class CorrelationStream():
    def __init__(self, prefix="SLAAR-LBSTREAM1", verbose=False, interval=1.0, empty_value = 1112223330):
        self.prefix = prefix
        self.verbose = verbose
        self.interval = interval
        self.empty_value = empty_value
        if self.prefix != ":":
            self.prefix = self.prefix + ":"
    
        self.t0=None
        self.pid=None       
        
        self.st=None 
        self.running = False
        self.task=None
                    

    def get_channel_list(self):
        ch=[]
        try:
            for i in range(20):
               v= caget(self.prefix + "NAME" + str(i+1))
               if v.strip()=="":
                    break
               ch.append(str(v.strip()))
        except:
            pass
        return ch 
    
    def ack_channel_list(self, channel_list):
        try:
            s=""
            for c in channel_list:
                s=s+c+"\n"
            s=s+"\x00"
            caput(self.prefix + "PACK_LIST",[ord(c) for c in s])    
        except:
            pass
            
    def start_stream(self, channel_list):
        try:    
            self.st=None    
            log("Starting stream: " + str(self.prefix))
            if len(channel_list)==0:
                raise Exception ("No channel defined")        
            self. st = Stream("pulse_id", dispatcher)
            self.st.setIncomplete("fill_null")
            for c in channel_list:
                self.st.addScalar(c, c, 1, 0)   
            self.st.initialize()
            self.st.start()
            self.st.waitCacheChange(10000)    #Wait stream be running before starting scan
            if self.st.take() is None:
                raise Exception("Error initializing data stream")   
            self.ack_channel_list(channel_list)
            log("Stream started: " + str(self.prefix))         
        except:
            self.stop_stream()
            self.st=None
            log(sys.exc_info()[1])
            
    def stop_stream(self):
        log("Closing stream: " + str(self.prefix))
        try:        
            if self.st:
                self.st.close()                    
                log("Stream closed: " + str(self.prefix)) 
        except:
            log(sys.exc_info()[1])
        finally:
            self.st=None
            self.ack_channel_list([])    
    
    def handle_message(self, msg, channel_list, buf):
        if self.t0 is None:
            self.t0  = time.time()
        now=time.time()
        num_channels = len(channel_list)
        size_buffer= 300 #int((len(buf)-100)/(len(channel_list)+1))  
        buf[0] = msg.pulseId
        buf[1] = num_channels
        buf[4] = self.empty_value
        #if (self.pid is not None) and ((self.pid+1) != msg.pulseId):
        #    msg("Missing pid:  +str(self.pid+1))
        self.pid = msg.pulseId
        #Count
        if buf[2] < size_buffer:
            buf[2] = buf[2]+1    
        #Index    
        buf[3] = buf[3]+1    
        if buf[3] == size_buffer:
             buf[3]=0 
        index = int(buf[3])*(num_channels+1) + 10    
        buf[index] = msg.pulseId
        index = index+1
        for v in msg.values():
            buf[index] = self.empty_value if ((v is None) or (math.isnan(v)))else v                       
            index = index+1    
        if now >= (self.t0 + self.interval):        
            if self.verbose:                
                print self.prefix, ":", to_list(buf[0:5])        
            self.t0  = time.time()
            return True
        return False

    
    def _run(self):
        log("Start running thread: " + str(self.prefix))
        channel_list = []      
        
        try:                 
            start_channel = Channel(self.prefix + "START_STOP", type = 'i')
            output_channel = Channel(self.prefix + "PACK_DATA", type = '[d')                   
            buf = to_array([0]*output_channel.get_size(),'d')            
            while self.running:
                started = (start_channel.get()==1)
                if started and not self.st:
                    buf[2] = 0
                    buf[3]= -1                  
                    channel_list=self.get_channel_list()
                    log("Started " + str(self.prefix) + " - Channel list: " + str(channel_list) )
                    self.start_stream(channel_list)                         
                    if self.st is not None:
                        class StreamListener (DeviceListener):    
                            def __init__(self, parent):
                                self.parent=parent
                            def onValueChanged(self, device, value, former): 
                                if self.parent.handle_message(value, channel_list, buf):
                                    output_channel.putq(buf)   
                        listener = StreamListener(self)                
                        self.st.addListener(listener)
                    
                elif self.st and not started:
                    log("Stopped " + str(self.prefix))
                    channel_list=[]
                    self.stop_stream()
                time.sleep(0.1)                    
        except:
            log(sys.exc_info()[1])              
        finally:
            log("Stop running thread: " + str(self.prefix))
            self.stop_stream()
            if output_channel: output_channel.close()
            if start_channel: start_channel.close()
            self.running = False
    
    def run(self):
        if self.running:
            return
        self.running = True
        self.task = fork(self._run)[0]
        
    def stop(self):
        if self.running:
            self.running = False
            if (self.task is not None):
                log("Waiting correlation stream thread to stop..." + str(self.prefix))
                join([self.task,])
                log("Done" + str(self.prefix))

    def is_running(self):
        return (self.task is not None) and not (self.task.isDone())
    

if False: 
    cs = CorrelationStream(prefix="SLAAR-LBSTREAM2")
    cs.run()
    try:
        while (cs.running):
            time.sleep(0.10)
    finally:
        cs.stop()