import Link from "next/link";
import { Check, X } from "lucide-react";
import { requireSession } from "@/server/auth";
import { dbForTenant } from "@/server/db";
import { PageHead, Pill } from "@/components/mockup-ui";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { approveTask, rejectTask, commentTask } from "@/server/actions/tasks";

const STATUS_TONE: Record<string, "ok" | "info" | "warn" | "mut"> = { OPEN: "info", DONE: "ok", REJECTED: "warn", CANCELLED: "mut" };
const STATUS_LABEL: Record<string, string> = { OPEN: "Offen", DONE: "Freigegeben", REJECTED: "Abgelehnt", CANCELLED: "Zurückgezogen" };
const KIND_LABEL: Record<string, string> = { submit: "eingereicht", approve: "freigegeben", reject: "abgelehnt", comment: "Kommentar" };

interface TaskWithComments {
  id: string; type: string; title: string; status: string;
  entityType: string | null; entityRef: string | null;
  assigneeId: string | null; createdById: string | null; createdAt: Date;
  comments: { id: string; authorId: string | null; kind: string; body: string; createdAt: Date }[];
}

function entityHref(t: TaskWithComments): string | null {
  return t.entityType === "policy_document" && t.entityRef ? `/policies/${t.entityRef}` : null;
}

function TaskCard({ task, me, name }: { task: TaskWithComments; me: string; name: (id: string | null) => string }) {
  const isAssignee = task.assigneeId === me;
  const isOpen = task.status === "OPEN";
  const href = entityHref(task);
  return (
    <div className="shadow-card rounded-xl border bg-card p-4">
      <div className="flex flex-wrap items-start justify-between gap-2">
        <div>
          <p className="font-heading text-sm font-semibold">
            {href ? <Link href={href} className="hover:underline">{task.title}</Link> : task.title}
          </p>
          <p className="text-[11.5px] text-muted-foreground">
            Eingereicht von {name(task.createdById)} · Freigeber {name(task.assigneeId)} · {task.createdAt.toLocaleDateString("de-DE")}
          </p>
        </div>
        <Pill tone={STATUS_TONE[task.status] ?? "mut"}>{STATUS_LABEL[task.status] ?? task.status}</Pill>
      </div>

      {task.comments.length > 0 && (
        <ul className="mt-3 space-y-1.5 border-t pt-3">
          {task.comments.map((c) => (
            <li key={c.id} className="text-[12.5px]">
              <span className="text-muted-foreground">{name(c.authorId)} · {KIND_LABEL[c.kind] ?? c.kind}:</span> {c.body}
            </li>
          ))}
        </ul>
      )}

      {isOpen && isAssignee && (
        <div className="mt-3 grid gap-2 border-t pt-3 sm:grid-cols-2">
          <form action={approveTask.bind(null, task.id)} className="flex gap-2">
            <Input name="note" placeholder="Kommentar (optional)" className="h-8" />
            <Button type="submit" size="sm"><Check className="size-4" /> Freigeben</Button>
          </form>
          <form action={rejectTask.bind(null, task.id)} className="flex gap-2">
            <Input name="note" placeholder="Grund (erforderlich)" required className="h-8" />
            <Button type="submit" variant="outline" size="sm"><X className="size-4" /> Ablehnen</Button>
          </form>
        </div>
      )}
      {isOpen && !isAssignee && (
        <p className="mt-3 border-t pt-3 text-[11.5px] text-muted-foreground">Wartet auf Freigabe durch {name(task.assigneeId)}.</p>
      )}

      <form action={commentTask.bind(null, task.id)} className="mt-2 flex gap-2">
        <Input name="body" placeholder="Kommentar hinzufügen…" className="h-8" />
        <Button type="submit" variant="ghost" size="sm">Kommentieren</Button>
      </form>
    </div>
  );
}

export default async function TasksPage() {
  const session = await requireSession();
  const db = dbForTenant(session.user.tenantId);
  const me = session.user.id;

  const [tasks, users] = await Promise.all([
    db.task.findMany({
      where: { OR: [{ assigneeId: me }, { createdById: me }] },
      include: { comments: { orderBy: { createdAt: "asc" } } },
      orderBy: [{ createdAt: "desc" }],
    }),
    db.user.findMany({ select: { id: true, name: true } }),
  ]);
  const name = (id: string | null) => users.find((u) => u.id === id)?.name ?? "—";

  const open = tasks.filter((t) => t.status === "OPEN");
  const resolved = tasks.filter((t) => t.status !== "OPEN");
  const myOpen = open.filter((t) => t.assigneeId === me);

  return (
    <main className="flex-1 p-6">
      <PageHead crumb="Aufgaben" title="Aufgaben & Freigaben" sub={`${myOpen.length} offene Freigabe(n) für Sie · ${open.length} offen gesamt`} />

      <section className="mt-4">
        <h2 className="mb-3 font-heading text-sm font-semibold">Offen</h2>
        <div className="space-y-3">
          {open.length === 0 && <p className="text-sm text-muted-foreground">Keine offenen Aufgaben.</p>}
          {open.map((t) => <TaskCard key={t.id} task={t} me={me} name={name} />)}
        </div>
      </section>

      {resolved.length > 0 && (
        <section className="mt-8">
          <h2 className="mb-3 font-heading text-sm font-semibold">Erledigt</h2>
          <div className="space-y-3">
            {resolved.map((t) => <TaskCard key={t.id} task={t} me={me} name={name} />)}
          </div>
        </section>
      )}
    </main>
  );
}