import {
  CaretNode,
  CaretParser,
  CaretPostfixParselet,
  TokensTag,
} from "@caret-js/core";
import { SubSupToken } from "../tokens/subsup";
import { SubscriptNode } from "../nodes/subscript";
import { ExponentNode } from "../nodes/exponent";

export class SubSupParselet extends CaretPostfixParselet {
  parse(parser: CaretParser, left: CaretNode): CaretNode {
    const token = parser.consume();
    this.assert(token instanceof SubSupToken, "Expected SubSupToken");

    const child = left;

    let sub = undefined;
    if (token.subscript) {
      sub = parser.parseSubStrand(token.subscript);
    }

    let sup = undefined;
    if (token.superscript) {
      sup = parser.parseSubStrand(token.superscript);
    }

    if (sub && sup) {
      return ExponentNode.from(SubscriptNode.from(child, sub), sup).addTag(
        new TokensTag([token])
      );
    }

    if (sub) {
      return SubscriptNode.from(child, sub).addTag(new TokensTag([token]));
    }

    if (sup) {
      return ExponentNode.from(child, sup).addTag(new TokensTag([token]));
    }

    return child;
  }
}