import sys
import time
import shlex
import argparse
import traceback
import subprocess
from uuid import UUID
from pathlib import Path

from gn_libs import jobs, sqlite3


def run_job(conn, job, outputs_directory: Path):
    """Run the job."""
    job_id = job["job_id"]
    stdout_file = outputs_directory.joinpath(f"{job_id}.stdout")
    stderr_file = outputs_directory.joinpath(f"{job_id}.stderr")
    try:
        with (# TODO: Add the output streams' files to job metadata
                stdout_file.open(mode="w") as outfile,
                stderr_file.open(mode="w") as errfile,
                subprocess.Popen(
                    shlex.split(job["command"]),
                    encoding="utf-8",
                    stdout=outfile,
                    stderr=errfile) as process):
            with (stdout_file.open(mode="r") as stdout_output,
                  stderr_file.open(mode="r") as stderr_output):
                while process.poll() is None:
                    jobs.update_metadata(conn, job_id, "status", "running")
                    jobs.push_to_stream(
                        conn, job_id, "stdout", stdout_output.read())
                    jobs.push_to_stream(
                        conn, job_id, "stderr", stderr_output.read())
                    time.sleep(1)
    except:
        jobs.update_metadata(conn, job_id, "status", "error")
        jobs.push_to_stream(conn, job_id, "stderr", traceback.format_exc())
        return 4


def parse_args():
    """Define and parse CLI args."""
    parser = argparse.ArgumentParser(
        prog="GN Jobs Launcher",
        description = (
            "Generic launcher and manager of jobs defined with gn-libs"))
    parser.add_argument(
        "jobs_db_uri",
        help="The URI to the SQLite3 database holding the jobs' details")
    parser.add_argument(
        "job_id", help="The id of the job being processed", type=UUID)
    parser.add_argument("outputs_directory",
                        help="Directory where output files will be created",
                        type=Path)
    return parser.parse_args()

def main():
    """Entry-point to this program."""
    args = parse_args()
    with (sqlite3.connection(args.jobs_db_uri) as conn,
          sqlite3.cursor(conn) as cursor):
        job = jobs.job(conn, args.job_id)
        if job:
            return run_job(conn, job, args.outputs_directory)

        jobs.update_metadata(conn, args.job_id, "status", "error")
        jobs.push_to_stream(conn, args.job_id, "stderr", "Job not found!")
        return 2

    return 3



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