@tdb/schema/src/schema/SchemaDefinition.ts

import { TJS, AJV } from '../common';

/**
 * A JSON schema for 1..n types.
 */
export class SchemaDefinition {
  public readonly types: string[];
  public readonly def: TJS.Definition;

  private _isValidSchema: boolean;
  private _validator: AJV.ValidateFunction;

  constructor(args: { type: string | string[]; def: TJS.Definition }) {
    this.types = Array.isArray(args.type) ? args.type : [args.type];
    this.def = args.def;
  }

  /**
   * Determines whether the schema itself is valid.
   */
  public get isValidSchema() {
    if (this._isValidSchema === undefined) {
      const ajv = AJV();
      this._isValidSchema = ajv.validateSchema(this.def);
    }
    return this._isValidSchema;
  }

  /**
   * Retrieves the version of JSON-schema.
   */
  public get schemaVersion() {
    return this.def.$schema;
  }

  /**
   * Validates the given data against the schema.
   */
  public validate(data: object) {
    return this.validator(data);
  }

  /**
   * INTERNAL
   */
  private get validator() {
    if (!this._validator) {
      const ajv = AJV();
      this._validator = ajv.compile(this.def);
    }
    return this._validator;
  }
}