#!/usr/bin/env python3

# imports

from pathlib import Path
from hashlib import sha256
import shlex
import subprocess
import sys

import requests

# config

MONITOR_DESC = """{{ description }}"""
MONITOR_COMMAND = """{{ command_str }}"""
USE_SHELL = {{ use_shell | ternary('True', 'False') }}

DATA_PATH = Path("""{{ data_path }}""")

TG_ENDPOINT = "https://api.telegram.org"
TG_KEY = """{{ bot_key }}"""
TG_RECIPIENT = """{{ recipient_id }}"""

# helpers

def print_error(*args, **kwargs):
    print(*args, file=sys.stderr, **kwargs)

def tg_msg(msg: str) -> None:
    print(f"Sending message using telegram:\n{msg}")
    ret = requests.post(f"{TG_ENDPOINT}/bot{TG_KEY}/sendMessage", data={
        "chat_id": TG_RECIPIENT,
        "disable_web_page_preview": 1,
        "parse_mode": "Markdown",
        "text": msg,
    })
    if 400 <= ret.status_code:
        raise Exception(f"Sending telegram message failed: {ret.status_code} {ret.text}")

def run_cmd(cmd: list, **kwargs) -> str:
    return subprocess.run(cmd, capture_output=True, check=True, text=True, **kwargs).stdout

def hash_data(data: str) -> bool:
    return sha256(data.encode("utf-8")).hexdigest()

def check_cmd(cmd_str: str, use_shell: bool, data_file: Path) -> str:
    cmd = shlex.split(cmd_str) if not use_shell else cmd_str
    old_hash = data_file.read_text() if data_file.exists() else None
    new_data = run_cmd(cmd, shell=use_shell)
    new_hash = hash_data(new_data)
    if old_hash == new_hash:
        return None
    data_file.write_text(new_hash)
    return new_data

if __name__ == "__main__":
    try:
        data = check_cmd(MONITOR_COMMAND, USE_SHELL, DATA_PATH)
        if data:
            tg_msg(f"{MONITOR_DESC} changed to:\n```\n{data}\n```")
    except Exception as e:
        tg_msg(f"Got exception while running command of {MONITOR_DESC}: {str(e)}")
        raise e