"""Custom loader."""

from __future__ import annotations

import fnmatch
import logging
import os
from collections.abc import Callable, Iterator
from io import StringIO, TextIOWrapper
from pathlib import Path
from typing import Any, TextIO

import yaml

try:
    from yaml import CSafeLoader as FastestAvailableSafeLoader

    HAS_C_LOADER = True
except ImportError:
    HAS_C_LOADER = False
    from yaml import (  # type: ignore[assignment]
        SafeLoader as FastestAvailableSafeLoader,
    )

from propcache.api import cached_property

from .const import SECRET_YAML
from .constructors import _construct_seq, _handle_mapping_tag, _handle_scalar_tag
from .exceptions import YAMLException, YamlTypeError
from .objects import Input, NodeDictClass
from .reference import _add_reference_to_node_class
from .reference_object import _add_reference

# mypy: allow-untyped-calls, no-warn-return-any

JSON_TYPE = list | dict | str

_LOGGER = logging.getLogger(__name__)


class Secrets:
    """Store secrets while loading YAML."""

    def __init__(self, config_dir: Path) -> None:
        """Initialize secrets."""
        self.config_dir = config_dir
        self._cache: dict[Path, dict[str, str]] = {}

    def get(self, requester_path: str, secret: str) -> str:
        """Return the value of a secret."""
        current_path = Path(requester_path)

        secret_dir = current_path
        while True:
            secret_dir = secret_dir.parent

            try:
                secret_dir.relative_to(self.config_dir)
            except ValueError:
                # We went above the config dir
                break

            secrets = self._load_secret_yaml(secret_dir)

            if secret in secrets:
                _LOGGER.debug(
                    "Secret %s retrieved from secrets.yaml in folder %s",
                    secret,
                    secret_dir,
                )
                return secrets[secret]

        raise YAMLException(f"Secret {secret} not defined")

    def _load_secret_yaml(self, secret_dir: Path) -> dict[str, str]:
        """Load the secrets yaml from path."""
        if (secret_path := secret_dir / SECRET_YAML) in self._cache:
            return self._cache[secret_path]

        _LOGGER.debug("Loading %s", secret_path)
        try:
            secrets = load_yaml(str(secret_path))

            if not isinstance(secrets, dict):
                raise YAMLException("Secrets is not a dictionary")

            if "logger" in secrets:
                logger = str(secrets["logger"]).lower()
                if logger == "debug":
                    _LOGGER.setLevel(logging.DEBUG)
                else:
                    _LOGGER.error(
                        (
                            "Error in secrets.yaml: 'logger: debug' expected, but"
                            " 'logger: %s' found"
                        ),
                        logger,
                    )
                del secrets["logger"]
        except FileNotFoundError:
            secrets = {}

        self._cache[secret_path] = secrets

        return secrets


class _LoaderMixin:
    """Mixin class with extensions for YAML loader."""

    name: str
    stream: Any

    @cached_property
    def get_name(self) -> str:
        """Get the name of the loader."""
        return self.name

    @cached_property
    def get_stream_name(self) -> str:
        """Get the name of the stream."""
        return getattr(self.stream, "name", "")


class FastSafeLoader(FastestAvailableSafeLoader, _LoaderMixin):
    """The fastest available safe loader, either C or Python."""

    def __init__(self, stream: Any, secrets: Secrets | None = None) -> None:
        """Initialize a safe line loader."""
        self.stream = stream

        # Set name in same way as the Python loader does in yaml.reader.__init__
        if isinstance(stream, str):
            self.name = "<unicode string>"
        elif isinstance(stream, bytes):
            self.name = "<byte string>"
        else:
            self.name = getattr(stream, "name", "<file>")

        super().__init__(stream)
        self.secrets = secrets


class PythonSafeLoader(yaml.SafeLoader, _LoaderMixin):
    """Python safe loader."""

    def __init__(self, stream: Any, secrets: Secrets | None = None) -> None:
        """Initialize a safe line loader."""
        super().__init__(stream)
        self.secrets = secrets


type LoaderType = FastSafeLoader | PythonSafeLoader


def load_yaml(
    fname: str | os.PathLike[str], secrets: Secrets | None = None
) -> JSON_TYPE | None:
    """
    Load a YAML file.

