#!/usr/bin/env python3

import os
import sys
import subprocess
import configparser
import socket
import datetime
import shutil
from pathlib import Path
import stat
import pwd
import grp


CONFIG_SYNC_VERSION = "1.0.0"
CONFIG_SYNC_FILE = "/etc/cfgs.conf"


# -----------------------------------------
# color defintions
# -----------------------------------------

class bcolors:
    HEADER = '\033[95m'
    OKBLUE = '\033[94m'
    OKGREEN = '\033[92m'
    WARNING = '\033[93m'
    FAIL = '\033[91m'
    ENDC = '\033[0m'
    BOLD = '\033[1m'
    UNDERLINE = '\033[4m'


# -----------------------------------------
# UI helper functions
# -----------------------------------------

def color_message(color, message, colorend=bcolors.ENDC, bold=False):
    if bold:
        return bcolors.BOLD + color_message(color, message, colorend, False)

    return color + message + colorend

def print_color(color, message, colorend=bcolors.ENDC, bold=False):
    print(color_message(color, message, colorend))

def check_dependencies():
    status = True
    try:
        subprocess.call(["git", "version"], stdout=subprocess.DEVNULL)
    except OSError:
        status = False
        print_color(bcolors.FAIL, "git cannot be found on your system!")
        print("Install git: pacman -S git")

    return status

def confirm(message, color=bcolors.WARNING):
    status = input(color_message(color, message + " [y/N]: "))
    return status and (status == "y" or status == "Y")

def print_splash():
    print_color(bcolors.HEADER, "---=== cfgs ===---")
    print("Version: " + CONFIG_SYNC_VERSION)
    print()
    print_color(bcolors.HEADER, "---=== USAGE ===---")
    print("cfgs init")
    print("cfgs add <file path>")
    print("cfgs remove <file path>")
    print("cfgs store")
    print("cfgs restore")
    sys.exit(1)


def init_dialog():
    config = get_config()
    print_color(bcolors.HEADER, "---=== Welcome to cfgs! ===---")
    print()

    if config['DEFAULT']['INITIALIZED']:
        if not confirm("WARNING: cfgs has already been initialized! Do you really want to change the configuration?"):
            print("Skipping new initialization!")
            sys.exit(0)

    local_path = input(color_message(bcolors.OKBLUE, "Enter the local storage directory for configuration files [" + config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + "]: "))
    if not local_path:
        local_path = config['DEFAULT']['LOCAL_STORAGE_DIRECTORY']
    config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] = local_path

    remote_repo = input(color_message(bcolors.OKBLUE, "Enter the remote repository url [" + config['GIT']['REMOTE_REPOSITORY'] + "]: "))
    if not remote_repo:
        remote_repo = config['GIT']['REMOTE_REPOSITORY']
    config['GIT']['REMOTE_REPOSITORY'] = remote_repo

    git_ssh_key = input(color_message(bcolors.OKBLUE, "Enter the path to the ssh key to use [" + config['GIT']['SSHKEY'] + "]: "))
    if not git_ssh_key:
        git_ssh_key = config['GIT']['SSHKEY']
    config['GIT']['SSHKEY'] = git_ssh_key

    git_user = input(color_message(bcolors.OKBLUE, "Enter the git user name (displayname) [" + config['GIT']['USER'] + "]: "))
    if not git_user:
        git_user = config['GIT']['USER']
    config['GIT']['USER'] = git_user

    git_email = input(color_message(bcolors.OKBLUE, "Enter the git user email address [" + config['GIT']['EMAIL'] + "]: "))
    if not git_email:
        git_email = config['GIT']['EMAIL']
    config['GIT']['EMAIL'] = git_email

    config['DEFAULT']['INITIALIZED'] = "True"

    update_config(config)


