#!/usr/bin/env python3
import argparse
import datetime as dt
import json
import os
import subprocess

CONFIG_NAME = ".psyncup.json"

epilog = (
    """\
This program reads configuration from a file called """
    + CONFIG_NAME
    + """,
which must be in the same directory as the script runs in. For example:

{
    "ssh_remote": "emiliko@10.0.0.1",
    "remote_dir": "/home/emiliko/.configs_pointer",
    "update_date": "2023-12-01_01:01:01_UTC",
    "exclude": [
        ".git",
        "bin/rewritten_in_rust/target"
    ]
}"""
)

parser = argparse.ArgumentParser(
    prog="PySynchronize Up v1.0.0",
    formatter_class=argparse.RawTextHelpFormatter,
    description="Wrapper around rsync to easily develop on multiple remotes",
    epilog=epilog,
)
parser.add_argument(
    "--debug",
    action="store_true",
    help="Show rsync progress bar and additional debugging info",
)
parser.add_argument(
    "--dry-run",
    action="store_true",
    help="Runs the rsync, without writing any changes to local or remote",
)
parser.add_argument(
    "--no-compress",
    action="store_true",
    help="Don't use -z when rsyncing. ~5x faster over 1G LAN",
)
parser.add_argument(
    "--no-delete",
    action="store_true",
    help="Don't delete all non-matching files when rsyncing",
)

group = parser.add_mutually_exclusive_group(required=True)
group.add_argument(
    "-c",
    "--check",
    action="store_true",
    help="Check if the latest sync has been pulled from remote",
)
group.add_argument(
    "-u",
    "--up",
    action="store_true",
    help="Overwrite remote with local changes",
)
group.add_argument(
    "-d",
    "--down",
    action="store_true",
    help="Overwrite local with remote changes",
)

args = parser.parse_args()

# ==== Read in config file ====
try:
    with open(CONFIG_NAME, "r") as f:
        config = json.load(f)

    config["ssh_remote"]
    config["remote_dir"]

    # Standardize rsync's handling of tailing /
    if config["remote_dir"][-1] == "/" and config["remote_dir"] != "/":
        config["remote_dir"] = config["remote_dir"][:-1]
except FileNotFoundError:
    print(f"ERROR: {CONFIG_NAME} file was not found in this directory")
    print(epilog)
    exit(1)
except KeyError as e:
    print(f"ERROR: {CONFIG_NAME} is missing required key {e}")
    exit(1)

# ==== Construct an rsync command ====
rsync_cmd = [
    "rsync",
    "--archive",
    "--human-readable",
]

if not args.no_compress:
    rsync_cmd.append("--compress")

if not args.no_delete:
    rsync_cmd.append("--delete-during")

if args.dry_run:
    rsync_cmd.append("--dry-run")

if args.debug:
    rsync_cmd.append("--info=progress2")

if config.get("exclude") is not None:
    for x in config["exclude"]:
        rsync_cmd.append(f"--exclude={x}")

ssh_cmd = [
    "ssh",
    config["ssh_remote"],
    f"cat {config['remote_dir']}/{CONFIG_NAME}",
]

remote_dir_str = config["ssh_remote"] + ":" + config["remote_dir"] + "/"

if args.debug:
    print("DEBUG rsync command: ", rsync_cmd)
    print("DEBUG ssh copy command: ", ssh_cmd)
    print("DEBUG rsync remote directory path: ", remote_dir_str)


# ==== Perform command =====
def run_check():
    check = subprocess.Popen(
        ssh_cmd,
        stdin=subprocess.DEVNULL,
        stdout=subprocess.PIPE,
        stderr=subprocess.DEVNULL,
    )

    try:
        remote_config_str = check.communicate(timeout=6)[0].decode("utf-8")
    except subprocess.TimeoutExpired:
        print("Failed to connect to remote (timed out)")
        exit(1)

    try:
        remote_config = json.loads(remote_config_str)
    except json.JSONDecodeError:
        print(f"Failed to read remote {CONFIG_NAME}")
        exit(1)

    if not remote_config.get("update_date"):
        print("Remote has no last update_date (probably in sync)")
    elif not config.get("update_date"):
        print("Out of date with remote")
    elif config["update_date"] > remote_config["update_date"]:
        print("Ahead of remote")
    elif config["update_date"] < remote_config["update_date"]:
        print("Behind remote")
    else:
        print("Up to date with remote")


def run_up():
    rsync_cmd.append(os.getcwd() + "/")
    rsync_cmd.append(remote_dir_str)

    config["update_date"] = dt.datetime.now(dt.timezone.utc).strftime(
        "%Y-%m-%d_%H:%M:%S_UTC"
    )
    with open(CONFIG_NAME, "w") as f:
        json.dump(config, f, indent=4)

    rsync_code = subprocess.call(rsync_cmd)

    if rsync_code != 0:
        print(f"Rsync exited with code {rsync_code}")
        exit(1)


def run_down():
    rsync_cmd.append(remote_dir_str)
    rsync_cmd.append(os.getcwd())

    rsync_code = subprocess.call(rsync_cmd)

    if rsync_code != 0:
        print(f"Rsync exited with code {rsync_code}")
        exit(1)


if __name__ == "__main__":
    if args.check:
        run_check()
    elif args.up:
        run_up()
    elif args.down:
        run_down()
    else:
        print("Unexpected error")
        exit(2)