import Database from 'better-sqlite3';

export interface BillingReportRepo {
  getReportedCents(customerId: string, period: string): number;
  upsertReportedCents(customerId: string, period: string, cumulativeCents: number): void;
}

export interface JobLockRepo {
  tryAcquireLock(name: string, ttlMs: number): boolean;
  releaseLock(name: string): void;
}

export class SqliteBillingReportRepo implements BillingReportRepo, JobLockRepo {
  constructor(
    private db: Database.Database,
    private now: () => number = Date.now,
  ) {
    this.db.exec(`
      CREATE TABLE IF NOT EXISTS billing_reports (
        customer_id TEXT NOT NULL,
        period TEXT NOT NULL,
        reported_cents INTEGER NOT NULL,
        reported_at_ms INTEGER NOT NULL,
        PRIMARY KEY (customer_id, period)
      )
    `);
    this.db.exec(`
      CREATE TABLE IF NOT EXISTS job_locks (
        name TEXT PRIMARY KEY,
        acquired_at_ms INTEGER NOT NULL
      )
    `);
  }

  getReportedCents(customerId: string, period: string): number {
    const row = this.db
      .prepare('SELECT reported_cents FROM billing_reports WHERE customer_id = ? AND period = ?')
      .get(customerId, period) as { reported_cents: number } | undefined;
    return row?.reported_cents ?? 0;
  }

  upsertReportedCents(customerId: string, period: string, cumulativeCents: number): void {
    this.db
      .prepare(
        `INSERT INTO billing_reports (customer_id, period, reported_cents, reported_at_ms)
         VALUES (?, ?, ?, ?)
         ON CONFLICT(customer_id, period) DO UPDATE SET
           reported_cents = excluded.reported_cents,
           reported_at_ms = excluded.reported_at_ms`,
      )
      .run(customerId, period, cumulativeCents, this.now());
  }

  tryAcquireLock(name: string, ttlMs: number): boolean {
    const result = this.db
      .prepare(
        `INSERT INTO job_locks (name, acquired_at_ms) VALUES (?, ?)
         ON CONFLICT(name) DO UPDATE SET acquired_at_ms = excluded.acquired_at_ms
         WHERE job_locks.acquired_at_ms <= excluded.acquired_at_ms - ?`,
      )
      .run(name, this.now(), ttlMs);
    return result.changes === 1;
  }

  releaseLock(name: string): void {
    this.db.prepare('DELETE FROM job_locks WHERE name = ?').run(name);
  }
}