import os
import re
import json
import argparse
from datetime import datetime
from typing import Callable, Any

import requests


def loadSettings(path: str | None) -> dict:
    '''
        Load the settings file.

        `path` Path to a settings file.
        By default the program will look for `$HOME/.config/dyn-gandi/config.json` and then `/etc/dyn-gandi.json`.
    '''

    if path is None:
        path = f"{os.path.expanduser('~')}/.config/dyn-gandi/config.json"

        if not os.path.exists(path):
            path = '/etc/dyn-gandi.json'

        if not os.path.exists(path):
            print(
                f"[ERROR] No config file found at '~/.config/dyn-gandi/config.json' or '/etc/dyn-gandi.json'")
            quit()

    if not os.path.exists(path):
        print(f"[ERROR] '{path}' does not exist.")
        quit()

    # TODO check integrity of the config file
    with open(path, 'r') as file:
        # Load as dictionary
        config = json.load(file)

        # API Key entries
        keys = config['api'].keys()

        # This will build up a copy of the API section with the API keys instead of filenames.
        mask = dict()

        # If the API key is a file the use the contents as a new key.
        for key in keys:
            api_key = key
            if os.path.exists(key):
                with open(key, 'r') as file:
                    api_key = file.readline().strip()
            mask[key] = api_key
        config['api'] = {mask[key]: value for key,
                         value in config['api'].items()}

    return config


def log(logline: str, path: str = './log.txt', stdout: bool = False) -> None:
    '''
        Appends `logline` at the end of the file file with a timestamp.

        `logline` The line to log.

        'path' Path to file where to log.

        `stdout` Wether to print to stdout instead of a file.
    '''

    line = f"[{datetime.now().strftime('%Y-%m-%d %H:%M:%S')}]{logline}"

    if stdout:
        print(line)
    else:
        with open(path, 'a') as file:
            file.write(line + '\n')


def getCurrentIP(resolvers: list[str], log: Callable[[str], Any]) -> str | None:
    '''
        Go through resolvers until one returns an IP.

        `resolvers` A list of IP resolvers.

        `log` A function which takes a string and logs it.
    '''

    for resolver in resolvers:
        response = requests.get(resolver)

        if response.ok:
            current_ip = response.text.strip()

            # It suffices to check whether the search is not None since the regex matches from beginning to end.
            is_ipv4 = re.search(
                '^((25[0-5]|(2[0-4]|1\d|[1-9]|)\d)\.?\\b){4}$', current_ip) is not None

            if is_ipv4:
                log(f"[OK][{resolver}] Current IP: '{current_ip}'")
                return current_ip  # Break if we have found our IP
            else:
                log(f"[ERROR][{resolver}] '{current_ip}' is not IPv4")
        else:
            log(f"[ERROR][{resolver}][{response.status_code}] {response.text}")

    return None


def checkRecords(api: dict[str, dict[str, list[str]]], current_ip: str, log: Callable[[str], Any]) -> dict[str, dict[str, list[str]]]:
    '''
        Return records that need to be renewed.

        `api` The API section of the settings file.

        `current_ip` The current IP address.

        `log` A function that takes in a string and logs it.
    '''

    # TODO: Detect TTL change

    records_to_renew = api
    for key, domains in api.items():
        headers = {'authorization': f"Apikey {key}"}

        for domain, _ in domains.items():
            response = requests.get(
                f"https://api.gandi.net/v5/livedns/domains/{domain}/records?rrset_type=A", headers=headers)

            if response.status_code == 200:
                records_to_renew[key][domain] = list(set(records_to_renew[key][domain]) - set(record['rrset_name'] for record in (
                    filter(lambda x: current_ip in x['rrset_values'], response.json()))))

                if (records := records_to_renew[key][domain]) != []:
                    log(f"[INFO][{','.join(records)}] Records need to be renewed")

            else:
                log(f"[ERROR][{domain}][{response.status_code}] {response.json()}")

    return records_to_renew


def renewRecords(api: dict[str, dict[str, list[str]]], current_ip: str, log: Callable[[str], Any], ttl: int = 300) -> None:
    '''
        Update records and create them, if they don't exist.

        `api` The API section of the settings file.

        `current_ip` The current IP address.

        `log` A function that takes a string and logs it.

        `ttl` How long a record should be cached.
    '''

    payload = json.dumps({
        'rrset_values': [current_ip],
        'rrset_ttl': ttl
    })

    for api_key, domains in api.items():
        headers = {
            'authorization': f"Apikey {api_key}",
            'content-type': 'application/json',
        }

        for domain, records in domains.items():
            for record in records:
                response = requests.put(
                    f"https://api.gandi.net/v5/livedns/domains/{domain}/records/{record}/A", data=payload, headers=headers)
                if response.status_code == 201:
                    log(f"[OK][{domain}][{record}] Renewed with IP '{current_ip}'")
                else:
                    log(f"[ERROR][{domain}][{record}][{response.status_code}] {response.json()}")


def parseArgs(args: list[str]) -> argparse.Namespace:
    '''
        Parse command-line arguments.

        `args` A list of user-supplied command line arguments.
    '''

    parser = argparse.ArgumentParser(
        description='A program that renews A records via the Gandi API v5.')

    parser.add_argument('--config', type=str, default=None,
                        help='Path to a config file.')
    parser.add_argument('--dry-run', action='store_true',
                        help='Just perform a dry-run.')

    return parser.parse_args(args)


def main():
    # Parse user-supplied command-line arguments.
    args = parseArgs(os.sys.argv[1:])

    # Read in the settings file.
    config = loadSettings(args.config)

    def logger(x: str) -> Any: return log(x, config['log_path'], args.dry_run)

    current_ip = getCurrentIP(config['resolvers'], logger)
    if current_ip is not None:
        records_to_renew = checkRecords(config['api'], current_ip, logger)

        # Do not perform an actual record change during a dry-run.
        if not args.dry_run:
            renewRecords(records_to_renew, current_ip, logger, config['ttl'])


if __name__ == '__main__':
    main()