# Copyright (C) 2012 Anaconda, Inc
# SPDX-License-Identifier: BSD-3-Clause
import json
from logging import getLogger
import os
from os.path import basename, isdir, isfile, join, lexists
import re

from ..base.constants import PREFIX_STATE_FILE
from ..auxlib.exceptions import ValidationError
from ..base.constants import CONDA_PACKAGE_EXTENSIONS, PREFIX_MAGIC_FILE, CONDA_ENV_VARS_UNSET_VAR
from ..base.context import context
from ..common.constants import NULL
from ..common.io import time_recorder
from ..common.path import get_python_site_packages_short_path, win_path_ok
from ..common.pkg_formats.python import get_site_packages_anchor_files
from ..common.serialize import json_load
from ..exceptions import (
    BasicClobberError, CondaDependencyError, CorruptedEnvironmentError, maybe_raise,
)
from ..gateways.disk.create import write_as_json_to_file
from ..gateways.disk.delete import rm_rf
from ..gateways.disk.read import read_python_record
from ..gateways.disk.test import file_path_is_writable
from ..models.match_spec import MatchSpec
from ..models.prefix_graph import PrefixGraph
from ..models.records import PackageRecord, PrefixRecord

log = getLogger(__name__)


class PrefixDataType(type):
    """Basic caching of PrefixData instance objects."""

    def __call__(cls, prefix_path, pip_interop_enabled=None):
        if prefix_path in PrefixData._cache_:
            return PrefixData._cache_[prefix_path]
        elif isinstance(prefix_path, PrefixData):
            return prefix_path
        else:
            prefix_data_instance = super().__call__(prefix_path, pip_interop_enabled)
            PrefixData._cache_[prefix_path] = prefix_data_instance
            return prefix_data_instance


class PrefixData(metaclass=PrefixDataType):
    _cache_ = {}

    def __init__(self, prefix_path, pip_interop_enabled=None):
        # pip_interop_enabled is a temporary parameter; DO NOT USE
        # TODO: when removing pip_interop_enabled, also remove from meta class
        self.prefix_path = prefix_path
        self.__prefix_records = None
        self.__is_writable = NULL
        self._pip_interop_enabled = (pip_interop_enabled
                                     if pip_interop_enabled is not None
                                     else context.pip_interop_enabled)

    @time_recorder(module_name=__name__)
    def load(self):
        self.__prefix_records = {}
        _conda_meta_dir = join(self.prefix_path, 'conda-meta')
        if lexists(_conda_meta_dir):
            conda_meta_json_paths = (
                p for p in
                (entry.path for entry in os.scandir(_conda_meta_dir))
                if p[-5:] == ".json"
            )
            for meta_file in conda_meta_json_paths:
                self._load_single_record(meta_file)
        if self._pip_interop_enabled:
            self._load_site_packages()

    def reload(self):
        self.load()
        return self

    def _get_json_fn(self, prefix_record):
        fn = prefix_record.fn
        known_ext = False
        # .dist-info is for things installed by pip
        for ext in CONDA_PACKAGE_EXTENSIONS + ('.dist-info',):
            if fn.endswith(ext):
                fn = fn.replace(ext, '')
                known_ext = True
        if not known_ext:
            raise ValueError("Attempted to make prefix record for unknown package type: %s" % fn)
        return fn + '.json'

    def insert(self, prefix_record):
        assert prefix_record.name not in self._prefix_records, \
            "Prefix record insertion error: a record with name %s already exists " \
            "in the prefix. This is a bug in conda. Please report it at " \
            "https://github.com/conda/conda/issues" % prefix_record.name

        prefix_record_json_path = join(self.prefix_path, 'conda-meta',
                                       self._get_json_fn(prefix_record))
        if lexists(prefix_record_json_path):
            maybe_raise(BasicClobberError(
                source_path=None,
                target_path=prefix_record_json_path,
                context=context,
            ), context)
            rm_rf(prefix_record_json_path)

        write_as_json_to_file(prefix_record_json_path, prefix_record)

        self._prefix_records[prefix_record.name] = prefix_record

    def remove(self, package_name):
        assert package_name in self._prefix_records

        prefix_record = self._prefix_records[package_name]

        prefix_record_json_path = join(self.prefix_path, 'conda-meta',
                                       self._get_json_fn(prefix_record))
        conda_meta_full_path = join(self.prefix_path, 'conda-meta', prefix_record_json_path)
        if self.is_writable:
            rm_rf(conda_meta_full_path)

        del self._prefix_records[package_name]

    def get(self, package_name, default=NULL):
        try:
            return self._prefix_records[package_name]
        except KeyError:
            if default is not NULL:
                return default
            else:
                raise

    def iter_records(self):
        return iter(self._prefix_records.values())

    def iter_records_sorted(self):
        prefix_graph = PrefixGraph(self.iter_records())
        return iter(prefix_graph.graph)

