"""Utils for dump die"""

# System Imports.
import copy
import inspect
import io
import linecache
import re
import tokenize
from collections.abc import Sequence
from decimal import Decimal
from enum import EnumMeta, Enum as OrigEnum
from tokenize import (
    generate_tokens,
    ENDMARKER,
    NAME,
    NEWLINE,
    NUMBER,
    OP,
    STRING,
)

# Third-Party Imports.
from django.core.exceptions import ObjectDoesNotExist
from django.http import QueryDict

# Internal Imports.
from django_dump_die.constants import COLORIZE_DUMPED_OBJECT_NAME, INCLUDE_FILENAME_LINENUMBER, PYTZ_PRESENT

# Imports that may not be accessible, depending on local python environment setup.
if PYTZ_PRESENT:
    import pytz


class Enum:
    """Enum faker class so an entire Enum can be dumped correctly."""
    def __init__(self, *args, **kwargs):
        """Set attrs on this class for each kwarg passed in."""
        for key, val in kwargs.items():
            setattr(self, key, val)


def get_dumped_object_info(obj, index_range=None, deepcopy=False):
    """Get all the required information to be able to dump an object"""
    # Get object filename, linenumber, and name
    filename, linenumber, obj_name = get_dumped_object_name_and_location(obj)

    # Process the object name to add coloring and/or put in correct format for the template.
    obj_name = process_object_name(obj_name)

    # Handle if function.
    function_doc = None
    if callable(obj) and not inspect.isclass(obj):
        function_doc = inspect.getdoc(obj)

    # Sanitize and validate provided index values.
    start_index, end_index = sanitize_index_range(index_range)

    # Handle if Enum by converting to a standard class.
    # NOTE: Dumping an Enum without conversion results in a blank string being dumped.
    if isinstance(obj, EnumMeta):
        obj = Enum(**obj.__members__)

    # Handle if deepcopy set.
    original_obj = None
    try:
        if deepcopy:
            original_obj = obj
            obj = copy.deepcopy(obj)
    except TypeError as type_error:
        original_obj = None
        raise TypeError(f"Object contains type that can't be deep copied. - {type_error}") from None

    return (filename, linenumber, obj_name, obj, function_doc, start_index, end_index, original_obj)


def get_dumped_object_name_and_location(object_needing_name):
    """Look at the stack frame to figure out what the dumped var is"""

    # Get the frame where the dump or dd occurred.
    base_frame = inspect.currentframe().f_back.f_back.f_back
    frame_info = inspect.getframeinfo(base_frame)

    # Default to not showing filename and lineno via setting to None
    linenumber = None
    filename = None
    # If we are to show the filename and linenumber
    if INCLUDE_FILENAME_LINENUMBER:
        # Get line number
        linenumber = frame_info.lineno
        # Get filename
        filename = frame_info.filename

    # Parse line that called, for full "name" to output.
    # Accounts for things like functions that span multiple lines.
    code_context = get_fully_qualified_dumped_line(base_frame, frame_info)

    # TODO: This work of using RegEx to get down to the dumped object name can probably be improved.
    # Establish a couple of regular expressions to fetch out what was passed to dump or dd.
    dump_pattern = r".*dump\((.*)[\)]"
    dd_pattern = r".*dd\((.*)[\)]"
    options_pattern = r"(.*)(?=,.*=.*)"
    # Find the results for both dump and dd.
    dumped_text_matches = re.findall(dump_pattern, code_context)
    dd_text_matches = re.findall(dd_pattern, code_context)
    # Determine if dumped or dd'd and put result in dumped_text
    dumped_text = 'Unknown_Object_Name'
    if dumped_text_matches:
        dumped_text = dumped_text_matches[0]
    elif dd_text_matches:
        dumped_text = dd_text_matches[0]

    while 'deepcopy' in dumped_text or 'index_range' in dumped_text:
        dumped_text_matches = re.findall(options_pattern, dumped_text)
        if dumped_text_matches:
            dumped_text = dumped_text_matches[0]
        else:
            break

    # If function get the callable name for each function name.
    if callable(object_needing_name) and not inspect.isclass(object_needing_name):
        dumped_text = get_callable_name(dumped_text, object_needing_name)

    return filename, linenumber, dumped_text


def get_fully_qualified_dumped_line(base_frame, frame_info):
    """Loop through frame info until we get full object name.

