traversal.py

from __future__ import annotations

import collections
import collections.abc
import contextlib
import functools
import http.cookies
import inspect
import itertools
import re
import typing
import xml.etree.ElementTree

from ._utils import (
    IDENTITY,
    NO_DEFAULT,
    ExtractorError,
    LazyList,
    deprecation_warning,
    get_elements_html_by_class,
    get_elements_html_by_attribute,
    get_elements_by_attribute,
    get_element_html_by_attribute,
    get_element_by_attribute,
    get_element_html_by_id,
    get_element_by_id,
    get_element_html_by_class,
    get_elements_by_class,
    get_element_text_and_html_by_tag,
    is_iterable_like,
    try_call,
    url_or_none,
    variadic,
)


def traverse_obj(
        obj, *paths, default=NO_DEFAULT, expected_type=None, get_all=True,
        casesense=True, is_user_input=NO_DEFAULT, traverse_string=False):
    """
    Safely traverse nested `dict`s and `Iterable`s

    >>> obj = [{}, {"key": "value"}]
    >>> traverse_obj(obj, (1, "key"))
    'value'

    Each of the provided `paths` is tested and the first producing a valid result will be returned.
    The next path will also be tested if the path branched but no results could be found.
    Supported values for traversal are `Mapping`, `Iterable`, `re.Match`,
    `xml.etree.ElementTree` (xpath) and `http.cookies.Morsel`.
    Unhelpful values (`{}`, `None`) are treated as the absence of a value and discarded.

    The paths will be wrapped in `variadic`, so that `'key'` is conveniently the same as `('key', )`.

    The keys in the path can be one of:
        - `None`:           Return the current object.
        - `set`:            Requires the only item in the set to be a type or function,
                            like `{type}`/`{type, type, ...}`/`{func}`. If a `type`, return only
                            values of this type. If a function, returns `func(obj)`.
        - `str`/`int`:      Return `obj[key]`. For `re.Match`, return `obj.group(key)`.
        - `slice`:          Branch out and return all values in `obj[key]`.
        - `Ellipsis`:       Branch out and return a list of all values.
        - `tuple`/`list`:   Branch out and return a list of all matching values.
                            Read as: `[traverse_obj(obj, branch) for branch in branches]`.
        - `function`:       Branch out and return values filtered by the function.
                            Read as: `[value for key, value in obj if function(key, value)]`.
                            For `Iterable`s, `key` is the index of the value.
                            For `re.Match`es, `key` is the group number (0 = full match)
                            as well as additionally any group names, if given.
        - `dict`:           Transform the current object and return a matching dict.
                            Read as: `{key: traverse_obj(obj, path) for key, path in dct.items()}`.
        - `any`-builtin:    Take the first matching object and return it, resetting branching.
        - `all`-builtin:    Take all matching objects and return them as a list, resetting branching.
        - `filter`-builtin: Return the value if it is truthy, `None` otherwise.

        `tuple`, `list`, and `dict` all support nested paths and branches.

    @params paths           Paths by which to traverse.
    @param default          Value to return if the paths do not match.
                            If the last key in the path is a `dict`, it will apply to each value inside
                            the dict instead, depth first. Try to avoid if using nested `dict` keys.
    @param expected_type    If a `type`, only accept final values of this type.
                            If any other callable, try to call the function on each result.
                            If the last key in the path is a `dict`, it will apply to each value inside
                            the dict instead, recursively. This does respect branching paths.
    @param get_all          If `False`, return the first matching result, otherwise all matching ones.
    @param casesense        If `False`, consider string dictionary keys as case insensitive.

    `traverse_string` is only meant to be used by YoutubeDL.prepare_outtmpl and is not part of the API

    @param traverse_string  Whether to traverse into objects as strings.
                            If `True`, any non-compatible object will first be
                            converted into a string and then traversed into.
                            The return value of that path will be a string instead,
                            not respecting any further branching.


    @returns                The result of the object traversal.
                            If successful, `get_all=True`, and the path branches at least once,
                            then a list of results is returned instead.
                            If no `default` is given and the last path branches, a `list` of results
                            is always returned. If a path ends on a `dict` that result will always be a `dict`.
    """
    if is_user_input is not NO_DEFAULT:
        deprecation_warning('The is_user_input parameter is deprecated and no longer works')

    casefold = lambda k: k.casefold() if isinstance(k, str) else k

    if isinstance(expected_type, type):
        type_test = lambda val: val if isinstance(val, expected_type) else None
    else:
        type_test = lambda val: try_call(expected_type or IDENTITY, args=(val,))

    def apply_key(key, obj, is_last):
        branching = False
        result = None

        if obj is None and traverse_string:
            if key is ... or callable(key) or isinstance(key, slice):
                branching = True
                result = ()

        elif key is None:
            result = obj

        elif isinstance(key, set):
            item = next(iter(key))
            if len(key) > 1 or isinstance(item, type):
                assert all(isinstance(item, type) for item in key)
                if isinstance(obj, tuple(key)):
                    result = obj
            else:
                result = try_call(item, args=(obj,))