    def all_subdir_urls(self):
        subdir_urls = set()
        for prefix_record in self.iter_records():
            subdir_url = prefix_record.channel.subdir_url
            if subdir_url and subdir_url not in subdir_urls:
                log.debug("adding subdir url %s for %s", subdir_url, prefix_record)
                subdir_urls.add(subdir_url)
        return subdir_urls

    def query(self, package_ref_or_match_spec):
        # returns a generator
        param = package_ref_or_match_spec
        if isinstance(param, str):
            param = MatchSpec(param)
        if isinstance(param, MatchSpec):
            return (prefix_rec for prefix_rec in self.iter_records()
                    if param.match(prefix_rec))
        else:
            assert isinstance(param, PackageRecord)
            return (prefix_rec for prefix_rec in self.iter_records() if prefix_rec == param)

    @property
    def _prefix_records(self):
        return self.__prefix_records or self.load() or self.__prefix_records

    def _load_single_record(self, prefix_record_json_path):
        log.debug("loading prefix record %s", prefix_record_json_path)
        with open(prefix_record_json_path) as fh:
            try:
                json_data = json_load(fh.read())
            except (UnicodeDecodeError, json.JSONDecodeError):
                # UnicodeDecodeError: catch horribly corrupt files
                # JSONDecodeError: catch bad json format files
                raise CorruptedEnvironmentError(self.prefix_path, prefix_record_json_path)

            # TODO: consider, at least in memory, storing prefix_record_json_path as part
            #       of PrefixRecord
            prefix_record = PrefixRecord(**json_data)

            # check that prefix record json filename conforms to name-version-build
            # apparently implemented as part of #2638 to resolve #2599
            try:
                n, v, b = basename(prefix_record_json_path)[:-5].rsplit('-', 2)
                if (n, v, b) != (prefix_record.name, prefix_record.version, prefix_record.build):
                    raise ValueError()
            except ValueError:
                log.warn("Ignoring malformed prefix record at: %s", prefix_record_json_path)
                # TODO: consider just deleting here this record file in the future
                return

            self.__prefix_records[prefix_record.name] = prefix_record

    @property
    def is_writable(self):
        if self.__is_writable == NULL:
            test_path = join(self.prefix_path, PREFIX_MAGIC_FILE)
            if not isfile(test_path):
                is_writable = None
            else:
                is_writable = file_path_is_writable(test_path)
            self.__is_writable = is_writable
        return self.__is_writable

    # # REMOVE: ?
    def _has_python(self):
        return 'python' in self._prefix_records

    @property
    def _python_pkg_record(self):
        """Return the prefix record for the package python."""
        return next(
            (prefix_record for prefix_record in self.__prefix_records.values()
             if prefix_record.name == 'python'),
            None
        )

    def _load_site_packages(self):
        """
        Load non-conda-installed python packages in the site-packages of the prefix.

        Python packages not handled by conda are installed via other means,
        like using pip or using python setup.py develop for local development.

        Packages found that are not handled by conda are converted into a
        prefix record and handled in memory.

        Packages clobbering conda packages (i.e. the conda-meta record) are
        removed from the in memory representation.
        """
        python_pkg_record = self._python_pkg_record

        if not python_pkg_record:
            return {}

        site_packages_dir = get_python_site_packages_short_path(python_pkg_record.version)
        site_packages_path = join(self.prefix_path, win_path_ok(site_packages_dir))

        if not isdir(site_packages_path):
            return {}

        # Get anchor files for corresponding conda (handled) python packages
        prefix_graph = PrefixGraph(self.iter_records())
        python_records = prefix_graph.all_descendants(python_pkg_record)
        conda_python_packages = get_conda_anchor_files_and_records(
            site_packages_dir, python_records
        )

        # Get all anchor files and compare against conda anchor files to find clobbered conda
        # packages and python packages installed via other means (not handled by conda)
        sp_anchor_files = get_site_packages_anchor_files(site_packages_path, site_packages_dir)
        conda_anchor_files = set(conda_python_packages)
        clobbered_conda_anchor_files = conda_anchor_files - sp_anchor_files
        non_conda_anchor_files = sp_anchor_files - conda_anchor_files

        # If there's a mismatch for anchor files between what conda expects for a package
        # based on conda-meta, and for what is actually in site-packages, then we'll delete
        # the in-memory record for the conda package.  In the future, we should consider
        # also deleting the record on disk in the conda-meta/ directory.
        for conda_anchor_file in clobbered_conda_anchor_files:
            prefix_rec = self._prefix_records.pop(conda_python_packages[conda_anchor_file].name)
            try:
                extracted_package_dir = basename(prefix_rec.extracted_package_dir)
            except AttributeError:
                extracted_package_dir = "-".join((
                    prefix_rec.name, prefix_rec.version, prefix_rec.build
                ))
            prefix_rec_json_path = join(
                self.prefix_path, "conda-meta", '%s.json' % extracted_package_dir
            )
            try:
                rm_rf(prefix_rec_json_path)
            except OSError:
                log.debug("stale information, but couldn't remove: %s", prefix_rec_json_path)
            else:
                log.debug("removed due to stale information: %s", prefix_rec_json_path)

