import logging
from dataclasses import dataclass
from datetime import datetime, timedelta
from pathlib import Path
from typing import Any

import emails
from jinja2 import Template
from jose import JWTError, jwt

from app.core.config import settings


@dataclass
class EmailData:
    html_content: str
    subject: str


def render_email_template(*, template_name: str, context: dict[str, Any]):
    template_str = (Path(settings.EMAIL_TEMPLATES_DIR) / template_name).read_text()
    html_content = Template(template_str).render(context)
    return html_content


def send_email(
    *,
    email_to: str,
    subject: str = "",
    html_content: str = "",
) -> None:
    assert settings.EMAILS_ENABLED, "no provided configuration for email variables"
    message = emails.Message(
        subject=subject,
        html=html_content,
        mail_from=(settings.EMAILS_FROM_NAME, settings.EMAILS_FROM_EMAIL),
    )
    smtp_options = {"host": settings.SMTP_HOST, "port": settings.SMTP_PORT}
    if settings.SMTP_TLS:
        smtp_options["tls"] = True
    if settings.SMTP_USER:
        smtp_options["user"] = settings.SMTP_USER
    if settings.SMTP_PASSWORD:
        smtp_options["password"] = settings.SMTP_PASSWORD
    response = message.send(to=email_to, smtp=smtp_options)
    logging.info(f"send email result: {response}")


def generate_test_email(email_to: str) -> EmailData:
    project_name = settings.PROJECT_NAME
    subject = f"{project_name} - Test email"
    html_content = render_email_template(
        template_name="test_email.html",
        context={"project_name": settings.PROJECT_NAME, "email": email_to},
    )
    return EmailData(html_content=html_content, subject=subject)


def generate_reset_password_email(email_to: str, email: str, token: str) -> EmailData:
    project_name = settings.PROJECT_NAME
    subject = f"{project_name} - Password recovery for user {email}"
    server_host = settings.SERVER_HOST
    link = f"{server_host}/reset-password?token={token}"
    html_content = render_email_template(
        template_name="reset_password.html",
        context={
            "project_name": settings.PROJECT_NAME,
            "username": email,
            "email": email_to,
            "valid_hours": settings.EMAIL_RESET_TOKEN_EXPIRE_HOURS,
            "link": link,
        },
    )
    return EmailData(html_content=html_content, subject=subject)


def generate_new_account_email(
    email_to: str, username: str, password: str
) -> EmailData:
    project_name = settings.PROJECT_NAME
    subject = f"{project_name} - New account for user {username}"
    link = settings.SERVER_HOST
    html_content = render_email_template(
        template_name="new_account.html",
        context={
            "project_name": settings.PROJECT_NAME,
            "username": username,
            "password": password,
            "email": email_to,
            "link": link,
        },
    )
    return EmailData(html_content=html_content, subject=subject)


def generate_password_reset_token(email: str) -> str:
    delta = timedelta(hours=settings.EMAIL_RESET_TOKEN_EXPIRE_HOURS)
    now = datetime.utcnow()
    expires = now + delta
    exp = expires.timestamp()
    encoded_jwt = jwt.encode(
        {"exp": exp, "nbf": now, "sub": email},
        settings.SECRET_KEY,
        algorithm="HS256",
    )
    return encoded_jwt


def verify_password_reset_token(token: str) -> str | None:
    try:
        decoded_token = jwt.decode(token, settings.SECRET_KEY, algorithms=["HS256"])
        return decoded_token["sub"]
    except JWTError:
        return None