    If opening the file raises an OSError it will be wrapped in a YAMLException,
    except for FileNotFoundError which will be re-raised.
    """
    try:
        with open(fname, encoding="utf-8") as conf_file:
            return parse_yaml(conf_file, secrets)
    except UnicodeDecodeError as exc:
        _LOGGER.error("Unable to read file %s: %s", fname, exc)
        raise YAMLException(exc) from exc
    except FileNotFoundError:
        raise
    except OSError as exc:
        raise YAMLException(exc) from exc


def load_yaml_dict(
    fname: str | os.PathLike[str], secrets: Secrets | None = None
) -> dict:
    """
    Load a YAML file and ensure the top level is a dict.

    Raise if the top level is not a dict.
    Return an empty dict if the file is empty.
    """
    loaded_yaml = load_yaml(fname, secrets)
    if loaded_yaml is None:
        loaded_yaml = {}
    if not isinstance(loaded_yaml, dict):
        raise YamlTypeError(f"YAML file {fname} does not contain a dict")
    return loaded_yaml


def parse_yaml(
    content: str | TextIO | StringIO, secrets: Secrets | None = None
) -> JSON_TYPE:
    """Parse YAML with the fastest available loader."""
    if not HAS_C_LOADER:
        return _parse_yaml_python(content, secrets)
    try:
        return _parse_yaml(FastSafeLoader, content, secrets)
    except yaml.YAMLError:
        # Loading failed, so we now load with the Python loader which has more
        # readable exceptions
        if isinstance(content, (StringIO, TextIO, TextIOWrapper)):
            # Rewind the stream so we can try again
            content.seek(0, 0)
        return _parse_yaml_python(content, secrets)


def _parse_yaml_python(
    content: str | TextIO | StringIO, secrets: Secrets | None = None
) -> JSON_TYPE:
    """Parse YAML with the python loader (this is very slow)."""
    try:
        return _parse_yaml(PythonSafeLoader, content, secrets)
    except yaml.YAMLError as exc:
        _LOGGER.error(str(exc))
        raise YAMLException(exc) from exc


def _parse_yaml(
    loader: type[FastSafeLoader | PythonSafeLoader],
    content: str | TextIO,
    secrets: Secrets | None = None,
) -> JSON_TYPE:
    """Load a YAML file."""
    return yaml.load(content, Loader=lambda stream: loader(stream, secrets))  # type: ignore[arg-type]  # noqa: S506


def _raise_if_no_value[NodeT: yaml.nodes.Node, R](
    func: Callable[[LoaderType, NodeT], R],
) -> Callable[[LoaderType, NodeT], R]:
    def wrapper(loader: LoaderType, node: NodeT) -> R:
        if not node.value:
            raise YAMLException(f"{node.start_mark}: {node.tag} needs an argument.")
        return func(loader, node)

    return wrapper


@_raise_if_no_value
def _include_yaml(loader: LoaderType, node: yaml.nodes.Node) -> JSON_TYPE:
    """
    Load another YAML file and embed it using the !include tag.

    Example:
        device_tracker: !include device_tracker.yaml

    """
    fname = os.path.join(os.path.dirname(loader.get_name), node.value)
    try:
        loaded_yaml = load_yaml(fname, loader.secrets)
        if loaded_yaml is None:
            loaded_yaml = NodeDictClass()
        return _add_reference(loaded_yaml, loader, node)
    except FileNotFoundError as exc:
        raise YAMLException(f"{node.start_mark}: Unable to read file {fname}") from exc


def _is_file_valid(name: str) -> bool:
    """Decide if a file is valid."""
    return not name.startswith(".")


def _find_files(directory: str, pattern: str) -> Iterator[str]:
    """Recursively load files in a directory."""
    for root, dirs, files in os.walk(directory, topdown=True):
        dirs[:] = [d for d in dirs if _is_file_valid(d)]
        for basename in sorted(files):
            if _is_file_valid(basename) and fnmatch.fnmatch(basename, pattern):
                filename = os.path.join(root, basename)
                yield filename


