module.exports = function(sql) {

  var module={};

  module.connection = function(socket) {

    console.log("new client");

    function emit(signal, data, info) {
      if (typeof data == 'string') {
        console.log("<- signal: "+signal+"("+data+")");
      } else {
        console.log("<- signal: "+signal);
      }
      if (info) console.log(info);
      socket.emit(signal, data);
    }

    function broadcast(signal, data) {
      console.log("<= signal: "+signal);
      socket.broadcast.emit(signal, data);
    }

    socket.on("message", function(msg) {
      console.log("-> signal: message");
      if (!msg || !msg.user || !msg.content) return emit("fail", "wrong message format");
      sql.query("select pubkey from user where name = ?", [msg.user],
                function(err, res, flds) {
                  if (err || !res || !res.length) return emit("fail", "unknown sender");
                  sql.query("insert into message set ?", {user: msg.user, msg: msg.content},
                            function(err, result) {
                              if (err) {
                                if (err.code=='ER_NET_PACKET_TOO_LARGE')
                                  return emit('fail', "message too large", err);
                                else
                                  return emit("fail", "cannot store message", err);
                              }
                              sql.query("select * from message, user"+
                                        " where message.id = ? and"+
                                        " message.user = user.name",
                                        [result.insertId],
                                        function(err, res, flds) {
                                          broadcast('message', res[0]);
                                          emit('message', res[0]);
                                        });
                            });
                });
    });

    socket.on("messages", function(msg) {
      console.log("-> signal: messages");
      sql.query("select * from message, user where message.user = user.name order by message.id", [],
                function(err, res, flds) {
                  emit('messages', res);
                });
    });

    socket.on("login", function(user) {
      console.log('-> signal: login('+user.name+')');
      if (!user.name || !user.pubkey) return emit("fail", "wrong login format");
      console.log("-> signal: login("+user.name+")");
      if (user.name=="safechat") return emit("fail", "user name safechat is reserved");
      sql.query("select name, pubkey from user where name = ?", [user.name],
                function(err, res, flds) {
                  if (err) return emit('fail', "login failed (db access)", err);
                  if (!res || res.length==0) {
                    sql.query("insert into user (name, pubkey) values (?,?)",
                              [user.name, user.pubkey], function(err, res, flds) {
                                if (err) return emit('fail', "create user failed", err);
                                broadcast("user", {
                                  name: user.name, exists: false, pubkey: user.pubkey
                                });
                                emit('login');
                              });
                  } else {
                    if (res[0].pubkey==user.pubkey) return emit('login');
                    emit('fail', "login failed - wrong credentials");
                  }
                });
    });
    
    socket.on("user", function(name, fn) {
      console.log("-> signal: user("+name+")");
      var result = {name: name, exists: false, pubkey: null};
      sql.query("select pubkey from user where name = ?", [name], function(err, res, flds) {
        console.log('user in db', err, res, flds)
        if (!err && res && res.length) {
          result.exists = true;
          result.pubkey = res[0].pubkey;
        }
        fn(result);
      });
    });
    
    socket.on("lookup", function(name, fn) {
      console.log("-> signal: lookup("+name+")")
      var result = false
      sql.query("select pubkey from user where name = ?",
                [name],
                function(err, res, flds) {
                  if (!err && res && res.length) {
                    result = true;
                  }
                  fn(result)
                });
    });
    
    socket.on("users", function(name) {
      console.log("-> signal: users");
      sql.query("select name, pubkey from user", [name], function(err, res, flds) {
        if (!err && res && res.length) emit('users', res);
      });
    });
    
  };
  
  return module;
};