'use server';

import { revalidatePath } from 'next/cache';

import { diffOf, recordAudit } from '@/lib/audit';
import { requireAdmin } from '@/lib/auth/actions';
import { prisma } from '@/lib/db';
import type { Slot } from '@/lib/schedule/types';
import {
  changedDays,
  DAY_NAMES_FR,
  hasErrors,
  normaliseWeek,
  toDraft,
  validateWeek,
  type WeekDraft,
} from '@/lib/schedule/week';

export type SaveWeekResult =
  | { ok: true; changed: number[] }
  | { ok: false; error: string; dayErrors?: Record<number, string[]> };

/**
 * Persists the reference week.
 *
 * Validation runs again here even though the form already checked: the client
 * is a convenience, not a guarantee, and this is the schedule the shop window
 * shows.
 */
export async function saveWeek(draft: WeekDraft): Promise<SaveWeekResult> {
  const gate = await requireAdmin();
  if (!gate.ok) {
    return { ok: false, error: gate.error };
  }

  const week = normaliseWeek(draft);
  const errors = validateWeek(week);
  if (hasErrors(errors)) {
    return { ok: false, error: 'Certains horaires sont invalides.', dayErrors: errors };
  }

  const existing = await prisma.weeklySchedule.findMany();
  const before = toDraft(
    existing.map((day) => ({
      dayOfWeek: day.dayOfWeek,
      isClosed: day.isClosed,
      slots: (day.slots as Slot[] | null) ?? [],
    })),
  );

  const changed = changedDays(before, week);
  if (changed.length === 0) {
    // Nothing moved: no write, no audit entry, no needless screen redraw.
    return { ok: true, changed: [] };
  }

  await prisma.$transaction(
    week.map((day) =>
      prisma.weeklySchedule.upsert({
        where: { dayOfWeek: day.dayOfWeek },
        update: { isClosed: day.isClosed, slots: day.slots },
        create: { dayOfWeek: day.dayOfWeek, isClosed: day.isClosed, slots: day.slots },
      }),
    ),
  );

  await recordAudit({
    userEmail: gate.value.email,
    action: 'weekly_schedule.update',
    entity: 'WeeklySchedule',
    diff: diffOf(summary(before), summary(week)),
  });

  revalidatePath('/admin');
  revalidatePath('/admin/horaires');

  return { ok: true, changed };
}

/**
 * One readable line per day for the audit trail. Storing the raw rows would
 * make the diff accurate and unreadable; the point of the log is that a human
 * can see what changed.
 */
function summary(week: WeekDraft): Record<string, string> {
  return Object.fromEntries(
    week.map((day) => [
      DAY_NAMES_FR[day.dayOfWeek] ?? String(day.dayOfWeek),
      day.isClosed || day.slots.length === 0
        ? 'Fermé'
        : day.slots.map((slot) => `${slot.open}–${slot.close}`).join(' · '),
    ]),
  );
}