import { randomUUID } from "node:crypto";
import { json, readJsonBody, requireAdmin } from "../../../_lib/auth";
import {
  CALENDAR_TONES,
  type CalendarSetting,
  type CalendarTone,
  MAX_CALENDARS,
  maskCalendarUrl,
  readSettings,
  saveSettings,
  validCalendarUrl,
} from "../../../_lib/store";

export const dynamic = "force-dynamic";

function publicView(calendars: CalendarSetting[]) {
  return calendars.map(({ id, name, tone, enabled, url }) => ({ id, name, tone, enabled, masked: maskCalendarUrl(url) }));
}

export async function GET(request: Request) {
  const denied = await requireAdmin(request);
  if (denied) return denied;
  const settings = await readSettings();
  return json({ calendars: publicView(settings.calendars), updatedAt: settings.updatedAt, tones: CALENDAR_TONES });
}

type IncomingCalendar = { id?: string; name?: string; tone?: string; enabled?: boolean; url?: string };

export async function PUT(request: Request) {
  const denied = await requireAdmin(request, { mutating: true });
  if (denied) return denied;
  const body = await readJsonBody<{ calendars?: IncomingCalendar[] }>(request);
  if (!body || !Array.isArray(body.calendars)) return json({ error: "Expected a calendars list." }, 400);
  if (body.calendars.length > MAX_CALENDARS) return json({ error: `At most ${MAX_CALENDARS} calendars.` }, 400);

  const existing = new Map((await readSettings()).calendars.map((calendar) => [calendar.id, calendar]));
  const next: CalendarSetting[] = [];
  for (const [index, entry] of body.calendars.entries()) {
    const label = entry.name?.trim() || `Calendar ${index + 1}`;
    const previous = entry.id ? existing.get(entry.id) : undefined;
    if (entry.id && !previous) return json({ error: `${label}: unknown calendar; reload the page.` }, 409);
    const suppliedUrl = typeof entry.url === "string" && entry.url.trim() ? entry.url : "";
    const url = suppliedUrl ? validCalendarUrl(suppliedUrl) : previous?.url;
    if (!url) {
      return json({ error: `${label}: paste a Google Calendar "Secret address in iCal format" (https://calendar.google.com/…/basic.ics).` }, 400);
    }
    next.push({
      id: previous?.id ?? randomUUID(),
      name: typeof entry.name === "string" ? entry.name.trim().slice(0, 50) : "",
      url,
      tone: CALENDAR_TONES.includes(entry.tone as CalendarTone) ? (entry.tone as CalendarTone) : "cyan",
      enabled: entry.enabled !== false,
    });
  }
  if (new Set(next.map((calendar) => calendar.url)).size !== next.length) return json({ error: "The same calendar is listed twice." }, 400);

  const saved = await saveSettings({ calendars: next }, `Saved ${next.length} calendar(s)`);
  console.log(`[admin] calendars saved (${saved.calendars.length})`);
  return json({ calendars: publicView(saved.calendars), updatedAt: saved.updatedAt });
}