import json
import shlex
from subprocess import PIPE, Popen, TimeoutExpired
from subprocess import run as subprocess_run


class QMAuthError(Exception):
    def __init__(self, msg, rc, response=None):
        super().__init__(msg, rc, response)
        self.msg = msg
        self.rc = rc
        self.response = response


class QMailAuthuser:
    def __init__(
        self, username, password, prog, mailbox_path, virtual_user, authenticator
    ):
        self._username = username
        self._password = password
        self._prog = prog
        self._mailbox_path = mailbox_path
        self._virtual_user = virtual_user
        self._authenticator = authenticator

    def verify_user(self):
        try:
            completed_proc = subprocess_run(
                f"{self._authenticator} true 3<&0",
                input=f"{self._username}\0{self._password}\0\0".encode(),
                shell=True,
                timeout=2,
            )
            if completed_proc.returncode == 0:
                return True
            if completed_proc.returncode == 1:
                return False
            else:
                raise QMAuthError("authentication error", completed_proc.returncode)
        except TimeoutExpired:
            return False

    def read_headers_for(self, folder, start, end, sort):
        return self.build_and_run("list", [folder, start, end, sort])

    def count(self, folder):
        return self.build_and_run("count", [folder])

    def show(self, folder, msgid):
        return self.build_and_run("read", [folder, msgid])

    def raw(self, folder, mid, path):
        return self.build_and_run("raw", [folder, mid, path])

    def search(self, pattern, folder):
        return self.build_and_run("search", [pattern, folder])

    def folders(self):
        res = self.build_and_run("folders")
        if isinstance(res, list):
            return [""] + res
        return res

    def move(self, mid, from_f, to_f):
        _resp = self.build_and_run("move", [mid, from_f, to_f])
        return True

    def remove(self, folder, msgid):
        _resp = self.build_and_run("remove", [folder, msgid])
        return True

    def _build_arg(self, user_mail_addr, mode, args):
        idx = user_mail_addr.find("@")
        user_name = user_mail_addr[:idx]

        return (
            " ".join(
                shlex.quote(str(x))
                for x in [
                    self._authenticator,
                    self._prog,
                    self._mailbox_path,
                    self._virtual_user,
                    user_name,
                    mode,
                    *args,
                ]
            )
            + " 3<&0"
        )

    def _read_qmauth(self, prog_and_args):
        popen = Popen(prog_and_args, stdin=PIPE, stdout=PIPE, shell=True)

        try:
            inp, _ = popen.communicate(
                f"{self._username}\0{self._password}\0\0".encode(), timeout=30
            )
            popen.wait(1)
        except TimeoutExpired:
            popen.terminate()

        if popen.poll() is None:
            popen.kill()
            popen.poll()

        rc = popen.returncode
        if rc in [0, 3]:
            try:
                a, b, c = inp.partition(b"\n")
                d = json.loads(a)
                if b:
                    resp = dict(head=d, body=c.decode())
                else:
                    resp = d
            except json.JSONDecodeError:
                raise QMAuthError("error decoding response", rc, inp)
            if rc == 3:
                raise QMAuthError("error reported by extractor", rc, resp)
        else:
            raise QMAuthError("got unsuccessful return code by qmail-authuser", rc, inp)

        return resp

    def build_and_run(self, mode, args=()):
        prog_and_args = self._build_arg(self._username, mode, args)
        return self._read_qmauth(prog_and_args)