@_raise_if_no_value
def _include_dir_named_yaml(loader: LoaderType, node: yaml.nodes.Node) -> NodeDictClass:
    """Load multiple files from directory as a dictionary."""
    mapping = NodeDictClass()
    loc = os.path.join(os.path.dirname(loader.get_name), node.value)
    for fname in _find_files(loc, "*.yaml"):
        filename = os.path.splitext(os.path.basename(fname))[0]
        if os.path.basename(fname) == SECRET_YAML:
            continue
        loaded_yaml = load_yaml(fname, loader.secrets)
        if loaded_yaml is None:
            # Special case, an empty file included by !include_dir_named is treated
            # as an empty dictionary
            loaded_yaml = NodeDictClass()
        mapping[filename] = loaded_yaml
    _add_reference_to_node_class(mapping, loader, node)
    return mapping


@_raise_if_no_value
def _include_dir_merge_named_yaml(
    loader: LoaderType, node: yaml.nodes.Node
) -> NodeDictClass:
    """Load multiple files from directory as a merged dictionary."""
    mapping = NodeDictClass()
    loc = os.path.join(os.path.dirname(loader.get_name), node.value)
    for fname in _find_files(loc, "*.yaml"):
        if os.path.basename(fname) == SECRET_YAML:
            continue
        loaded_yaml = load_yaml(fname, loader.secrets)
        if isinstance(loaded_yaml, dict):
            mapping.update(loaded_yaml)
    _add_reference_to_node_class(mapping, loader, node)
    return mapping


@_raise_if_no_value
def _include_dir_list_yaml(
    loader: LoaderType, node: yaml.nodes.Node
) -> list[JSON_TYPE]:
    """Load multiple files from directory as a list."""
    loc = os.path.join(os.path.dirname(loader.get_name), node.value)
    return [
        loaded_yaml
        for f in _find_files(loc, "*.yaml")
        if os.path.basename(f) != SECRET_YAML
        and (loaded_yaml := load_yaml(f, loader.secrets)) is not None
    ]


@_raise_if_no_value
def _include_dir_merge_list_yaml(
    loader: LoaderType, node: yaml.nodes.Node
) -> JSON_TYPE:
    """Load multiple files from directory as a merged list."""
    loc: str = os.path.join(os.path.dirname(loader.get_name), node.value)
    merged_list: list[JSON_TYPE] = []
    for fname in _find_files(loc, "*.yaml"):
        if os.path.basename(fname) == SECRET_YAML:
            continue
        loaded_yaml = load_yaml(fname, loader.secrets)
        if isinstance(loaded_yaml, list):
            merged_list.extend(loaded_yaml)
    return _add_reference(merged_list, loader, node)


def _env_var_yaml(loader: LoaderType, node: yaml.nodes.Node) -> str:
    """Load environment variables and embed it into the configuration YAML."""
    args = node.value.split()

    # Check for a default value
    if len(args) > 1:
        return os.getenv(args[0], " ".join(args[1:]))
    if args[0] in os.environ:
        return os.environ[args[0]]
    _LOGGER.error("Environment variable %s not defined", node.value)
    raise YAMLException(node.value)


def secret_yaml(loader: LoaderType, node: yaml.nodes.Node) -> JSON_TYPE:
    """Load secrets and embed it into the configuration YAML."""
    if loader.secrets is None:
        raise YAMLException("Secrets not supported in this YAML file")

    return loader.secrets.get(loader.get_name, node.value)


def add_constructor(tag: Any, constructor: Any) -> None:
    """Add to constructor to all loaders."""
    for yaml_loader in (FastSafeLoader, PythonSafeLoader):
        yaml_loader.add_constructor(tag, constructor)


add_constructor("!include", _include_yaml)
add_constructor(yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG, _handle_mapping_tag)
add_constructor(yaml.resolver.BaseResolver.DEFAULT_SCALAR_TAG, _handle_scalar_tag)
add_constructor(yaml.resolver.BaseResolver.DEFAULT_SEQUENCE_TAG, _construct_seq)
add_constructor("!env_var", _env_var_yaml)
add_constructor("!secret", secret_yaml)
add_constructor("!include_dir_list", _include_dir_list_yaml)
add_constructor("!include_dir_merge_list", _include_dir_merge_list_yaml)
add_constructor("!include_dir_named", _include_dir_named_yaml)
add_constructor("!include_dir_merge_named", _include_dir_merge_named_yaml)
add_constructor("!input", Input.from_node)