/**
 * @preserve Copyright (c) 2014-2015 IONU Security, Inc. All rights reserved.
 * 
 * @file Permissions class for management and signature generation
 */


PERMISSION_KEY_OWNER = 'owner';
PERMISSION_KEY_TOPIC = 'topic';

PERMISSION_READ = 'read';
PERMISSION_WRITE = 'write';
PERMISSION_ADMIN = 'admin';
/*
PERMISSION_DOORWAY = 'doorway';
PERMISSION_STREAM = 'stream';
PERMISSION_HIDE = 'hide';
*/
PERMISSION_ASSIGNMENT_SUFFIX = 'Assign';

PERMISSION_ROOT_KEY = 'perms';
PERMISSION_TYPE_KEY = 'type';		// unset/empty 'file'; 'group'
PERMISSION_MEMBERS_KEY = "mbrs";
PERMISSION_SIGNATURE_KEY = "signature";
PERMISSION_DIGEST_KEY = "digest";

/**
 * Permissions object
 * @constructor
 * @param {string|object} perms  - JSON string or object
 */
function Permissions (perms) {
  if (!(this instanceof Permissions)){
    return new Permissions (perms);
  }
  if (typeof perms === 'string') {
    this.perms = JSON.parse (perms);
  }
  else if (typeof perms === 'object') {
    this.perms = perms;
  }
  else {
    var error = new Error ('Invalid permissions');
    throw error;
  }
}

function createPermissionsFromOffice(officeId){
  return createPermissionsFromCollaborators(officeId, [officeId]);
}

function createPermissionsFromCollaborators(owner, offices, noSub){
  var p = {read:[], write:[], admin:[], readAssign:[], writeAssign:[], adminAssign:[]};
  for (var i = 0; i < offices.length; ++i) {
    var officeId = offices[i];
    if (officeId.match(/^urn:sl/) && !noSub) {
      officeId = officeId.replace(/^urn:sl:.{6}:/,'').replace(/:.*/,'');
    }
    p.read.push(officeId);
    p.write.push(officeId);
    p.admin.push(officeId);
    p.readAssign.push(officeId);
    p.writeAssign.push(officeId);
    p.adminAssign.push(officeId);
    //p.hideAssign.push(officeId);
  }
  p.owner = owner||'';
  if (typeof p.owner === 'object'){
	  p.owner = p.owner._id.replace(/^urn:sl:.{6}:/,'').replace(/:.*/,'');
  }
  p = new Permissions(p);
  return p;
}

function createPermissionsFromTeam(owner, teamUrn){
	return createPermissionsFromCollaborators(owner, [teamUrn], true);
}

// Define the prototype methods for Permissions object
Permissions.prototype = {
  constructor: Permissions,

  /**
   * Add all unique references from the current permission key
   *
   * @param {array} set of all unique references
   * @param {string} perms for key, e.g. read/readAssign...
   * @return {array} set of all unique references
   */
  addUniqueReferences: function (refs, perms) {
    if (perms !== undefined) {
      var numPerms = perms.length;
      for (var j = 0; j < numPerms; ++j) {
        var permVal = perms[j];
        if (permVal === PERMISSION_KEY_OWNER) {
          permVal = this.perms.owner;
        }
        var urn = permVal;
        if (urn.slice (0, 3) !== 'urn') {
          urn = this.urnPrefix + permVal + '::';
        }
        var len = refs.length;
        var found = false;
        for (var i = 0; i < len; ++i) {
          if (refs[i] == urn) {
            found = true;
            break;
          }
        }
        if (found === false) {
          refs.push (urn);
        }
      }
    }
    return refs;
  },

