#!/usr/bin/env python

"""Verify the integrity of the domain blocklist
"""

import io
import sys
from collections import Counter

from publicsuffixlist import PublicSuffixList
from requests import get


blocklist = "disposable_email_blocklist.conf"
allowlist = "allowlist.conf"

files = {
    filename: open(filename).read().splitlines() for filename in [allowlist, blocklist]
}


def download_suffixes():
    with open("public_suffix_list.dat", "wb") as file:
        response = get("https://publicsuffix.org/list/public_suffix_list.dat")
        file.write(response.content)


def check_for_public_suffixes(filename):
    lines = files[filename]
    suffix_detected = False
    psl = None
    with open("public_suffix_list.dat", "r") as latest:
        psl = PublicSuffixList(latest)
    for i, line in enumerate(lines):
        current_line = line.strip()
        public_suffix = psl.publicsuffix(current_line)
        if public_suffix == current_line:
            print(
                f"The line number {i+1} contains just a public suffix: {current_line}"
            )
            suffix_detected = True
    if suffix_detected:
        print(
            "At least one valid public suffix found in {!r}, please "
            "remove it. See https://publicsuffix.org for details on why this "
            "shouldn't be blocklisted.".format(filename)
        )
        sys.exit(1)


def check_for_third_level_domains(filename):
    with open("public_suffix_list.dat", "r") as latest:
        psl = PublicSuffixList(latest)

    invalid = {
        line
        for line in files[filename]
        if len(psl.privateparts(line.strip())) > 1
    }
    if invalid:
        print("The following domains contain a third or lower level domain in {!r}:".format(filename))
        for line in sorted(invalid):
            print("* {}".format(line))
        sys.exit(1)


def check_for_non_lowercase(filename):
    lines = files[filename]
    invalid = set(lines) - set(line.lower() for line in lines)
    if invalid:
        print("The following domains should be lowercased in {!r}:".format(filename))
        for line in sorted(invalid):
            print("* {}".format(line))
        sys.exit(1)


def check_for_duplicates(filename):
    lines = files[filename]
    count = Counter(lines) - Counter(set(lines))
    if count:
        print("The following domains appear twice in {!r}:".format(filename))
        for line in sorted(count):
            print("* {}".format(line))
        sys.exit(1)


def check_sort_order(filename):
    lines = files[filename]
    for a, b in zip(lines, sorted(lines)):
        if a != b:
            print("The list is not sorted in {!r}:".format(filename))
            print("* {!r} should come before {!r}".format(b, a))
            sys.exit(1)


def check_for_intersection(filename_a, filename_b):
    a = files[filename_a]
    b = files[filename_b]
    intersection = set(a) & set(b)
    if intersection:
        print("The following domains appear in both lists:")
        for line in sorted(intersection):
            print("* {}".format(line))
        sys.exit(1)


if __name__ == "__main__":
    # Download the list of public suffixes
    download_suffixes()

    # Check if any domains have a public suffix
    check_for_public_suffixes(blocklist)

    # Check if any domains are a third or lower level domain
    check_for_third_level_domains(blocklist)

    # Check if any domains are not lowercase
    check_for_non_lowercase(allowlist)
    check_for_non_lowercase(blocklist)

    # Check if any domains are duplicated in the same list
    check_for_duplicates(allowlist)
    check_for_duplicates(blocklist)

    # Check if any lists are not sorted
    check_sort_order(allowlist)
    check_sort_order(blocklist)

    # Check if any domains are in both the allowlist and blocklist
    check_for_intersection(allowlist, blocklist)

    print("All domain entries seem valid.")