//===============================================
//  Imports
//===============================================
import { Glob } from "bun";

//===============================================
//  Loader Definition
//===============================================
interface ILoader<T extends object> {
  id: string;
  cache: T[];
  source: string;

  collect: () => Promise<ThisType<this>>;
  validate: (data: Partial<T>) => Promise<T | null>;
  getJSON: () => T[];
}

//===============================================
//  Loader Implementation
//===============================================
export abstract class Loader<T extends object> implements ILoader<T> {
  public abstract id: string;
  public cache: T[] = [];
  public source: string;

  public constructor(source: string) {
    if (!source)
      throw new Error(
        "Class of type Loader was initialized without the *required* source parameter.",
      );

    this.source = source;
  }

  /**
   * Recursively collects data from a directory based on the path specificed in dataSource property.
   */
  public async collect() {
    const glob = new Glob(`**/**.ts`);
    const iterator = glob.scan(this.source);

    try {
      for await (const path of iterator) {
        let moduleDefault: T | null;

        try {
          const module = await import(`${this.source}/${path}`);
          moduleDefault = module.default;

          if (!moduleDefault) continue;
        } catch {
          continue;
        }

        const final = await this.validate(moduleDefault);
        if (!final) continue;

        this.cache.push(final);
      }
    } catch {
      console.error(`[Voidy] Specified loader target ${this.source} doesn't exist. Skipping...`);
      return this;
    }

    return this;
  }

  /**
   * Validates a singular element during data collection, and returns whatever should be written to the cache.
   */
  public abstract validate(data: Partial<T>): Promise<T | null>;

  /**
   * Returns the JSON-ified contents of the loader cache
   */
  public getJSON() {
    return this.cache;
  }
}