    Required for definitions of things that span multiple lines, within a given dump/dd statement.
    """

    line_num = base_frame.f_lineno - 1
    code_context = ''
    counter = None
    total_loops = 0
    # Loop through lines until counter goes back to 0, to account for newlines.
    # Counter increments for every proper ( token found, and decrements for every proper ) token found.
    # Additional checks are present so that the page does not hang forever, in event of input we did not account for.
    while counter is None or (0 < counter < 100 and total_loops < 1000):
        total_loops += 1

        # Initialize counter for first loop.
        if counter is None:
            counter = 0

        # Check line for parsing actual name info.
        line_num += 1
        line = linecache.getline(frame_info.filename, line_num, base_frame.f_globals)
        code_context += line

        # Get the tokens out of the string.
        # NOTE: generate_tokens returns an iterator and not a data structure.
        tokens = generate_tokens(io.StringIO(line).readline)

        # Iterate through all tokens from line, and adjust counter if paren tokens are found.
        try:
            for token in tokens:
                if token.exact_type == 7:
                    counter += 1
                elif token.exact_type == 8:
                    counter -= 1

        except tokenize.TokenError:
            # Seems to only come up for end of line. We can safely ignore, probably?
            pass

    # Strip out extra whitespace, if present.
    code_context = re.sub(r'\s+', ' ', code_context)

    # Return final result.
    return code_context


def process_object_name(object_name):
    """Process the object name into a dictionary of parts that can be colorized in output"""

    # List to return for the name
    name = []

    # If the dumped object name should be colorized
    if COLORIZE_DUMPED_OBJECT_NAME:

        # List of function names
        functions = []

        # List of params
        params = []

        # Get the tokens out of the string
        # NOTE: generate_tokens returns an iterator and not a data structure.
        tokens = generate_tokens(io.StringIO(object_name).readline)

        # Stores all tokens extracted from the iterator.
        all_tokens = []
        # Stores the previous token as we iterate.
        previous_token = ''
        # Whether we are inside a param list. Default to False
        in_param_list = False

        # Convert the tokens from the iterator to a list of tokens.
        # Also, store the tokens that are function names or params for later color processing.
        for token in tokens:
            # Store token for later processing.
            all_tokens.append(token)
            # Convert for readability
            token_number = token[0]
            token_value = token[1]

            # If token is a opening paren
            if token_number == OP and token.exact_type == 7:
                # Append previous token to the function list
                functions.append(previous_token)
                # Flip flag to indicate that we are now processing the parameter list.
                in_param_list = True

            # If we are inside the param list and not at the ending paren
            if in_param_list and token.exact_type != 8:
                # Append the token to the list of params
                params.append(token_value)
            else:
                in_param_list = False

            # Update the previous token to the current one.
            previous_token = token_value

        # Iterate over tokens classifying them with a CSS class.
        for token_number, token_value, _, _, _ in all_tokens:

            # Ignore newlines and endmarkers
            if token_number == NEWLINE or token_number == ENDMARKER:
                continue

            if token_number == NAME and token_value == 'Unknown_Object_Name':
                # Use empty color as object name can't be determined
                css_class = 'empty'
            elif token_number == NAME and is_const(token_value):
                # Use constant color.
                css_class = 'constant'
            elif token_number == STRING:
                # Use string color.
                css_class = 'string'
            elif token_number == NUMBER:
                # Use number color.
                css_class = 'number'
            elif token_number == OP and token_value in '(){}[]':
                # Use braces color.
                css_class = 'braces'
            elif token_value in functions:
                # Use function color
                css_class = 'function'
            elif token_value in params:
                # User param color
                css_class = 'params'
            else:
                # Use default color.
                css_class = 'dumped_name'

            # Append the info on to the name list
            name.append({
                'css_class': css_class,
                'value': token_value,
            })

    else:
        # Convert object name to the format expected by the template.
        name.append({
            'css_class': '',
            'value': object_name,
        })

    return name


def sanitize_index_range(index_range):
    """
    Validates and sanitizes passed index values.
    """
    # Set index defaults.
    start_index = None
    end_index = None

    # First check if index_range is an iterable.
    if isinstance(index_range, Sequence):
        # Handle for length 2 or more (we ignore values past second index).
        if len(index_range) > 1:
            # Assume is index range. Split values onto indexes.
            start_index = index_range[0]
            end_index = index_range[1]

        # Handle for length exactly 1.
        elif len(index_range) == 1:
            # Assume user typo'd somehow and meant literal start index.
            start_index = index_range[0]

    else:
        # Non-iterable. Assume user passed single start-index value.
        start_index = index_range

    # Sanitize if start_index set.
    if start_index:
        try:
            start_index = int(start_index)
        except TypeError:
            start_index = None

    # Sanitize if end_index set.
    if end_index:
        try:
            end_index = int(end_index)
        except Exception:
            end_index = None

    return start_index, end_index


# region Object Property Functions


def generate_unique_from_obj(obj):
    """Generate a unique identifier for the object passed in."""

    # Create unique via hash and fallback to id on exception.
    try:
        unique = hash(obj)
    except Exception:
        unique = id(obj)
    # Append the class name to the unique to really make unique.
    unique = f'{get_class_name(obj)}_{unique}'

    return unique


def get_members(obj):
    """Attempts to get object members. Falls back to an empty list."""

