed when instantiating these action objects
        python_version = cls._get_python_version(target_prefix,
                                                 prefix_recs_to_unlink,
                                                 packages_info_to_link)
        transaction_context['target_python_version'] = python_version
        sp = get_python_site_packages_short_path(python_version)
        transaction_context['target_site_packages_short_path'] = sp

        transaction_context['temp_dir'] = join(target_prefix, '.condatmp')

        remove_menu_action_groups = []
        unlink_action_groups = []
        for prefix_rec in prefix_recs_to_unlink:
            unlink_action_groups.append(ActionGroup(
                'unlink',
                prefix_rec,
                make_unlink_actions(transaction_context, target_prefix, prefix_rec),
                target_prefix))

            remove_menu_action_groups.append(ActionGroup(
                'remove_menus',
                prefix_rec,
                RemoveMenuAction.create_actions(
                    transaction_context, prefix_rec, target_prefix),
                target_prefix))

        if unlink_action_groups:
            axns = UnregisterEnvironmentLocationAction(transaction_context, target_prefix),
            unregister_action_groups = [ActionGroup('unregister', None, axns, target_prefix)]
        else:
            unregister_action_groups = ()

        matchspecs_for_link_dists = match_specs_to_dists(packages_info_to_link, update_specs)
        link_action_groups = []
        entry_point_action_groups = []
        compile_action_groups = []
        make_menu_action_groups = []
        record_axns = []
        for pkg_info, lt, spec in zip(packages_info_to_link, link_types,
                                      matchspecs_for_link_dists):
            link_ag = ActionGroup(
                'link',
                pkg_info,
                cls._make_link_actions(transaction_context, pkg_info,
                                       target_prefix, lt, spec),
                target_prefix)
            link_action_groups.append(link_ag)

            entry_point_ag = ActionGroup(
                'entry_point',
                pkg_info,
                cls._make_entry_point_actions(
                    transaction_context, pkg_info, target_prefix,
                    lt, spec, link_action_groups),
                target_prefix)
            entry_point_action_groups.append(entry_point_ag)

            compile_ag = ActionGroup(
                'compile',
                pkg_info,
                cls._make_compile_actions(
                    transaction_context, pkg_info, target_prefix,
                    lt, spec, link_action_groups),
                target_prefix)
            compile_action_groups.append(compile_ag)

            make_menu_ag = ActionGroup(
                'make_menus',
                pkg_info,
                MakeMenuAction.create_actions(
                    transaction_context, pkg_info, target_prefix, lt),
                target_prefix)
            make_menu_action_groups.append(make_menu_ag)

            all_link_path_actions = concatv(link_ag.actions,
                                            compile_ag.actions,
                                            entry_point_ag.actions,
                                            make_menu_ag.actions)
            record_axns.extend(CreatePrefixRecordAction.create_actions(
                transaction_context, pkg_info, target_prefix, lt, spec, all_link_path_actions))

        prefix_record_groups = [ActionGroup('record', None, record_axns, target_prefix)]

        # We're post solve here.  The update_specs are explicit requests.  We need to neuter
        #    any historic spec that was neutered prior to the solve.
        history_actions = UpdateHistoryAction.create_actions(
            transaction_context, target_prefix, remove_specs, update_specs, neutered_specs
        )
        register_actions = RegisterEnvironmentLocationAction(transaction_context, target_prefix),
        register_action_groups = [ActionGroup('register', None,
                                              register_actions + history_actions,
                                              target_prefix)]
        return PrefixActionGroup(
            remove_menu_action_groups,
            unlink_action_groups,
            unregister_action_groups,
            link_action_groups,
            register_action_groups,
            compile_action_groups,
            make_menu_action_groups,
            entry_point_action_groups,
            prefix_record_groups,
        )

    @staticmethod
    def _verify_individual_level(prefix_action_group):
        all_actions = concat(axngroup.actions
                             for action_groups in prefix_action_group
                             for axngroup in action_groups)

        # run all per-action (per-package) verify methods
        #   one of the more important of these checks is to verify that a file listed in
        #   the packages manifest (i.e. info/files) is actually contained within the package
        error_results = []
        for axn in all_actions:
            if axn.verified:
                continue
            error_result = axn.verify()
            if error_result:
                formatted_error = ''.join(format_exception_only(type(error_result), error_result))
                log.debug("Verification error in action %s\n%s", axn, formatted_error)
                error_results.append(error_result)
        return error_results

