context.py

import logging
from abc import ABC, abstractmethod
from collections import defaultdict
from collections.abc import Mapping, MutableMapping, MutableSequence, Sequence
from contextlib import contextmanager
from copy import deepcopy
from dataclasses import dataclass, field, replace
from typing import Any, Dict, List, Optional, Union

from funcy import identity, lfilter, nullcontext, select

from dvc.exceptions import DvcException
from dvc.parsing.interpolate import (
    get_expression,
    get_matches,
    is_exact_string,
    normalize_key,
    recurse,
    str_interpolate,
    validate_value,
)

logger = logging.getLogger(__name__)
SeqOrMap = Union[Sequence, Mapping]
DictStr = Dict[str, Any]


class ContextError(DvcException):
    pass


class ReservedKeyError(ContextError):
    def __init__(self, keys, path=None):
        from dvc.utils.humanize import join

        self.keys = keys
        self.path = path

        n = "key" + ("s" if len(keys) > 1 else "")
        msg = f"attempted to modify reserved {n} {join(keys)}"
        if path:
            msg += f" in '{path}'"
        super().__init__(msg)


class MergeError(ContextError):
    def __init__(self, key, new, into):
        self.key = key
        to_node = into[key]
        if not isinstance(to_node, Node) or not isinstance(new, Node):
            super().__init__(
                f"cannot merge '{key}' as it already exists in {into}"
            )
            return

        assert isinstance(to_node, Node)
        assert isinstance(new, Node)
        preexisting = to_node.meta.source
        new_src = new.meta.source
        path = new.meta.path()
        super().__init__(
            f"cannot redefine '{path}' from '{new_src}'"
            f" as it already exists in '{preexisting}'"
        )


class ParamsLoadError(ContextError):
    pass


class KeyNotInContext(ContextError, KeyError):
    def __init__(self, key: str) -> None:
        self.key: str = key
        super().__init__(f"Could not find '{key}'")

    def __str__(self):
        return self.msg


class VarsAlreadyLoaded(ContextError):
    pass


def _merge(into, update, overwrite):
    for key, val in update.items():
        if isinstance(into.get(key), Mapping) and isinstance(val, Mapping):
            _merge(into[key], val, overwrite)
        else:
            if key in into and not overwrite:
                raise MergeError(key, val, into)
            into[key] = val
            assert isinstance(into[key], Node)


def recurse_not_a_node(data: dict):
    def func(item):
        assert not isinstance(item, Node)

    return recurse(func)(data)


@dataclass
class Meta:
    source: Optional[str] = None
    dpaths: List[str] = field(default_factory=list)
    local: bool = True

    @staticmethod
    def update_path(meta: "Meta", path: Union[str, int]):
        dpaths = meta.dpaths[:] + [str(path)]
        return replace(meta, dpaths=dpaths)

    def __str__(self):
        string = self.source or "<local>"
        string += ":" + self.path()
        return string

    def path(self):
        return ".".join(self.dpaths)


def _default_meta() -> Meta:
    return Meta()


class Node:
    meta: Meta

    def get_sources(self):
        raise NotImplementedError

    @property
    @abstractmethod
    def value(self):
        pass


@dataclass
class Value(Node):
    _value: Any
    meta: Meta = field(
        compare=False, default_factory=_default_meta, repr=False
    )

    def __repr__(self):
        return repr(self._value)

    def __str__(self) -> str:
        return str(self._value)

    def get_sources(self):
        return {self.meta.source: self.meta.path()}

    @property
    def value(self):
        return self._value


PRIMITIVES = (int, float, str, bytes, bool)


class Container(Node, ABC):
    meta: Meta
    data: Union[list, dict]
    _key_transform = staticmethod(identity)

    def __init__(self, meta=None) -> None:
        self.meta = meta or _default_meta()

    def _convert(self, key, value):
        meta = Meta.update_path(self.meta, key)
        return self._convert_with_meta(value, meta)

    @staticmethod
    def _convert_with_meta(value, meta: Meta = None):
        if value is None or isinstance(value, PRIMITIVES):
            assert meta
            return Value(value, meta=meta)
        if isinstance(value, Node):
            return value
        if isinstance(value, (list, dict)):
            assert meta
            container = CtxDict if isinstance(value, dict) else CtxList
            return container(value, meta=meta)
        msg = (
            "Unsupported value of type "
            f"'{type(value).__name__}' in '{meta}'"
        )
        raise TypeError(msg)

    def __repr__(self):
        return repr(self.data)

    def __getitem__(self, key):
        return self.data[key]

    def __setitem__(self, key, value):
        self.data[key] = self._convert(key, value)

    def __delitem__(self, key):
        del self.data[key]

    def __len__(self):
        return len(self.data)

    def __iter__(self):
        return iter(self.data)

    def __eq__(self, o):
        container = type(self)
        if isinstance(o, container):
            return o.data == self.data
        return container(o) == self