# -----------------------------------------
# local config helper functions
# -----------------------------------------

def validate_or_create_config(config):
    if not os.path.exists(CONFIG_SYNC_FILE):
        print_color(bcolors.OKBLUE, "Creating default configuration file: " + CONFIG_SYNC_FILE)
        config['DEFAULT'] = {}
        config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] = "/opt/cfgs/storage"
        config['DEFAULT']['INITIALIZED'] = ""
        config['GIT'] = {}
        config['GIT']['REMOTE_REPOSITORY'] = ""
        config['GIT']['USER'] = "cfgs"
        config['GIT']['EMAIL'] = "cfgs@" + socket.gethostname()
        config['GIT']['SSHKEY'] = str(Path.home()) + "/.ssh/id_rsa"

        update_config(config)
    else:
        config.read(CONFIG_SYNC_FILE)

    return config


def get_config():
    config = configparser.ConfigParser()
    config = validate_or_create_config(config)

    return config


def update_config(config):
    try:
        config.write(open(CONFIG_SYNC_FILE, 'w'))
    except PermissionError as e:
        print_color(bcolors.FAIL, "Unable to write config file! Error: " + e.strerror)
        sys.exit(1)
    except Exception as e:
        print_color(bcolors.FAIL, "Unable to write config file! Error: " + str(e))
        sys.exit(1)


def create_initialization_file(path):
    try:
        with open(path + "/cfgs.info", mode='w') as file:
            file.write('cfgs repo initialized: %s. host: %s\n' % ( datetime.datetime.now(), socket.gethostname() ))
    except PermissionError as e:
        print_color(bcolors.FAIL, "Unable to write initialization file! Error: " + e.strerror)
        sys.exit(1)
    except Exception as e:
        print_color(bcolors.FAIL, "Unable to write initialization file! Error: " + str(e))
        sys.exit(1)

    try:
        open(path + "/cfgs.db", mode='a').close()
    except PermissionError as e:
        print_color(bcolors.FAIL, "Unable to write database file! Error: " + e.strerror)
        sys.exit(1)
    except Exception as e:
        print_color(bcolors.FAIL, "Unable to write database file! Error: " + str(e))
        sys.exit(1)


# -----------------------------------------
# local database helper functions
# -----------------------------------------

def add_file_to_db(file_path):
    config = get_config()
    try:
        insert = True
        with open(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + "/cfgs.db", "r+") as search:
            for line in search:
                line = line.rstrip()  # remove '\n' at end of line
                if file_path == line:
                    insert = False
        if insert:
            with open(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + "/cfgs.db", mode='a') as file:
                file.write('%s\n' % (file_path))
    except PermissionError as e:
        print_color(bcolors.FAIL, "Unable to write db file! Error: " + e.strerror)
        sys.exit(1)
    except Exception as e:
        print_color(bcolors.FAIL, "Unable to write db file! Error: " + str(e))
        sys.exit(1)


def delete_file_from_db(file_path):
    config = get_config()
    try:
        with open(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + "/cfgs.db", "r+") as search:
            lines = search.readlines()
            search.seek(0)
            for line in lines:
                if line.rstrip() != file_path:
                    search.write(line.rstrip() + "\n")
            search.truncate()
    except PermissionError as e:
        print_color(bcolors.FAIL, "Unable to write db file! Error: " + e.strerror)
        sys.exit(1)
    except Exception as e:
        print_color(bcolors.FAIL, "Unable to write db file! Error: " + str(e))
        sys.exit(1)


# -----------------------------------------
# git helper functions
# -----------------------------------------

def git_setup_ssh_environment():
    config = get_config()

    os.environ['GIT_SSH_COMMAND'] = "ssh -i " + config['GIT']['SSHKEY']


def git_is_repo(path):
    return subprocess.call(["git", "branch"], stderr=subprocess.DEVNULL, stdout=subprocess.DEVNULL, cwd=path) == 0


def git_set_author(path, user, email):
    status = subprocess.call(["git", "config", "user.name", user], stderr=subprocess.STDOUT, stdout=subprocess.DEVNULL, cwd=path) == 0
    status |= subprocess.call(["git", "config", "user.email", email], stderr=subprocess.STDOUT, stdout=subprocess.DEVNULL, cwd=path) == 0

    return status


def git_set_upstream(path, remote_url):
    # make sure that remote origin does not exist
    status = subprocess.call(["git", "remote", "rm", "origin"], stderr=subprocess.DEVNULL, stdout=subprocess.DEVNULL, cwd=path) == 0
    # now add new origin
    status |= subprocess.call(["git", "remote", "add", "origin", remote_url], cwd=path) == 0

