"use client";

import * as React from "react";
import { useSession } from "next-auth/react";
import { Loader2, Mail, ShieldCheck, ShieldAlert, UserCircle2 } from "lucide-react";

import { api } from "@/lib/trpc";
import { Skeleton } from "@/components/ui/skeleton";

const SOURCE_LABELS: Record<string, string> = {
  primary: "Primary",
  "oauth:github": "GitHub",
  "oauth:google": "Google",
  "oauth:authentik": "Authentik",
  manual: "Manually verified",
};

function sourceLabel(source: string): string {
  return SOURCE_LABELS[source] ?? source;
}

/**
 * Best-effort "X ago" without pulling in a date library. The "Linked emails"
 * row only needs coarse buckets ("just now", "3d ago", "2mo ago") — we never
 * surface the raw timestamp on this page, so jitter is fine.
 */
function relativeTime(when: Date | string | null | undefined): string {
  if (!when) return "never";
  const then = when instanceof Date ? when.getTime() : new Date(when).getTime();
  const diffMs = Date.now() - then;
  if (Number.isNaN(diffMs) || diffMs < 0) return "just now";
  const sec = Math.floor(diffMs / 1000);
  if (sec < 60) return "just now";
  const min = Math.floor(sec / 60);
  if (min < 60) return `${min}m ago`;
  const hr = Math.floor(min / 60);
  if (hr < 24) return `${hr}h ago`;
  const day = Math.floor(hr / 24);
  if (day < 30) return `${day}d ago`;
  const mo = Math.floor(day / 30);
  if (mo < 12) return `${mo}mo ago`;
  const yr = Math.floor(day / 365);
  return `${yr}y ago`;
}

export default function ProfileSettingsPage() {
  const { data: session } = useSession();
  const identitiesQuery = api.identity.listMine.useQuery();

  return (
    <div className="mx-auto max-w-2xl px-8 py-10">
      <div className="mb-8 flex items-center gap-3">
        <div className="flex h-10 w-10 items-center justify-center rounded-lg bg-primary/10">
          <UserCircle2 className="size-5 text-primary" />
        </div>
        <div>
          <h1 className="text-xl font-semibold">Profile</h1>
          <p className="text-xs text-muted-foreground">
            Personal account settings. These apply to you across every workspace.
          </p>
        </div>
      </div>

      <section className="rounded-lg border border-border bg-card p-6 shadow-sm">
        <header className="mb-4 flex items-start justify-between gap-4">
          <div>
            <h2 className="text-sm font-semibold">Linked emails</h2>
            <p className="mt-1 text-xs text-muted-foreground">
              Workspace invites sent to any of these addresses will be accepted under
              your account. Verified emails are confirmed by the provider that
              supplied them — we do not trust an unverified claim.
            </p>
          </div>
          {session?.user?.email ? (
            <div className="flex items-center gap-2 rounded-md bg-muted px-2.5 py-1 text-xs text-muted-foreground">
              <Mail className="size-3.5" aria-hidden />
              <span>Signed in as {session.user.email}</span>
            </div>
          ) : null}
        </header>

        {identitiesQuery.isLoading ? (
          <ul className="space-y-2">
            {[0, 1].map((i) => (
              <li key={i}>
                <Skeleton className="h-14 w-full" />
              </li>
            ))}
          </ul>
        ) : identitiesQuery.isError ? (
          <p className="text-sm text-destructive" role="alert">
            Could not load your linked emails. Refresh to retry.
          </p>
        ) : (identitiesQuery.data?.length ?? 0) === 0 ? (
          // Should never happen for an authenticated user (the migration backfills
          // a primary identity for every existing users row) but cheaper to render
          // a friendly empty state than to throw on the page.
          <p className="text-sm text-muted-foreground">
            No emails linked. This is unexpected — please contact support.
          </p>
        ) : (
          <ul className="space-y-2">
            {identitiesQuery.data!.map((identity) => (
              <li
                key={identity.id}
                className="flex items-center justify-between gap-4 rounded-md border border-border bg-background px-4 py-3"
              >
                <div className="min-w-0">
                  <div className="flex items-center gap-2">
                    <span className="truncate text-sm font-medium">
                      {identity.email}
                    </span>
                    <span className="rounded bg-muted px-1.5 py-0.5 text-[10px] font-medium uppercase tracking-wide text-muted-foreground">
                      {sourceLabel(identity.source)}
                    </span>
                  </div>
                  <p className="mt-0.5 text-xs text-muted-foreground">
                    Last used {relativeTime(identity.lastUsedAt ?? identity.createdAt)}
                  </p>
                </div>
                {identity.verified ? (
                  <div className="flex items-center gap-1.5 text-xs text-emerald-600">
                    <ShieldCheck className="size-3.5" aria-hidden />
                    <span>Verified</span>
                  </div>
                ) : (
                  <div className="flex items-center gap-1.5 text-xs text-amber-600">
                    <ShieldAlert className="size-3.5" aria-hidden />
                    <span>Pending</span>
                  </div>
                )}
              </li>
            ))}
          </ul>
        )}

        <footer className="mt-5 rounded-md bg-muted/40 px-3 py-2 text-[11px] text-muted-foreground">
          To link another email, sign in via that email&apos;s OAuth provider
          (e.g. GitHub or Google) while signed in here. A manual verification
          flow is on the roadmap.
        </footer>
      </section>
    </div>
  );
}