  /**
   * Get all the unique references in urn format, sorted with '|' delimiter and optional topic id
   *
   * @param {string} van - urn string urn:sl:000000:::
   * @return {string} ordered set of all references
   */
  getOrderedReferences: function (van) {
    var refs = [];
    var owner = this.perms.owner;
    var permissionKeys = [PERMISSION_READ,PERMISSION_WRITE,PERMISSION_ADMIN/*,PERMISSION_DOORWAY,PERMISSION_STREAM,PERMISSION_HIDE*/];
    var numKeys = permissionKeys.length, key = null;
    this.urnPrefix = '';
    if (van !== undefined && van !== null) {
      var urnFields = van.split (':');
      if (urnFields.length > 4) {
        this.urnPrefix = urnFields[0] + ':' + urnFields[1] + ':' + urnFields[2] + ':';
      }
    }
    for (var i = 0; i < numKeys; ++i) {
      key = permissionKeys[i];
      var perms = this.perms[key];
      refs = this.addUniqueReferences (refs, perms);
      key = permissionKeys[i] + PERMISSION_ASSIGNMENT_SUFFIX;
      perms = this.perms[key];
      refs = this.addUniqueReferences (refs, perms);
    }
    refs.sort();
    var delim = '';
    var str = '';
    refs.forEach(function(value) {
      str += delim + value;
      delim = '|';
    });
    // Append "topic"...
    var topic = this.perms[PERMISSION_KEY_TOPIC];
    if (topic !== undefined && topic.length > 0) {
      str += delim + topic;
    }
    return str;
  },

  /**
   * Convert permissions to ordered JSON string for path hash computation
   * removes "owner" property, replaces "owner" in perms arrays with urn
   *
   * @param {string} van - urn string urn:sl:000000:::
   * @return {string} ordered set of all references and optional topic
   */
  getSignature: function (van) {
    var perms = this.getOrderedReferences (van);
    var md = forge.md.md5.create();
    md.update (perms);
    var sig = md.digest().toHex();
    return sig.substring (0, 12);
  },

  /**
   * Convert permissions to ordered JSON string for path hash computation
   * removes "owner" property, replaces "owner" in perms arrays with urn
   *
   * @return {string} JSON string
   */
  toOrderedString: function() {
    var permissionKeys = [PERMISSION_READ,PERMISSION_WRITE,PERMISSION_ADMIN/*,PERMISSION_DOORWAY,PERMISSION_STREAM,PERMISSION_HIDE*/];
    var json = '{';
    var numKeys = permissionKeys.length, key = null;
    var comma = '';
    var owner = this.perms.owner;
    for (var i = 0; i < 2; ++i) {
      var suffix = (i == 0) ? '' : PERMISSION_ASSIGNMENT_SUFFIX;
      for (var j = 0; j < numKeys; ++j) {
         key = permissionKeys[j] + suffix;
         var perms = this.perms[key];
         if (perms === undefined) {
           continue;
         }
         perms.sort();
         var numPerms = perms.length;
         json += comma + '"' + key + '":[';
         var bHasOwner = false;
         for (var k = 0; k < numPerms; ++k) {
            var permVal = perms[k];
            if (permVal === owner) {
              bHasOwner = true;
            }
            if (permVal === PERMISSION_KEY_OWNER) {
              if (bHasOwner === true) {
                // we already emitted the UUID for owner so don't do it again
                // note that normal "assign" logic prevents all other duplicate values
                continue;
              }
              else {
                permVal = owner;
              }
            }

            if (k > 0) {
               json += ',';
            }
            json += '"' + permVal + '"';
         }
         json += ']';
         comma = ",";
      }
    }

    // Append "topic"...
    var topic = this.perms[PERMISSION_KEY_TOPIC];
    if (topic !== undefined && topic.length > 0) {
      json += ',"' + PERMISSION_KEY_TOPIC + '":"' + topic + '"';
    }
    json += '}';
    return json;
  },

  /**
   * Generate the path hash, left 12 bytes of hex encoded MD5 hash of the ordered JSON permissions
   *
   * @return {string} path hash
   */
  getPathHash: function () {
    var perms = this.toOrderedString();
    var md = forge.md.md5.create();
    md.update (perms);
    var sig = md.digest().toHex();
    return sig.substring (0, 12);
  }

}