    return status


def git_init_repo(path):
    status = subprocess.call(["git", "init"], cwd=path) == 0

    return status


def git_push(path, message = "configuration update"):
    status = subprocess.call(["git", "add", "-A"], cwd=path) == 0
    status |= subprocess.call(["git", "commit", "-a", "-m", message], cwd=path) == 0
    status |= subprocess.call(["git", "push", "-u", "origin", "master"], cwd=path) == 0

    return status


def git_pull(path):
    status = subprocess.call(["git", "pull", "origin", "master"], cwd=path) == 0

    return status


def git_check_status(status):
    config = get_config()
    if not status:
        print_color(bcolors.FAIL, "FATAL: Git operation failed! Repository has to be recovered manually!", bold=True)
        print_color(bcolors.FAIL, "FATAL: Repository path: " + config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'])
        sys.exit(1)


# -----------------------------------------
# main business logic
# -----------------------------------------

def init_local_repo():
    config = get_config()

    print("Setting up local repository.")
    if not os.path.exists(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY']):
        print_color(bcolors.OKBLUE, "Creating new directory: " + config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'])
        try:
            os.makedirs(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'])
        except OSError as e:
            print_color(bcolors.FAIL, "Failed to create local repository directory: " + e.strerror)
            sys.exit(1)

    # init git repo
    if not git_is_repo(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY']):
        git_init_repo(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'])

    git_check_status(git_set_author(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'], config['GIT']['USER'], config['GIT']['EMAIL']))
    git_check_status(git_set_upstream(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'], config['GIT']['REMOTE_REPOSITORY']))

    git_setup_ssh_environment()

    git_check_status(git_pull(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY']))
    create_initialization_file(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'])
    git_check_status(git_push(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'], "cfgs initialized"))
    git_check_status(git_pull(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY']))

    print_color(bcolors.OKGREEN, "cfgs initialization successfull!")
    print_color(bcolors.OKBLUE, "You can now use cfgs to keep your config files up to date.")


def add_file(filepath):
    config = get_config()
    abs_path = os.path.abspath(filepath)

    if not os.path.exists(abs_path):
        print_color(bcolors.WARNING, "Invalid file, skipping!")
        sys.exit(1)
    else:
        print_color(bcolors.OKBLUE, "Adding '" + abs_path + "' to cfgs...")

    local_path = config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + abs_path

    if os.path.exists(local_path):
        print_color(bcolors.WARNING, "File is already registered to cfgs, skipping!")
        sys.exit(1)
    else:
        target_directory = os.path.abspath(os.path.join(local_path, os.pardir))
        if not os.path.exists(target_directory):
            os.makedirs(target_directory)

        file_stat = os.stat(abs_path)
        file_permissions = file_stat[stat.ST_MODE]
        file_owner = file_stat[stat.ST_UID]
        file_group = file_stat[stat.ST_GID]
        file_owner_name = pwd.getpwuid(file_owner).pw_name
        file_group_name = grp.getgrgid(file_group).gr_name

        try:
            with open(local_path + ".cfgs", mode='w') as file:
                file.write('%s;%s;%s;%s;%s;%s' % ( file_permissions, file_owner, file_group, file_owner_name, file_group_name, socket.gethostname() ))
        except PermissionError as e:
            print_color(bcolors.FAIL, "Unable to write stat file! Error: " + e.strerror)
            sys.exit(1)
        except Exception as e:
            print_color(bcolors.FAIL, "Unable to write stat file! Error: " + str(e))
            sys.exit(1)

        shutil.copy2(abs_path, local_path)
        os.chown(local_path, file_owner, file_group)
        os.remove(abs_path)
        os.symlink(local_path, abs_path)
        os.chown(abs_path, file_owner, file_group, follow_symlinks=False)

        add_file_to_db(abs_path)

        print_color(bcolors.OKGREEN, "File added to cfgs!")
        print_color(bcolors.OKBLUE, "Use cfgs store to push the file to the remote repository!")


def remove_file(filepath):
    config = get_config()
    abs_path = os.path.abspath(filepath)

    local_path = config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + abs_path

    if not os.path.exists(local_path):
        print_color(bcolors.WARNING, "File not registered to cfgs, skipping!")
        sys.exit(1)
    else:
        print_color(bcolors.OKBLUE, "Removing '" + abs_path + "' from cfgs...")

