import * as api from './apiServer.js';
import * as md from './markdown.js';

class PostToChannel {
  constructor(channel, body) {
    this.channel = channel;
    this.body = body;
    this.renderedBody = md.render(body);
  }

  async send() {
    return await api.retry(() => api.postToChannel(this.channel, this.body));
  }
}

class DeleteMessage {
  constructor(messageId) {
    this.messageId = messageId;
  }

  async send() {
    return await api.retry(() => api.deleteMessage(this.messageId));
  }
}

class CreateChannel {
  constructor(name) {
    this.name = name;
  }

  async send() {
    return await api.retry(() => api.createChannel(this.name));
  }
}

export class Outbox {
  pending = $state([]);

  static empty() {
    return new Outbox([]);
  }

  constructor(pending) {
    this.pending = pending;
  }

  enqueue(operation) {
    this.pending.push(operation);
    this.start();
  }

  createChannel(name) {
    this.enqueue(new CreateChannel(name));
  }

  postToChannel(channel, body) {
    this.enqueue(new PostToChannel(channel, body));
  }

  deleteMessage(messageId) {
    this.enqueue(new DeleteMessage(messageId));
  }

  start() {
    if (this.sending) {
      return;
    }
    // This is a promise transform primarily to keep the management of `this.sending` in one place,
    // rather than spreading it across multiple methods.
    this.sending = this.drain().finally(() => {
      this.sending = null;
    });
  }

  async drain() {
    while (this.pending.length > 0) {
      const operation = this.pending[0];

      await operation.send();
      this.pending.shift();
    }
  }
}