import os
import tarfile
import time
from datetime import timedelta

import pendulum
from airflow.decorators import dag
from airflow.decorators import task
from airflow.models.param import Param
from airflow.operators.python import get_current_context
from airflow.providers.amazon.aws.hooks.s3 import S3Hook
from botocore.exceptions import ClientError

import dag_utils

EXECUTION_TIMEOUT = int(os.getenv("EXECUTION_TIMEOUT", 6))

default_args = {
    "execution_timeout": timedelta(days=EXECUTION_TIMEOUT),
    "retries": int(os.getenv("DEFAULT_TASK_RETRIES", 1)),
    "retry_delay": timedelta(seconds=int(os.getenv("DEFAULT_RETRY_DELAY_SECONDS", 60))),
}


def load_file_obj_with_backoff(hook: S3Hook, fileobj, key: str, bucket: str, replace: bool) -> bool:
    delay = 10  # initial delay
    delay_incr = 10  # additional delay in each loop
    max_delay = 60  # max delay of one loop. Total delay is (max_delay**2)/2

    while delay < max_delay:
        try:
            return hook.load_file_obj(fileobj,
                                      key,
                                      bucket,
                                      replace=replace)
        except ClientError as err:
            code = err.response.get('Error', {}).get('Code', '')
            if code in ['NoSuchBucket']:
                print(f"Error: {code}. Check s3path: s3://{bucket}/{key}")
                raise err
            time.sleep(delay)
            delay += delay_incr


@dag(
    dag_id="s3_untar",
    dag_display_name="S3 streaming untar",
    start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
    schedule=None,
    catchup=False,
    default_args=default_args,
    params={
        "S3_CONN_ID": Param("s3_conn", type='string', description="Airflow connection of S3 endpoint"),
        "src_bucket": Param(dag_utils.get_default_bucket(), type='string',
                            description="Override S3 default bucket for source"),
        "src_key": Param("", type='string', description="File to untar"),
        "dst_bucket": Param(dag_utils.get_default_bucket(), type='string',
                            description="Override S3 default bucket for destination"),
        "dst_key_prefix": Param("", type='string', description="Key prefix for unarchived files"),
    },
    tags=["s3", "tools"],
)
def s3_untar():
    @task
    def untar():
        context = get_current_context()
        hook = S3Hook(context["params"]["S3_CONN_ID"], transfer_config_args={'use_threads': False})
        src_bucket = context['params']['src_bucket']
        dst_bucket = context['params']['dst_bucket']
        dst_key_prefix = os.path.normpath(context["params"]["dst_key_prefix"])

        existing_keys = dict.fromkeys(hook.list_keys(bucket_name=dst_bucket,
                                                     prefix=dst_key_prefix + "/"), 0)
        s3_obj = hook.get_key(context["params"]["src_key"], bucket_name=src_bucket)

        with tarfile.open(fileobj=s3_obj.get()["Body"], mode='r|*') as tar:
            for member in tar:
                dst_key = os.path.normpath(dst_key_prefix + "/" + member.name)
                # Ignore directories, links, devices, fifos, etc.
                if (not member.isfile()) or member.name.endswith('/'):
                    print(f"Skipping {member.name}: is not a file")
                    continue
                if dst_key in existing_keys:
                    print(f"Skipping {member.name}: already exists")
                    continue
                print(f"Extracting {member.name} to {dst_key}")
                fileobj = tar.extractfile(member)
                fileobj.seekable = lambda: False
                load_file_obj_with_backoff(hook, fileobj,
                                           dst_key,
                                           dst_bucket,
                                           replace=True)

    untar()


s3_untar()