    @staticmethod
    def _verify_prefix_level(target_prefix_AND_prefix_action_group_tuple):
        # further verification of the whole transaction
        # for each path we are creating in link_actions, we need to make sure
        #   1. each path either doesn't already exist in the prefix, or will be unlinked
        #   2. there's only a single instance of each path
        #   3. if the target is a private env, leased paths need to be verified
        #   4. make sure conda-meta/history file is writable
        #   5. make sure envs/catalog.json is writable; done with RegisterEnvironmentLocationAction
        # TODO: 3, 4

        # this strange unpacking is to help the parallel execution work.  Unpacking
        #    tuples in the map call could be done with a lambda, but that is then not picklable,
        #    which precludes the use of ProcessPoolExecutor (but not ThreadPoolExecutor)
        target_prefix, prefix_action_group = target_prefix_AND_prefix_action_group_tuple

        unlink_action_groups = prefix_action_group.unlink_action_groups
        prefix_record_groups = prefix_action_group.prefix_record_groups

        lower_on_win = lambda p: p.lower() if on_win else p
        unlink_paths = set(lower_on_win(axn.target_short_path)
                           for grp in unlink_action_groups
                           for axn in grp.actions
                           if isinstance(axn, UnlinkPathAction))
        # we can get all of the paths being linked by looking only at the
        #   CreateLinkedPackageRecordAction actions
        create_lpr_actions = (axn
                              for grp in prefix_record_groups
                              for axn in grp.actions
                              if isinstance(axn, CreatePrefixRecordAction))

        error_results = []
        # Verification 1. each path either doesn't already exist in the prefix, or will be unlinked
        link_paths_dict = defaultdict(list)
        for axn in create_lpr_actions:
            for link_path_action in axn.all_link_path_actions:
                if isinstance(link_path_action, CompileMultiPycAction):
                    target_short_paths = link_path_action.target_short_paths
                elif isinstance(link_path_action, CreateNonadminAction):
                    continue
                else:
                    target_short_paths = ((link_path_action.target_short_path, )
                                          if not hasattr(link_path_action, 'link_type') or
                                          link_path_action.link_type != LinkType.directory
                                          else tuple())
                for path in target_short_paths:
                    path = lower_on_win(path)
                    link_paths_dict[path].append(axn)
                    if path not in unlink_paths and lexists(join(target_prefix, path)):
                        # we have a collision; at least try to figure out where it came from
                        colliding_prefix_rec = first(
                            (prefix_rec for prefix_rec in
                             PrefixData(target_prefix).iter_records()),
                            key=lambda prefix_rec: path in prefix_rec.files
                        )
                        if colliding_prefix_rec:
                            error_results.append(KnownPackageClobberError(
                                path,
                                axn.package_info.repodata_record.dist_str(),
                                colliding_prefix_rec.dist_str(),
                                context,
                            ))
                        else:
                            error_results.append(UnknownPackageClobberError(
                                path,
                                axn.package_info.repodata_record.dist_str(),
                                context,
                            ))

        # Verification 2. there's only a single instance of each path
        for path, axns in iteritems(link_paths_dict):
            if len(axns) > 1:
                error_results.append(SharedLinkPathClobberError(
                    path,
                    tuple(axn.package_info.repodata_record.dist_str() for axn in axns),
                    context,
                ))
        return error_results

    @staticmethod
    def _verify_transaction_level(prefix_setups):
        # 1. make sure we're not removing conda from conda's env
        # 2. make sure we're not removing a conda dependency from conda's env
        # 3. enforce context.disallowed_packages
        # 4. make sure we're not removing pinned packages without no-pin flag
        # 5. make sure conda-meta/history for each prefix is writable
        # TODO: Verification 4

        conda_prefixes = (join(context.root_prefix, 'envs', '_conda_'), context.root_prefix)
        conda_setups = tuple(setup for setup in itervalues(prefix_setups)
                             if setup.target_prefix in conda_prefixes)

        conda_unlinked = any(prec.name == 'conda'
                             for setup in conda_setups
                             for prec in setup.unlink_precs)

        conda_prec, conda_final_setup = next(
            ((prec, setup)
             for setup in conda_setups
             for prec in setup.link_precs
             if prec.name == 'conda'),
            (None, None)
        )

        if conda_unlinked and conda_final_setup is None:
            # means conda is being unlinked and not re-linked anywhere
            # this should never be able to be skipped, even with --force
            yield RemoveError("This operation will remove conda without replacing it with\n"
                              "another version of conda.")