    def select(self, key: str):
        index, *rems = key.split(sep=".", maxsplit=1)
        index = index.strip()
        index = self._key_transform(index)
        try:
            d = self[index]
        except LookupError as exc:
            raise ValueError(
                f"Could not find '{index}' in {self.data}"
            ) from exc

        if not rems:
            return d

        rem = rems[0]
        if not isinstance(d, Container):
            raise ValueError(
                f"{index} is a primitive value, cannot get '{rem}'"
            )
        return d.select(rem)

    def get_sources(self):
        return {}


class CtxList(Container, MutableSequence):
    _key_transform = staticmethod(int)

    def __init__(self, values: Sequence, meta: Meta = None):
        super().__init__(meta=meta)
        self.data: list = []
        self.extend(values)

    def insert(self, index: int, value):
        self.data.insert(index, self._convert(index, value))

    def get_sources(self):
        return {self.meta.source: self.meta.path()}

    @property
    def value(self):
        return [node.value for node in self]

    def __deepcopy__(self, _):
        # optimization: we don't support overriding a list
        new = CtxList([])
        new.data = self.data[:]  # Short-circuiting __setitem__
        return new


class CtxDict(Container, MutableMapping):
    def __init__(self, mapping: Mapping = None, meta: Meta = None, **kwargs):
        super().__init__(meta=meta)

        self.data: dict = {}
        if mapping:
            self.update(mapping)
        self.update(kwargs)

    def __setitem__(self, key, value):
        if not isinstance(key, str):
            # limitation for the interpolation
            # ignore other kinds of keys
            return
        return super().__setitem__(key, value)

    def merge_update(self, other, overwrite=False):
        _merge(self, other, overwrite=overwrite)

    @property
    def value(self):
        return {key: node.value for key, node in self.items()}

    def __deepcopy__(self, _):
        new = CtxDict()
        for k, v in self.items():
            new.data[k] = (
                deepcopy(v) if isinstance(v, Container) else v
            )  # short-circuiting __setitem__
        return new


class Context(CtxDict):
    def __init__(self, *args, **kwargs):
        """
        Top level mutable dict, with some helpers to create context and track
        """
        super().__init__(*args, **kwargs)
        self._track = False
        self._tracked_data = defaultdict(dict)
        self.imports = {}
        self._reserved_keys = {}

    @contextmanager
    def track(self):
        self._track = True
        yield self._tracked_data

        self._track = False
        self._tracked_data = defaultdict(dict)

    def _track_data(self, node):
        if not self._track or not isinstance(node, Node):
            return

        assert isinstance(node, Node)
        if node.meta and node.meta.local:
            return

        for source, keys in node.get_sources().items():
            if not source:
                continue
            params_file = self._tracked_data[source]
            keys = [keys] if isinstance(keys, str) else keys
            params_file.update({key: node.value for key in keys})

    def select(
        self, key: str, unwrap: bool = False
    ):  # pylint: disable=arguments-differ
        """Select the item using key, similar to `__getitem__`
           but can track the usage of the data on interpolation
           as well and can get from nested data structure by using
           "." separated key (eg: "key1.key2.key3")

        Args:
            key: key to select value from
            unwrap: Convert CtxList/CtxDict/Value items to it's original data
                    Defaults to False. Note that the default is different from
                    `resolve`.
        """
        normalized = normalize_key(key)
        try:
            node = super().select(normalized)
        except ValueError as exc:
            raise KeyNotInContext(key) from exc

        assert isinstance(node, Node)
        self._track_data(node)
        return node.value if unwrap else node

    @classmethod
    def load_from(
        cls, fs, path: str, select_keys: List[str] = None
    ) -> "Context":
        from dvc.utils.serialize import load_path

        if not fs.exists(path):
            raise ParamsLoadError(f"'{path}' does not exist")
        if fs.isdir(path):
            raise ParamsLoadError(f"'{path}' is a directory")

        data = load_path(path, fs)
        if not isinstance(data, Mapping):
            typ = type(data).__name__
            raise ParamsLoadError(
                f"expected a dictionary, got '{typ}' in file '{path}'"
            )

        if select_keys:
            try:
                data = {key: data[key] for key in select_keys}
            except KeyError as exc:
                key, *_ = exc.args
                raise ParamsLoadError(
                    f"could not find '{key}' in '{path}'"
                ) from exc

        meta = Meta(source=path, local=False)
        ctx = cls(data, meta=meta)
        ctx.imports[path] = select_keys
        return ctx

    def merge_update(self, other: "Context", overwrite=False):
        matches = select(lambda key: key in other, self._reserved_keys.keys())
        if matches:
            raise ReservedKeyError(matches)
        return super().merge_update(other, overwrite=overwrite)

    def merge_from(self, fs, item: str, wdir: str, overwrite=False):
        path, _, keys_str = item.partition(":")
        path = fs.path.normpath(fs.path.join(wdir, path))

