import random
import string
import re

import structlog
import tempfile
from datetime import datetime
from dateutil.relativedelta import relativedelta

from dateutil.parser import ParserError, parse
from django.utils.text import slugify

from libraries.constants import (
    DEFAULT_LIBRARIES_LANDING_VIEW,
    SELECTED_BOOST_VERSION_COOKIE_NAME,
    SELECTED_LIBRARY_VIEW_COOKIE_NAME,
    LATEST_RELEASE_URL_PATH_STR,
)
from versions.models import Version

logger = structlog.get_logger()


def decode_content(content):
    """Decode bytes to string."""
    if isinstance(content, bytes):
        return content.decode("utf-8")
    return content


def generate_fake_email(val: str) -> str:
    """Slugify a string to make a fake email.

    Would not necessarily be unique -- this is a lazy way for us to avoid creating
    multiple new user records for one contributor who contributes to multiple libraries.
    """
    slug = slugify(val)
    local_email = slug.replace("-", "_")[:50]
    return f"{local_email}@example.com"


def generate_random_string(length=4):
    characters = string.ascii_letters
    random_string = "".join(random.choice(characters) for _ in range(length))
    return random_string


def version_within_range(
    version: str, min_version: str = None, max_version: str = None
):
    """Direct string comparison, assuming 'version', 'min_version', and 'max_version'
    follow the same format.

    Expects format `boost-1.84.0`
    """
    if min_version and version < min_version:
        return False
    if max_version and version > max_version:
        return False
    return True


def get_first_last_day_last_month():
    now = datetime.now()
    first_day_this_month = now.replace(day=1)
    last_day_last_month = first_day_this_month - relativedelta(days=1)
    first_day_last_month = last_day_last_month.replace(day=1)
    return first_day_last_month, last_day_last_month


def parse_date(date_str):
    """Parses a date string to a datetime. Does not return an error."""
    try:
        return parse(date_str)
    except ParserError:
        logger.info("parse_date_invalid_date", date_str=date_str)
        return None


def write_content_to_tempfile(content):
    """Accepts string or bytes content, writes it to a temporary file, and returns the
    file object."""
    with tempfile.NamedTemporaryFile(delete=False) as temp_file:
        if isinstance(content, bytes):
            temp_file = open(temp_file.name, "wb")
        temp_file.write(content)
        temp_file.close()
    return temp_file


def get_version_from_url(request):
    return request.GET.get("version")


def get_version_from_cookie(request):
    return request.COOKIES.get(SELECTED_BOOST_VERSION_COOKIE_NAME)


def get_view_from_url(request):
    return request.resolver_match.kwargs.get("library_view_str")


def get_view_from_cookie(request):
    return request.COOKIES.get(SELECTED_LIBRARY_VIEW_COOKIE_NAME)


def set_view_in_cookie(response, view):
    allowed_views = {"grid", "list", "categorized"}
    if view not in allowed_views:
        return
    response.set_cookie(SELECTED_LIBRARY_VIEW_COOKIE_NAME, view)


def get_prioritized_version(request):
    """
    Version Priorities:
    1. URL parameter
    2. Cookie
    3. Default to latest version
    """
    url_version = get_version_from_url(request)
    cookie_version = get_version_from_cookie(request)
    default_version = None
    return url_version or cookie_version or default_version


def get_prioritized_library_view(request):
    """
    View Priorities:
    1. URL parameter
    2. Cookie
    3. Default to grid view
    """
    url_view = get_view_from_url(request)
    cookie_view = get_view_from_cookie(request)
    return url_view or cookie_view or DEFAULT_LIBRARIES_LANDING_VIEW


def get_category(request):
    return request.GET.get("category", "")


def determine_selected_boost_version(request_value, request):
    valid_versions = Version.objects.version_dropdown_strict()
    version_slug = request_value or get_version_from_cookie(request)
    if version_slug in [v.slug for v in valid_versions] + [LATEST_RELEASE_URL_PATH_STR]:
        return version_slug
    else:
        logger.warning(f"Invalid version slug in cookies: {version_slug}")
        return None


def set_selected_boost_version(version_slug: str, response) -> None:
    """Update the selected version in the cookies."""
    valid_versions = Version.objects.version_dropdown_strict()
    if version_slug in [v.slug for v in valid_versions]:
        response.set_cookie(SELECTED_BOOST_VERSION_COOKIE_NAME, version_slug)
    elif version_slug == LATEST_RELEASE_URL_PATH_STR:
        response.delete_cookie(SELECTED_BOOST_VERSION_COOKIE_NAME)
    else:
        logger.warning(f"Attempted to set invalid version slug: {version_slug}")


def library_doc_latest_transform(url):
    p = re.compile(r"^(/doc/libs/)[0-9_]+(/\S+)$")
    if p.match(url):
        url = p.sub(rf"\1{LATEST_RELEASE_URL_PATH_STR}\2", url)
    return url


def get_documentation_url(library_version, latest):
    """Get the documentation URL for the current library."""

    def find_documentation_url(library_version):
        # If we know the library-version docs are missing, return the version docs
        if library_version.missing_docs:
            return library_version.version.documentation_url
        # If we have the library-version docs and they are valid, return those
        elif library_version.documentation_url:
            return library_version.documentation_url
        # If we wind up here, return the version docs
        else:
            return library_version.version.documentation_url

    # Get the URL for the version.
    url = find_documentation_url(library_version)
    # Remove the "boost_" prefix from the URL.
    url = url.replace("boost_", "")
    if latest:
        url = library_doc_latest_transform(url)

    return url