        elif isinstance(key, (list, tuple)):
            branching = True
            result = itertools.chain.from_iterable(
                apply_path(obj, branch, is_last)[0] for branch in key)

        elif key is ...:
            branching = True
            if isinstance(obj, http.cookies.Morsel):
                obj = dict(obj, key=obj.key, value=obj.value)
            if isinstance(obj, collections.abc.Mapping):
                result = obj.values()
            elif is_iterable_like(obj) or isinstance(obj, xml.etree.ElementTree.Element):
                result = obj
            elif isinstance(obj, re.Match):
                result = obj.groups()
            elif traverse_string:
                branching = False
                result = str(obj)
            else:
                result = ()

        elif callable(key):
            branching = True
            if isinstance(obj, http.cookies.Morsel):
                obj = dict(obj, key=obj.key, value=obj.value)
            if isinstance(obj, collections.abc.Mapping):
                iter_obj = obj.items()
            elif is_iterable_like(obj) or isinstance(obj, xml.etree.ElementTree.Element):
                iter_obj = enumerate(obj)
            elif isinstance(obj, re.Match):
                iter_obj = itertools.chain(
                    enumerate((obj.group(), *obj.groups())),
                    obj.groupdict().items())
            elif traverse_string:
                branching = False
                iter_obj = enumerate(str(obj))
            else:
                iter_obj = ()

            result = (v for k, v in iter_obj if try_call(key, args=(k, v)))
            if not branching:  # string traversal
                result = ''.join(result)

        elif isinstance(key, dict):
            iter_obj = ((k, _traverse_obj(obj, v, False, is_last)) for k, v in key.items())
            result = {
                k: v if v is not None else default for k, v in iter_obj
                if v is not None or default is not NO_DEFAULT
            } or None

        elif isinstance(obj, collections.abc.Mapping):
            if isinstance(obj, http.cookies.Morsel):
                obj = dict(obj, key=obj.key, value=obj.value)
            result = (try_call(obj.get, args=(key,)) if casesense or try_call(obj.__contains__, args=(key,)) else
                      next((v for k, v in obj.items() if casefold(k) == key), None))

        elif isinstance(obj, re.Match):
            if isinstance(key, int) or casesense:
                with contextlib.suppress(IndexError):
                    result = obj.group(key)

            elif isinstance(key, str):
                result = next((v for k, v in obj.groupdict().items() if casefold(k) == key), None)

        elif isinstance(key, (int, slice)):
            if is_iterable_like(obj, (collections.abc.Sequence, xml.etree.ElementTree.Element)):
                branching = isinstance(key, slice)
                with contextlib.suppress(IndexError):
                    result = obj[key]
            elif traverse_string:
                with contextlib.suppress(IndexError):
                    result = str(obj)[key]

        elif isinstance(obj, xml.etree.ElementTree.Element) and isinstance(key, str):
            xpath, _, special = key.rpartition('/')
            if not special.startswith('@') and not special.endswith('()'):
                xpath = key
                special = None

            # Allow abbreviations of relative paths, absolute paths error
            if xpath.startswith('/'):
                xpath = f'.{xpath}'
            elif xpath and not xpath.startswith('./'):
                xpath = f'./{xpath}'

            def apply_specials(element):
                if special is None:
                    return element
                if special == '@':
                    return element.attrib
                if special.startswith('@'):
                    return try_call(element.attrib.get, args=(special[1:],))
                if special == 'text()':
                    return element.text
                raise SyntaxError(f'apply_specials is missing case for {special!r}')

            if xpath:
                result = list(map(apply_specials, obj.iterfind(xpath)))
            else:
                result = apply_specials(obj)

        return branching, result if branching else (result,)

    def lazy_last(iterable):
        iterator = iter(iterable)
        prev = next(iterator, NO_DEFAULT)
        if prev is NO_DEFAULT:
            return

        for item in iterator:
            yield False, prev
            prev = item

        yield True, prev

    def apply_path(start_obj, path, test_type):
        objs = (start_obj,)
        has_branched = False

        key = None
        for last, key in lazy_last(variadic(path, (str, bytes, dict, set))):
            if not casesense and isinstance(key, str):
                key = key.casefold()

            if key in (any, all):
                has_branched = False
                filtered_objs = (obj for obj in objs if obj not in (None, {}))
                if key is any:
                    objs = (next(filtered_objs, None),)
                else:
                    objs = (list(filtered_objs),)
                continue

            if key is filter:
                objs = filter(None, objs)
                continue

            if __debug__ and callable(key):
                # Verify function signature
                inspect.signature(key).bind(None, None)

            new_objs = []
            for obj in objs:
                branching, results = apply_key(key, obj, last)
                has_branched |= branching
                new_objs.append(results)

            objs = itertools.chain.from_iterable(new_objs)

        if test_type and not isinstance(key, (dict, list, tuple)):
            objs = map(type_test, objs)

        return objs, has_branched, isinstance(key, dict)