        if conda_final_setup is None:
            # means we're not unlinking then linking a new package, so look up current conda record
            conda_final_prefix = context.conda_prefix
            pd = PrefixData(conda_final_prefix)
            pkg_names_already_lnkd = tuple(rec.name for rec in pd.iter_records())
            pkg_names_being_lnkd = ()
            pkg_names_being_unlnkd = ()
            conda_linked_depends = next(
                (record.depends for record in pd.iter_records() if record.name == 'conda'),
                ()
            )
        else:
            conda_final_prefix = conda_final_setup.target_prefix
            pd = PrefixData(conda_final_prefix)
            pkg_names_already_lnkd = tuple(rec.name for rec in pd.iter_records())
            pkg_names_being_lnkd = tuple(prec.name for prec in conda_final_setup.link_precs or ())
            pkg_names_being_unlnkd = tuple(prec.name for prec in conda_final_setup.unlink_precs
                                           or ())
            conda_linked_depends = conda_prec.depends

        if conda_final_prefix in prefix_setups:
            for conda_dependency in conda_linked_depends:
                dep_name = MatchSpec(conda_dependency).name
                if dep_name not in pkg_names_being_lnkd and (
                        dep_name not in pkg_names_already_lnkd or
                        dep_name in pkg_names_being_unlnkd):
                    yield RemoveError("'%s' is a dependency of conda and cannot be removed from\n"
                                      "conda's operating environment." % dep_name)

        # Verification 3. enforce disallowed_packages
        disallowed = tuple(MatchSpec(s) for s in context.disallowed_packages)
        for prefix_setup in itervalues(prefix_setups):
            for prec in prefix_setup.link_precs:
                if any(d.match(prec) for d in disallowed):
                    yield DisallowedPackageError(prec)

        # Verification 5. make sure conda-meta/history for each prefix is writable
        for prefix_setup in itervalues(prefix_setups):
            test_path = join(prefix_setup.target_prefix, PREFIX_MAGIC_FILE)
            test_path_existed = lexists(test_path)
            dir_existed = None
            try:
                dir_existed = mkdir_p(dirname(test_path))
                open(test_path, "a").close()
            except EnvironmentError:
                if dir_existed is False:
                    rm_rf(dirname(test_path))
                yield EnvironmentNotWritableError(prefix_setup.target_prefix)
            else:
                if not dir_existed:
                    rm_rf(dirname(test_path))
                elif not test_path_existed:
                    rm_rf(test_path)

    def _verify(self, prefix_setups, prefix_action_groups):
        transaction_exceptions = tuple(
            exc for exc in UnlinkLinkTransaction._verify_transaction_level(prefix_setups) if exc
        )
        if transaction_exceptions:
            return transaction_exceptions

        exceptions = []
        for exc in self.verify_executor.map(UnlinkLinkTransaction._verify_individual_level,
                                            itervalues(prefix_action_groups)):
            if exc:
                exceptions.extend(exc)
        for exc in self.verify_executor.map(
                UnlinkLinkTransaction._verify_prefix_level,
                iteritems(prefix_action_groups)):
            if exc:
                exceptions.extend(exc)
        return exceptions

    def _execute(self, all_action_groups):
        # unlink unlink_action_groups and unregister_action_groups
        unlink_actions = tuple(group for group in all_action_groups if group.type == "unlink")
        # link unlink_action_groups and register_action_groups
        link_actions = list(group for group in all_action_groups if group.type == "link")
        compile_actions = list(group for group in all_action_groups if group.type == "compile")
        entry_point_actions = list(group for group in all_action_groups
                                   if group.type == "entry_point")
        record_actions = list(group for group in all_action_groups if group.type == "record")
        make_menu_actions = list(group for group in all_action_groups
                                 if group.type == "make_menus")
        remove_menu_actions = list(group for group in all_action_groups
                                   if group.type == "remove_menus")

        with signal_handler(conda_signal_handler), time_recorder("unlink_link_execute"):
            exceptions = []
            with Spinner("Executing transaction", not context.verbosity and not context.quiet,
                         context.json):

                # Execute unlink actions
                for (group, register_group, install_side) in (
                        (unlink_actions, "unregister", False),
                        (link_actions, "register", True)):

                    if not install_side:
                        # uninstalling menus must happen prior to unlinking, or else they might
                        #   call something that isn't there anymore
                        for axngroup in remove_menu_actions:
                            UnlinkLinkTransaction._execute_actions(axngroup)

                    for axngroup in group:
                        is_unlink = axngroup.type == 'unlink'
                        target_prefix = axngroup.target_prefix
                        prec = axngroup.pkg_data
                        run_script(target_prefix if is_unlink else prec.extracted_package_dir,
                                   prec,
                                   'pre-unlink' if is_unlink else 'pre-link',
                                   target_prefix)

                    # parallel block 1:
                    for exc in self.execute_executor.map(UnlinkLinkTransaction._execute_actions,
                                                         group):
                        if exc:
                            exceptions.append(exc)

                    # post link scripts may employ entry points.  Do them before post-link.
                    if install_side:
                        for axngroup in entry_point_actions:
                            UnlinkLinkTransaction._execute_actions(axngroup)

