import defineFunction from "../defineFunction"
import ParseError from "../ParseError"
import { assertNodeType } from "../parseNode"

// \@char is an internal function that takes a grouped decimal argument like
// {123} and converts into symbol with code 123.  It is used by the *macro*
// \char defined in macros.js.
defineFunction({
  type: "textord",
  names: ["\\@char"],
  props: {
    numArgs: 1,
    allowedInText: true
  },
  handler({ parser, token }, args) {
    const arg = assertNodeType(args[0], "ordgroup")
    const group = arg.body
    let number = ""
    for (let i = 0; i < group.length; i++) {
      const node = assertNodeType(group[i], "textord")
      number += node.text
    }
    const code = parseInt(number)
    if (isNaN(code)) {
      throw new ParseError(`\\@char has non-numeric argument ${number}`, token)
    }
    return {
      type: "textord",
      mode: parser.mode,
      text: String.fromCodePoint(code)
    }
  }
})