#!/usr/bin/env python3
import os
import sys
import time
from datetime import datetime
import subprocess as sp
from subprocess import call
import tempfile

LIST_MESSAGES_LIMIT = "30"

chan_dir = ".config/gab/channels" ## not used yet. todo: move all gab channel logs to this dir
current_user = os.environ.get('USER')
log = {}

help_text = """
GAB - A simple chat interface

syntax: gab [flag] [value]

flag                     value
--------------------     ---------------
-h, --help, help
-m, --msg, msg           Quoted text with the msg being added to chat
-l, --list, list         An integer representing the number of rows you'd like 
                           to view, default 5
-b, --block, block       A username to block/ignore
-u, --unblock, unblock   A username to unblock/unignore
-c, --channel, channel   Name of the channel you would like to join or create. 
                           An empty value lists the available channels. 
-n, --new, new           Check for new, unread messages.
-N, --new-verbose, new-verbose Check for new, unread messages, creating output
                         even when no new messages exist.

Channels names ending in ! are private. They can be joined by anyone that 
knows they exist, but will not be listed in the channel listings. To return
to the main/default channel, simply switch channels to 'gab':
    gab channel gab

Examples:
    gab msg "Good afternoon!"
    gab list 20
    gab block annoyingperson
    gab channel my-secret-channel!
    gab channel a-public-channel
    gab unblock somedude
"""

title = "\033[1mGAB v2.2\033[0m"

def get_chan():
    fp = "/home/{}/.gab_chan".format(current_user)

    if not os.path.isfile(fp):
        return ""

    with open(fp, 'r') as chanfile:
        channel = chanfile.read().split("\n")[0].strip()
        if channel:
            channel = "-" + channel
        return channel

def blocked_users():
    fp = "/home/{}/.gab_block".format(current_user)

    if not os.path.isfile(fp):
        return []

    with open(fp, 'r') as blockfile:
        return blockfile.read().split("\n")

def get_files(channel):
    return [[x, "/home/{}/.gab{}".format(x, channel)] for x in os.listdir("/home/") if x not in blocked_users() and os.access("/home/"+x, os.R_OK)]


def get_user_channels(user_dir):
    chans = {"gab"}
    for y in os.listdir(user_dir):
        if len(y) > 5 and y[:5] == ".gab-" and y[-1] != "!":
            chans.add(y[5:])
    return chans


def get_chan_list():
    chans = {"gab"}
    for x in os.listdir("/home/"):
        if not os.access("/home/" + x, os.R_OK):
            continue
        for y in os.listdir("/home/" + x):
            if len(y) > 5 and y[:5] == ".gab-" and y[-1] != "!":
                chans.add(y[5:])
    return chans

    
def list_channels():
    chans = get_chan_list()
    chan = get_chan()
    print(title)
    print("\n\033[1mAvailable channels\033[0m:")
    for x in chans:
      if chan[1:] == x:
        x = x + " *"
      elif chan == "" and x == "gab":
        x = x + " *"
      print(x)


def read_file(user, path, num_lines):
    global log
    if os.path.isfile(path) and os.access(path, os.R_OK):
        if "/home/" + current_user + "/" in path:
            os.utime(path, None) ## update file's timestamp on each read
        with open(path, "r") as f:
            for line in range(num_lines):
                msg = f.readline().split("|", 1)
                dt = msg[0].strip()
                if len(msg) == 2 and float(dt) < time.time():
                    msg = msg[1].strip()
                    if msg[:3] == "/me":
                        log[dt] = "\033[7m * * * \033[0m \033[3m{}\033[0m".format(msg.replace("/me", user))
                    else:
                        log[dt] = "\033[7m {} \033[0m {}\033[0m".format(user, msg)


def list_messages(count=LIST_MESSAGES_LIMIT):
    global log
    chan = get_chan()
    files = get_files(chan)

    try:
        count = int(count)
    except ValueError:
        print("Error parsing list number, using default: 5")
        count = 5

    for x in files:
        read_file(x[0], x[1], count)

    sorted_keys = list(log.keys())
    if len(sorted_keys) > 0: 
        sorted_keys.sort(reverse=True)
        last_time = float(sorted_keys[0])
        sorted_keys = sorted_keys[:min(len(sorted_keys), count)]
        sorted_keys.sort(reverse=False)
        print(title)
        print("Current channel: \033[1m{}\033[0m".format(chan[1:] if chan else "gab"))
        print("Last message: {}".format(diff_time_from_now(last_time)))
        print("\n- - -")
        for key in range(min(count, len(sorted_keys))):
            print(log[sorted_keys[key]])
            print("- - -")
    else:
        print(title)
        print("Current channel: \033[1m{}\033[0m".format(chan[1:] if chan else "gab"))
        print()
        print("There are no messages to display")


def diff_time_from_now(t, n=time.time()):
    diff = n - t
    diff = int(diff)
    out = ""

    # Days
    if diff // (3600 * 24) > 0:
        days = diff // (3600 * 24)
        out += "{}d ".format(days)
        diff = diff - (days * 3600 * 24)

