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

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

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"))
MAIL_FROM = os.getenv("MAIL_FROM", "noreply@example.com")
MAIL_TO = os.getenv("MAIL_TO", "destination@example.com")


@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: str = Form(...),
    telno: str = Form(...),
    mail: str = Form(...),
    apparatsname: str = Form(...),
    subject: str = Form(...),
    semester_type: str = Form(...),  # "summer" or "winter"
    semester_year: str = Form(...),
    authorname: list[str] = Form(...),
    year: list[str] = Form(...),
    booktitle: list[str] = Form(...),
    signature: list[str] = Form(...),
):
    # Build XML
    root = Element("form_submission")

    static_data = SubElement(root, "static")
    SubElement(static_data, "name").text = name
    SubElement(static_data, "lastname").text = lastname
    SubElement(static_data, "title").text = title
    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}"
    # 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]
        SubElement(book, "signature").text = signature[i]

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

    # Send mail
    msg = MIMEText(xml_data, "xml")
    msg["Subject"] = "New Form Submission"
    msg["From"] = MAIL_FROM
    msg["To"] = MAIL_TO

    with smtplib.SMTP(SMTP_HOST, SMTP_PORT) as server:
        server.send_message(msg)

    return RedirectResponse("/", status_code=303)