import {
  AtKeyword,
  Semicolon,
  LeftCurlyBracket,
  RightCurlyBracket,
} from '../../tokenizer/index.js';

function consumeRaw(startToken) {
  return this.Raw(
    startToken,
    this.consumeUntilLeftCurlyBracketOrSemicolon,
    true
  );
}

function isDeclarationBlockAtrule() {
  for (let offset = 1, type; (type = this.lookupType(offset)); offset++) {
    if (type === RightCurlyBracket) {
      return true;
    }

    if (type === LeftCurlyBracket || type === AtKeyword) {
      return false;
    }
  }

  return false;
}

export const name = 'Atrule';
export const walkContext = 'atrule';
export const structure = {
  name: String,
  prelude: ['AtrulePrelude', 'Raw', null],
  block: ['Block', null],
};

export function parse() {
  const start = this.tokenStart;
  let name;
  let nameLowerCase;
  let prelude = null;
  let block = null;

  this.eat(AtKeyword);

  name = this.substrToCursor(start + 1);
  nameLowerCase = name.toLowerCase();
  this.skipSC();

  // parse prelude
  if (
    this.eof === false &&
    this.tokenType !== LeftCurlyBracket &&
    this.tokenType !== Semicolon
  ) {
    if (this.parseAtrulePrelude) {
      prelude = this.parseWithFallback(
        this.AtrulePrelude.bind(this, name),
        consumeRaw
      );
    } else {
      prelude = consumeRaw.call(this, this.tokenIndex);
    }

    this.skipSC();
  }

  switch (this.tokenType) {
    case Semicolon:
      this.next();
      break;

    case LeftCurlyBracket:
      if (
        hasOwnProperty.call(this.atrule, nameLowerCase) &&
        typeof this.atrule[nameLowerCase].block === 'function'
      ) {
        block = this.atrule[nameLowerCase].block.call(this);
      } else {
        // TODO: should consume block content as Raw?
        block = this.Block(isDeclarationBlockAtrule.call(this));
      }

      break;
  }

  return {
    type: 'Atrule',
    loc: this.getLocation(start, this.tokenStart),
    name,
    prelude,
    block,
  };
}

export function generate(node) {
  this.token(AtKeyword, '@' + node.name);

  if (node.prelude !== null) {
    this.node(node.prelude);
  }

  if (node.block) {
    this.node(node.block);
  } else {
    this.token(Semicolon, ';');
  }
}