/**
 * Utilities relating to PHP version numbers. This compares version numbers
 * using the algorithm followed by Composer (see
 * https://getcomposer.org/doc/04-schema.md#version).
 */
'use strict';

const {listCompare} = require('./version.js');

// Return a negative value if v1 < v2,
// zero if v1 = v2,
// a positive value otherwise.
//
// See https://getcomposer.org/doc/04-schema.md#version
// and https://github.com/badges/shields/issues/319#issuecomment-74411045
function compare(v1, v2) {
  // Omit the starting `v`.
  var rawv1 = omitv(v1);
  var rawv2 = omitv(v2);
  try {
    var v1data = numberedVersionData(rawv1);
    var v2data = numberedVersionData(rawv2);
  } catch(e) {
    return asciiVersionCompare(rawv1, rawv2);
  }

  // Compare the numbered part (eg, 1.0.0 < 2.0.0).
  var numbersCompare = listCompare(v1data.numbers, v2data.numbers);
  if (numbersCompare !== 0) {
    return numbersCompare;
  }

  // Compare the modifiers (eg, alpha < beta).
  if (v1data.modifier < v2data.modifier) {
    return -1;
  } else if (v1data.modifier > v2data.modifier) {
    return 1;
  }

  // Compare the modifier counts (eg, alpha1 < alpha3).
  if (v1data.modifierCount < v2data.modifierCount) {
    return -1;
  } else if (v1data.modifierCount > v2data.modifierCount) {
    return 1;
  }

  return 0;
}
exports.compare = compare;

function latest(versions) {
  var latest = versions[0];
  for (var i = 1; i < versions.length; i++) {
    if (compare(latest, versions[i]) < 0) {
      latest = versions[i];
    }
  }
  return latest;
}
exports.latest = latest;

// Whether a version is stable.
function isStable(version) {
  var rawVersion = omitv(version);
  try {
    var versionData = numberedVersionData(rawVersion);
  } catch(e) {
    return false;
  }
  // normal or patch
  return (versionData.modifier === 3) || (versionData.modifier === 4);
}
exports.isStable = isStable;

// === Private helper functions ===

// Remove the starting v in a string.
function omitv(version) {
  if (version.charCodeAt(0) === 118) { // v
    return version.slice(1);
  } else {
    return version;
  }
}

// Return a negative value if v1 < v2,
// zero if v1 = v2, a positive value otherwise.
function asciiVersionCompare(v1, v2) {
  if (v1 < v2) {
    return -1;
  } else if (v1 > v2) {
    return 1;
  } else {
    return 0;
  }
}

// Take a version without the starting v.
// eg, '1.0.x-beta'
// Return { numbers: [1,0,something big], modifier: 2, modifierCount: 1 }
function numberedVersionData(version) {
  // A version has a numbered part and a modifier part
  // (eg, 1.0.0-patch, 2.0.x-dev).
  var parts = version.split('-');
  var numbered = parts[0];

  // Aliases that get caught here.
  if (numbered === 'dev') {
    return {
      numbers: parts[1],
      modifier: 5,
      modifierCount: 1,
    };
  }

  var modifierLevel = 3;
  var modifierLevelCount = 0;

  if (parts.length > 1) {
    var modifier = parts[parts.length - 1];
    var firstLetter = modifier.charCodeAt(0);
    var modifierLevelCountString;

    // Modifiers: alpha < beta < RC < normal < patch < dev
    if (firstLetter === 97) { // a
      modifierLevel = 0;
      if (/^alpha/.test(modifier)) {
        modifierLevelCountString = + (modifier.slice(5));
      } else {
        modifierLevelCountString = + (modifier.slice(1));
      }
    } else if (firstLetter === 98) { // b
      modifierLevel = 1;
      if (/^beta/.test(modifier)) {
        modifierLevelCountString = + (modifier.slice(4));
      } else {
        modifierLevelCountString = + (modifier.slice(1));
      }
    } else if (firstLetter === 82) { // R
      modifierLevel = 2;
      modifierLevelCountString = + (modifier.slice(2));
    } else if (firstLetter === 112) { // p
      modifierLevel = 4;
      if (/^patch/.test(modifier)) {
        modifierLevelCountString = + (modifier.slice(5));
      } else {
        modifierLevelCountString = + (modifier.slice(1));
      }
    } else if (firstLetter === 100) { // d
      modifierLevel = 5;
      if (/^dev/.test(modifier)) {
        modifierLevelCountString = + (modifier.slice(3));
      } else {
        modifierLevelCountString = + (modifier.slice(1));
      }
    }

    // If we got the empty string, it defaults to a modifier count of 1.
    if (!modifierLevelCountString) {
      modifierLevelCount = 1;
    } else {
      modifierLevelCount = + modifierLevelCountString;
    }
  }

  // Try to convert to a list of numbers.
  var toNum = function(s) {
    var n = +s;
    if (n !== n) {  // If n is NaN…
      n = 0xffffffff;
    }
    return n;
  };
  var numberList = numbered.split('.').map(toNum);

  return {
    numbers: numberList,
    modifier: modifierLevel,
    modifierCount: modifierLevelCount,
  };
}