import gzip
import os
import shutil
import subprocess
import sys
import tempfile
from datetime import datetime


def main():
    pg_dumpall_cmd = os.environ.get("PG_DUMPALL_CMD", "/usr/bin/pg_dumpall")
    database_host = os.environ.get("DATABASE_HOST", "localhost")
    database_port = os.environ.get("DATABASE_PORT", "5432")
    database_user = os.environ.get("DATABASE_USER", "postgres")

    try:
        ssh_host = os.environ["SSH_HOST"]
    except KeyError:
        sys.exit(
            "Error: Please provide a valid ssh host configuration through the SSH_HOST "
            'environment variable. E.g. SSH_HOST="user@host:/some/path/"'
        )

    backupfilename = (
        f"all-databases-{datetime.now().strftime('%Y-%m-%d_%Hh%Mm%Ss.%A')}.sql"
    )

    with tempfile.TemporaryDirectory() as tmpdirname:
        backupfilepath = os.path.join(tmpdirname, backupfilename)

        subprocess.run(
            [
                pg_dumpall_cmd,
                "-h",
                database_host,
                "-p",
                database_port,
                "-U",
                database_user,
                "-f",
                backupfilepath,
            ]
        )

        compressedfilepath = os.path.join(tmpdirname, f"{backupfilename}.gz")

        with open(backupfilepath, "rb") as backupfile:
            with gzip.open(compressedfilepath, "wb") as compressedfile:
                shutil.copyfileobj(backupfile, compressedfile)

        subprocess.run(["scp", compressedfilepath, ssh_host])


if __name__ == "__main__":
    main()