import { Injectable } from '@nestjs/common';
import { berlinDayOf, daysBetween } from '../common/dates';
import { readRule } from '../automation/rule-config';
import { seasonStateFromRow } from '../phenology/phenology-row';
import type { DbClient } from '../prisma/db-client';
import { calendarSeasonState } from './season-calendar';
import type { SeasonState } from './season-types';

/** A stored row not updated for longer than this (days) means the job missed its runs. */
const MAX_ROW_AGE_DAYS = 2;

/**
 * The season of apiaries: the stored state of the current year
 * (ApiaryPhenology, written by the phenology step and the reports) where
 * there is one and the job kept it fresh (updated at most MAX_ROW_AGE_DAYS
 * days ago), else the calendar state. A stale row falls back to the calendar
 * instead of recomputing GTS on the fly: that would read a year of weather per
 * apiary on every read path, the calendar costs nothing. Callers do not see
 * the difference.
 */
@Injectable()
export class SeasonService {
  /** The season state of each given apiary on `today` (YYYY-MM-DD, Berlin). */
  async statesFor(
    db: DbClient,
    apiaryIds: readonly string[],
    today: string,
  ): Promise<Map<string, SeasonState>> {
    const states = new Map<string, SeasonState>();
    if (apiaryIds.length === 0) {
      return states;
    }
    const ids = [...new Set(apiaryIds)];
    const { config } = await readRule(db, 'PHENOLOGY');
    const rows = await db.apiaryPhenology.findMany({
      where: { apiaryId: { in: ids }, year: Number(today.slice(0, 4)) },
      include: { apiary: { select: { latitude: true, longitude: true } } },
    });
    const stored = new Map(rows.map((row) => [row.apiaryId, row]));
    for (const apiaryId of ids) {
      const found = stored.get(apiaryId);
      const row =
        found !== undefined &&
        daysBetween(berlinDayOf(found.updatedAt), today) <= MAX_ROW_AGE_DAYS
          ? found
          : undefined;
      states.set(
        apiaryId,
        row === undefined
          ? calendarSeasonState(apiaryId, today, config)
          : seasonStateFromRow(
              row,
              config,
              row.apiary.latitude !== null && row.apiary.longitude !== null,
              today,
            ),
      );
    }
    return states;
  }
}