#!/usr/bin/env python3
from backup import FileBackend, get_backend, Change
import os
import click
import json
import sqlite3
import sys


@click.command()
@click.argument("lightning-dir", type=click.Path(exists=True))
@click.argument("backend-url")
def init(lightning_dir, backend_url):
    destination = backend_url
    backend = get_backend(destination, create=True)
    backend.version, backend.prev_version = 0, 0
    backend.offsets = [512, 0]
    backend.version_count = 0
    backend.write_metadata()

    lock_file = os.path.join(lightning_dir, "backup.lock")
    db_file = os.path.join(lightning_dir, "lightningd.sqlite3")

    with open(lock_file, "w") as f:
        f.write(json.dumps({
            'backend_url': destination,
        }))

    # TODO Take a snapshot

    data_version = 0
    if os.path.exists(db_file):
        print("Found an existing database at {db_file}, initializing the backup with a snapshot".format(db_file=db_file))
        # Peek into the DB to see if we have
        db = sqlite3.connect(db_file)
        cur = db.cursor()
        rows = cur.execute("SELECT intval FROM vars WHERE name = 'data_version'")
        data_version = rows.fetchone()[0]

        snapshot = Change(
            version=data_version,
            snapshot=open(db_file, 'rb').read(),
            transaction=None
        )
        if not backend.add_change(snapshot):
            print("Could not write snapshot to backend")
            sys.exit(1)
        else:
            print("Successfully written initial snapshot to {destination}".format(destination=destination))
    else:
        print("Database does not exist yet, created an empty backup file")

    print("Initialized backup backend {destination}, you can now start c-lightning".format(
        destination=destination,
    ))


@click.command()
@click.argument("backend-url")
@click.argument("restore-destination")
def restore(backend_url, restore_destination):
    destination = backend_url
    backend = get_backend(destination)
    backend.restore(restore_destination)


@click.group()
def cli():
    pass


cli.add_command(init)
cli.add_command(restore)

if __name__ == "__main__":
    cli()