                    # Run post-link or post-unlink scripts and registering AFTER link/unlink,
                    #    because they may depend on files in the prefix.  Additionally, run
                    #    them serially, just in case order matters (hopefully not)
                    for axngroup in group:
                        exc = UnlinkLinkTransaction._execute_post_link_actions(axngroup)
                        if exc:
                            exceptions.append(exc)

                    # parallel block 2:
                    composite_ag = []
                    if install_side:
                        composite_ag.extend(record_actions)
                        # consolidate compile actions into one big'un for better efficiency
                        individual_actions = [axn for ag in compile_actions for axn in ag.actions]
                        if individual_actions:
                            composite = AggregateCompileMultiPycAction(*individual_actions)
                            composite_ag.append(ActionGroup('compile', None, [composite],
                                                            composite.target_prefix))
                    # functions return None unless there was an exception
                    for exc in self.execute_executor.map(UnlinkLinkTransaction._execute_actions,
                                                         composite_ag):
                        if exc:
                            exceptions.append(exc)

                    # must do the register actions AFTER all link/unlink is done
                    register_actions = tuple(group for group in all_action_groups
                                             if group.type == register_group)
                    for axngroup in register_actions:
                        exc = UnlinkLinkTransaction._execute_actions(axngroup)
                        if exc:
                            exceptions.append(exc)
                    if exceptions:
                        break
                    if install_side:
                        # uninstalling menus must happen prior to unlinking, or else they might
                        #   call something that isn't there anymore
                        for axngroup in make_menu_actions:
                            UnlinkLinkTransaction._execute_actions(axngroup)
            if exceptions:
                # might be good to show all errors, but right now we only show the first
                e = exceptions[0]
                axngroup = e.errors[1]

                action, is_unlink = (None, axngroup.type == 'unlink')
                prec = axngroup.pkg_data

                if prec:
                    log.error("An error occurred while %s package '%s'." % (
                            'uninstalling' if is_unlink else 'installing',
                            prec.dist_str()))

                # reverse all executed packages except the one that failed
                rollback_excs = []
                if context.rollback_enabled:
                    with Spinner("Rolling back transaction",
                                 not context.verbosity and not context.quiet, context.json):
                        reverse_actions = reversed(tuple(all_action_groups))
                        for axngroup in reverse_actions:
                            excs = UnlinkLinkTransaction._reverse_actions(axngroup)
                            rollback_excs.extend(excs)

                raise CondaMultiError(tuple(concatv(
                    ((e.errors[0], e.errors[2:])
                     if isinstance(e, CondaMultiError)
                     else (e,)),
                    rollback_excs,
                )))
            else:
                for axngroup in all_action_groups:
                    for action in axngroup.actions:
                        action.cleanup()

    @staticmethod
    def _execute_actions(axngroup):
        target_prefix = axngroup.target_prefix
        prec = axngroup.pkg_data

        conda_meta_dir = join(target_prefix, 'conda-meta')
        if not isdir(conda_meta_dir):
            mkdir_p(conda_meta_dir)

        try:
            if axngroup.type == 'unlink':
                log.info("===> UNLINKING PACKAGE: %s <===\n"
                         "  prefix=%s\n",
                         prec.dist_str(), target_prefix)

            elif axngroup.type == 'link':
                log.info("===> LINKING PACKAGE: %s <===\n"
                         "  prefix=%s\n"
                         "  source=%s\n",
                         prec.dist_str(), target_prefix, prec.extracted_package_dir)

            for action in axngroup.actions:
                action.execute()
        except Exception as e:  # this won't be a multi error
            # reverse this package
            reverse_excs = ()
            if context.rollback_enabled:
                reverse_excs = UnlinkLinkTransaction._reverse_actions(axngroup)
            return CondaMultiError(tuple(concatv(
                (e,),
                (axngroup,),
                reverse_excs,
            )))

    @staticmethod
    def _execute_post_link_actions(axngroup):
        target_prefix = axngroup.target_prefix
        is_unlink = axngroup.type == 'unlink'
        prec = axngroup.pkg_data
        if prec:
            try:
                run_script(target_prefix, prec, 'post-unlink' if is_unlink else 'post-link',
                           activate=True)
            except Exception as e:  # this won't be a multi error
                # reverse this package
                reverse_excs = ()
                if context.rollback_enabled:
                    reverse_excs = UnlinkLinkTransaction._reverse_actions(axngroup)
                return CondaMultiError(tuple(concatv(
                    (e,),
                    (axngroup,),
                    reverse_excs,
                )))

