# Copyright (C) 2012 Anaconda, Inc
# SPDX-License-Identifier: BSD-3-Clause
"""Backend logic implementation for `conda doctor`."""

from __future__ import annotations

import json
import os
from logging import getLogger
from pathlib import Path

from requests.exceptions import RequestException

from ....base.context import context
from ....core.envs_manager import get_user_environments_txt_file
from ....exceptions import CondaError
from ....gateways.connection.session import get_session
from ....gateways.disk.read import compute_sum
from ... import CondaHealthCheck, hookimpl

logger = getLogger(__name__)

OK_MARK = "✅"
X_MARK = "❌"


def check_envs_txt_file(prefix: str | os.PathLike | Path) -> bool:
    """Checks whether the environment is listed in the environments.txt file"""
    prefix = Path(prefix)
    envs_txt_file = Path(get_user_environments_txt_file())

    def samefile(path1: Path, path2: Path) -> bool:
        try:
            return path1.samefile(path2)
        except FileNotFoundError:
            # FileNotFoundError: path doesn't exist
            return path1 == path2

    try:
        for line in envs_txt_file.read_text().splitlines():
            stripped_line = line.strip()
            if stripped_line and samefile(prefix, Path(stripped_line)):
                return True
    except (IsADirectoryError, FileNotFoundError, PermissionError) as err:
        logger.error(
            f"{envs_txt_file} could not be "
            f"accessed because of the following error: {err}"
        )
    return False


def excluded_files_check(filename: str) -> bool:
    excluded_extensions = (".pyc", ".pyo")
    return filename.endswith(excluded_extensions)


def find_packages_with_missing_files(prefix: str | Path) -> dict[str, list[str]]:
    """Finds packages listed in conda-meta which have missing files."""
    packages_with_missing_files = {}
    prefix = Path(prefix)
    for file in (prefix / "conda-meta").glob("*.json"):
        for file_name in json.loads(file.read_text()).get("files", []):
            # Add warnings if json file has missing "files"
            if (
                not excluded_files_check(file_name)
                and not (prefix / file_name).exists()
            ):
                packages_with_missing_files.setdefault(file.stem, []).append(file_name)
    return packages_with_missing_files


def find_altered_packages(prefix: str | Path) -> dict[str, list[str]]:
    """Finds altered packages"""
    altered_packages = {}

    prefix = Path(prefix)
    for file in (prefix / "conda-meta").glob("*.json"):
        try:
            metadata = json.loads(file.read_text())
        except Exception as exc:
            logger.error(
                f"Could not load the json file {file} because of the following error: {exc}."
            )
            continue

        try:
            paths_data = metadata["paths_data"]
            paths = paths_data["paths"]
        except KeyError:
            continue

        if paths_data.get("paths_version") != 1:
            continue

        for path in paths:
            _path = path.get("_path")
            old_sha256 = path.get("sha256_in_prefix")
            if _path is None or old_sha256 is None:
                continue

            file_location = prefix / _path
            if not file_location.is_file():
                continue

            try:
                new_sha256 = compute_sum(file_location, "sha256")
            except OSError as err:
                raise CondaError(
                    f"Could not generate checksum for file {file_location} "
                    f"because of the following error: {err}."
                )

            if old_sha256 != new_sha256:
                altered_packages.setdefault(file.stem, []).append(_path)

    return altered_packages


def missing_files(prefix: str, verbose: bool) -> None:
    missing_files = find_packages_with_missing_files(prefix)
    if missing_files:
        print(f"{X_MARK} Missing Files:\n")
        for package_name, missing_files in missing_files.items():
            if verbose:
                delimiter = "\n  "
                print(f"{package_name}:{delimiter}{delimiter.join(missing_files)}")
            else:
                print(f"{package_name}: {len(missing_files)}\n")
    else:
        print(f"{OK_MARK} There are no packages with missing files.\n")


def altered_files(prefix: str, verbose: bool) -> None:
    altered_packages = find_altered_packages(prefix)
    if altered_packages:
        print(f"{X_MARK} Altered Files:\n")
        for package_name, altered_files in altered_packages.items():
            if verbose:
                delimiter = "\n  "
                print(f"{package_name}:{delimiter}{delimiter.join(altered_files)}\n")
            else:
                print(f"{package_name}: {len(altered_files)}\n")
    else:
        print(f"{OK_MARK} There are no packages with altered files.\n")


def env_txt_check(prefix: str, verbose: bool) -> None:
    if check_envs_txt_file(prefix):
        print(f"{OK_MARK} The environment is listed in the environments.txt file.\n")
    else:
        print(f"{X_MARK} The environment is not listed in the environments.txt file.\n")


def requests_ca_bundle_check(prefix: str, verbose: bool) -> None:
    # Use a channel aliases url since users may be on an intranet and
    # have customized their conda setup to point to an internal mirror.
    ca_bundle_test_url = context.channel_alias.urls()[0]

    requests_ca_bundle = os.getenv("REQUESTS_CA_BUNDLE")
    if not requests_ca_bundle:
        return
    elif not Path(requests_ca_bundle).exists():
        print(
            f"{X_MARK} Env var `REQUESTS_CA_BUNDLE` is pointing to a non existent file.\n"
        )
    else:
        session = get_session(ca_bundle_test_url)
        try:
            response = session.get(ca_bundle_test_url)
            response.raise_for_status()
            print(f"{OK_MARK} `REQUESTS_CA_BUNDLE` was verified.\n")
        except (OSError, RequestException) as e:
            print(
                f"{X_MARK} The following error occured while verifying `REQUESTS_CA_BUNDLE`: {e}\n"
            )


@hookimpl
def conda_health_checks():
    yield CondaHealthCheck(name="Missing Files", action=missing_files)
    yield CondaHealthCheck(name="Altered Files", action=altered_files)
    yield CondaHealthCheck(name="Environment.txt File Check", action=env_txt_check)
    yield CondaHealthCheck(
        name="REQUESTS_CA_BUNDLE Check", action=requests_ca_bundle_check
    )