"""Utility helpers used across the application."""
from __future__ import annotations

import logging
import smtplib
from email.header import Header
from email.mime.text import MIMEText
from functools import wraps
from typing import Callable, Iterable, List

from flask import abort, current_app
from flask_login import current_user


logger = logging.getLogger(__name__)


# ---------------------------------------------------------------------------
# Access control decorators
# ---------------------------------------------------------------------------

def _require_roles(roles: Iterable[str]) -> Callable:
    """Abort with 403 when the current user does not own one of the roles."""

    def decorator(view_func: Callable) -> Callable:
        @wraps(view_func)
        def wrapper(*args, **kwargs):
            if not current_user.is_authenticated or current_user.role not in roles:
                abort(403)
            return view_func(*args, **kwargs)

        return wrapper

    return decorator


def admin_required(view_func: Callable) -> Callable:
    """Limit a view to administrator accounts only."""

    return _require_roles({"admin"})(view_func)


def editor_or_admin_required(view_func: Callable) -> Callable:
    """Limit a view to editor or administrator accounts."""

    return _require_roles({"editor", "admin"})(view_func)


# ---------------------------------------------------------------------------
# History helpers
# ---------------------------------------------------------------------------

def add_history_log(spec_id: int, action: str, details: str = "") -> None:
    """Persist a history record for an action executed on a spec."""

    from models import SpecHistory, db
    entry = SpecHistory(
        spec_id=spec_id,
        user_id=current_user.id if current_user.is_authenticated else None,
        action=action,
        details=details,
    )
    db.session.add(entry)
    db.session.commit()


# ---------------------------------------------------------------------------
# Notification helpers
# ---------------------------------------------------------------------------

def process_recipients(recipients_str: str | None) -> List[str]:
    """Convert a semicolon separated string into a list of unique addresses."""

    if not recipients_str:
        return []

    normalized = recipients_str.replace("\r", ";").replace("\n", ";")
    candidates = [item.strip() for item in normalized.split(";") if item.strip()]

    seen: set[str] = set()
    result: List[str] = []
    for email in candidates:
        if email not in seen:
            seen.add(email)
            result.append(email)
    return result


def send_email(to_addrs: Iterable[str], subject: str, body: str) -> bool:
    """Send an HTML email using the SMTP configuration in Flask config."""

    recipients = list(to_addrs)
    if not recipients:
        logger.info("send_email skipped: no recipients provided")
        return False

    cfg = current_app.config
    smtp_server = cfg.get("SMTP_SERVER")
    smtp_port = int(cfg.get("SMTP_PORT", 25))
    use_tls = bool(cfg.get("SMTP_USE_TLS", False))
    use_ssl = bool(cfg.get("SMTP_USE_SSL", False))
    sender = cfg.get("SMTP_SENDER_EMAIL")
    password = cfg.get("SMTP_SENDER_PASSWORD", "")
    auth_required = bool(cfg.get("SMTP_AUTH_REQUIRED", False))

    logger.debug(
        "Preparing email: subject=%s recipients=%s server=%s:%s use_tls=%s use_ssl=%s auth_required=%s",
        subject,
        recipients,
        smtp_server,
        smtp_port,
        use_tls,
        use_ssl,
        auth_required,
    )

    message = MIMEText(body, "html", "utf-8")
    message["Subject"] = Header(subject, "utf-8")
    message["From"] = sender
    message["To"] = ", ".join(recipients)

    try:
        if use_ssl and smtp_port == 465:
            server = smtplib.SMTP_SSL(smtp_server, smtp_port)
        else:
            server = smtplib.SMTP(smtp_server, smtp_port)

        if use_tls and smtp_port == 587:
            server.starttls()

        if auth_required and password:
            server.login(sender, password)

        server.sendmail(sender, recipients, message.as_string())
        server.quit()
        logger.info("Email sent to %s (subject=%s)", recipients, subject)
        return True

    except smtplib.SMTPException as exc:
        logger.error("SMTP error while sending email: %s", exc)
    except Exception as exc:  # pragma: no cover
        logger.exception("Unexpected error while sending email: %s", exc)

    return False