// This file is in tools/package-version-parser.js and is symlinked into
// packages/package-version-parser/package-version-parser.js. It's part
// of both the tool and the package!  We don't use uniload for it because
// it needs to be used as part of initializing the uniload catalog.

var inTool = typeof Package === 'undefined';

var PV;
if (inTool) {
  PV = exports;
} else {
  PackageVersion = PV = {};
}

var semver = inTool ? require ('semver') : Npm.require('semver');
var __ = inTool ? require('underscore') : _;

// Conceptually we have three types of constraints:
// 1. "compatible-with" - A@x.y.z - constraints package A to version x.y.z or
//    higher, as long as the version is backwards compatible with x.y.z.
//    "pick A compatible with x.y.z"
//    It is the default type.
// 2. "exactly" - A@=x.y.z - constraints package A only to version x.y.z and
//    nothing else.
//    "pick A exactly at x.y.z"
// 3. "any-reasonable" - "A"
//    Basically, this means any version of A ... other than ones that have
//    dashes in the version (ie, are prerelease) ... unless the prerelease
//    version has been explicitly selected (which at this stage in the game
//    means they are mentioned in a top-level constraint in the top-level
//    call to the resolver).
PV.parseVersionConstraint = function (versionString, options) {
  options = options || {};
  var versionDesc = { version: null, type: "any-reasonable",
                      constraintString: versionString };

  if (!versionString) {
    return versionDesc;
  }

  if (versionString.charAt(0) === '=') {
    versionDesc.type = "exactly";
    versionString = versionString.substr(1);
  } else {
    versionDesc.type = "compatible-with";
  }

  // This will throw if the version string is invalid.
  PV.getValidSemverVersion(versionString);

  versionDesc.version = versionString;

  return versionDesc;
};


// Check to see if the versionString that we pass in is valid semver, as far as
// Meteor is concerned.
//
// Returns the output of semver.valid, which is a valid semver string (if
// versionString is valid semver) WITHOUT THE BUILD ID. Otherwise, throws.
PV.getValidSemverVersion = function (versionString) {

  // NPM's semver spec supports things like 'v1.0.0' and considers them valid,
  // but we don't. Everything before the + or - should be of the x.x.x form.
  var mainVersion = versionString.split('+')[0].split('-')[0];
  if (! /^\d+\.\d+\.\d+$/.test(mainVersion)) {
      throwVersionParserError(
        "Version string must look like semver (eg '1.2.3'), not '"
          + versionString + "'.");
  };

  var cleanVersion = semver.valid(versionString);
  if (! cleanVersion ) {
    throwVersionParserError(
      "Version string must look like semver (eg '1.2.3'), not '"
        + versionString + "'.");
  }

  return cleanVersion;
};


PV.parseConstraint = function (constraintString, options) {
  if (typeof constraintString !== "string")
    throw new TypeError("constraintString must be a string");
  options = options || {};

  var splitted = constraintString.split('@');

  var constraint = { name: "", version: null,
                     type: "any-reasonable", constraintString: null };
  var name = splitted[0];
  var versionString = splitted[1];

  if (splitted.length > 2) {
    // throw error complaining about @
    PV.validatePackageName('a@');
  }
  PV.validatePackageName(name);

  constraint.name = name;

  if (splitted.length === 2 && !versionString) {
    throwVersionParserError(
      "Version constraint for package '" + name +
        "' cannot be empty; leave off the @ if you don't want to constrain " +
        "the version.");
  }

  if (versionString) {
    __.extend(constraint,
              PV.parseVersionConstraint(versionString, options));
  }

  return constraint;
};

PV.validatePackageName = function (packageName, options) {
  options = options || {};

  var badChar = packageName.match(/[^a-z0-9:.\-]/);
  if (badChar) {
    if (options.detailedColonExplanation) {
      throwVersionParserError(
        "Bad character in package name: " + JSON.stringify(badChar[0]) +
          ".\n\nPackage names can only contain lowercase ASCII alphanumerics, " +
          "dash, or dot.\nIf you plan to publish a package, it must be " +
          "prefixed with your\nMeteor Developer Account username and a colon.");
    }
    throwVersionParserError(
      "Package names can only contain lowercase ASCII alphanumerics, dash, " +
        "dot, or colon, not " + JSON.stringify(badChar[0]) + ".");
  }
  if (!/[a-z]/.test(packageName)) {
    throwVersionParserError("Package names must contain a lowercase ASCII letter.");
  }
  if (packageName[0] === '.') {
    throwVersionParserError("Package names may not begin with a dot.");
  }
};

var throwVersionParserError = function (message) {
  var e = new Error(message);
  e.versionParserError = true;
  throw e;
};

// XXX if we were better about consistently only using functions in this file,
// we could just do this using the constraintString field
PV.constraintToVersionString = function (parsedConstraint) {
  if (parsedConstraint.type === "any-reasonable")
    return "";
  if (parsedConstraint.type === "compatible-with")
    return parsedConstraint.version;
  if (parsedConstraint.type === "exactly")
    return "=" + parsedConstraint.version;
  throw Error("Unknown constraint type: " + parsedConstraint.type);
};

PV.constraintToFullString = function (parsedConstraint) {
  return parsedConstraint.name + "@" + PV.constraintToVersionString(
    parsedConstraint);
};