import { Injectable, Logger } from '@nestjs/common';
import { loggableError } from '../common/loggable-error';
import { DomainEventsService } from '../domain-events/domain-events.service';
import { PrismaService } from '../prisma/prisma.service';
import {
  catchUpEvents,
  DAILY_EVALUATION_RULES,
  DailyRule,
} from './daily-evaluation.rules';
import { Job, JobResult } from './job';
import { JobName } from './job-names';

/**
 * Records the time-based domain events (CronJob 04:30): one rule per type,
 * see DAILY_EVALUATION_RULES. An occurrence is recorded on every run within
 * CATCH_UP_DAYS after its day under the same daily dedupe key, so a missed
 * run is caught up and a repeated one adds nothing. The result counts the
 * events that were new, per type.
 */
@Injectable()
export class DailyEvaluationJob implements Job {
  readonly name: JobName = 'daily-evaluation';
  private readonly logger = new Logger(DailyEvaluationJob.name);

  constructor(
    private readonly prisma: PrismaService,
    private readonly events: DomainEventsService,
  ) {}

  /** Evaluates the current day of the database clock. */
  async run(): Promise<JobResult> {
    const [{ now }] = await this.prisma.$queryRaw<
      { now: Date }[]
    >`SELECT now() AS "now"`;
    return this.evaluate(now);
  }

  /**
   * Runs every rule for `today`. A failing rule is logged and does not stop
   * the others - their events are committed - but fails the run, so it
   * shows on the System page; the next run catches up.
   */
  async evaluate(today: Date): Promise<JobResult> {
    const counts: [string, number][] = [];
    const failed: string[] = [];
    for (const rule of DAILY_EVALUATION_RULES) {
      try {
        counts.push([rule.type, await this.evaluateRule(rule, today)]);
      } catch (error: unknown) {
        const { message, stack } = loggableError(error);
        this.logger.error(`Rule "${rule.type}" failed: ${message}`, stack);
        failed.push(rule.type);
      }
    }
    if (failed.length > 0) {
      throw new Error(`Daily evaluation failed for: ${failed.join(', ')}`);
    }
    return Object.fromEntries(counts);
  }

  /** One transaction per type; returns how many events were new. */
  private async evaluateRule(rule: DailyRule, today: Date): Promise<number> {
    const events = catchUpEvents(
      await rule.occurrences(this.prisma, today),
      today,
    );
    if (events.length === 0) {
      return 0;
    }
    return this.prisma.$transaction((tx) => this.events.recordAll(tx, events));
  }
}