    # Hours
    if diff // 3600 > 0:
        out += "{}h ".format(diff // 3600)
        diff = diff - (diff // 3600 * 3600)

    # Minutes
    if diff // 60 > 0:
        out += "{}m ".format(diff // 60)
        diff = diff - (diff // 60 * 60)

    # Seconds
    out += "{}s ago".format(diff)

    return out


def add_message(msg):
    timestamp = str(time.time())
    output = "{}|{}\n".format(timestamp, msg.strip())
    fp = "/home/{}/.gab{}".format(current_user, get_chan())
    try:
        with open(fp, 'r') as original: 
            data = original.read(12000)
        with open(fp, 'w') as modified: 
            modified.write(output)
            modified.write(data)
    except FileNotFoundError:
        with open(fp, 'a') as modified: 
            modified.write(output)
    except:
        print("Error adding text to chatlog")
        return
    
    print("Successfully added text to chatlog")

    try:
        os.chmod(fp, 0o644)
    except PermissionError:
        print("You do not have permission to modify the chatlog")
    except FileNotFoundError:
        print("The chatlog does not exist")


def block_user(user_to_block):
    fp = "/home/{}/.gab_block".format(current_user)
    block_fp = "/home/{}/".format(user_to_block)
    if not os.path.isdir(block_fp):
        print("User '{}' does not exist, no action taken".format(user_to_block))
        return

    with open(fp, 'a') as blockfile:
        blockfile.write(user_to_block)
        blockfile.write("\n")

    print("User '{}' has been blocked, you will not see their messages".format(user_to_block))
    return


def unblock_user(user_to_unblock):
    fp = "/home/{}/.gab_block".format(current_user)
    unblock_fp = "/home/{}/".format(user_to_unblock)

    if not os.path.isfile(fp):
        print("You do not have any users on your block list, no action taken")
        return

    if not os.path.isdir(unblock_fp):
        print("User '{}' does not exist, no action taken".format(user_to_unblock))
        return

    blocked_users_list = [x for x in blocked_users() if x != user_to_unblock]

    with open(fp, 'w') as blocked:
        blocked.write("\n".join(blocked_users_list))

    print("User '{}' has been removed from your block list".format(user_to_unblock))


def switch_channel(newchan):
    chan = newchan
    if newchan == "gab":
        newchan = ""

    fp = "/home/{}/.gab_chan".format(current_user)

    with open(fp, 'w') as chanfile:
        chanfile.write(newchan)

    print("You are now viewing the '{}' channel.".format(chan))
    list_messages()


def new_scan(silent=True):
    unread_chans = [] 
    chans = get_user_channels("/home/" + current_user)

    for c in chans:
        my_timestamp = chan_timestamp = 0.0
        if c == "gab":
            files = get_files("")
        else:
            files = get_files("-" + c)

        for f in files:
            if os.path.isfile(f[1]):
                try:
                    with open(f[1]) as fh:
                        timestamp = float(fh.readline().split("|")[0])
                        if timestamp > float(chan_timestamp):
                            chan_timestamp = timestamp
                        if f[0] == current_user:
                            atime= time.ctime(os.stat(f[1]).st_atime)
                            my_timestamp = time.mktime(datetime.strptime(atime, "%a %b %d %H:%M:%S %Y").timetuple())
                except:
                    continue
        if my_timestamp - chan_timestamp < 0:
            unread_chans.append(c)
 
    if len(unread_chans):
        print("New gab messages in: " + ", ".join(unread_chans))
    else:
        if silent == False:
            print("gab: no unread messages.")
        exit(1)


def parse_command():
    args = sys.argv[1:]
    if not len(args):
        list_messages()
    elif args[0] in ["-h", "--help", "help"]:
        print(help_text)
    elif args[0] in ["list", "--list", "-l"]:
        if len(args) == 2:
            list_messages(args[1])
        else:
            print("Invalid command input to 'list'")
    elif args[0] in ["new", "--new", "-n"]:
        new_scan() 
    elif args[0] in ["new-verbose", "--new-verbose", "-N"]:
        new_scan(silent=False)
    elif args[0] in ["-m", "--msg", "msg"]:
        if len(args) < 2:
            # code from https://stackoverflow.com/a/6309753
            EDITOR = os.environ.get('EDITOR') if os.environ.get('EDITOR') else 'vi'
            with tempfile.NamedTemporaryFile(suffix=".tmp") as tf:
                tf.flush()
                call([EDITOR, tf.name])
                tf.seek(0)
                edited_message = tf.read()
                lines = edited_message.decode("utf-8").split("\n")
                for line in lines:
                    if len(line.split()):
                        add_message(line)

        elif len(args) > 2:
            print("Expected a message, but received too many arguments. Did you put your message in quotes?")
        else:
            add_message(args[1])
    elif args[0] in ["-b", "--block", "block"]:
        if len(args) < 2:
            print("Expected a user to block, but one was not received")
        elif len(args) > 2:
            print("Expected a user to block, but received too many arguments")
        else:
            block_user(args[1])
    elif args[0] in ["-u", "--unblock", "unblock"]:
        if len(args) < 2:
            print("Expected a user to unblock, but one was not received")
        elif len(args) > 2:
            print("Expected a user to unblock, but received too many arguments")
        else:
            unblock_user(args[1])
    elif args[0] in ["-c", "--channel", "channel"]:
        if len(args) < 2:
            #  print("Returning to default channel.")
            #  switch_channel("gab")
            list_channels()
        elif len(args) > 2:
            print("Expected a channel to join, but received too many arguments")
        else:
            switch_channel(args[1])
    else:
        print("Unknown command: {}".format(args[0]))


if __name__ == '__main__':
    parse_command()