import LtxParser from "ltx/lib/parsers/ltx.js";
import Element from "ltx/lib/Element.js";
import { EventEmitter } from "@xmpp/events";

import XMLError from "./XMLError.js";

class Parser extends EventEmitter {
  constructor() {
    super();
    const parser = new LtxParser();
    this.root = null;
    this.cursor = null;

    parser.on("startElement", this.onStartElement.bind(this));
    parser.on("endElement", this.onEndElement.bind(this));
    parser.on("text", this.onText.bind(this));

    this.parser = parser;
  }

  onStartElement(name, attrs) {
    const element = new Element(name, attrs);

    const { root, cursor } = this;

    if (!root) {
      this.root = element;
      this.emit("start", element);
    } else if (cursor !== root) {
      cursor.append(element);
    }

    this.cursor = element;
  }

  onEndElement(name) {
    const { root, cursor } = this;
    if (name !== cursor.name) {
      // <foo></bar>
      this.emit("error", new XMLError(`${cursor.name} must be closed.`));
      return;
    }

    if (cursor === root) {
      this.emit("end", root);
      return;
    }

    if (!cursor.parent) {
      cursor.parent = root;
      this.emit("element", cursor);
      this.cursor = root;
      return;
    }

    this.cursor = cursor.parent;
  }

  onText(str) {
    const { cursor } = this;
    if (!cursor) {
      this.emit("error", new XMLError(`${str} must be a child.`));
      return;
    }

    cursor.t(str);
  }

  write(data) {
    this.parser.write(data);
  }

  end(data) {
    if (data) {
      this.parser.write(data);
    }
  }
}

Parser.XMLError = XMLError;

export default Parser;