    @staticmethod
    def _reverse_actions(axngroup, reverse_from_idx=-1):
        target_prefix = axngroup.target_prefix

        # reverse_from_idx = -1 means reverse all actions
        prec = axngroup.pkg_data

        if axngroup.type == 'unlink':
            log.info("===> REVERSING PACKAGE UNLINK: %s <===\n"
                     "  prefix=%s\n", prec.dist_str(), target_prefix)

        elif axngroup.type == 'link':
            log.info("===> REVERSING PACKAGE LINK: %s <===\n"
                     "  prefix=%s\n", prec.dist_str(), target_prefix)

        exceptions = []
        if reverse_from_idx < 0:
            reverse_actions = axngroup.actions
        else:
            reverse_actions = axngroup.actions[:reverse_from_idx+1]
        for axn_idx, action in reversed(tuple(enumerate(reverse_actions))):
            try:
                action.reverse()
            except Exception as e:
                log.debug("action.reverse() error in action %r", action, exc_info=True)
                exceptions.append(e)
        return exceptions

    @staticmethod
    def _get_python_version(target_prefix, pcrecs_to_unlink, packages_info_to_link):
        # this method determines the python version that will be present at the
        # end of the transaction
        linking_new_python = next((package_info for package_info in packages_info_to_link
                                   if package_info.repodata_record.name == 'python'),
                                  None)
        if linking_new_python:
            # is python being linked? we're done
            full_version = linking_new_python.repodata_record.version
            assert full_version
            log.debug("found in current transaction python version %s", full_version)
            return get_major_minor_version(full_version)

        # is python already linked and not being unlinked? that's ok too
        linked_python_version = get_python_version_for_prefix(target_prefix)
        if linked_python_version:
            find_python = (lnkd_pkg_data for lnkd_pkg_data in pcrecs_to_unlink
                           if lnkd_pkg_data.name == 'python')
            unlinking_this_python = next(find_python, None)
            if unlinking_this_python is None:
                # python is not being unlinked
                log.debug("found in current prefix python version %s", linked_python_version)
                return linked_python_version

        # there won't be any python in the finished environment
        log.debug("no python version found in prefix")
        return None

    @staticmethod
    def _make_link_actions(transaction_context, package_info, target_prefix, requested_link_type,
                           requested_spec):
        required_quad = transaction_context, package_info, target_prefix, requested_link_type

        file_link_actions = LinkPathAction.create_file_link_actions(*required_quad)
        create_directory_actions = LinkPathAction.create_directory_actions(
            *required_quad, file_link_actions=file_link_actions
        )
        create_nonadmin_actions = CreateNonadminAction.create_actions(*required_quad)

        # if requested_spec:
        #     application_entry_point_actions = CreateApplicationEntryPointAction.create_actions(
        #         *required_quad
        #     )
        #     application_softlink_actions = CreateApplicationSoftlinkAction.create_actions(
        #         *required_quad
        #     )
        # else:
        #     application_entry_point_actions = ()
        #     application_softlink_actions = ()
        # leased_paths = tuple(axn.leased_path_entry for axn in concatv(
        #     application_entry_point_actions,
        #     application_softlink_actions,
        # ))

        # if requested_spec:
        #     register_private_env_actions = RegisterPrivateEnvAction.create_actions(
        #         transaction_context, package_info, target_prefix, requested_spec, leased_paths
        #     )
        # else:
        #     register_private_env_actions = ()

        # the ordering here is significant
        return tuple(concatv(
            create_directory_actions,
            file_link_actions,
            create_nonadmin_actions,
            # application_entry_point_actions,
            # register_private_env_actions,
        ))

    @staticmethod
    def _make_entry_point_actions(transaction_context, package_info, target_prefix,
                                  requested_link_type, requested_spec, link_action_groups):
        required_quad = transaction_context, package_info, target_prefix, requested_link_type
        return CreatePythonEntryPointAction.create_actions(*required_quad)

    @staticmethod
    def _make_compile_actions(transaction_context, package_info, target_prefix,
                              requested_link_type, requested_spec, link_action_groups):
        required_quad = transaction_context, package_info, target_prefix, requested_link_type
        link_action_group = next(ag for ag in link_action_groups if ag.pkg_data == package_info)
        return CompileMultiPycAction.create_actions(*required_quad,
                                                    file_link_actions=link_action_group.actions)

    def _make_legacy_action_groups(self):
        # this code reverts json output for plan back to previous behavior
        #   relied on by Anaconda Navigator and nb_conda
        legacy_action_groups = []

        if self._pfe is None:
            self._get_pfe()

