import { CachedZone, DNSRecord, 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;
  }

  search(
    cached: CachedZone,
    name?: string,
    type?: DNSRecordType,
    value?: string,
    strict = false
  ): DNSRecord[] {
    return cached.zone.records.filter((zone) => {
      if (type && zone.type !== type) {
        return false;
      }

      if (name && zone.name !== name) {
        return false;
      }

      if (value && ((!strict && !zone.value.includes(value as string)) ||
                    (strict && zone.value !== value))) {
        return false;
      }

      return true;
    }).map((record) => {
      const inx = cached.zone.records.indexOf(record);
      return {
        ...record,
        index: inx
      }
    })
  }

  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!');
    }

    try {
      await this.validator.validateAndSave(name, zone);
    } catch (e) {
      // Reload previous state
      if (e.message.contains('Validation')) {
        await this.load(name, zone.file);
      }
      throw e;
    }
  }

  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);
      }
    }
  }
}