#!/usr/bin/env python3

import sys
import logging
from logger import logger
import log_statistics
import reader
import parser
import argparse
from enum import StrEnum

class Commands(StrEnum):
    PARSE = "parse"
    IPV4 = "ipv4",
    USER = "user",
    TYPE = "type",
    RANDOM = "random",
    DURATION = "duration",
    FREQ = "freq"

def main(args):
    stdout_handler = logging.StreamHandler(sys.stdout)
    stdout_handler.addFilter(lambda log: log.levelno <= logging.WARNING)
    stdout_handler.setLevel(logging.DEBUG)
    stdout_handler.setFormatter(logging.Formatter('%(levelname)s - %(name)s - %(message)s'))

    stderr_handler = logging.StreamHandler(sys.stderr)
    stderr_handler.setLevel(logging.ERROR)
    stderr_handler.setFormatter(logging.Formatter('%(levelname)s - %(name)s - %(message)s'))

    logger.addHandler(stdout_handler)
    logger.addHandler(stderr_handler)
    
    if args.log_level == "NONE":
        logger.disabled = True
    else:
        logger.setLevel(args.log_level)

    try:
        logs = reader.read_logs(args.filename)
    except:
        logger.critical(f"Could not open file {args.filename}")
        exit(1)

    if args.subcommand == Commands.PARSE:
        for line in logs:
            print(f"{line.timestamp.strftime('%d/%m:%H:%M:%S')};{line.hostname};{line.pid};{line.message}")
    #1.1.2
    if args.subcommand == Commands.IPV4:
        for line in logs:
            print(*parser.get_ipv4s_from_log(line), sep=", ")
    #1.1.3
    elif args.subcommand == Commands.USER:
        for line in logs:
            print(parser.get_user_from_log(line) or "")
    #1.1.4
    elif args.subcommand == Commands.TYPE:
        for line in logs:
            print(parser.get_message_type(line.message))
    #1.3.1
    elif args.subcommand == Commands.RANDOM:
        random_logs = log_statistics.random_user_logs(list(logs), args.n)
        for line in random_logs:
            print(line.original_line)
    #1.3.2
    elif args.subcommand == Commands.DURATION:
        log_list = list(logs)
        if args.group_by_users:
            durations_by_user = log_statistics.get_average_session_duration_by_user(log_list)
            for (username, (avg_time, stdev)) in sorted(durations_by_user.items(), key=lambda x: x[1], reverse=True):
                print(f"{username}: average={avg_time:.4f}s, stdev={stdev:.4f}s")
        else:
            (avg_time, stdev) = log_statistics.get_average_session_duration(log_list)
            print(f"average={avg_time:.4f}s, stdev={stdev:.4f}s")
    #1.3.3
    elif args.subcommand == Commands.FREQ:
        log_list = list(logs)
        (most, least) = log_statistics.get_most_and_least_frequent_user(log_list)
        if most and least:
            print(f"most frequent user - {most[0]} - {most[1]} login(s)")
            print(f"least frequent user - {least[0]} - {least[1]} login(s)")
        else:
            print("could not determine most and least frequent user")


def positive_int(arg):
    try:
        val = int(arg)
    except ValueError:
        raise argparse.ArgumentTypeError("Must be an integer")
    if val < 0:
        raise argparse.ArgumentTypeError("Must be greater than or equal to 0")
    return val



def parse_args():
    parser = argparse.ArgumentParser(description="Script for analyzing sshd logs")

    #1.4.1
    parser.add_argument("filename", help="Path of the file to be read")
    #1.4.2
    parser.add_argument("--log-level", choices=["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL", "NONE"], default="INFO", help="Level of logging, default is info")


    #1.4.3
    subparsers = parser.add_subparsers(dest="subcommand", title="subcommands", required=True)
    
    subparsers.add_parser(Commands.PARSE, help="Parse logs into semicolon separated structure")

    subparsers.add_parser(Commands.IPV4, help="Get all IPv4 addresses from log messsages")

    subparsers.add_parser(Commands.USER, help="Extract user from log messages")
    
    subparsers.add_parser(Commands.TYPE, help="Get type of log message")

    random_parser = subparsers.add_parser(Commands.RANDOM, help="Get specified amount (default is 3) of random logs from random user")
    random_parser.add_argument("-n", type=positive_int, default=3, help="Amount of random logs to be returned")

    duration_parser = subparsers.add_parser(Commands.DURATION, help="Get average session duration and standard deviation")
    duration_parser.add_argument("--group-by-users", action="store_true", help="Whether session durations should be calculated for each user separately")

    subparsers.add_parser(Commands.FREQ, help="Get most and least frequently logging users")

    return parser.parse_args()

if __name__ == "__main__":
    args = parse_args()
    main(args)