#
#   load_parsers.py
#   
#   Search for and load files which parse logs for particular services
#

import imp
import importlib
import os
import glob
from pathlib import Path
from sys import path
from typing import NamedTuple

parser_dir = "/usr/share/logparse/"
main_module = "__init__"
default_parsers = ["cron", "httpd", "postfix", "smbd", "sshd", "sudo", "temperature", "zfs"]

import logging
logger = logging.getLogger(__name__)

class Parser():
    def __init__(self, name, path=None, info=None):
        self.name = str(name)
        self.path = Path(path) if path else None
        self.info = dict(info) if info else None

def findall():
    logger.debug("Searching for parsers in {0}".format(parser_dir))
    path.append(os.path.abspath(parser_dir))
    parsers = []
    parser_candidates = os.listdir(parser_dir)
    for parser_name in parser_candidates:
        location = os.path.join(parser_dir, parser_name)
        if not os.path.isdir(location) or not main_module + '.py' in os.listdir(location):
            logger.warning("Rejecting parser {0} due to invalid structure".format(location))
            continue
        info = imp.find_module(main_module, [location])
        parser_obj = Parser(parser_name, location, info)
        parsers.append(parser_obj)
        logger.debug("Added parser {0}".format(parser_obj.name))
    return parsers

def search(name):
    logger.debug("Searching for parser {0}".format(name))
    if name in default_parsers:
        logger.debug("Found parser {0} in default modules".format(name))
        return Parser('.'.join(__name__.split('.')[:-1] + [name]))
    else:
        return None

def load(parser):
    logger.debug("Loading parser {0} from {1}".format(parser.name, parser.path if parser.path != None else "defaults"))
    return importlib.import_module(parser.name)