import os,sys,logging
import signal, time
from xmlrpc.server import SimpleXMLRPCServer, SimpleXMLRPCRequestHandler
import threading
import queue
import socket
import io
import sqlite3
import bb.server.xmlrpcclient
import prserv
import prserv.db
import errno
import select

logger = logging.getLogger("BitBake.PRserv")

if sys.hexversion < 0x020600F0:
    print("Sorry, python 2.6 or later is required.")
    sys.exit(1)

class Handler(SimpleXMLRPCRequestHandler):
    def _dispatch(self,method,params):
        try:
            value=self.server.funcs[method](*params)
        except:
            import traceback
            traceback.print_exc()
            raise
        return value

PIDPREFIX = "/tmp/PRServer_%s_%s.pid"
singleton = None


class PRServer(SimpleXMLRPCServer):
    def __init__(self, dbfile, logfile, interface, daemon=True):
        ''' constructor '''
        try:
            SimpleXMLRPCServer.__init__(self, interface,
                                        logRequests=False, allow_none=True)
        except socket.error:
            ip=socket.gethostbyname(interface[0])
            port=interface[1]
            msg="PR Server unable to bind to %s:%s\n" % (ip, port)
            sys.stderr.write(msg)
            raise PRServiceConfigError

        self.dbfile=dbfile
        self.daemon=daemon
        self.logfile=logfile
        self.working_thread=None
        self.host, self.port = self.socket.getsockname()
        self.pidfile=PIDPREFIX % (self.host, self.port)

        self.register_function(self.getPR, "getPR")
        self.register_function(self.quit, "quit")
        self.register_function(self.ping, "ping")
        self.register_function(self.export, "export")
        self.register_function(self.dump_db, "dump_db")
        self.register_function(self.importone, "importone")
        self.register_introspection_functions()

        self.quitpipein, self.quitpipeout = os.pipe()

        self.requestqueue = queue.Queue()
        self.handlerthread = threading.Thread(target = self.process_request_thread)
        self.handlerthread.daemon = False

    def process_request_thread(self):
        """Same as in BaseServer but as a thread.

        In addition, exception handling is done here.

        """
        iter_count = 1
        # 60 iterations between syncs or sync if dirty every ~30 seconds
        iterations_between_sync = 60

        bb.utils.set_process_name("PRServ Handler")

        while not self.quitflag:
            try:
                (request, client_address) = self.requestqueue.get(True, 30)
            except queue.Empty:
                self.table.sync_if_dirty()
                continue
            if request is None:
                continue
            try:
                self.finish_request(request, client_address)
                self.shutdown_request(request)
                iter_count = (iter_count + 1) % iterations_between_sync
                if iter_count == 0:
                    self.table.sync_if_dirty()
            except:
                self.handle_error(request, client_address)
                self.shutdown_request(request)
                self.table.sync()
            self.table.sync_if_dirty()

    def sigint_handler(self, signum, stack):
        if self.table:
            self.table.sync()

    def sigterm_handler(self, signum, stack):
        if self.table:
            self.table.sync()
        self.quit()
        self.requestqueue.put((None, None))

    def process_request(self, request, client_address):
        self.requestqueue.put((request, client_address))

    def export(self, version=None, pkgarch=None, checksum=None, colinfo=True):
        try:
            return self.table.export(version, pkgarch, checksum, colinfo)
        except sqlite3.Error as exc:
            logger.error(str(exc))
            return None

    def dump_db(self):
        """
        Returns a script (string) that reconstructs the state of the
        entire database at the time this function is called. The script
        language is defined by the backing database engine, which is a
        function of server configuration.
        Returns None if the database engine does not support dumping to
        script or if some other error is encountered in processing.
        """
        buff = io.StringIO()
        try:
            self.table.sync()
            self.table.dump_db(buff)
            return buff.getvalue()
        except Exception as exc:
            logger.error(str(exc))
            return None
        finally:
            buff.close()

    def importone(self, version, pkgarch, checksum, value):
        return self.table.importone(version, pkgarch, checksum, value)

    def ping(self):
        return not self.quitflag

    def getinfo(self):
        return (self.host, self.port)

    def getPR(self, version, pkgarch, checksum):
        try:
            return self.table.getValue(version, pkgarch, checksum)
        except prserv.NotFoundError:
            logger.error("can not find value for (%s, %s)",version, checksum)
            return None
        except sqlite3.Error as exc:
            logger.error(str(exc))
            return None

    def quit(self):
        self.quitflag=True
        os.write(self.quitpipeout, b"q")
        os.close(self.quitpipeout)
        return

    def work_forever(self,):
        self.quitflag = False
        # This timeout applies to the poll in TCPServer, we need the select 
        # below to wake on our quit pipe closing. We only ever call into handle_request
        # if there is data there.
        self.timeout = 0.01

        bb.utils.set_process_name("PRServ")

