import os
import sys
import logging
import timer
from typing import List, Tuple, Iterable
from ping import Ping


class TagLog:
    """
    Thread-safe abstraction of log file. Enables easy implementation of
    different log file type if desired.
    """

    def __init__(self, log_file: str) -> None:
        self.log_file = log_file
        self.lock_file = self.log_file + ".lock"
        self.got_lock = False
        self.acquire_lock()

    def __del__(self):
        self.release_lock()

    def acquire_lock(self):
        """ Acquire lock file and terminate if it already exists. """
        if os.path.isfile(self.lock_file):
            m = "Could not get lock {}".format(self.lock_file)
            logging.debug(m)
            sys.exit(1)
        else:
            with open(self.lock_file, 'w') as f:
                f.write("")
            self.got_lock = True
            logging.debug("Acquired lock_file={}".format(self.lock_file))

    def release_lock(self):
        """
        Release lock. Executed during object destruction, so no need to call
        explicitly.
        """
        if not self.got_lock:
            return

        if os.path.isfile(self.lock_file):
            os.remove(self.lock_file)
            logging.debug("Released lock_file={}".format(self.lock_file))
        else:
            logging.debug("Lock already released.")

    def exists(self):
        """True if log file exists and contains at least one valid ping."""
        try:
            self.last_ping()
        except (FileNotFoundError, AttributeError):
            return False
        return True

    def last_ping(self) -> Ping:
        """Returns last Ping if there is one. Exception otherwise."""
        with open(self.log_file, 'r') as f:
            ping = Ping.line_to_ping(f.readlines()[-1])
        return ping

    def last_ping_time(self) -> int:
        """Returns last ping time f there is one. Exception otherwise."""
        return self.last_ping().time

    def last_tags(self) -> List[str]:
        """Returs the tags of the last ping."""
        try:
            return self.last_ping().tags
        except:
            return []

    def all_pings(self) -> Iterable[Ping]:
        """Returns an iterator over all pings in the log."""
        with open(self.log_file, 'r') as f:
            for line in f.readlines():
                try:
                    yield Ping.line_to_ping(line)
                except AttributeError:
                    logging.error("Invalid line {}".format(line))

    def grep(self, start: int, end: int) -> List[Ping]:
        """Returns all pings between start and end as an iterator."""
        for ping in self.all_pings():
            if ping.time >= start and ping.time <= end:
                yield ping

    def validate(self, verbose: bool = True) -> bool:
        """
        Iterates over log and returns True if all lines are valid Pings.
        Returns False otherwise. Also prints some statistics.
        """
        unique_tags = set()
        total_tags, valid_pings, invalid_pings  = 0, 0, 0
        previous_time, initial_time, last_time = 0, 0, 0
        with open(self.log_file, 'r') as f:
            for line_number, line in enumerate(f.readlines()):
                try:
                    p = Ping.line_to_ping(line)
                    unique_tags |= set(p.tags)
                    valid_pings += 1
                    total_tags += len(p.tags)
                    if initial_time == 0:
                        initial_time = p.time
                    if p.time <= previous_time:
                        m = "Line {} not ascending. Please fix order."
                        logging.error(m.format(line_number))
                    else:
                        last_time = p.time
                        previous_time = p.time
                except AttributeError:
                    m = "Line {}: {} is not a valid ping."
                    logging.error(m.format(line_number, line.strip()))
                    invalid_pings += 1

        start_time = timer.time_to_str(initial_time)
        print("You have started tagging on {}.".format(start_time))
        print("Your TagTime log contains {} valid pings.".format(valid_pings))
        if invalid_pings > 0:
            print("It also contains {} invalid pings.".format(invalid_pings))
        m = "You have logged {} unique tags and {} tags in total."
        print(m.format(len(unique_tags), total_tags))
        last_time = timer.time_to_str(last_time)
        print("You have last tagged on {}.".format(last_time))

        if invalid_pings > 0:
            return False
        return True


    def get_tags(self) -> List[Tuple[int, str]]:
        """
        Returns a list of tuples where the first element is an integer and the
        second element is a tag-string sorted from highest to lowest number of
        occurences. For example, when called on a log with this content:

        1600805511 quz bar  [2020.09.22 16:11:51 TUE]
        1600806947 quz off  [2020.09.22 16:35:47 TUE]

        The function would return:

        [(2, quz), (1, bar), (1, off)]
        """
        if not self.exists():
            return []

        def add_tags(new_tags, tag_bag):
            for t in new_tags:
                try:
                    tag_bag[t] += 1
                except KeyError:
                    tag_bag[t] = 1

        tags = {}
        with open(self.log_file, 'r') as f:
            for line in f.readlines():
                try:
                    p = Ping.line_to_ping(line)
                except:
                    continue
                add_tags(p.tags, tags)
        tags = [(value, key) for key, value in tags.items()]
        return sorted(tags, reverse=True)

    def log_ping(self, ping: Ping, annotate_time: bool = False, line_len: int = 79):
        """
        Creates a line from time, tags, and comments, and writes it into the
        log.

        If linelen is provided log_ping replicates the behavior of the original
        Perl implementation and creates human-readable date/time annotation
        comment right aligned to linelen.
        """
        line = Ping.ping_to_line(ping, annotate_time, line_len)
        with open(self.log_file, 'a') as f:
            logging.debug("Logged {}".format(line))
            f.write(line + "\n")

    def log_line(self, line: str):
        """Append line to log file. No questions asked."""
        with open(self.log_file, 'a') as f:
            if line.endswith("\n"):
                f.write(line)
                line = line.strip()
            else:
                f.write(line + "\n")
            logging.debug("Logged {}".format(line))