#!/usr/bin/python3
## A simple tool to configure services and create sql users/databases

import os
import subprocess
import secrets
import argparse


# only allow aA-zZ, 0-9 and below "special" characters in passwords
ALLOWED_CHARS = [ord('!'), ord('@'), ord('#'), ord('%'), ord('&')]\
                + list(range(48,58))\
                + list(range(64,90))\
                + list(range(97,123))

# convert ints back to characters
ALLOWED_CHARS = [chr(c) for c in ALLOWED_CHARS]


def gen_pass(l):
    """gen_pass returns a password of length l from ALLOWED_CHARS"""

    password = ""
    for i in range(int(l)):
        password += secrets.choice(ALLOWED_CHARS)
    
    return password

def get_var(key):
    """get_var() gets user input to confirm/replace empty keys"""

    while True:
        user_input = input(
                f"{key} is empty, enter value (leave blank for password):\n")

        if user_input == "":
            prompt = "provided value is empty, choose an option below\n"\
                + "\t1) generate password\n"\
                + "\t2) leave blank\n"\
                + "\t3) back\n"
            choice = input(prompt) 
            while choice not in ["1","2","3"]:
                print(f"error: {choice} unrecognized, please enter 1,2 or 3")
                choice = input(prompt)

            if choice == "1":
                return gen_pass(32)
            if choice == "2":
                return user_input
            if choice == "3":
                continue
        else:
            # run until user confirms input
            confirm = input(f"set {key} to {user_input} (y/N)?")
            if confirm in ["y", "Y"]:
                return user_input

def parse_env(env_file):
    """parse_env returns a dictionary of env vars parsed from the base file

    :service: is a string of the service name to parse, must match folder name
    """

    if os.path.isfile(env_file):
        print(f"{env_file} not found... skipping")
        return

    f = open(env_file)
    c = dict()
    for line in f:
        # skip comments
        if line[0] == "#":
            continue
        if line.isspace():
            continue

        kv = line.strip('\n').split("=")

        key = kv[0]
        val = kv[1].strip('"')

        if val == "":
            val = get_var(key)

        c[key] = val

    return c

def gen_env(kv):
    """gen_env takes in a dictionary and returns the formatted env file text as a string

    :kv: is a dictionary of strings mapping env var to value
        ex) "HOME": "/home/user/"
    """
    env = ""
    for key, value in kv.items():
        env += f"{key}=\"{value}\"\n"

    return env

def gen_init(service, force=False):
    """gen_init takes in a service name and creates a service file"""

    service_file = f"init/{service}.service"
    # prevent overwrite
    if os.path.isfile(service_file) and not force:
        print(f"{service_file} already exists... skipping")
        return

    PWD = os.getenv("PWD")
    contents = f"""[Unit]
Description=Starts {service}
After=docker.service

[Service]
Type=oneshot
RemainAfterExit=true
WorkingDirectory={PWD}/{service}
ExecStart=/usr/bin/docker compose up -d
ExecStop=/usr/bin/docker compose down

[Install]
WantedBy=multi-user.target"""

    f = open(service_file, 'w')
    f.write(contents)
    f.close()
     
def enable_service(service, force=False):

    gen_init(service,force)
    subprocess.run(["sudo", "install", "-m", "644", f"init/{service}.service", "/etc/systemd/system/"])
    subprocess.run(["sudo", "systemctl", "enable", f"{service}"])
    subprocess.run(["sudo", "systemctl", "start", f"{service}"])


def config_service(service, force=False):
    """config_service processes service env vars to generate private .env file

    :service: is a string of the name of the folder to write the .env to
        also requires file service/env to source base config from
    :force: is an optional parameter to overwrite existing file
        default is False
    """

    enable_service(service, force)

    priv_file = f"{service}/priv/env"

    # prevent overwrite
    if os.path.isfile(priv_file) and not force:
        print(f"{priv_file} already exists... skipping")
        return parse_env(priv_file)


    c = parse_env(f"{service}/env")

    subprocess.run(["mkdir", "-p", f"{service}/priv"])
    f = open(priv_file, 'w')
    f.write(gen_env(c))
    f.close()

    return c

def main():
    parser = argparse.ArgumentParser(
            description="takes in a service to configure a private .env file and generate sql users/databases")

    parser.add_argument('service', nargs="+", help="service to configure env for")
    parser.add_argument('-f', '--force', action="store_true", help="overwrite existing files")

    args = parser.parse_args()

    sql = ""
    for service in args.service:
        print(f"\nsetting up {service}...")
        c = config_service(service, args.force)

    print("success")

main()