        # Create prefix records for python packages not handled by conda
        new_packages = {}
        for af in non_conda_anchor_files:
            try:
                python_record = read_python_record(self.prefix_path, af, python_pkg_record.version)
            except OSError as e:
                log.info("Python record ignored for anchor path '%s'\n  due to %s", af, e)
                continue
            except ValidationError:
                import sys
                exc_type, exc_value, exc_traceback = sys.exc_info()
                import traceback
                tb = traceback.format_exception(exc_type, exc_value, exc_traceback)
                log.warn("Problem reading non-conda package record at %s. Please verify that you "
                         "still need this, and if so, that this is still installed correctly. "
                         "Reinstalling this package may help.", af)
                log.debug("ValidationError: \n%s\n", "\n".join(tb))
                continue
            if not python_record:
                continue
            self.__prefix_records[python_record.name] = python_record
            new_packages[python_record.name] = python_record

        return new_packages

    def _get_environment_state_file(self):
        env_vars_file = join(self.prefix_path, PREFIX_STATE_FILE)
        if lexists(env_vars_file):
            with open(env_vars_file) as f:
                prefix_state = json.loads(f.read())
        else:
            prefix_state = {}
        return prefix_state

    def _write_environment_state_file(self, state):
        env_vars_file = join(self.prefix_path, PREFIX_STATE_FILE)
        with open(env_vars_file, 'w') as f:
            f.write(json.dumps(state, ensure_ascii=False, default=lambda x: x.__dict__))

    def get_environment_env_vars(self):
        prefix_state = self._get_environment_state_file()
        env_vars_all = dict(prefix_state.get("env_vars", {}))
        env_vars = {k: v for k, v in env_vars_all.items() if v != CONDA_ENV_VARS_UNSET_VAR}
        return env_vars

    def set_environment_env_vars(self, env_vars):
        env_state_file = self._get_environment_state_file()
        current_env_vars = env_state_file.get('env_vars')
        if current_env_vars:
            current_env_vars.update(env_vars)
        else:
            env_state_file['env_vars'] = env_vars
        self._write_environment_state_file(env_state_file)
        return env_state_file.get('env_vars')

    def unset_environment_env_vars(self, env_vars):
        env_state_file = self._get_environment_state_file()
        current_env_vars = env_state_file.get('env_vars')
        if current_env_vars:
            for env_var in env_vars:
                if env_var in current_env_vars.keys():
                    current_env_vars[env_var] = CONDA_ENV_VARS_UNSET_VAR
            self._write_environment_state_file(env_state_file)
        return env_state_file.get('env_vars')


def get_conda_anchor_files_and_records(site_packages_short_path, python_records):
    """Return the anchor files for the conda records of python packages."""
    anchor_file_endings = ('.egg-info/PKG-INFO', '.egg/EGG-INFO/PKG-INFO', '.dist-info/RECORD', '.egg-info')
    conda_python_packages = {}

    matcher = re.compile(
        r"^{}/[^/]+(?:{})$".format(
            re.escape(site_packages_short_path),
            r"|".join(re.escape(fn) for fn in anchor_file_endings)
        )
    ).match

    for prefix_record in python_records:
        anchor_paths = tuple(fpath for fpath in prefix_record.files if matcher(fpath))
        if len(anchor_paths) > 1:
            anchor_path = sorted(anchor_paths, key=len)[0]
            log.info("Package %s has multiple python anchor files.\n"
                     "  Using %s", prefix_record.record_id(), anchor_path)
            conda_python_packages[anchor_path] = prefix_record
        elif anchor_paths:
            conda_python_packages[anchor_paths[0]] = prefix_record

    return conda_python_packages


def get_python_version_for_prefix(prefix):
    # returns a string e.g. "2.7", "3.4", "3.5" or None
    py_record_iter = (rcrd for rcrd in PrefixData(prefix).iter_records() if rcrd.name == 'python')
    record = next(py_record_iter, None)
    if record is None:
        return None
    next_record = next(py_record_iter, None)
    if next_record is not None:
        raise CondaDependencyError("multiple python records found in prefix %s" % prefix)
    elif record.version[3].isdigit():
        return record.version[:4]
    else:
        return record.version[:3]


def delete_prefix_from_linked_data(path):
    '''Here, path may be a complete prefix or a dist inside a prefix'''
    linked_data_path = next((key for key in sorted(PrefixData._cache_, reverse=True)
                             if path.startswith(key)),
                            None)
    if linked_data_path:
        del PrefixData._cache_[linked_data_path]
        return True
    return False