    target_directory = os.path.abspath(os.path.join(abs_path, os.pardir))
    if not os.path.exists(target_directory):
        os.makedirs(target_directory)

    if os.path.exists(abs_path):
        if not confirm("Do you really want to override the local file '" + abs_path + "'?", bcolors.OKBLUE):
            print_color(bcolors.WARNING, "Skipping removal process!")
            sys.exit(0)
        else:
            os.remove(abs_path)

    shutil.copy2(local_path, abs_path)

    file_stat = os.stat(local_path)
    file_permissions = file_stat[stat.ST_MODE]
    file_owner = file_stat[stat.ST_UID]
    file_group = file_stat[stat.ST_GID]

    os.chown(abs_path, file_owner, file_group)
    os.chmod(abs_path, file_permissions)
    os.remove(local_path)
    os.remove(local_path + ".cfgs")

    delete_file_from_db(abs_path)

    print_color(bcolors.OKGREEN, "File removed from cfgs!")
    print_color(bcolors.OKBLUE, "Use cfgs store to push the file to the remote repository!")


def store():
    config = get_config()
    git_setup_ssh_environment()
    git_push(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'])

    print_color(bcolors.OKGREEN, "cfgs store successfull!")
    print_color(bcolors.OKBLUE, "You can now restore the configuration on your other systems.")


def update_local_metadata():
    config = get_config()
    with open(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + "/cfgs.db", "r") as search:
        for line in search:
            abs_path = line.rstrip()  # remove '\n' at end of line
            local_path = config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + abs_path

            if not os.path.exists(local_path):
                print_color(bcolors.WARNING, "Invalid file in database, skipping! (" + abs_path + ")")
            else:
                with open(local_path + ".cfgs", "r") as metadata_file:
                    metadata_string = metadata_file.readline().rstrip()
                    metadata = metadata_string.split(";")

                    file_permissions = int(metadata[0])
                    file_owner = int(metadata[1])
                    file_group = int(metadata[2])

                    os.chmod(local_path, file_permissions)
                    os.chown(local_path, file_owner, file_group)


def restore():
    config = get_config()
    git_setup_ssh_environment()
    git_pull(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'])

    update_local_metadata()

    if not confirm("Do you really want to restore files from the repository? Local files will be overwritten!"):
        print_color(bcolors.WARNING, "Skipping restore process!")
        sys.exit(0)
    else:
        with open(config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + "/cfgs.db", "r") as search:
            for line in search:
                abs_path = line.rstrip()  # remove '\n' at end of line
                local_path = config['DEFAULT']['LOCAL_STORAGE_DIRECTORY'] + abs_path

                if not os.path.exists(local_path):
                    print_color(bcolors.WARNING, "Invalid file, skipping!")
                else:
                    target_directory = os.path.abspath(os.path.join(abs_path, os.pardir))
                    if not os.path.exists(target_directory):
                        os.makedirs(target_directory)

                    if os.path.exists(abs_path):
                        os.remove(abs_path)

                    os.symlink(local_path, abs_path)

                    file_stat = os.stat(local_path)
                    file_owner = file_stat[stat.ST_UID]
                    file_group = file_stat[stat.ST_GID]

                    os.chown(abs_path, file_owner, file_group, follow_symlinks=False)

    print_color(bcolors.OKGREEN, "cfgs restore successfull!")
    print_color(bcolors.OKBLUE, "Configuration files have been updated. A reboot might be required.")


# -----------------------------------------
# main entry point
# -----------------------------------------

def main(argv):
    if not check_dependencies():
        sys.exit(1)

    if len(argv) == 2:
        arg = argv[1]
        if arg == "init":
            init_dialog()
            init_local_repo()
            sys.exit(0)
        elif arg == "store":
            store()
        elif arg == "restore":
            restore()
        else:
            print_splash()
    elif len(argv) == 3:
        arg = argv[1]
        config_file = argv[2]

        if arg == "add":
            add_file(config_file)
        elif arg == "remove":
            remove_file(config_file)
        else:
            print_splash()
    else:
        print_splash()


if __name__ == "__main__":
    main(sys.argv)