#!/usr/bin/python3
# vim: tabstop=4 softtabstop=4 shiftwidth=4 expandtab


import sys
import os
import re
import pwd
import grp
import subprocess
import json
import jinja2


SETTINGS_PATH = "settings.json"
SYSTEMD_TEMPLATE = "systemd/webtemplate.service.jinja2"
FLASK_TEMPLATE = "flask/main.py.jinja2"
REPOSITORY_WEBROOT = "webroot"


def read_settings():
    """Read the SETTINGS_PATH File and return a Dictionary with its Content"""

    with open(SETTINGS_PATH, "r") as settings:
        settings = settings.read()

    settings = json.loads(settings)

    # check for valid project name
    if not re.match(r"\A[a-z]+\Z", settings["project_name"]):
        print("Please provide a project_name in settings.json containing only characters from a to z in lower case")
        sys.exit(1)

    # check for valid project description
    if not re.match(r"\A[a-z|A-Z|0-9| ]+\Z", settings["project_description"]):
        print("Please provide a project description in settings.json containing only characters from a to z and numbers")
        sys.exit(1)

    # check for valid webroot path
    if not re.match(r"\A(/[a-z|A-Z|0-9|_|-|\.]*)+\Z", settings["webroot"]):
        print("Please select an absolute and valid path as webroot in settings.json")
        sys.exit(1)

    # check for valid framework selection
    if not settings["framework"] in [None, "flask", "actix"]:
        print("Unknown framework in settings.json")
        sys.exit(1)

    # check for valid framework port
    if not int(settings["framework_port"]) >= 1:
        print("Please select a valid framework_port in settings.json")
        sys.exit(1)

    # check for valid framework bind address
    if not re.match(r"\A([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])(\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])){3}\Z", settings["framework_bind"]):
        print("Please provide a valid IP address as framework_bind in settings.json")
        sys.exit(1)

    # check for valid user
    users = []
    for user in pwd.getpwall():
        users.append(user[0])  # append just the name
    if not settings["user"] in users:
        print("User '{}' does not exist on this system. Please select a valid user in settings.json".format(settings["user"]))
        sys.exit(1)

    # check for valid group
    groups = []
    for group in grp.getgrall():
        groups.append(group[0])  # append just the name
    if not settings["group"] in groups:
        print("Group '{}' does not exist on this system. Please select a valid group in settings.json".format(settings["group"]))
        sys.exit(1)

    return settings


def build_systemd_file(settings):
    """Generate Systemd Unit File with Settings from SETTINGS_PATH"""

    with open(SYSTEMD_TEMPLATE, "r") as template:
        template = template.read()

    template = jinja2.Template(template)
    systemd_file = template.render(settings)

    subprocess.call("mkdir -p systemd/build", shell=True)
    file_path = "systemd/build/{}.service".format(settings["project_name"])

    with open(file_path, "w") as _file:
        _file.write(systemd_file)


def build_flask(settings):
    """Generate Python Flask File with Settings from SETTINGS_PATH"""

    with open(FLASK_TEMPLATE, "r") as template:
        template = template.read()
    
    template = jinja2.Template(template)
    flask_file = template.render(settings)

    subprocess.call("mkdir -p flask/build", shell=True)

    file_path = "flask/build/{}".format(settings["project_name"])
    
    with open(file_path, "w") as _file:
        _file.write(flask_file)


def install_webroot(settings):
    """Install every File from the Repositories Webroot to the Systems Webroot"""

    for directory, subdirs, files in os.walk(REPOSITORY_WEBROOT, topdown=False):
        for _file in files:
            path_to_file = os.path.join(directory, _file)
            relative_path = os.path.relpath(path_to_file, REPOSITORY_WEBROOT)
            target_path = os.path.join(settings["webroot"], relative_path)
            subprocess.run("install -Dm 644 {} {}".format(path_to_file, target_path), shell=True)


def uninstall_webroot(settings):
    """Uninstalls every File from the Systems Webroot"""

    path_to_delete = os.path.join(settings["webroot"], "*")
    subprocess.run("rm -rf {}".format(path_to_delete), shell=True)


def install_flask(settings):
    """Install the Executable for the Dynamic Web Server"""

    subprocess.call("sudo mkdir -p /opt/{}".format(settings["project_name"]), shell=True)
    subprocess.call("sudo install -Dm 744 flask/build/{0} /opt/{0}/{0}".format(settings["project_name"]), shell=True)
    order = "sudo find /opt/{0} -exec chown -R {1}:{2}".format(
        settings["project_name"],
        settings["user"],
        settings["group"]
    )
    order += " {} \;"
    subprocess.call(order, shell=True)


def uninstall_flask(settings):
    """Uninstall the Executable for the Dynamic Web Server"""

    subprocess.call("sudo rm -rf /opt/{}".format(settings["project_name"]), shell=True)


def install_systemd_file(settings):
    """Install the Systemd Unit for launching the dynamic Web Server"""

    if settings["framework"] != None:
        subprocess.call("sudo install -Dm 644 systemd/build/{0}.service /etc/systemd/system/{0}.service".format(settings["project_name"]), shell=True)
        subprocess.call("sudo systemctl daemon-reload", shell=True)


def uninstall_systemd_file(settings):
    """Uninstall the Systemd Unit for launching the dynamic Web Server"""

    if settings["framework"] != None:
        subprocess.call("sudo rm /etc/systemd/system/{0}.service".format(settings["project_name"]), shell=True)


def main():
    """The main Function"""

    settings = read_settings()  # get settings from SETTINGS_PATH

    # just one argument is allowed:
    if len(sys.argv) != 2:
        print("Provide exactly one parameter")
        sys.exit(1)

    # execute given command
    command = sys.argv[1]
    if command == "build_systemd_file":
        build_systemd_file(settings)
    elif command == "build_framework":
        if settings["framework"] == "flask":
            build_flask(settings)
        elif settings["framework"] == "actix-web":
            print("actix-web is not yet implemented ...")
            sys.exit(1)
        elif settings["framework"] == None:
            pass
        else:
            print("Unknown web framework selected")
            sys.exit(1)
    elif command == "install_webroot":
        install_webroot(settings)
    elif command == "uninstall_webroot":
        uninstall_webroot(settings)
    elif command == "install_framework":
        if settings["framework"] == "flask":
            install_flask(settings)
        elif settings["framework"] == "actix-web":
            print("actix-web is not yet implemented ...")
            sys.exit(1)
        elif settings["framework"] == None:
            pass
        else:
            print("Unknown web framework selected")
            sys.exit(1)
    elif command == "uninstall_framework":
        if settings["framework"] == "flask":
            uninstall_flask(settings)
        elif settings["framework"] == "actix-web":
            print("actix-web is not yet implemented ...")
            sys.exit(1)
        elif settings["framework"] == None:
            pass
        else:
            print("Unknown web framework selected")
            sys.exit(1)
    elif command == "install_systemd_file":
        install_systemd_file(settings)
    elif command == "uninstall_systemd_file":
        uninstall_systemd_file(settings)
    else:
        print("Unknown command")
        sys.exit(1)


if __name__ == "__main__":
    main()