        select_keys = lfilter(bool, keys_str.split(",")) if keys_str else None
        if path in self.imports:
            if not select_keys and self.imports[path] is None:
                return  # allow specifying complete filepath multiple times
            self.check_loaded(path, item, select_keys)

        ctx = Context.load_from(fs, path, select_keys)

        try:
            self.merge_update(ctx, overwrite=overwrite)
        except ReservedKeyError as exc:
            raise ReservedKeyError(exc.keys, item) from exc

        cp = ctx.imports[path]
        if path not in self.imports:
            self.imports[path] = cp
        elif cp:
            self.imports[path].extend(cp)

    def check_loaded(self, path, item, keys):
        if not keys and isinstance(self.imports[path], list):
            raise VarsAlreadyLoaded(
                f"cannot load '{item}' as it's partially loaded already"
            )
        elif keys and self.imports[path] is None:
            raise VarsAlreadyLoaded(
                f"cannot partially load '{item}' as it's already loaded."
            )
        elif isinstance(self.imports[path], list):
            if not set(keys).isdisjoint(set(self.imports[path])):
                raise VarsAlreadyLoaded(
                    f"cannot load '{item}' as it's partially loaded already"
                )

    def load_from_vars(
        self,
        fs,
        vars_: List,
        wdir: str,
        stage_name: str = None,
        default: str = None,
    ):
        if default:
            to_import = fs.path.join(wdir, default)
            if fs.exists(to_import):
                self.merge_from(fs, default, wdir)
            else:
                msg = "%s does not exist, it won't be used in parametrization"
                logger.trace(msg, to_import)  # type: ignore[attr-defined]

        stage_name = stage_name or ""
        for index, item in enumerate(vars_):
            assert isinstance(item, (str, dict))
            if isinstance(item, str):
                self.merge_from(fs, item, wdir)
            else:
                joiner = "." if stage_name else ""
                meta = Meta(source=f"{stage_name}{joiner}vars[{index}]")
                self.merge_update(Context(item, meta=meta))

    def __deepcopy__(self, _):
        new = Context(super().__deepcopy__(_))
        new.meta = deepcopy(self.meta)
        new.imports = deepcopy(self.imports)
        new._reserved_keys = deepcopy(self._reserved_keys)
        return new

    @classmethod
    def clone(cls, ctx: "Context") -> "Context":
        """Clones given context."""
        return deepcopy(ctx)

    @contextmanager
    def reserved(self, *keys: str):
        """Allow reserving some keys so that they cannot be overwritten.

        Ideally, we should delegate this to a separate container
        and support proper namespacing so that we could support `env` features.
        But for now, just `item` and `key`, this should do.
        """
        # using dict to make the error messages ordered
        new = dict.fromkeys(
            [key for key in keys if key not in self._reserved_keys]
        )
        self._reserved_keys.update(new)
        try:
            yield
        finally:
            for key in new.keys():
                self._reserved_keys.pop(key)

    @contextmanager
    def set_temporarily(self, to_set: DictStr, reserve: bool = False):
        cm = self.reserved(*to_set) if reserve else nullcontext()

        non_existing = frozenset(to_set.keys() - self.keys())
        prev = {key: self[key] for key in to_set if key not in non_existing}
        temp = CtxDict(to_set)
        self.update(temp)

        try:
            with cm:
                yield
        finally:
            self.update(prev)
            for key in non_existing:
                self.data.pop(key, None)

    def resolve(
        self, src, unwrap=True, skip_interpolation_checks=False, key=None
    ) -> Any:
        """Recursively resolves interpolation and returns resolved data.

        Args:
            src: Data (str/list/dict etc.) to resolve
            unwrap: Unwrap CtxDict/CtxList/Value to it's original data if
                inside `src`. Defaults to True.
            skip_interpolation_checks: Skip interpolation checks for error
                The callee is responsible to check for errors in advance.

        >>> c = Context({"three": 3})
        >>> c.resolve({"lst": [1, 2, "${three}"]})
        {'lst': [1, 2, 3]}
        """
        func = recurse(self.resolve_str)
        return func(src, unwrap, skip_interpolation_checks, key)

    def resolve_str(
        self, src: str, unwrap=True, skip_interpolation_checks=False, key=None
    ) -> str:
        """Resolves interpolated string to it's original value,
        or in case of multiple interpolations, a combined string.

        >>> c = Context({"enabled": True})
        >>> c.resolve_str("${enabled}")
        True
        >>> c.resolve_str("enabled? ${enabled}")
        'enabled? true'
        """
        matches = get_matches(src)
        if is_exact_string(src, matches):
            # replace "${enabled}", if `enabled` is a boolean, with it's actual
            # value rather than it's string counterparts.
            expr = get_expression(
                matches[0], skip_checks=skip_interpolation_checks
            )
            value = self.select(expr, unwrap=unwrap)
            validate_value(value, key)
            return value
        # but not "${num} days"
        return str_interpolate(
            src, matches, self, skip_checks=skip_interpolation_checks, key=key
        )


if __name__ == "__main__":
    import doctest

    doctest.testmod()