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# the Apache License, Version 2.0 (the "License"); you may
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#
# 	http://www.apache.org/licenses/LICENSE-2.0
#
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import difflib
import enum
import json
import re
from collections import abc
from typing import Any


class Flag(enum.Flag):
    FLAT_DICT = enum.auto()
    DUMP_EQUALS = enum.auto()


def dump(o: Any, flags: Flag = Flag(0)) -> str:
    """dump creates a human-readable multiline text to make easy to visualize the content of a JSON like object.

    :param o: the object the dump has to be obtained from.
    :param flags:
        flags & FLAT_DICT != 0: it will squash nested objects to make simple reading them.
    :return: JSON human-readable multiline text representation of the input object.
    """
    lines: abc.Sequence[str] = _dump(o, flags)
    return "\n".join(lines)


_HAS_DIFF = re.compile(r"^\+ ", flags=re.MULTILINE)


def diff(old: Any, new: Any, flags: Flag = Flag(0)) -> str:
    """diff creates a human-readable multiline text to make easy to visualize the difference of content between two JSON like object.

    :param old: the old object the diff dump has to be obtained from.
    :param new: the new object the diff dump has to be obtained from.
    :param flags:
        flags & Flags.FLAT_DICT: it squashes nested objects to make simple reading them;
        flags & Flags.DUMP_EQUALS: in case there is no difference it will print the same as dump function.
    :return: JSON human-readable multiline text representation of the difference between input objects, if any, or '' otherwise.
    """
    if Flag.DUMP_EQUALS not in flags and old == new:
        return ""
    ret = "\n".join(difflib.ndiff(_dump(old, flags), _dump(new, flags)))
    if Flag.DUMP_EQUALS not in flags and _HAS_DIFF.search(ret) is None:
        return ""
    return ret


def _dump(o: Any, flags: Flag) -> abc.Sequence[str]:
    """Lower level wrapper to json.dump method"""
    if Flag.FLAT_DICT in flags:
        # It reduces nested dictionary to a flat one to improve readability.
        o = flat(o)
    return json.dumps(o, indent=2, sort_keys=True).splitlines()


def flat(o: Any) -> dict[str, str]:
    """Given a JSON like object, it produces a key value flat dictionary of strings easy to read and compare.
    :param o: a JSON like object
    :return: a flat dictionary
    """
    return dict(_flat(o))


def _flat(o: Any) -> abc.Generator[tuple[str, str], None, None]:
    """Recursive helper function generating the content for the flat dictionary.

    :param o: a JSON like object
    :return: a generator of (key, value) pairs.
    """
    if isinstance(o, (str, bytes)):
        yield "", str(o)
    elif isinstance(o, abc.Mapping):
        for k1, v1 in o.items():
            for k2, v2 in _flat(v1):
                if k2:
                    yield f"{k1}.{k2}", v2
                else:
                    yield k1, v2
    elif isinstance(o, abc.Sequence):
        for k1, v1 in enumerate(o):
            for k2, v2 in _flat(v1):
                if k2:
                    yield f"{k1}.{k2}", v2
                else:
                    yield str(k1), v2
    else:
        yield "", json.dumps(o)