        for q, (prefix, setup) in enumerate(iteritems(self.prefix_setups)):
            actions = defaultdict(list)
            if q == 0:
                self._pfe.prepare()
                download_urls = set(axn.url for axn in self._pfe.cache_actions)
                actions['FETCH'].extend(prec for prec in self._pfe.link_precs
                                        if prec.url in download_urls)

            actions['PREFIX'] = setup.target_prefix
            for prec in setup.unlink_precs:
                actions['UNLINK'].append(prec)
            for prec in setup.link_precs:
                # TODO (AV): maybe add warnings about unverified packages here;
                # be warned that doing so may break compatibility with other
                # applications.
                actions['LINK'].append(prec)

            legacy_action_groups.append(actions)

        return legacy_action_groups

    def print_transaction_summary(self):
        legacy_action_groups = self._make_legacy_action_groups()

        download_urls = set(axn.url for axn in self._pfe.cache_actions)

        for actions, (prefix, stp) in zip(legacy_action_groups, iteritems(self.prefix_setups)):
            change_report = self._calculate_change_report(prefix, stp.unlink_precs, stp.link_precs,
                                                          download_urls, stp.remove_specs,
                                                          stp.update_specs)
            change_report_str = self._change_report_str(change_report)
            print(ensure_text_type(change_report_str))

        return legacy_action_groups

    def _change_report_str(self, change_report):
        # TODO (AV): add warnings about unverified packages in this function
        builder = ['', '## Package Plan ##\n']
        builder.append('  environment location: %s' % change_report.prefix)
        builder.append('')
        if change_report.specs_to_remove:
            builder.append('  removed specs:%s'
                           % dashlist(sorted(text_type(s) for s in change_report.specs_to_remove),
                                      indent=4))
            builder.append('')
        if change_report.specs_to_add:
            builder.append('  added / updated specs:%s'
                           % dashlist(sorted(text_type(s) for s in change_report.specs_to_add),
                                      indent=4))
            builder.append('')

        def channel_filt(s):
            if context.show_channel_urls is False:
                return ''
            if context.show_channel_urls is None and s == DEFAULTS_CHANNEL_NAME:
                return ''
            return s

        def print_dists(dists_extras):
            lines = []
            fmt = "    %-27s|%17s"
            lines.append(fmt % ('package', 'build'))
            lines.append(fmt % ('-' * 27, '-' * 17))
            for prec, extra in dists_extras:
                line = fmt % (strip_global(prec.namekey) + '-' + prec.version, prec.build)
                if extra:
                    line += extra
                lines.append(line)
            return lines

        convert_namekey = lambda x: ("0:" + x[7:]) if x.startswith("global:") else x
        strip_global = lambda x: x[7:] if x.startswith("global:") else x

        if change_report.fetch_precs:
            builder.append("\nThe following packages will be downloaded:\n")

            disp_lst = []
            total_download_bytes = 0
            for prec in sorted(change_report.fetch_precs,
                               key=lambda x: convert_namekey(x.namekey)):
                size = prec.size
                extra = '%15s' % human_bytes(size)
                total_download_bytes += size
                schannel = channel_filt(text_type(prec.channel.canonical_name))
                if schannel:
                    extra += '  ' + schannel
                disp_lst.append((prec, extra))
            builder.extend(print_dists(disp_lst))

            builder.append(' ' * 4 + '-' * 60)
            builder.append(" " * 43 + "Total: %14s" % human_bytes(total_download_bytes))

        def diff_strs(unlink_prec, link_prec):
            channel_change = unlink_prec.channel.name != link_prec.channel.name
            subdir_change = unlink_prec.subdir != link_prec.subdir
            version_change = unlink_prec.version != link_prec.version
            build_change = unlink_prec.build != link_prec.build

            builder_left = []
            builder_right = []

            if channel_change or subdir_change:
                if unlink_prec.channel.name is not None:
                    builder_left.append(unlink_prec.channel.name)
                if link_prec.channel.name is not None:
                    builder_right.append(link_prec.channel.name)
            if subdir_change:
                builder_left.append("/" + unlink_prec.subdir)
                builder_right.append("/" + link_prec.subdir)
            if (channel_change or subdir_change) and (version_change or build_change):
                builder_left.append("::" + unlink_prec.name + "-")
                builder_right.append("::" + link_prec.name + "-")
            if version_change or build_change:
                builder_left.append(unlink_prec.version + "-" + unlink_prec.build)
                builder_right.append(link_prec.version + "-" + link_prec.build)

            return ''.join(builder_left), ''.join(builder_right)

        def add_single(display_key, disp_str):
            if len(display_key) > 18:
                display_key = display_key[:17] + "~"
            builder.append("  %-18s %s" % (display_key, disp_str))

