"use client";

import { Suspense, useState } from "react";
import Link from "next/link";
import { useSearchParams } from "next/navigation";
import { CalendarClock, Trash2 } from "lucide-react";

import { StandaloneShell } from "@/components/layout/standalone-shell";
import {
  StandaloneCard,
  StandaloneCardHeader,
} from "@/components/layout/standalone-card";
import { PageSpinner } from "@/components/ui/page-spinner";
import { formatPurgeDay, parsePurgeDate } from "@/lib/purge-date";

// The last screen of a deletion. `DELETE /user` composes the purge date and hands it
// back exactly once; the account is dark by the time this renders, so there is no
// session left to ask for it again and nothing to poll. It arrives on the URL because
// that is what survives the page load the deletion ends in - see
// `delete-account-card.tsx`. The restore screen names the same date from the other
// end of the window, and both parse it through `lib/purge-date.ts`.
//
// Reachable on its own terms as well: a reload, a bookmark, or the back button after
// leaving. A visit with no date is not an error, it is somebody who kept the tab -
// the copy just stops short of naming a day it cannot know.
//
// Chrome-free (see `NO_CHROME_ROUTES` in `app-shell.tsx`), like the other terminal
// auth-flow screens: the header's user menu belongs to a session that no longer
// exists, and the only way on from here is out.
export function GoodbyePageContent() {
  // Not what makes the build pass. `useSearchParams()` is a context read on the
  // client and suspends only while a *static* shell is being validated at build
  // time, which `export const instant = false` on the root layout switches off for
  // every route in this app - see `DECISIONS.md`, "The click paints the
  // destination's frame, and the page is what paints it". Nothing under this
  // boundary suspends, so this fallback never commits.
  return (
    <Suspense fallback={<PageSpinner />}>
      <GoodbyeWithPurgeDate />
    </Suspense>
  );
}

function GoodbyeWithPurgeDate() {
  const searchParams = useSearchParams();
  return <GoodbyeContent purgeAfter={searchParams.get("purge_after")} />;
}

function GoodbyeContent({ purgeAfter }: { purgeAfter: string | null }) {
  // The clock, read once and kept: whether the deadline has passed is a question
  // about the moment this page opened, and re-reading it on every render would make
  // the copy depend on when React happened to re-render rather than on the date.
  const [loadedAt] = useState(() => Date.now());
  // An unparseable value reads as no value at all. Anything could have edited the
  // URL, and a date that renders as "Invalid Date" on the screen someone is reading
  // for the one fact it carries is worse than a screen that admits it hasn't got it.
  const purgeOn = parsePurgeDate(purgeAfter);
  // Whether the deadline is behind us, which is all this can honestly claim to know.
  // Two different visitors reach it: an instance running
  // `ACCOUNT_DELETION_GRACE_DAYS=0`, whose `purge_after` is already past when the
  // response is composed, and anyone reloading, bookmarking or going Back to this URL
  // after their own window ran out. An elapsed timestamp cannot tell those apart, so
  // the copy below talks about the date rather than about how the instance is
  // configured.
  const deadlinePassed = purgeOn !== null && purgeOn.getTime() <= loadedAt;

  return (
    <StandaloneShell className="text-center">
      <StandaloneCard>
        {deadlinePassed ? (
          <StandaloneCardHeader
            icon={Trash2}
            iconClassName="text-muted-foreground"
            title="Your account has been deleted"
            description="The date it was due to be erased on has passed, so your dives, dive drafts, dive sites, trips, courses, certifications, gear, contacts, people and tags are no longer recoverable."
          />
        ) : (
          <>
            <StandaloneCardHeader
              icon={CalendarClock}
              iconClassName="text-muted-foreground"
              title="Your account has been deleted"
              description={
                purgeOn ? (
                  <>
                    You&apos;re signed out everywhere, and nothing has been
                    erased yet. Your dives, dive drafts, dive sites, trips,
                    courses, certifications, gear, contacts, people and tags
                    will be permanently erased on{" "}
                    <span className="font-medium text-foreground">
                      {formatPurgeDay(purgeOn)}
                    </span>
                    .
                  </>
                ) : (
                  "You're signed out everywhere, and nothing has been erased yet. The confirmation email we've just sent you names the date everything is permanently erased on."
                )
              }
            />
            {/* The way back, in the same words as the confirmation email and the
                Danger Zone card - all three describe one behaviour, so reword them
                together. Signing in reaches an offer to restore, not a session. */}
            <p className="text-sm text-muted-foreground">
              Deleted by mistake? Sign in again before{" "}
              {purgeOn ? "that date" : "the date in that email"} and you&apos;ll
              be offered your account back. Afterwards, nothing can be restored.
            </p>
          </>
        )}
      </StandaloneCard>

      <p className="text-sm text-muted-foreground mt-8">
        Thanks for diving with us.{" "}
        <Link href="/" className="text-primary hover:underline">
          Back to the home page
        </Link>
      </p>
    </StandaloneShell>
  );
}