__filename__="threads.py"
__author__="Bob Mottram"
__license__="AGPL3+"
__version__="1.1.0"
__maintainer__="Bob Mottram"
__email__="bob@freedombone.net"
__status__="Production"

import threading
import os
import sys
import trace
import time
import datetime

class threadWithTrace(threading.Thread):
    def __init__(self, *args, **keywords):
        self.startTime=datetime.datetime.utcnow()
        self.isStarted=False
        tries=0
        while tries<3:
            try:
                self._args,self._keywords=args,keywords
                threading.Thread.__init__(self,*self._args,**self._keywords) 
                self.killed=False
                break
            except Exception as e:
                print('ERROR: threads.py/__init__ failed - '+str(e))
                time.sleep(1)
                tries+=1
  
    def start(self): 
        tries=0
        while tries<3:
            try:
                self.__run_backup=self.run 
                self.run=self.__run       
                threading.Thread.start(self)
                break
            except Exception as e:
                print('ERROR: threads.py/start failed - '+str(e))
                time.sleep(1)
                tries+=1
        # note that this is set True even if all tries failed
        self.isStarted=True

    def __run(self):
        sys.settrace(self.globaltrace)
        self.__run_backup()
        self.run=self.__run_backup

    def globaltrace(self, frame, event, arg): 
        if event == 'call': 
            return self.localtrace
        else:
            return None

    def localtrace(self, frame, event, arg): 
        if self.killed: 
            if event == 'line': 
                raise SystemExit() 
        return self.localtrace 
  
    def kill(self): 
        self.killed=True

    def clone(self,fn):
        return threadWithTrace(target=fn, \
                               args=self._args, \
                               daemon=True)        

def removeDormantThreads(baseDir: str,threadsList: [],debug: bool) -> None:
    """Removes threads whose execution has completed
    """
    if len(threadsList)==0:
        return

    dormantThreads=[]
    currTime=datetime.datetime.utcnow()
    changed=False

    # which threads are dormant?
    noOfActiveThreads=0
    for th in threadsList:
        removeThread=False        

        if th.isStarted:
            if not th.is_alive():
                if (currTime-th.startTime).total_seconds()>10:
                    if debug:
                        print('DEBUG: thread is not alive ten seconds after start')
                    removeThread=True
            # timeout for started threads
            if (currTime-th.startTime).total_seconds()>600:
                if debug:
                    print('DEBUG: started thread timed out')
                removeThread=True
        else:
            # timeout for threads which havn't been started
            if (currTime-th.startTime).total_seconds()>600:
                if debug:
                    print('DEBUG: unstarted thread timed out')
                removeThread=True

        if removeThread:
            dormantThreads.append(th)
        else:
            noOfActiveThreads+=1
    if debug:
        print('DEBUG: '+str(noOfActiveThreads) + ' active threads out of '+str(len(threadsList)))

    # remove the dormant threads
    dormantCtr=0
    for th in dormantThreads:
        if debug:
            print('DEBUG: Removing dormant thread '+str(dormantCtr))
        dormantCtr+=1        
        threadsList.remove(th)
        th.kill()
        changed=True

    # start scheduled threads
    if len(threadsList)<10:
        ctr=0
        for th in threadsList:
            if not th.isStarted:
                print('Starting new send thread '+str(ctr))
                th.start()
                changed=True
                break
            ctr+=1

    if not changed:
        return

    if debug:
        sendLogFilename=baseDir+'/send.csv'
        try:
            with open(sendLogFilename, "a+") as logFile:
                logFile.write(currTime.strftime("%Y-%m-%dT%H:%M:%SZ")+','+str(noOfActiveThreads)+','+str(len(threadsList))+'\n')
        except:
            pass