    # Get initial member set or empty list.
    members = inspect.getmembers(obj)

    # Add type specific members that will not be included from the use of the inspect.getmembers function.
    if is_dict(obj):
        if isinstance(obj, QueryDict):
            # Django QueryDict members. Has handling for multiple unique values referencing the same key.
            # https://docs.djangoproject.com/en/dev/ref/request-response/#querydict-objects
            obj_copy = copy.deepcopy(obj)
            for key in obj.keys():
                item = obj_copy.pop(key)
                members.append((key, item))
        else:
            # Standard dictionary members.
            members.extend(obj.items())

    elif is_iterable(obj):
        # Lists, sets, etc.
        if _is_indexable(obj):
            # Use indexes as left half.
            members.extend(list(enumerate(obj)))
        elif is_set(obj):
            # Use None as left half. Most likely a set.
            members.extend([(None, x) for x in obj])
    elif is_enum_member(obj):
        # Prevent enum entry from recursively showing up in entries members.
        members = [m for m in members if not is_enum_member(m[1])]

    return members


def get_class_name(obj):
    """Get class name of an object."""
    name = None
    try:
        name = obj.__class__.__name__
    except Exception:
        pass
    return name


def get_callable_name(obj_name, obj):
    """Get callable name of an object"""

    # Get the method signature and fall back to simply appending
    # parentheses to the method name on exception.
    try:
        obj_name += safe_str(inspect.signature(obj))
    except Exception:
        obj_name += '()'
    return obj_name


def get_callable_params(obj):
    """Get callable params of an object"""

    # Get the method signature and fall back to simply returning
    # parentheses on exception.
    try:
        signature = safe_str(inspect.signature(obj))
    except Exception:
        signature = '()'

    signature_minus_parentheses = signature[1:-1]

    return signature_minus_parentheses


def get_obj_type(obj):
    """Determines the string representation of object's type."""

    # Get default type value.
    obj_type = type(obj).__name__

    # Special handling for certain types.
    if obj_type == 'NoneType':
        obj_type = 'null'
    elif PYTZ_PRESENT and isinstance(obj, pytz.BaseTzInfo):
        obj_type = 'pytz_timezone'

    return obj_type


def safe_repr(obj):
    """Call repr() and ignore ObjectDoesNotExist."""
    str_obj = ''
    try:
        str_obj = repr(obj)
    except ObjectDoesNotExist:
        # NOTE: A list of deleted db objects will cause repr(list) to fail.
        # So, we detect this and print out the __class__ of the contents of
        # the list.
        str_obj = f'<{obj.__class__} DELETED>'

    return str_obj


def safe_str(obj):
    """Call str() and ignore TypeErrors if str() doesn't return a string."""
    str_obj = ''
    try:
        str_obj = str(obj)
    except (TypeError, ObjectDoesNotExist):
        str_obj = safe_repr(obj)

    return str_obj


def is_iterable(obj):
    """Return True if object can be iterated."""
    try:
        iter(obj) and len(obj)
    except NotImplementedError:
        return False
    except TypeError:
        return False
    except ValueError:
        return False
    return True


def is_query(obj):
    """Return True if object is most likely a query."""
    if obj is not None:
        return _in_dir(obj, 'as_manager') and _in_dir(obj, 'all') and _in_dir(obj, 'filter')


def is_dict(obj):
    """Return True if object is most likely a dict."""
    if obj is not None:
        return _in_dir(obj, 'items') and _in_dir(obj, 'keys') and _in_dir(obj, 'values')


def is_set(obj):
    """Return True if object is most likely a dict."""
    return isinstance(obj, set) or isinstance(obj, frozenset)

def is_enum_member(obj):
    """Return True if object is most likely a enum"""
    return issubclass(type(obj), OrigEnum)

def is_const(obj):
    """Return True if object is most likely a constant."""
    if obj is not None:
        return isinstance(obj, str) and obj[0].isalpha() and obj.upper() == obj


def is_key(obj):
    """Return True if object is most likely a key."""
    if obj is not None and isinstance(obj, str):
        return "'" in obj


def is_number(obj):
    """Return True if object is most likely a number."""
    if obj is not None:
        return (
            isinstance(obj, (int, float, Decimal))
            or (getattr(obj, 'isnumeric', None) and obj.isnumeric())
        )


def is_private(obj):
    """Return True if object is private."""
    if obj is not None:
        return isinstance(obj, str) and obj.startswith('_')


def is_magic(obj):
    """Return True if object is private."""
    if obj is not None:
        return isinstance(obj, str) and obj.startswith('__') and obj.endswith('__')


def _in_dir(obj, attr):
    """Simpler hasattr() function without side effects."""
    return attr in dir(obj)


def _is_indexable(obj):
    """Return True if object can be indexed."""
    if isinstance(obj, Sequence):
        return True
    else:
        return False

# endregion Object Property Functions