import { CachedZone, SOARecord } from '../models/interfaces';
import { readZoneFile } from './reader';
import { DNSRecordType } from './records';
import { ReloadExecutor } from './rndc';
import { ValidatorExecutor } from './validator';

export class DNSCache {
  private cached: Record<string, CachedZone> = {};

  constructor(
    private rndc: ReloadExecutor,
    private validator: ValidatorExecutor,
    private ttl = 1600
  ) {}

  has(name: string): boolean {
    return this.cached[name] != null;
  }

  async get(name: string): Promise<CachedZone | null> {
    const cached = this.cached[name];
    if (!cached) {
      return null;
    }

    if (cached.changed.getTime() < new Date().getTime() - this.ttl * 1000) {
      return this.load(name, cached.file);
    }

    return this.cached[name];
  }

  async set(name: string, zone: CachedZone): Promise<void> {
    this.cached[name] = zone;
  }

  async load(name: string, file: string): Promise<CachedZone> {
    const zoneFile = await readZoneFile(file);
    const cache = {
      name,
      file,
      zone: zoneFile,
      added: new Date(),
      changed: new Date()
    }
    this.cached[name] = cache;
    return cache;
  }

  async save(name: string): Promise<void> {
    const zone = await this.get(name);
    if (!zone) {
      throw new Error('No such cached zone file!');
    }

    await this.validator.validateAndSave(name, zone);
  }

  async update(name: string, newZone?: CachedZone, skipReload = false): Promise<void> {
    let zone: CachedZone | null;
    if (newZone) {
      zone = newZone;
    } else {
      zone = await this.get(name);
    }

    if (!zone) {
      throw new Error('No such cached zone file!');
    }

    zone.changed = new Date();
    const soa = zone.zone.records.find((record) => record.type === DNSRecordType.SOA) as SOARecord;
    soa.serial = Math.floor(Date.now() / 1000);

    this.set(name, zone);
    await this.save(name);

    if (!skipReload) {
      try {
        await this.rndc.reload(name);
      } catch (e) {
        console.warn('%s automatic zone reload failed:', name, e.stack);
      }
    }
  }
}