        # DB connection must be created after all forks
        self.db = prserv.db.PRData(self.dbfile)
        self.table = self.db["PRMAIN"]

        logger.info("Started PRServer with DBfile: %s, IP: %s, PORT: %s, PID: %s" %
                     (self.dbfile, self.host, self.port, str(os.getpid())))

        self.handlerthread.start()
        while not self.quitflag:
            ready = select.select([self.fileno(), self.quitpipein], [], [], 30)
            if self.quitflag:
                break
            if self.fileno() in ready[0]:
                self.handle_request()
        self.handlerthread.join()
        self.db.disconnect()
        logger.info("PRServer: stopping...")
        self.server_close()
        os.close(self.quitpipein)
        return

    def start(self):
        if self.daemon:
            pid = self.daemonize()
        else:
            pid = self.fork()
            self.pid = pid

        # Ensure both the parent sees this and the child from the work_forever log entry above
        logger.info("Started PRServer with DBfile: %s, IP: %s, PORT: %s, PID: %s" %
                     (self.dbfile, self.host, self.port, str(pid)))

    def delpid(self):
        os.remove(self.pidfile)

    def daemonize(self):
        """
        See Advanced Programming in the UNIX, Sec 13.3
        """
        try:
            pid = os.fork()
            if pid > 0:
                os.waitpid(pid, 0)
                #parent return instead of exit to give control 
                return pid
        except OSError as e:
            raise Exception("%s [%d]" % (e.strerror, e.errno))

        os.setsid()
        """
        fork again to make sure the daemon is not session leader, 
        which prevents it from acquiring controlling terminal
        """
        try:
            pid = os.fork()
            if pid > 0: #parent
                os._exit(0)
        except OSError as e:
            raise Exception("%s [%d]" % (e.strerror, e.errno))

        self.cleanup_handles()
        os._exit(0)

    def fork(self):
        try:
            pid = os.fork()
            if pid > 0:
                return pid
        except OSError as e:
            raise Exception("%s [%d]" % (e.strerror, e.errno))

        bb.utils.signal_on_parent_exit("SIGTERM")
        self.cleanup_handles()
        os._exit(0)

    def cleanup_handles(self):
        signal.signal(signal.SIGINT, self.sigint_handler)
        signal.signal(signal.SIGTERM, self.sigterm_handler)
        os.chdir("/")

        sys.stdout.flush()
        sys.stderr.flush()

        # We could be called from a python thread with io.StringIO as
        # stdout/stderr or it could be 'real' unix fd forking where we need
        # to physically close the fds to prevent the program launching us from
        # potentially hanging on a pipe. Handle both cases.
        si = open('/dev/null', 'r')
        try:
            os.dup2(si.fileno(),sys.stdin.fileno())
        except (AttributeError, io.UnsupportedOperation):
            sys.stdin = si
        so = open(self.logfile, 'a+')
        try:
            os.dup2(so.fileno(),sys.stdout.fileno())
        except (AttributeError, io.UnsupportedOperation):
            sys.stdout = so
        try:
            os.dup2(so.fileno(),sys.stderr.fileno())
        except (AttributeError, io.UnsupportedOperation):
            sys.stderr = so

        # Clear out all log handlers prior to the fork() to avoid calling
        # event handlers not part of the PRserver
        for logger_iter in logging.Logger.manager.loggerDict.keys():
            logging.getLogger(logger_iter).handlers = []

        # Ensure logging makes it to the logfile
        streamhandler = logging.StreamHandler()
        streamhandler.setLevel(logging.DEBUG)
        formatter = bb.msg.BBLogFormatter("%(levelname)s: %(message)s")
        streamhandler.setFormatter(formatter)
        logger.addHandler(streamhandler)

        # write pidfile
        pid = str(os.getpid()) 
        pf = open(self.pidfile, 'w')
        pf.write("%s\n" % pid)
        pf.close()

        self.work_forever()
        self.delpid()

class PRServSingleton(object):
    def __init__(self, dbfile, logfile, interface):
        self.dbfile = dbfile
        self.logfile = logfile
        self.interface = interface
        self.host = None
        self.port = None

    def start(self):
        self.prserv = PRServer(self.dbfile, self.logfile, self.interface, daemon=False)
        self.prserv.start()
        self.host, self.port = self.prserv.getinfo()

    def getinfo(self):
        return (self.host, self.port)

class PRServerConnection(object):
    def __init__(self, host, port):
        if is_local_special(host, port):
            host, port = singleton.getinfo()
        self.host = host
        self.port = port
        self.connection, self.transport = bb.server.xmlrpcclient._create_server(self.host, self.port)

    def terminate(self):
        try:
            logger.info("Terminating PRServer...")
            self.connection.quit()
        except Exception as exc:
            sys.stderr.write("%s\n" % str(exc))

    def getPR(self, version, pkgarch, checksum):
        return self.connection.getPR(version, pkgarch, checksum)

    def ping(self):
        return self.connection.ping()

    def export(self,version=None, pkgarch=None, checksum=None, colinfo=True):
        return self.connection.export(version, pkgarch, checksum, colinfo)

