import { TokenStream } from './token_stream.js';

export class TemplateEngine {
  async render(fileName) {
    const ts = new TokenStream();
    await ts.loadFile(fileName);

    let buffer = '';

    while (!ts.eof()) {
      const token = ts.next();

      switch (token.type) {
        case 'raw':
          buffer += this._renderRaw(token.value);
          break;
        case 'inline':
          buffer += this._renderInline(token.value);
          break;
        case 'inline_unescaped':
          buffer += this._renderInlineUnescaped(token.value);
          break;
        case 'inline_statement':
          buffer += this._renderInlineStatement(token.value);
          break;
        case 'inline_statement_unescaped':
          buffer += this._renderInlineStatementUnescaped(token.value);
          break;
        case 'statement':
          buffer += this._renderStatement(token.value);
          break;
        case 'comment':
          buffer += this._renderComment(token.value);
          break;
        default:
          throw new Error(`Unrecognized token: ${token.type}`);
      }
    }

    return buffer;
  }

  _renderComment(value) {
    return `# ${value}\n`;
  }

  _renderStatement(value) {
    return `${value}\n`;
  }

  _renderInline(value) {
    return `printf '%s' "${value}" | jq -Rrj @html;\n`;
  }

  _renderInlineUnescaped(value) {
    return `printf '%s' "${value}";\n`;
  }

  _renderInlineStatement(value) {
    return `printf '%s' "$(${value})" | jq -Rrj @html;\n`;
  }

  _renderInlineStatementUnescaped(value) {
    return `printf '%s' "$(${value})";\n`;
  }

  _renderRaw(value) {
    const lines = value.split('\n');

    let buffer = '';

    for (let i = 0; i < lines.length; i++) {
      const line = lines[i];
      const isLastLine = i === lines.length - 1;

      if (isLastLine && !line.length) break;

      const formatString = isLastLine ? '%s' : '%s\\n';

      buffer += `printf '${formatString}' '${line.replace("'", "'\\''")}';\n`;
    }

    return buffer;
  }
}

/* Convenience function for quickly rendering a file */
export function renderFile(fileName) {
  const tp = new TemplateEngine();
  return tp.render(fileName);
}