        def add_double(display_key, left_str, right_str):
            if len(display_key) > 18:
                display_key = display_key[:17] + "~"
            if len(left_str) > 38:
                left_str = left_str[:37] + "~"
            builder.append("  %-18s %38s --> %s" % (display_key, left_str, right_str))

        def fmt_sig_status(prec):
            if not context.extra_safety_checks:
                return ""

            status = getattr(prec, "metadata_signature_status", None)
            if not context.extra_safety_checks or status is None:
                # TODO (AV): deal with virtual packages more sensibly
                status_str = ""
            elif status == MetadataSignatureStatus.verified:
                # TODO (AV): replaced hard-coded signer name with data from key
                status_str = " (INFO: package metadata is signed by Anaconda and trusted)"
            elif status == MetadataSignatureStatus.unsigned:
                status_str = ""
            else:
                status_str = " (WARNING: metadata signature verification failed)"
            return status_str

        if change_report.new_precs:
            builder.append("\nThe following NEW packages will be INSTALLED:\n")
            for namekey in sorted(change_report.new_precs, key=convert_namekey):
                link_prec = change_report.new_precs[namekey]
                display_key = strip_global(namekey)
                display_str = link_prec.record_id() + fmt_sig_status(link_prec)
                add_single(display_key, display_str)

        if change_report.removed_precs:
            builder.append("\nThe following packages will be REMOVED:\n")
            for namekey in sorted(change_report.removed_precs, key=convert_namekey):
                unlink_prec = change_report.removed_precs[namekey]
                builder.append("  " + "-".join(
                    (unlink_prec.name, unlink_prec.version, unlink_prec.build)
                ))

        if change_report.updated_precs:
            builder.append("\nThe following packages will be UPDATED:\n")
            for namekey in sorted(change_report.updated_precs, key=convert_namekey):
                unlink_prec, link_prec = change_report.updated_precs[namekey]
                display_key = strip_global(namekey)
                left_str, right_str = diff_strs(unlink_prec, link_prec)
                right_str += fmt_sig_status(link_prec)
                add_double(display_key, left_str, right_str)

        if change_report.superseded_precs:
            builder.append("\nThe following packages will be SUPERSEDED "
                           "by a higher-priority channel:\n")
            for namekey in sorted(change_report.superseded_precs, key=convert_namekey):
                unlink_prec, link_prec = change_report.superseded_precs[namekey]
                display_key = strip_global(namekey)
                left_str, right_str = diff_strs(unlink_prec, link_prec)
                right_str += fmt_sig_status(link_prec)
                add_double(display_key, left_str, right_str)

        if change_report.downgraded_precs:
            builder.append("\nThe following packages will be DOWNGRADED:\n")
            for namekey in sorted(change_report.downgraded_precs, key=convert_namekey):
                unlink_prec, link_prec = change_report.downgraded_precs[namekey]
                display_key = strip_global(namekey)
                left_str, right_str = diff_strs(unlink_prec, link_prec)
                right_str += fmt_sig_status(link_prec)
                add_double(display_key, left_str, right_str)
        builder.append('')
        builder.append('')
        return "\n".join(builder)

    @staticmethod
    def _calculate_change_report(prefix, unlink_precs, link_precs, download_urls, specs_to_remove,
                                 specs_to_add):
        unlink_map = {prec.namekey: prec for prec in unlink_precs}
        link_map = {prec.namekey: prec for prec in link_precs}
        unlink_namekeys, link_namekeys = set(unlink_map), set(link_map)

        removed_precs = {namekey: unlink_map[namekey]
                         for namekey in (unlink_namekeys - link_namekeys)}
        new_precs = {namekey: link_map[namekey]
                     for namekey in (link_namekeys - unlink_namekeys)}

        # updated means a version increase, or a build number increase
        # downgraded means a version decrease, or build number decrease, but channel canonical_name
        #   has to be the same
        # superseded then should be everything else left over
        updated_precs = {}
        downgraded_precs = {}
        superseded_precs = {}

        common_namekeys = link_namekeys & unlink_namekeys
        for namekey in common_namekeys:
            unlink_prec, link_prec = unlink_map[namekey], link_map[namekey]
            unlink_vo = VersionOrder(unlink_prec.version)
            link_vo = VersionOrder(link_prec.version)
            build_number_increases = link_prec.build_number > unlink_prec.build_number
            if link_vo == unlink_vo and build_number_increases or link_vo > unlink_vo:
                updated_precs[namekey] = (unlink_prec, link_prec)
            elif (link_prec.channel.name == unlink_prec.channel.name
                    and link_prec.subdir == unlink_prec.subdir):
                if link_prec == unlink_prec:
                    # noarch: python packages are re-linked on a python version change
                    # just leave them out of the package report
                    continue
                downgraded_precs[namekey] = (unlink_prec, link_prec)
            else:
                superseded_precs[namekey] = (unlink_prec, link_prec)

