import json
import logging
import logging.handlers
import os
from queue import Queue
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler

from pipeline import Pipeline

class Daemon:
    def __init__(self, config):
        self.queue_dir = config['daemon']['queue']
        self.error_dir = config['daemon']['error']
        self.logger = logging.getLogger('play-daemon')
        self.logger.setLevel('DEBUG')
        if 'mail_level' in config['daemon']:
            from_addr = config['daemon']['mail_from']
            to_addr = config['daemon']['mail_to']
            subject = config['daemon']['mail_subject']
            maillog = logging.handlers.SMTPHandler('localhost',
                                                   from_addr,
                                                   [to_addr],
                                                   subject)
            maillog.setLevel(config['daemon']['mail_level'])
            self.logger.addHandler(maillog)
        syslog = logging.StreamHandler()
        syslog.setLevel(config['daemon'].get('log_level', 'ERROR'))
        self.logger.addHandler(syslog)

        self.pipeline = Pipeline(config)
        self.queue = Queue()
        self.watcher = Observer()
        self.watcher.schedule(QueueUpdater(self.queue), self.queue_dir)
        self.watcher.start()
        for p in os.listdir(self.queue_dir):
            path = os.path.join(self.queue_dir, p)
            if os.path.isfile(path):
                self.queue.put(path)

    def do_processing(self):
        while True:
            try:
                next_job = self.queue.get()
                pres_id = os.path.basename(next_job)
                queue_item = None
                with open(next_job) as f:
                    queue_item = json.load(f)
                self.pipeline.process(pres_id, queue_item)
            except KeyboardInterrupt:
                return
            except Exception as e:
                msg = "Exception during processing of queue item %s: %s"
                self.logger.exception(msg, pres_id, queue_item, exc_info=e)
                # write the que info and error to disk for play-api to display the status
                with open(os.path.join(self.error_dir, pres_id), 'w') as f:
                    queue_item['error'] = e
                    json.dump(queue_item, f)


class QueueUpdater(FileSystemEventHandler):
    def __init__(self, queue):
        self.queue = queue
        
    def on_created(self, event):
        self.queue.put(event.src_path)