#!/usr/bin/env python
# Author: Sean Fitzgerald
# Date: 2018/2/5
import socket
import google.cloud.happybase as hb
from google.cloud import bigtable as bt
import sys
import os.path

import logging
logging.basicConfig(level=logging.DEBUG)

CHECKPOINT_FILE = "/tmp/bigtable_backfill.checkpoint"

def create_socket(host, port):
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((host, port))
    return s


def relay_batch(metrics, sock):
    for metric in metrics:
        sock.send(metric)


def relay_messages(source_project, source_db, source_table_name, dest_carbon_ip):
    client = bt.Client(project=source_project, admin=True)
    instance = client.instance(source_db)
    connection = hb.Connection(instance=instance)

    table = connection.table(source_table_name)
    last_key = None
    if os.path.exists(CHECKPOINT_FILE):
        f = open(CHECKPOINT_FILE, 'r')
        last_key = f.read()
        f.close()

    while True:
        cursor = table.scan(row_start=last_key) if last_key else table.scan()
        try:
            key_count = 0
            for key, row in cursor:
                s = create_socket(dest_carbon_ip, 2003)
                batch = []
                metric_name = key.rsplit(":", 1)[0]
                for col in row.keys():
                    ts = col.split(":")[1]
                    val = row[col]
                    carbon_msg = "%s %s %s\n" % (metric_name, str(val), str(ts))
                    batch.append(carbon_msg)
                relay_batch(batch, s)
                last_key = key
                key_count += 1

                if key_count % 100 == 0 and key_count > 0:
                    print("Refreshing checkpoint...")
                    f = open(CHECKPOINT_FILE, 'w')
                    f.write(last_key)
                    f.close()
                    raise Exception("Checkpoint...")
            break
        except Exception as e:
            logging.exception("Failed to write batch")