import { ensureDatabase } from "./bootstrap";
import { DomainError, runRetentionMaintenance, type RetentionMaintenanceResult } from "./repository";
import {
  ACQUIRE_RETENTION_JOB_SQL,
  COMPLETE_RETENTION_JOB_SQL,
  FAIL_RETENTION_JOB_SQL,
  RETENTION_JOB_KEY,
  RETENTION_RUNNING_STALE_MS,
} from "./retention";

export type ScheduledRetentionOutcome =
  | { status: "skipped"; reason: "already_running" }
  | { status: "succeeded"; result: RetentionMaintenanceResult };

function scheduledTimestamp(value: number): string {
  if (!Number.isFinite(value)) {
    throw new TypeError("scheduled retention requires a finite timestamp");
  }
  const timestamp = new Date(value);
  if (!Number.isFinite(timestamp.getTime())) {
    throw new TypeError("scheduled retention requires a valid timestamp");
  }
  return timestamp.toISOString();
}

function safeErrorCode(error: unknown): string {
  if (error instanceof DomainError && /^[a-z0-9_]{3,64}$/.test(error.code)) {
    return error.code;
  }
  return "retention_maintenance_failed";
}

export async function runScheduledRetentionMaintenance(
  db: D1Database,
  scheduledTime: number,
): Promise<ScheduledRetentionOutcome> {
  await ensureDatabase();

  const scheduledAt = scheduledTimestamp(scheduledTime);
  const startedAt = new Date().toISOString();
  const staleBefore = new Date(
    new Date(startedAt).getTime() - RETENTION_RUNNING_STALE_MS,
  ).toISOString();
  const runId = `maintenance_${crypto.randomUUID().replaceAll("-", "")}`;
  const acquired = await db
    .prepare(ACQUIRE_RETENTION_JOB_SQL)
    .bind(
      RETENTION_JOB_KEY,
      runId,
      "scheduled",
      scheduledAt,
      startedAt,
      startedAt,
      startedAt,
      staleBefore,
    )
    .run();
  if (Number(acquired.meta.changes ?? 0) !== 1) {
    return { status: "skipped", reason: "already_running" };
  }

  try {
    const result = await runRetentionMaintenance({
      actorId: "system:scheduled-retention",
      confirmed: true,
      reason: "每日自动清理已经到期的技术记录",
      now: startedAt,
    });
    const completedAt = new Date().toISOString();
    const completion = await db
      .prepare(COMPLETE_RETENTION_JOB_SQL)
      .bind(
        completedAt,
        completedAt,
        JSON.stringify(result),
        completedAt,
        RETENTION_JOB_KEY,
        runId,
      )
      .run();
    if (Number(completion.meta.changes ?? 0) !== 1) {
      throw new DomainError(
        "retention_run_fenced",
        "到期数据清理完成，但运行状态已经被更新的任务接管",
        409,
      );
    }
    return { status: "succeeded", result };
  } catch (error) {
    const failedAt = new Date().toISOString();
    await db
      .prepare(FAIL_RETENTION_JOB_SQL)
      .bind(
        failedAt,
        safeErrorCode(error),
        failedAt,
        RETENTION_JOB_KEY,
        runId,
      )
      .run();
    throw error;
  }
}