// PROTOTYPE:
//  function isvalidmail(email,allowFullname):Boolean


function isDigit(ch) {
 if ( (ch >= '0') && (ch <= '9') ) return true;
 else return false;
}

function isAlpha(ch) {
  if ( ((ch >= 'a') && (ch <= 'z')) || ((ch >= 'A') && (ch <= 'Z')) ) return true;
  else return false;
}

function isAlphanum(ch) {
  if ( isAlpha( ch ) || isDigit( ch ) ) return true;
  else return false;
}

function notIn( str1, str2 ) {
  var i = 0;
  var j = str2.length;
  
  for ( ; i<j; i++ ) {
    var str3 =  str2.charAt(i);
    if (str1.indexOf(str3) != -1) return false;
  }
  return true;
}

function checkUsername(username, mustBeQuoted) {
  var i = 0;
  var j = username.length;
  
  if (username.charAt(0) != '"') {
    if ((username.charAt(0) <  ' ') || (username.charAt(0) >  '~') ||
        !notIn( mustBeQuoted, username.charAt(0))) return false;
        
    for( i=1; i<j; i++ ) {
      if (((username.charAt(i) < ' ') || (username.charAt(i) >  '~') ||
          !notIn ( mustBeQuoted, username.charAt(i))) && 
          (username.charAt(i-1) != '\\')) return false;
    }
  } else {
    if (username.charAt(j-1) != '"' ) return false;
    for( i=1; i<j-1; i++ ) {
      if (((username.charAt(i) == '\n') || (username.charAt(i) == '\r') ||
           (username.charAt(i) == '\"')) && 
          (username.charAt(i-1) != '\\')) return false;
  } }
  return true;
}

function checkNr(nr) {
  var i=0;
  var j=nr.length;

  if (j<1) return false;

  for( ; i<j; i++ ) {
    if ((nr.charAt(i) < '0') || (nr.charAt(i) > '9')) return false;
  }
  return true;
}

function checkIpnr(ipnr) {
  var iL=0;
  var iC=0;
  var i=0;
  var sNr = "";

  for( ; i< ipnr.length; i++ ) {
    if (ipnr.charAt(i) == '.') {
      if (!iL || (iL> 3) || parseInt( sNr,10 ) > 255 ) return false;
      iC++;
      iL = 0;
      sNr = "";
      continue;
    }
    if (isDigit(ipnr.charAt(i))) {
      iL++;
      sNr = sNr + ipnr.charAt(i);
      continue;
    }
    return false;
  }
  if (parseInt(sNr,10) > 255 ) return false;
  if (((iC==3) && (iL>=1) && (iL<=3)) || ((iC==4) && (!iL) ) ) return true;
  else return false;
}

function checkFqdn(fqdn) {
  var iL=0;
  var iC=0;
  var i=fqdn.length-1;

  if ((fqdn.charAt(0) == '.') || (fqdn.charAt(0) == '-')) return false;
  if (fqdn.charAt(i) == '.' ) i=i-1;

  for( ; i>=0; i--) {
    if ( fqdn.charAt(i) == '.' ) {
      if ((iL < 2) && (iC < 2)) return false;
      if (fqdn.charAt(i-1) == '-' ) return false;
      iC++;
      iL = 0;
      continue;
    }
    if (isAlphanum(fqdn.charAt(i))) {
      iL++;
      continue;
    }
    if (fqdn.charAt(i) == '-') {
      if (!iL) return false;
      iL++;
      continue;
    }
    return false;
  }
  if (!iC || ((iL==1) && (iC<2)) || (!iL && (iC==1))) return false;
  return true;
}

function checkHostname(hostname) {
  if (hostname.charAt(0) == '[') {
    if (hostname.charAt(hostname.length-1) != ']') return false;
    var ipnr = hostname.substring(1, hostname.length -1);
    return checkIpnr(ipnr);
  }
  if (hostname.charAt(0) == '#') {
    var nr = hostname.substring(1, hostname.length );
    return checkNr(nr);
  }
  return checkFqdn(hostname);
}

function checkEmailAdr(address) {
  var status = true;
  var username = "";
  var hostname = "";

  if (address.length < 8) return false;

  var seperate = address.lastIndexOf("@");
  if ( seperate == -1 ) return false;

  username = address.substring(0, seperate );
  if (!checkUsername(username, "<>()[],;:@\" ")) return false;

  hostname = address.substring(seperate+1, address.length );
  if (!checkHostname(hostname)) return false;
  return true;
}

function isvalidmail(email,allowFullname) {
  var existFullname = false;
  var status = true;
  var fullname = "";
  var adress = "";
  if (email.length < 8) return false;
  var emailBegin = email.indexOf("<");
  var emailEnd = email.lastIndexOf(">");

  if ((emailBegin == -1) && (emailEnd == -1)) return checkEmailAdr( email );
  if (((emailBegin == -1) && (emailEnd != -1)) ||
       ((emailBegin != -1) && (emailEnd == -1))) return false;
  adress = email.substring(emailBegin+1, emailEnd);
  if (!checkEmailAdr(adress)) return false;
  if (email.length == adress.length + 2) return true;
  else if (!allowFullname) return false;

  if (emailEnd == (email.length-1)) {
    if (emailBegin == 0 ) return true;
    if (email.charAt(emailBegin -1) != ' ') return false;
    fullname = email.substring(0, emailBegin-1);
    return checkUsername(fullname, "<>()[],;:@\"" );
  }
  return false;
}