#!/usr/bin/env python
# coding: utf-8

# # Continuous capture of output from wurlitzer to a logger
# 
# Illustration for [minrk/wurlitzer#76](https://github.com/minrk/wurlitzer/issues/76).
#                   
# First, set up a logger. This one logs to stdout and includes the timestamp,
# so we can see how often log lines are produced.

# In[37]:


import logging

logger = logging.getLogger("test-log-pipe")
logger.handlers[:] = []
logger.setLevel(logging.INFO)
h = logging.StreamHandler(sys.stdout)
h.setLevel(logging.INFO)
h.setFormatter(logging.Formatter("[{name} {asctime}] {msg}", style="{"))
logger.addHandler(h)
logger.info("test message")


# Next, we need to create a Writable (anything with a `write` method),
# which will take lines and put them onto the logger

# In[38]:


import io

class LogPipe(io.BufferedWriter):
    """Writeable that writes lines to a Logger object as they are written"""
    def __init__(self, logger):
        self.logger = logger
        self.buf = ""
    
    def write(self, chunk):
        """Given chunk, split into lines

        Log each line as a discrete message

        If it ends with a partial line, save it until the next one
        """
        if self.buf:
            chunk = self.buf + chunk
        lines = chunk.splitlines(True)
        if not lines[-1].endswith("\n"):
            self.buf = lines[-1]
            lines = lines[:-1]
        else:
            self.buf = ""
            
        for line in lines:
            self.logger.info(line.rstrip())

pipe = LogPipe(logger)


# Test it out: pipe anything written to low-level stderr to our logger (which writes to stdout)

# In[39]:


import sys
import time

import wurlitzer

logger.info("start")
with wurlitzer.pipes(stdout=None, stderr=pipe):
    for i in range(15):
        sys.__stderr__.write(f"step {i}\n")
        time.sleep(0.1)
logger.info("end")