from __future__ import unicode_literals

import abc
from collections import OrderedDict
from contextlib import contextmanager
from hashlib import md5
from typing import Text, Iterable, Union, Optional, Dict, List

from ..._vendor import six
from ..._vendor.pathlib2 import Path

from clearml_agent.definitions import ENV_VENV_CACHE_PATH
from clearml_agent.helper.base import mkstemp, safe_remove_file, join_lines, select_for_platform
from clearml_agent.helper.console import ensure_binary
from clearml_agent.helper.os.folder_cache import FolderCache
from clearml_agent.helper.process import Executable, Argv, PathLike


@six.add_metaclass(abc.ABCMeta)
class PackageManager(object):
    """
    ABC for classes providing python package management interface
    """

    _selected_manager = None
    _cwd = None
    _pip_version = None
    _config_cache_folder = 'agent.venvs_cache.path'
    _config_cache_max_entries = 'agent.venvs_cache.max_entries'
    _config_cache_free_space_threshold = 'agent.venvs_cache.free_space_threshold_gb'
    _config_cache_lock_timeout = 'agent.venvs_cache.lock_timeout'
    _config_pip_legacy_resolver = 'agent.package_manager.pip_legacy_resolver'

    def __init__(self):
        self._cache_manager = None
        self._existing_packages = []
        self._base_install_flags = []

    @abc.abstractproperty
    def bin(self):
        # type: () -> PathLike
        pass

    @abc.abstractmethod
    def create(self):
        pass

    @abc.abstractmethod
    def remove(self):
        pass

    @abc.abstractmethod
    def install_from_file(self, path):
        pass

    @abc.abstractmethod
    def freeze(self, freeze_full_environment=False):
        pass

    @abc.abstractmethod
    def load_requirements(self, requirements):
        pass

    @abc.abstractmethod
    def install_packages(self, *packages):
        # type: (Iterable[Text]) -> None
        """
        Install packages, upgrading depends on config
        """
        pass

    @abc.abstractmethod
    def _install(self, *packages):
        # type: (Iterable[Text]) -> None
        """
        Run install command
        """
        pass

    @abc.abstractmethod
    def uninstall_packages(self, *packages):
        # type: (Iterable[Text]) -> None
        pass

    def add_extra_install_flags(self, extra_flags):  # type: (List[str]) -> None
        if extra_flags:
            extra_flags = [
                e for e in extra_flags if e not in list(self._base_install_flags)
            ]
            self._base_install_flags = list(self._base_install_flags) + list(extra_flags)

    def remove_extra_install_flags(self, extra_flags):  # type: (List[str]) -> bool
        if extra_flags:
            _base_install_flags = [
                e for e in self._base_install_flags if e not in list(extra_flags)
            ]
            if self._base_install_flags != _base_install_flags:
                self._base_install_flags = _base_install_flags
                return True
        return False

    def upgrade_pip(self):
        result = self._install(
            *select_for_platform(
                windows=self.get_pip_versions(),
                linux=self.get_pip_versions()
            ),
            "--upgrade"
        )

        packages = (self.freeze(freeze_full_environment=True) or dict()).get("pip")
        if packages:
            from clearml_agent.helper.package.requirements import RequirementsManager
            from .requirements import MarkerRequirement, SimpleVersion

            # store existing packages so that we can check if we can skip preinstalled packages
            # we will only check "@ file" "@ vcs" for exact match
            self._existing_packages = RequirementsManager.parse_requirements_section_to_marker_requirements(
                packages, skip_local_file_validation=True)

            try:
                pip_pkg = next(p for p in self._existing_packages if p.name == "pip")
            except StopIteration:
                pip_pkg = None

            # check if we need to list the pip version as well
            if pip_pkg:
                MarkerRequirement.pip_new_version = SimpleVersion.compare_versions(pip_pkg.version, ">=", "20")

            # add --use-deprecated=legacy-resolver to pip install to avoid mismatched packages issues
            self._add_legacy_resolver_flag(pip_pkg.version)

        return result

    def _add_legacy_resolver_flag(self, pip_pkg_version):
        if not self.session.config.get(self._config_pip_legacy_resolver, None):
            return

        from .requirements import SimpleVersion

        match_versions = self.session.config.get(self._config_pip_legacy_resolver)
        matched = False
        for rule in match_versions:
            matched = False
            # make sure we match all the parts of the rule
            for a_version in rule.split(","):
                o, v = SimpleVersion.split_op_version(a_version.strip())
                matched = SimpleVersion.compare_versions(pip_pkg_version, o, v)
                if not matched:
                    break
            # if the rule is fully matched we have a match
            if matched:
                break

        legacy_resolver_flags = ["--use-deprecated=legacy-resolver"]
        if matched:
            print("INFO: Using legacy resolver for PIP to avoid inconsistency with package versions!")
            self.add_extra_install_flags(legacy_resolver_flags)
        elif self.remove_extra_install_flags(legacy_resolver_flags):
            print("INFO: removing pip legacy resolver!")

