#!/usr/bin/env python3

import sys
from collections import namedtuple

from neo4j.v1 import GraphDatabase

Config = namedtuple('Config', ['objname', 'relname', 'batch_size'])


def create_records(db, dep_dict, config):
    with db.session() as session:
        create_records_with_session(session, dep_dict, config)


def create_records_with_session(session, dep_dict, config):
    tx = session.begin_transaction()
    index = 0
    mutation = """
    MERGE (src:{objname} {{name: $src}})
    MERGE (dest:{objname} {{name: $dest}})
    MERGE (src)-[dep:{relname}]->(dest)
    """.format(objname=config.objname, relname=config.relname)
    for src, dests in dep_dict.items():
        for dest in dests:
            tx.run(mutation, src=src, dest=dest)
            if index % config.batch_size == config.batch_size - 1:
                print("{}: Committing...".format(index + 1), file=sys.stderr)
                tx.commit()
                tx = session.begin_transaction()
            index += 1
    tx.commit()


def main():
    import argparse
    import json
    import os

    parser = argparse.ArgumentParser()
    parser.add_argument('-U', '--url', default='bolt://localhost:7687')
    parser.add_argument('-u', '--username')
    parser.add_argument('-p', '--password')
    parser.add_argument('-b', '--batchsize', type=int, default=10000)
    parser.add_argument('-o', '--objname', default='Package')
    parser.add_argument('-r', '--relname', default='DEPENDS')
    parser.add_argument('file', nargs='*')
    args = parser.parse_args()
    if args.username:
        username = args.username
    else:
        username = os.getenv('NEO4J_USERNAME', 'neo4j')
    if args.password:
        password = args.password
    else:
        password = os.getenv('NEO4J_PASSWORD', 'neo4j')

    db = GraphDatabase.driver(args.url, auth=(username, password))
    config = Config(objname=args.objname, relname=args.relname, batch_size=args.batchsize)
    if args.file:
        for fpath in args.file:
            with open(fpath) as f:
                dep_dict = json.load(f)
                create_records(db, dep_dict, config)
    else:
        dep_dict = json.load(sys.stdin)
        create_records(db, dep_dict, config)


if __name__ == '__main__':
    main()