/**
 * Utilities relating to Lua 'rocks' version numbers.
 * This compares version numbers using the algorithm
 * followed by luarocks command-line utility
 */
'use strict';

// Compare two arrays containing splitted and transformed to
// positive/negative numbers parts of version strings,
// respecting negative/missing values:
// [1, 2, 1] > [1, 2], but [1, 2, -1] < [1, 2] ([1, 2] is aligned to [1, 2, 0])
// Return a negative value if v1 < v2,
// zero if v1 = v2,
// a positive value otherwise.
function compareVersionLists(v1, v2) {
  const maxLength = Math.max(v1.length, v2.length);
  let p1, p2;
  for (let i = 0; i < maxLength; i++) {
    p1 = v1[i] || 0;
    p2 = v2[i] || 0;
    if (p1 > p2) return 1;
    if (p1 < p2) return -1;
  }
  return 0;
}
exports.compareVersionLists = compareVersionLists;

// Parse a dotted version string to an array of numbers
// 'rc', 'pre', 'beta', 'alpha' are converted to negative numbers
function parseVersion(versionString) {
  versionString = versionString.toLowerCase().replace('-', '.');
  let versionList = [];
  versionString.split('.').forEach(function(versionPart) {
    let parsedPart = /(\d*)([a-z]*)(\d*)/.exec(versionPart);
    if (parsedPart[1]) {
      versionList.push(parseInt(parsedPart[1]));
    }
    if (parsedPart[2]) {
      let weight;
      // calculate weight as a negative number
      // 'rc' > 'pre' > 'beta' > 'alpha' > any other value
      switch (parsedPart[2]) {
        case 'alpha':
        case 'beta':
        case 'pre':
        case 'rc':
          weight = (parsedPart[2].charCodeAt(0) - 128) * 100;
          break;
        default:
          weight = -10000;
      }
      // add positive number, i.e. 'beta5' > 'beta2'
      weight += parseInt(parsedPart[3]) || 0;
      versionList.push(weight);
    }
  });
  return versionList;
}
exports.parseVersion = parseVersion;