        fetch_precs = set(prec for prec in link_precs if prec.url in download_urls)
        change_report = ChangeReport(prefix, specs_to_remove, specs_to_add, removed_precs,
                                     new_precs, updated_precs, downgraded_precs, superseded_precs,
                                     fetch_precs)
        return change_report


def run_script(prefix, prec, action='post-link', env_prefix=None, activate=False):
    """
    call the post-link (or pre-unlink) script, and return True on success,
    False on failure
    """
    path = join(prefix,
                'Scripts' if on_win else 'bin',
                '.%s-%s.%s' % (prec.name, action, 'bat' if on_win else 'sh'))
    if not isfile(path):
        return True

    env = os.environ.copy()

    if action == 'pre-link':  # pragma: no cover
        # old no-arch support; deprecated
        is_old_noarch = False
        try:
            with open(path) as f:
                script_text = ensure_text_type(f.read())
            if ((on_win and "%PREFIX%\\python.exe %SOURCE_DIR%\\link.py" in script_text)
                    or "$PREFIX/bin/python $SOURCE_DIR/link.py" in script_text):
                is_old_noarch = True
        except Exception as e:
            log.debug(e, exc_info=True)

        env['SOURCE_DIR'] = prefix
        if not is_old_noarch:
            warnings.warn(dals("""
            Package %s uses a pre-link script. Pre-link scripts are potentially dangerous.
            This is because pre-link scripts have the ability to change the package contents in the
            package cache, and therefore modify the underlying files for already-created conda
            environments.  Future versions of conda may deprecate and ignore pre-link scripts.
            """) % prec.dist_str())

    script_caller = None
    if on_win:
        try:
            comspec = get_comspec()  # fail early with KeyError if undefined
        except KeyError:
            log.info("failed to run %s for %s due to COMSPEC KeyError", action, prec.dist_str())
            return False
        if activate:
            script_caller, command_args = wrap_subprocess_call(
                context.root_prefix,
                prefix,
                context.dev,
                False,
                ("@CALL", path),
            )
        else:
            command_args = [comspec, '/d', '/c', path]
    else:
        shell_path = 'sh' if 'bsd' in sys.platform else 'bash'
        if activate:
            script_caller, command_args = wrap_subprocess_call(
                context.root_prefix,
                prefix,
                context.dev,
                False,
                (".", path),
            )
        else:
            shell_path = 'sh' if 'bsd' in sys.platform else 'bash'
            command_args = [shell_path, "-x", path]

    env['ROOT_PREFIX'] = context.root_prefix
    env['PREFIX'] = env_prefix or prefix
    env['PKG_NAME'] = prec.name
    env['PKG_VERSION'] = prec.version
    env['PKG_BUILDNUM'] = prec.build_number
    env['PATH'] = os.pathsep.join((dirname(path), env.get('PATH', '')))

    log.debug("for %s at %s, executing script: $ %s",
              prec.dist_str(), env['PREFIX'], ' '.join(command_args))
    try:
        response = subprocess_call(command_args, env=env, path=dirname(path), raise_on_error=False)
        if response.rc != 0:
            m = messages(prefix)
            if action in ('pre-link', 'post-link'):
                if 'openssl' in prec.dist_str():
                    # this is a hack for conda-build string parsing in the conda_build/build.py
                    #   create_env function
                    message = "%s failed for: %s" % (action, prec)
                else:
                    message = dals("""
                    %s script failed for package %s
                    location of failed script: %s
                    ==> script messages <==
                    %s
                    ==> script output <==
                    stdout: %s
                    stderr: %s
                    return code: %s
                    """) % (action, prec.dist_str(), path, m or "<None>",
                            response.stdout, response.stderr, response.rc)
                raise LinkError(message)
            else:
                log.warn("%s script failed for package %s\n"
                         "consider notifying the package maintainer", action, prec.dist_str())
                return False
        else:
            messages(prefix)
            return True
    finally:
        if script_caller is not None:
            if 'CONDA_TEST_SAVE_TEMPS' not in os.environ:
                rm_rf(script_caller)
            else:
                log.warning('CONDA_TEST_SAVE_TEMPS :: retaining run_script {}'.format(
                    script_caller))


def messages(prefix):
    path = join(prefix, '.messages.txt')
    try:
        if isfile(path):
            with open(path) as fi:
                m = fi.read()
                if hasattr(m, "decode"):
                    m = m.decode('utf-8')
                print(m, file=sys.stderr if context.json else sys.stdout)
                return m
    finally:
        rm_rf(path)