    def _traverse_obj(obj, path, allow_empty, test_type):
        results, has_branched, is_dict = apply_path(obj, path, test_type)
        results = LazyList(item for item in results if item not in (None, {}))
        if get_all and has_branched:
            if results:
                return results.exhaust()
            if allow_empty:
                return [] if default is NO_DEFAULT else default
            return None

        return results[0] if results else {} if allow_empty and is_dict else None

    for index, path in enumerate(paths, 1):
        is_last = index == len(paths)
        try:
            result = _traverse_obj(obj, path, is_last, True)
            if result is not None:
                return result
        except _RequiredError as e:
            if is_last:
                # Reraise to get cleaner stack trace
                raise ExtractorError(e.orig_msg, expected=e.expected) from None

    return None if default is NO_DEFAULT else default


def value(value, /):
    return lambda _: value


def require(name, /, *, expected=False):
    def func(value):
        if value is None:
            raise _RequiredError(f'Unable to extract {name}', expected=expected)

        return value

    return func


class _RequiredError(ExtractorError):
    pass


@typing.overload
def subs_list_to_dict(*, ext: str | None = None) -> collections.abc.Callable[[list[dict]], dict[str, list[dict]]]: ...


@typing.overload
def subs_list_to_dict(subs: list[dict] | None, /, *, ext: str | None = None) -> dict[str, list[dict]]: ...


def subs_list_to_dict(subs: list[dict] | None = None, /, *, ext=None):
    """
    Convert subtitles from a traversal into a subtitle dict.
    The path should have an `all` immediately before this function.

    Arguments:
    `ext`      The default value for `ext` in the subtitle dict

    In the dict you can set the following additional items:
    `id`       The subtitle id to sort the dict into
    `quality`  The sort order for each subtitle
    """
    if subs is None:
        return functools.partial(subs_list_to_dict, ext=ext)

    result = collections.defaultdict(list)

    for sub in subs:
        if not url_or_none(sub.get('url')) and not sub.get('data'):
            continue
        sub_id = sub.pop('id', None)
        if sub_id is None:
            continue
        if ext is not None and not sub.get('ext'):
            sub['ext'] = ext
        result[sub_id].append(sub)
    result = dict(result)

    for subs in result.values():
        subs.sort(key=lambda x: x.pop('quality', 0) or 0)

    return result


@typing.overload
def find_element(*, attr: str, value: str, tag: str | None = None, html=False): ...


@typing.overload
def find_element(*, cls: str, html=False): ...


@typing.overload
def find_element(*, id: str, tag: str | None = None, html=False): ...


@typing.overload
def find_element(*, tag: str, html=False): ...


def find_element(*, tag=None, id=None, cls=None, attr=None, value=None, html=False):
    # deliberately using `id=` and `cls=` for ease of readability
    assert tag or id or cls or (attr and value), 'One of tag, id, cls or (attr AND value) is required'
    ANY_TAG = r'[\w:.-]+'

    if attr and value:
        assert not cls, 'Cannot match both attr and cls'
        assert not id, 'Cannot match both attr and id'
        func = get_element_html_by_attribute if html else get_element_by_attribute
        return functools.partial(func, attr, value, tag=tag or ANY_TAG)

    elif cls:
        assert not id, 'Cannot match both cls and id'
        assert tag is None, 'Cannot match both cls and tag'
        func = get_element_html_by_class if html else get_elements_by_class
        return functools.partial(func, cls)

    elif id:
        func = get_element_html_by_id if html else get_element_by_id
        return functools.partial(func, id, tag=tag or ANY_TAG)

    index = int(bool(html))
    return lambda html: get_element_text_and_html_by_tag(tag, html)[index]


@typing.overload
def find_elements(*, cls: str, html=False): ...


@typing.overload
def find_elements(*, attr: str, value: str, tag: str | None = None, html=False): ...


def find_elements(*, tag=None, cls=None, attr=None, value=None, html=False):
    # deliberately using `cls=` for ease of readability
    assert cls or (attr and value), 'One of cls or (attr AND value) is required'

    if attr and value:
        assert not cls, 'Cannot match both attr and cls'
        func = get_elements_html_by_attribute if html else get_elements_by_attribute
        return functools.partial(func, attr, value, tag=tag or r'[\w:.-]+')

    assert not tag, 'Cannot match both cls and tag'
    func = get_elements_html_by_class if html else get_elements_by_class
    return functools.partial(func, cls)


def trim_str(*, start=None, end=None):
    def trim(s):
        if s is None:
            return None
        start_idx = 0
        if start and s.startswith(start):
            start_idx = len(start)
        if end and s.endswith(end):
            return s[start_idx:-len(end)]
        return s[start_idx:]

    return trim


def get_first(obj, *paths, **kwargs):
    return traverse_obj(obj, *((..., *variadic(keys)) for keys in paths), **kwargs, get_all=False)


def dict_get(d, key_or_keys, default=None, skip_false_values=True):
    for val in map(d.get, variadic(key_or_keys)):
        if val is not None and (val or not skip_false_values):
            return val
    return default