#!/usr/local/bin/python3.9
"""Account registration service for the 40250 server (PORT: 40250 has no in-client registration).

POST /register with a form body `login=..&password=..&social_id=..` inserts a row into
account.account the same way the existing accounts are stored (password = MySQL PASSWORD()).
The reply is one plain-text line the client shows directly: `OK` or `ERR <CODE>`, where CODE is
BAD_LOGIN, BAD_PASSWORD, BAD_SOCIAL_ID, EXISTS, RATE_LIMIT, BAD_REQUEST or SERVER.

Deployed to /usr/metin2/server/register/ and started by /usr/local/etc/rc.d/mt_register.
"""
import argparse
import re
import subprocess
import sys
import threading
import time
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from urllib.parse import parse_qs

LOGIN_RE = re.compile(r"^[A-Za-z0-9]{4,16}$")          # LoginWindow ID_EditLine input_limit 16
PASSWORD_RE = re.compile(r"^[\x21-\x7e]{4,16}$")       # printable ASCII, Password_EditLine input_limit 16
SOCIAL_ID_RE = re.compile(r"^[0-9]{7}$")               # the delete code introselect asks for

RATE_WINDOW = 3600
RATE_MAX = 5          # successful registrations per IP per hour
MAX_BODY = 1024

_rate_lock = threading.Lock()
_rate = {}            # ip -> [timestamps of successful registrations]


def log(msg):
    sys.stdout.write(time.strftime("%Y-%m-%d %H:%M:%S ") + msg + "\n")
    sys.stdout.flush()


def rate_limited(ip):
    now = time.time()
    with _rate_lock:
        hits = [t for t in _rate.get(ip, []) if now - t < RATE_WINDOW]
        _rate[ip] = hits
        return len(hits) >= RATE_MAX


def rate_record(ip):
    with _rate_lock:
        _rate.setdefault(ip, []).append(time.time())


def create_account(login, password, social_id):
    # Every value is validated above; the password additionally travels as hex so no quoting
    # can leak into the statement.
    sql = ("INSERT INTO account.account (login, password, social_id, status, create_time, last_play) "
           "VALUES ('%s', PASSWORD(UNHEX('%s')), '%s', 'OK', NOW(), NOW())"
           % (login, password.encode("ascii").hex(), social_id))
    r = subprocess.run(["/usr/local/bin/mysql", "-uroot", "-N", "-e", sql], capture_output=True, text=True, timeout=10)
    if r.returncode == 0:
        return "OK"
    if "Duplicate entry" in r.stderr or "ERROR 1062" in r.stderr:
        return "ERR EXISTS"
    log("mysql error: " + r.stderr.strip())
    return "ERR SERVER"


class Handler(BaseHTTPRequestHandler):
    server_version = "mt-register/1"

    def log_message(self, fmt, *args):
        pass

    def reply(self, code, text):
        body = (text + "\n").encode("ascii")
        self.send_response(code)
        self.send_header("Content-Type", "text/plain")
        self.send_header("Content-Length", str(len(body)))
        self.send_header("Connection", "close")
        self.end_headers()
        self.wfile.write(body)

    def do_GET(self):
        if self.path == "/ping":
            self.reply(200, "OK")
        else:
            self.reply(404, "ERR BAD_REQUEST")

    def do_POST(self):
        ip = self.client_address[0]
        if self.path != "/register":
            return self.reply(404, "ERR BAD_REQUEST")
        try:
            n = int(self.headers.get("Content-Length", "0"))
        except ValueError:
            n = -1
        if n < 0 or n > MAX_BODY:
            return self.reply(400, "ERR BAD_REQUEST")
        try:
            form = parse_qs(self.rfile.read(n).decode("ascii"), keep_blank_values=True)
        except (UnicodeDecodeError, ValueError):
            return self.reply(400, "ERR BAD_REQUEST")
        login = form.get("login", [""])[0]
        password = form.get("password", [""])[0]
        social_id = form.get("social_id", [""])[0]
        if not LOGIN_RE.match(login):
            result = "ERR BAD_LOGIN"
        elif not PASSWORD_RE.match(password):
            result = "ERR BAD_PASSWORD"
        elif not SOCIAL_ID_RE.match(social_id):
            result = "ERR BAD_SOCIAL_ID"
        elif rate_limited(ip):
            result = "ERR RATE_LIMIT"
        else:
            result = create_account(login.lower(), password, social_id)
            if result == "OK":
                rate_record(ip)
        log("%s register %s -> %s" % (ip, login, result))
        self.reply(200, result)


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--bind", default="0.0.0.0")
    ap.add_argument("--port", type=int, default=11080)
    args = ap.parse_args()
    httpd = ThreadingHTTPServer((args.bind, args.port), Handler)
    log("listening on %s:%d" % (args.bind, args.port))
    httpd.serve_forever()


if __name__ == "__main__":
    main()