    def dump_db(self):
        return self.connection.dump_db()

    def importone(self, version, pkgarch, checksum, value):
        return self.connection.importone(version, pkgarch, checksum, value)

    def getinfo(self):
        return self.host, self.port

def start_daemon(dbfile, host, port, logfile):
    ip = socket.gethostbyname(host)
    pidfile = PIDPREFIX % (ip, port)
    try:
        pf = open(pidfile,'r')
        pid = int(pf.readline().strip())
        pf.close()
    except IOError:
        pid = None

    if pid:
        sys.stderr.write("pidfile %s already exist. Daemon already running?\n"
                            % pidfile)
        return 1

    server = PRServer(os.path.abspath(dbfile), os.path.abspath(logfile), (ip,port))
    server.start()

    # Sometimes, the port (i.e. localhost:0) indicated by the user does not match with
    # the one the server actually is listening, so at least warn the user about it
    _,rport = server.getinfo()
    if port != rport:
        sys.stdout.write("Server is listening at port %s instead of %s\n"
                         % (rport,port))
    return 0

def stop_daemon(host, port):
    import glob
    ip = socket.gethostbyname(host)
    pidfile = PIDPREFIX % (ip, port)
    try:
        pf = open(pidfile,'r')
        pid = int(pf.readline().strip())
        pf.close()
    except IOError:
        pid = None

    if not pid:
        # when server starts at port=0 (i.e. localhost:0), server actually takes another port,
        # so at least advise the user which ports the corresponding server is listening
        ports = []
        portstr = ""
        for pf in glob.glob(PIDPREFIX % (ip,'*')):
            bn = os.path.basename(pf)
            root, _ = os.path.splitext(bn)
            ports.append(root.split('_')[-1])
        if len(ports):
            portstr = "Wrong port? Other ports listening at %s: %s" % (host, ' '.join(ports))

        sys.stderr.write("pidfile %s does not exist. Daemon not running? %s\n"
                         % (pidfile,portstr))
        return 1

    try:
        PRServerConnection(ip, port).terminate()
    except:
        logger.critical("Stop PRService %s:%d failed" % (host,port))

    try:
        if pid:
            wait_timeout = 0
            print("Waiting for pr-server to exit.")
            while is_running(pid) and wait_timeout < 50:
                time.sleep(0.1)
                wait_timeout += 1

            if is_running(pid):
                print("Sending SIGTERM to pr-server.")
                os.kill(pid,signal.SIGTERM)
                time.sleep(0.1)

            if os.path.exists(pidfile):
                os.remove(pidfile)

    except OSError as e:
        err = str(e)
        if err.find("No such process") <= 0:
            raise e

    return 0

def is_running(pid):
    try:
        os.kill(pid, 0)
    except OSError as err:
        if err.errno == errno.ESRCH:
            return False
    return True

def is_local_special(host, port):
    if host.strip().upper() == 'localhost'.upper() and (not port):
        return True
    else:
        return False

class PRServiceConfigError(Exception):
    pass

def auto_start(d):
    global singleton

    # Shutdown any existing PR Server
    auto_shutdown()

    host_params = list(filter(None, (d.getVar('PRSERV_HOST') or '').split(':')))
    if not host_params:
        return None

    if len(host_params) != 2:
        logger.critical('\n'.join(['PRSERV_HOST: incorrect format',
                'Usage: PRSERV_HOST = "<hostname>:<port>"']))
        raise PRServiceConfigError

    if is_local_special(host_params[0], int(host_params[1])) and not singleton:
        import bb.utils
        cachedir = (d.getVar("PERSISTENT_DIR") or d.getVar("CACHE"))
        if not cachedir:
            logger.critical("Please set the 'PERSISTENT_DIR' or 'CACHE' variable")
            raise PRServiceConfigError
        bb.utils.mkdirhier(cachedir)
        dbfile = os.path.join(cachedir, "prserv.sqlite3")
        logfile = os.path.join(cachedir, "prserv.log")
        singleton = PRServSingleton(os.path.abspath(dbfile), os.path.abspath(logfile), ("localhost",0))
        singleton.start()
    if singleton:
        host, port = singleton.getinfo()
    else:
        host = host_params[0]
        port = int(host_params[1])

    try:
        connection = PRServerConnection(host,port)
        connection.ping()
        realhost, realport = connection.getinfo()
        return str(realhost) + ":" + str(realport)
        
    except Exception:
        logger.critical("PRservice %s:%d not available" % (host, port))
        raise PRServiceConfigError

def auto_shutdown():
    global singleton
    if singleton:
        host, port = singleton.getinfo()
        try:
            PRServerConnection(host, port).terminate()
        except:
            logger.critical("Stop PRService %s:%d failed" % (host,port))

        try:
            os.waitpid(singleton.prserv.pid, 0)
        except ChildProcessError:
            pass
        singleton = None

def ping(host, port):
    conn=PRServerConnection(host, port)
    return conn.ping()