import { join } from "node:path";
import { walkSync } from "jsr:@std/fs";

import { Entity } from "../entity.ts";
import State from "../state.ts";

const entities: Record<string, typeof Entity> = {}
const classes_path = join(Deno.cwd(), 'classes');

if(State.Environment == 'PROCESSOR') {
  for(const dirEntry of walkSync(classes_path, { includeDirs: false })) {
    const entity_import = await import(`file://${dirEntry.path}`);
    const entity = Object.values(entity_import)[0] as typeof Entity;
    if(entity?.__is_typeof_entity || entity instanceof Entity) entities[entity.name] = entity;
  }
}

type TaskEvent = 'succeed' | 'fail' | 'finished'

export class Task {
  static readonly HOST_URL: string = Deno.env.get('HOST_URL')!;

  readonly id: string
  readonly method: string
  readonly entity_name: string
  readonly args: any[]
  readonly has_run: boolean = false
  private readonly fns: Record<TaskEvent, VagueFunction[]> = { succeed: [], fail: [], finished: [] }
  private socket: WebSocket;

  private constructor(socket: WebSocket, { id, method, entity_name, args }: I_ProcessorRequest) {
    this.socket = socket;

    this.id = id;
    this.method = method;
    this.entity_name = entity_name;
    this.args = args;

    Queue.add(this);
  }

  on(event: TaskEvent, fn: VagueFunction) {
    this.fns[event].push(fn);
  }

  async run() {
    if(this.has_run) return;

    (this as any).has_run = true;

    const entity = entities[this.entity_name];
    if(!entity) return this.fail(`Could not find [${this.entity_name}]!`);

    const method = (entity as any)[this.method] as VagueFunction;
    if(!method) return this.fail(`Could not find [${this.entity_name}::${this.method}()]!`);

    try {
      const response = await method.apply(entity, this.args) as Record<string, any>;
      return this.succeed(response);
    } catch(e: any) {
      return this.fail(`An error ocurred when trying to execute [${this.entity_name}::${this.method}()]`, e);
    }
  }

  private succeed(data: Record<string, any>) {
    for(const fn of this.fns.succeed) fn();
    for(const fn of this.fns.finished) fn();

    return this.sendResponse({
      id: this.id,
      success: true,
      data
    })
  }

  private fail(message: string, error?: Error) {
    for(const fn of this.fns.fail) fn();
    for(const fn of this.fns.finished) fn();

    return this.sendResponse({
      id: this.id,
      success: false,
      message,
      error: error && { name: error.name, message: error.message, cause: error.cause }
    })
  }

  private sendResponse(body: I_ProcessorResponse) {
    this.socket.send(JSON.stringify(body));
  }

  // #region Queue Management

  static async Queue(socket: WebSocket, request: I_ProcessorRequest) {
    return new Task(socket, request);
  }
}

class Queue {
  protected static tasks: Task[] = []
  protected static is_running: boolean = false;

  static add(task: Task) {
    this.tasks.push(task);

    this.process_queue();
  }

  private static async process_queue() {
    if(this.is_running) return;

    if(this.tasks.length == 0) return this.is_running = false;

    const task = this.tasks.shift();

    await task!.run();

    this.is_running = false;

    this.process_queue();
  }

  private constructor() {}
}