import os
import re
import time

from django.conf import settings
from django.shortcuts import render
from rest_framework.decorators import api_view, permission_classes
from rest_framework.permissions import AllowAny, IsAdminUser
from rest_framework.response import Response
from rest_framework import status
from rest_framework.exceptions import NotFound, APIException

try:
    import docker
except ImportError:
    docker = None

LOCAL_RE = re.compile(r"^[a-z0-9](?:[a-z0-9._-]{0,62}[a-z0-9])?$")

ANSI_RE = re.compile(r"\x1B\[[0-?]*[ -/]*[@-~]")
EMAIL_RE = re.compile(r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}")


# ----------------------------
# Feature toggle
# ----------------------------
def _require_enabled():
    if not getattr(settings, "MAIL_SIGNUP_ENABLED", False):
        raise NotFound("Not Found")  # 숨김(404)


# ----------------------------
# Docker-mailserver exec helpers
# ----------------------------
def _docker_client():
    """
    Uses docker socket mounted into this container:
      /var/run/docker.sock
    """
    if docker is None:
        raise APIException("Python package 'docker' is not installed in this server image.")

    sock = getattr(settings, "MAIL_DOCKER_SOCK", None) or os.getenv("MAIL_DOCKER_SOCK", "unix://var/run/docker.sock")
    try:
        client = docker.DockerClient(base_url=sock)
        # ping to ensure socket is usable
        client.ping()
        return client
    except Exception as e:
        raise APIException(f"Docker socket is not available. Check /var/run/docker.sock mount. ({e})")


def _dms_container_name() -> str:
    return getattr(settings, "MAIL_DMS_CONTAINER", None) or os.getenv("MAIL_DMS_CONTAINER", "dms-mailserver")


def _dms_exec(setup_args):
    """
    Runs docker-mailserver's internal `setup` command:
      docker exec dms-mailserver setup <args...>

    Example:
      _dms_exec(["email", "list"])
      _dms_exec(["email", "add", "user@domain", "password"])
    """
    client = _docker_client()
    name = _dms_container_name()

    try:
        c = client.containers.get(name)
    except Exception as e:
        raise APIException(f"Cannot find mailserver container '{name}'. ({e})")

    # Try to execute: setup <args...>
    try:
        res = c.exec_run(["setup", *setup_args], demux=True)
        out, err = res.output
        stdout = (out or b"").decode("utf-8", errors="ignore").strip()
        stderr = (err or b"").decode("utf-8", errors="ignore").strip()

        if res.exit_code != 0:
            # show meaningful error to API consumer
            raise ValueError(stderr or stdout or "docker-mailserver setup failed")

        return stdout

    except ValueError:
        raise
    except Exception as e:
        raise APIException(f"Failed to exec into '{name}'. ({e})")
    

def _wait_until_exists(address: str, tries: int = 3, delay: float = 0.3) -> bool:
    addr = address.strip().lower()
    for _ in range(tries):
        if addr in _email_list():
            return True
        time.sleep(delay)
    return False

def _email_list():
    raw = _dms_exec(["email", "list"])
    raw = ANSI_RE.sub("", raw)  # 색상코드 제거
    # 어떤 형식이 와도 이메일만 뽑아냄
    emails = set(m.group(0).strip().lower() for m in EMAIL_RE.finditer(raw))
    return sorted(emails)


# ----------------------------
# Views
# ----------------------------
def signup_page(request):
    _require_enabled()
    return render(request, "mail/signup.html")


@api_view(["POST"])
@permission_classes([AllowAny])
def request_account(request):
    _require_enabled()

    invite_expected = getattr(settings, "MAIL_INVITE_CODE", None) or os.getenv("MAIL_INVITE_CODE", "")
    dms_domain = getattr(settings, "MAIL_DMS_DOMAIN", None) or os.getenv("MAIL_DMS_DOMAIN", "")

    local = (request.data.get("local") or "").strip().lower()
    password = request.data.get("password") or ""
    invite = (request.data.get("invite") or "").strip()

    if not invite_expected or invite != invite_expected:
        return Response({"detail": "초대코드가 올바르지 않습니다."}, status=status.HTTP_403_FORBIDDEN)

    if not dms_domain:
        return Response(
            {"detail": "서버 설정(MAIL_DMS_DOMAIN)이 비어있습니다."},
            status=status.HTTP_500_INTERNAL_SERVER_ERROR,
        )

    if not LOCAL_RE.match(local):
        return Response(
            {"detail": "아이디 형식이 올바르지 않습니다. (영문소문자/숫자/._- 허용)"},
            status=status.HTTP_400_BAD_REQUEST,
        )

    if len(password) < 5:
        return Response(
            {"detail": "비밀번호는 5자 이상으로 설정하세요."},
            status=status.HTTP_400_BAD_REQUEST,
        )

    address = f"{local}@{dms_domain}"

    try:
        emails = _email_list()
        if address in emails:
            return Response({"message": f"ℹ️ {address} 는 이미 존재합니다. (email list에서 확인됨)"})

        # Create account inside dms-mailserver
        _dms_exec(["email", "add", address, password])

        if _wait_until_exists(address):
            return Response({"message": f"✅ {address} 계정이 잘 만들어졌습니다! (email list에서 확인됨)"})

        return Response({"detail": "계정 생성 후 list에서 확인이 안 됩니다. 다시 제출 버튼을 눌러서 확인해보시거나 관리자에게 문의해주세요."}, status=500)

    except ValueError as e:
        msg = str(e)
        if "already exists" in msg.lower():
            return Response({"message": f"ℹ️ {address} 는 이미 존재합니다."})
        return Response({"detail": msg}, status=status.HTTP_400_BAD_REQUEST)
    except Exception as e:
        return Response({"detail": f"서버 오류: {e}"}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)


@api_view(["GET"])
@permission_classes([IsAdminUser])
def admin_list(request):
    _require_enabled()

    try:
        emails = _email_list()
        return Response({"count": len(emails), "emails": emails})
    except Exception as e:
        return Response({"detail": f"서버 오류: {e}"}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)