const DEBUG = process.env['DEBUG'];
  
  const validator = require('./validator');
  
  function reverseString(str) {
      return str.split('').reverse().join('');
  }
  
  module.exports = (src, maxLength) => {
      const head = src.slice(0, maxLength);
      const tail = src.slice(maxLength);
      
      if (validator(head, tail)) {
          if (DEBUG) console.log(`TRUNCATE-PARAGRAPH: straight result src='${src}' maxLength=${maxLength}`);
          return [head.trim(), tail.trim()];
      }
  
      const reverseI = reverseString(head).search(/[
  ., ;-]/);
      if (reverseI === -1) {
          // if (DEBUG) console.log(`TRUNCATE-PARAGRAPH: out of boundary src='${src}' maxLength=${maxLength}`);
          return [head.trim(), tail.trim()];
      }
  
      const i = src.slice(0, maxLength - reverseI).trim().length;
      // if (DEBUG) console.log(`TRUNCATE-PARAGRAPH: calculated src='${src}' maxLength=${maxLength} i=${i}`);
      return [
          src.slice(0, i).trim(),
          src.slice(i).trim(),
      ]
  }