import os
import re
import smtplib
from email.mime.text import MIMEText
from typing import Optional
from xml.etree.ElementTree import Element, SubElement, tostring

from dotenv import load_dotenv
from fastapi import FastAPI, Form, HTTPException, Request, status
from fastapi.responses import HTMLResponse, RedirectResponse
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates

load_dotenv()
app = FastAPI()
templates = Jinja2Templates(directory="app/templates")

# Serve static files (CSS, images)
app.mount("/static", StaticFiles(directory="app/static"), name="static")

# add somewhere near the top-level constants
EMAIL_REGEX = re.compile(r"^[^@\s]+@[^@\s]+\.[^@\s]+$")

# SMTP / email configuration via environment
SMTP_HOST = os.getenv("SMTP_HOST", "smtp")
SMTP_PORT = int(os.getenv("SMTP_PORT", "25"))
SENDER_MAIL = os.getenv("SENDER_MAIL", "noreply@example.com")
MAIL_TO = os.getenv("MAIL_TO", "destination@example.com")
MAIL_USERNAME = os.getenv("MAIL_USERNAME")
MAIL_PASSWORD = os.getenv("MAIL_PASSWORD")

print(
    f"Using SMTP server {SMTP_HOST}:{SMTP_PORT} with user {MAIL_USERNAME}"
    f" to send from {SENDER_MAIL} to {MAIL_TO}"
)


@app.get("/", response_class=HTMLResponse)
async def show_form(request: Request):
    return templates.TemplateResponse("form.html", {"request": request})


@app.post("/submit")
async def handle_form(
    request: Request,
    name: str = Form(...),
    lastname: str = Form(...),
    title: Optional[str] = Form(None),
    telno: str = Form(...),
    mail: str = Form(...),
    apparatsname: str = Form(...),
    subject: str = Form(...),
    semester_type: str = Form(...),  # "summer" or "winter"
    semester_year: str = Form(...),
    dauerapparat: bool = Form(False),
    authorname: list[str] = Form(...),
    year: list[str] = Form(...),
    booktitle: list[str] = Form(...),
    signature: Optional[list[str]] = Form(None),
):
    # Build XML
    root = Element("form_submission")

    static_data = SubElement(root, "static")
    SubElement(static_data, "name").text = name
    SubElement(static_data, "lastname").text = lastname
    # Title is optional
    SubElement(static_data, "title").text = title or ""
    SubElement(static_data, "telno").text = telno
    SubElement(static_data, "mail").text = mail
    SubElement(static_data, "apparatsname").text = apparatsname
    SubElement(static_data, "subject").text = subject
    SubElement(static_data, "semester").text = f"{semester_type} {semester_year}"
    SubElement(static_data, "dauerapparat").text = "true" if dauerapparat else "false"
    # inside handle_form(), right after parameters are received, before building XML:
    # Basic email validation (server-side)
    if not EMAIL_REGEX.match(mail):
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Invalid email address format.",
        )
    books = SubElement(root, "books")
    for i in range(len(authorname)):
        book = SubElement(books, "book")
        SubElement(book, "authorname").text = authorname[i]
        SubElement(book, "year").text = year[i]
        SubElement(book, "title").text = booktitle[i]
        # Signature is optional; write empty string if not provided
        sig_value = ""
        if signature and i < len(signature):
            sig_raw = signature[i] or ""
            sig_value = sig_raw.strip()
        SubElement(book, "signature").text = sig_value

    xml_data = tostring(root, encoding="unicode")

    # Send mail
    msg = MIMEText(xml_data, "xml")
    msg["Subject"] = "Antrag für neuen Semesterapparat"
    msg["From"] = SENDER_MAIL
    msg["To"] = MAIL_TO

    with smtplib.SMTP_SSL(SMTP_HOST, SMTP_PORT) as server:
        server.connect(SMTP_HOST, SMTP_PORT)
        # Login only if credentials are provided
        if MAIL_USERNAME and MAIL_PASSWORD:
            server.login(MAIL_USERNAME, MAIL_PASSWORD)

        server.send_message(msg, from_addr=SENDER_MAIL, to_addrs=[MAIL_TO])

    return RedirectResponse("/", status_code=303)