"""
The public side of unsubscribing: the page an email's Unsubscribe link opens, and the one-click
POST that mail apps send on the reader's behalf. Nothing here needs a sign-in; the signed link
is the proof. The page asks for a click (GET never unsubscribes) so link scanners that open
every link in a message do not remove people by accident.
"""

from __future__ import annotations

import html

from fastapi import APIRouter
from fastapi.responses import HTMLResponse

from backend import unsubscribe

router = APIRouter()


@router.get("/u/{token}", response_class=HTMLResponse)
def unsubscribe_page(token: str):
    try:
        _, email = unsubscribe.parse_token(token)
    except ValueError as exc:
        return HTMLResponse(unsubscribe.page("Link not valid", f"<p>{html.escape(str(exc))}.</p>"), status_code=400)
    return unsubscribe.page(
        "Unsubscribe",
        f"<p>Stop emails to <b>{html.escape(email)}</b>?</p>"
        f'<form method="post"><button style="font:inherit;padding:10px 18px;cursor:pointer">Unsubscribe</button></form>',
    )


@router.post("/u/{token}", response_class=HTMLResponse)
def unsubscribe_now(token: str):
    try:
        email = unsubscribe.unsubscribe_with_token(token)
    except ValueError as exc:
        return HTMLResponse(unsubscribe.page("Link not valid", f"<p>{html.escape(str(exc))}.</p>"), status_code=400)
    return unsubscribe.page("You are unsubscribed", f"<p>{html.escape(email)} will not get more emails from this sender.</p>")