    def get_python_command(self, extra=()):
        # type: (...) -> Executable
        return Argv(self.bin, *extra)

    @contextmanager
    def temp_file(self, prefix, contents, suffix=".txt"):
        # type: (Union[Text, Iterable[Text]], Iterable[Text], Text) -> Text
        """
        Write contents to a temporary file, yielding its path. Finally, delete it.
        :param prefix: file name prefix
        :param contents: text lines to write
        :param suffix: file name suffix
        """
        f, temp_path = mkstemp(suffix=suffix, prefix=prefix)
        with f:
            f.write(
                contents
                if isinstance(contents, six.text_type)
                else join_lines(contents)
            )
        try:
            yield temp_path
        finally:
            if not self.session.debug_mode:
                safe_remove_file(temp_path)

    def set_selected_package_manager(self):
        # set this instance as the selected package manager
        # this is helpful when we want out of context requirement installations
        PackageManager._selected_manager = self

    @property
    def cwd(self):
        return self._cwd

    @cwd.setter
    def cwd(self, value):
        self._cwd = value

    @classmethod
    def out_of_scope_install_package(cls, package_name, *args):
        if PackageManager._selected_manager is not None:
            # noinspection PyBroadException
            try:
                result = PackageManager._selected_manager.install_packages(package_name, *args)
                if result not in (0, None, True):
                    return False
            except Exception:
                return False

            try:
                from .requirements import Requirement, MarkerRequirement
                req = MarkerRequirement(Requirement.parse(package_name))

                # if pip was part of the requirements, make sure we update the flags
                # add --use-deprecated=legacy-resolver to pip install to avoid mismatched packages issues
                if req.name == "pip" and req.version:
                    PackageManager._selected_manager._add_legacy_resolver_flag(req.version)
            except Exception as e:
                print("WARNING: Error while parsing pip version legacy [{}]".format(e))

        return True

    @classmethod
    def out_of_scope_freeze(cls, freeze_full_environment=False):
        if PackageManager._selected_manager is not None:
            # noinspection PyBroadException
            try:
                return PackageManager._selected_manager.freeze(freeze_full_environment)
            except Exception:
                pass
        return []

    @classmethod
    def set_pip_version(cls, version):
        if not version:
            return

        if isinstance(version, (list, tuple)):
            versions = version
        else:
            versions = [version]

        cls._pip_version = []
        for version in versions:
            version = version.strip()
            if ('=' in version) or ('~' in version) or ('<' in version) or ('>' in version):
                cls._pip_version.append(version)
            else:
                cls._pip_version.append("==" + version)

    @classmethod
    def get_pip_versions(cls, pip="pip", wrap=''):
        return [
            (wrap + pip + version + wrap)
            for version in cls._pip_version or [""]
        ]

    def get_cached_venv(self, requirements, docker_cmd, python_version, cuda_version, destination_folder):
        # type: (Dict, Optional[Union[dict, str]], Optional[str], Optional[str], Path) -> Optional[Path]
        """
        Copy a cached copy of the venv (based on the requirements) into destination_folder.
        Return None if failed or cached entry does not exist
        """
        if not self._get_cache_manager():
            return None

        try:
            keys = self._generate_reqs_hash_keys(requirements, docker_cmd, python_version, cuda_version)
            return self._get_cache_manager().copy_cached_entry(keys, destination_folder)
        except Exception as ex:
            print("WARNING: Failed accessing venvs cache at {}: {}".format(destination_folder, ex))
            print("WARNING: Skipping venv cache - folder not accessible!")
            return None

    def add_cached_venv(
            self,
            requirements,  # type: Union[Dict, List[Dict]]
            docker_cmd,   # type: Optional[Union[dict, str]]
            python_version,  # type: Optional[str]
            cuda_version,  # type: Optional[str]
            source_folder,  # type:  Path
            exclude_sub_folders=None  # type: Optional[List[str]]
    ):
        # type: (...) -> ()
        """
        Copy the local venv folder into the venv cache (keys are based on the requirements+python+docker).
        """
        if not self._get_cache_manager():
            return

