/**
 * Auto-import public holidays for all active resources.
 *
 * For each resource, determines the applicable federal state from:
 *   1. resource.federalState (explicit, e.g. "BY")
 *   2. Falls back to federal-only holidays when no state is set
 *
 * Creates Vacation entries with type PUBLIC_HOLIDAY and status APPROVED.
 * Duplicate-safe: skips holidays that already exist (by date + type + resourceId).
 */

import { getPublicHolidays } from "@planarchy/shared";

interface MinimalVacation {
  resourceId: string;
  startDate: Date;
  endDate: Date;
}

interface AutoImportDb {
  resource: {
    findMany: (args: {
      where: { isActive: boolean };
      select: { id: string; federalState: string };
    }) => Promise<Array<{ id: string; federalState: string | null }>>;
  };
  vacation: {
    findMany: (args: unknown) => Promise<MinimalVacation[]>;
    createMany: (args: { data: unknown[]; skipDuplicates?: boolean }) => Promise<{ count: number }>;
  };
}

export interface AutoImportResult {
  year: number;
  holidaysCreated: number;
  resourcesProcessed: number;
  skippedExisting: number;
}

/**
 * Import public holidays for all active resources in a given year.
 * Returns the number of holiday vacation records created.
 */
export async function autoImportPublicHolidays(
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  db: any,
  year: number,
): Promise<AutoImportResult> {
  const resources: Array<{ id: string; federalState: string | null }> = await db.resource.findMany({
    where: { isActive: true },
    select: { id: true, federalState: true },
  });

  if (resources.length === 0) {
    return { year, holidaysCreated: 0, resourcesProcessed: 0, skippedExisting: 0 };
  }

  // Group resources by federal state (null = federal-only holidays)
  const byState = new Map<string | null, string[]>();
  for (const resource of resources) {
    const state = resource.federalState ?? null;
    const group = byState.get(state) ?? [];
    group.push(resource.id);
    byState.set(state, group);
  }

  let totalCreated = 0;
  let totalSkipped = 0;

  for (const [state, resourceIds] of byState) {
    const holidays = getPublicHolidays(year, state ?? undefined);
    if (holidays.length === 0) continue;

    for (const holiday of holidays) {
      const holidayDate = new Date(holiday.date);

      // Find existing records for this date + type to skip duplicates
      const existing: MinimalVacation[] = await db.vacation.findMany({
        where: {
          resourceId: { in: resourceIds },
          type: "PUBLIC_HOLIDAY",
          startDate: holidayDate,
          endDate: holidayDate,
        },
        select: { resourceId: true, startDate: true, endDate: true },
      });

      const existingResourceIds = new Set(existing.map((v: MinimalVacation) => v.resourceId));
      const newResourceIds = resourceIds.filter((id) => !existingResourceIds.has(id));

      totalSkipped += existingResourceIds.size;

      if (newResourceIds.length === 0) continue;

      const records = newResourceIds.map((resourceId) => ({
        resourceId,
        type: "PUBLIC_HOLIDAY",
        status: "APPROVED",
        startDate: holidayDate,
        endDate: holidayDate,
        note: holiday.name,
        isHalfDay: false,
        approvedAt: new Date(),
      }));

      const result = await db.vacation.createMany({
        data: records,
        skipDuplicates: true,
      });

      totalCreated += result.count;
    }
  }

  return {
    year,
    holidaysCreated: totalCreated,
    resourcesProcessed: resources.length,
    skippedExisting: totalSkipped,
  };
}