"use server";

import { revalidatePath } from "next/cache";
import { z } from "zod";
import type { PoolClient } from "pg";
import { db } from "@/lib/db";
import { requireStaff } from "@/lib/auth";
import { applicationSchema, idSchema, roundSchema, slotSchema, type ActionResult } from "@/lib/validation";
import { InputError } from "@/lib/corrections";
import { acceptApplication, drawRound, invitationHash, newInvitation, submitApplication } from "@/lib/admissions";
import { localClock } from "@/lib/time";

async function transaction(work: (client: PoolClient) => Promise<void>): Promise<ActionResult> {
  let client: PoolClient | undefined;
  try {
    client = await db.connect();
    await client.query("BEGIN");
    await work(client);
    await client.query("COMMIT");
  } catch (error) {
    if (client) await client.query("ROLLBACK");
    if (error instanceof InputError) return { error: error.message };
    console.error("Aufnahme / Slot speichern fehlgeschlagen", error);
    return { error: "Speichern fehlgeschlagen. Bitte erneut versuchen." };
  } finally { client?.release(); }
  revalidatePath("/admissions");
  revalidatePath("/slots");
  revalidatePath("/");
  return { success: true };
}

export async function createRound(input: unknown): Promise<ActionResult & { code?: string; roundId?: string }> {
  const staff = await requireStaff();
  const parsed = roundSchema.safeParse(input);
  if (!parsed.success) return { error: parsed.error.issues[0].message };
  if (parsed.data.expiresOn < localClock().day) return { error: "Die Anmeldefrist darf nicht in der Vergangenheit liegen." };
  const code = newInvitation();
  let roundId: string | undefined;
  const result = await transaction(async (client) => {
    const round = await client.query<{ id: string }>("INSERT INTO admission_rounds(name, code_hash, expires_on, created_by) VALUES ($1, $2, $3, $4) RETURNING id",
      [parsed.data.name, invitationHash(code), parsed.data.expiresOn, staff.id]);
    roundId = round.rows[0].id;
  });
  return result.error ? result : { ...result, code, roundId };
}

export async function rotateInvitation(roundId: unknown): Promise<ActionResult & { code?: string }> {
  await requireStaff();
  const parsed = idSchema.safeParse(roundId);
  if (!parsed.success) return { error: "Ungültige Aufnahmerunde." };
  const code = newInvitation();
  const result = await transaction(async (client) => {
    const updated = await client.query("UPDATE admission_rounds SET code_hash = $2 WHERE id = $1 AND status = 'open' RETURNING id",
      [parsed.data, invitationHash(code)]);
    if (!updated.rowCount) throw new InputError("Nur offene Runden können einen neuen Einladungscode erhalten.");
  });
  return result.error ? result : { ...result, code };
}

export async function closeRound(roundId: unknown): Promise<ActionResult> {
  await requireStaff();
  const parsed = idSchema.safeParse(roundId);
  if (!parsed.success) return { error: "Ungültige Aufnahmerunde." };
  return transaction(async (client) => {
    const result = await client.query("UPDATE admission_rounds SET status = 'closed' WHERE id = $1 AND status = 'open' RETURNING id", [parsed.data]);
    if (!result.rowCount) throw new InputError("Diese Runde ist nicht mehr offen. Bitte neu laden.");
  });
}

export async function runDraw(input: unknown): Promise<ActionResult> {
  const staff = await requireStaff();
  const parsed = z.object({ roundId: idSchema, places: z.number().int().min(1).max(10000) }).safeParse(input);
  if (!parsed.success) return { error: "Bitte eine gültige Platzzahl zwischen 1 und 10.000 eingeben." };
  return transaction((client) => drawRound(client, parsed.data.roundId, parsed.data.places, staff.id));
}

export async function confirmAdmission(applicationId: unknown): Promise<ActionResult> {
  const staff = await requireStaff();
  const parsed = idSchema.safeParse(applicationId);
  if (!parsed.success) return { error: "Ungültige Anmeldung." };
  return transaction((client) => acceptApplication(client, parsed.data, staff.id));
}

export async function registerChild(input: unknown): Promise<ActionResult> {
  const parsed = applicationSchema.safeParse(input);
  if (!parsed.success) return { error: parsed.error.issues[0].message };
  try {
    await db.query("DELETE FROM application_limits WHERE window_start < now() - interval '1 day'");
    const limit = await db.query<{ attempts: number }>(`INSERT INTO application_limits(key_hash, attempts, window_start)
      VALUES ($1, 1, now()) ON CONFLICT(key_hash) DO UPDATE SET
      attempts = CASE WHEN application_limits.window_start < now() - interval '1 hour' THEN 1 ELSE application_limits.attempts + 1 END,
      window_start = CASE WHEN application_limits.window_start < now() - interval '1 hour' THEN now() ELSE application_limits.window_start END RETURNING attempts`,
    [invitationHash(`${parsed.data.code}:${parsed.data.email}`)]);
    if (limit.rows[0].attempts > 10) return { error: "Zu viele Anmeldungen. Bitte in einer Stunde erneut versuchen." };
  } catch (error) {
    console.error("Anmeldelimit prüfen fehlgeschlagen", error);
    return { error: "Die Anmeldung ist gerade nicht erreichbar. Bitte später erneut versuchen." };
  }
  return transaction((client) => submitApplication(client, parsed.data));
}

export async function addSlot(input: unknown): Promise<ActionResult> {
  await requireStaff();
  const parsed = slotSchema.safeParse(input);
  if (!parsed.success) return { error: parsed.error.issues[0].message };
  return transaction(async (client) => {
    const result = await client.query(`INSERT INTO pickup_slots(starts_at, ends_at) VALUES ($1, $2)
      ON CONFLICT(starts_at, ends_at) DO UPDATE SET active = true WHERE NOT pickup_slots.active RETURNING id`,
    [parsed.data.start, parsed.data.end]);
    if (!result.rowCount) throw new InputError("Dieses Abholfenster existiert bereits.");
  });
}

export async function toggleSlot(input: unknown): Promise<ActionResult> {
  await requireStaff();
  const parsed = z.object({ id: idSchema, active: z.boolean() }).safeParse(input);
  if (!parsed.success) return { error: "Ungültiger Abholslot." };
  return transaction(async (client) => {
    const result = await client.query("UPDATE pickup_slots SET active = $2 WHERE id = $1 RETURNING id", [parsed.data.id, parsed.data.active]);
    if (!result.rowCount) throw new InputError("Abholslot nicht gefunden.");
  });
}