        print('Adding venv into cache: {}'.format(source_folder))

        try:
            keys = self._generate_reqs_hash_keys(requirements, docker_cmd, python_version, cuda_version)
            return self._get_cache_manager().add_entry(
                keys=keys, source_folder=source_folder, exclude_sub_folders=exclude_sub_folders)
        except Exception as ex:
            print("WARNING: Failed accessing venvs cache at {}: {}".format(source_folder, ex))
            print("WARNING: Skipping venv cache - folder not accessible!")
            return None

    def get_cache_folder(self):
        # type: () -> Optional[Path]
        if not self._get_cache_manager():
            return
        return self._get_cache_manager().get_cache_folder()

    def get_last_used_entry_cache(self):
        # type: () -> Optional[Path]
        """
        :return: the last used cached folder entry
        """
        if not self._get_cache_manager():
            return
        return self._get_cache_manager().get_last_copied_entry()

    def is_cached_enabled(self):
        if not self._cache_manager:
            cache_folder = ENV_VENV_CACHE_PATH.get() or self.session.config.get(self._config_cache_folder, None)
            if not cache_folder:
                return False
        return True

    @classmethod
    def _generate_reqs_hash_keys(cls, requirements_list, docker_cmd, python_version, cuda_version):
        # type: (Union[Dict, List[Dict]], Optional[Union[dict, str]], Optional[str], Optional[str]) -> List[str]
        requirements_list = requirements_list or dict()
        if not isinstance(requirements_list, (list, tuple)):
            requirements_list = [requirements_list]
        docker_cmd = dict(docker_cmd=docker_cmd) if isinstance(docker_cmd, str) else docker_cmd or dict()
        docker_cmd = OrderedDict(sorted(docker_cmd.items(), key=lambda t: t[0]))
        if 'docker_cmd' in docker_cmd:
            # we only take the first part of the docker_cmd which is the docker image name
            docker_cmd['docker_cmd'] = docker_cmd['docker_cmd'].strip('\r\n\t ').split(' ')[0]

        keys = []
        strip_chars = '\n\r\t '
        for requirements in requirements_list:
            pip, conda = ('pip', 'conda')
            pip_reqs = requirements.get(pip, '')
            conda_reqs = requirements.get(conda, '')
            if isinstance(pip_reqs, str):
                pip_reqs = pip_reqs.split('\n')
            if isinstance(conda_reqs, str):
                conda_reqs = conda_reqs.split('\n')
            pip_reqs = sorted([p.strip(strip_chars) for p in pip_reqs
                               if p.strip(strip_chars) and not p.strip(strip_chars).startswith('#')])
            conda_reqs = sorted([p.strip(strip_chars) for p in conda_reqs
                                 if p.strip(strip_chars) and not p.strip(strip_chars).startswith('#')])
            if not pip_reqs and not conda_reqs:
                continue
            # do not process "-r" or "--requirement" because we cannot know what we have in the git repo.
            if any(r.strip().startswith('-r ') or r.strip().startswith('--requirement ') for r in pip_reqs):
                continue
            hash_text = '{class_type}\n{docker_cmd}\n{cuda_ver}\n{python_version}\n{pip_reqs}\n{conda_reqs}'.format(
                class_type=str(cls),
                docker_cmd=str(docker_cmd or ''),
                cuda_ver=str(cuda_version or ''),
                python_version=str(python_version or ''),
                pip_reqs=str(pip_reqs or ''),
                conda_reqs=str(conda_reqs or ''),
            )
            keys.append(md5(ensure_binary(hash_text)).hexdigest())
        return sorted(list(set(keys)))

    def _get_cache_manager(self):
        if not self._cache_manager:
            cache_folder = None
            try:
                cache_folder = ENV_VENV_CACHE_PATH.get() or self.session.config.get(self._config_cache_folder, None)
                if not cache_folder:
                    return None

                max_entries = int(self.session.config.get(self._config_cache_max_entries, 10))
                free_space_threshold = float(self.session.config.get(self._config_cache_free_space_threshold, 0))
                self._cache_manager = FolderCache(
                    cache_folder, max_cache_entries=max_entries,
                    min_free_space_gb=free_space_threshold,
                    lock_timeout_seconds=self.session.config.get(self._config_cache_lock_timeout, None))
            except Exception as ex:
                print("WARNING: Failed accessing venvs cache at {}: {}".format(cache_folder, ex))
                print("WARNING: Skipping venv cache - folder not accessible!")
                return None

        return self._cache_manager