import os

import botocore
from boto3 import Session, client
from flask import current_app

FILE_LOCATION_STRUCTURE = 'service-{}-notify/{}.csv'

default_access_key = os.environ.get('AWS_ACCESS_KEY_ID')
default_secret_key = os.environ.get('AWS_SECRET_ACCESS_KEY')
default_region = os.environ.get('AWS_REGION')


def get_s3_file(
    bucket_name, file_location, access_key=default_access_key, secret_key=default_secret_key, region=default_region
):
    s3_file = get_s3_object(bucket_name, file_location, access_key, secret_key, region)
    return s3_file.get()['Body'].read().decode('utf-8')


def get_s3_object(
    bucket_name, file_location, access_key=default_access_key, secret_key=default_secret_key, region=default_region
):
    session = Session(aws_access_key_id=access_key, aws_secret_access_key=secret_key, region_name=region)
    s3 = session.resource('s3')
    return s3.Object(bucket_name, file_location)


def file_exists(
    bucket_name, file_location, access_key=default_access_key, secret_key=default_secret_key, region=default_region
):
    try:
        # try and access metadata of object
        get_s3_object(bucket_name, file_location, access_key, secret_key, region).metadata
        return True
    except botocore.exceptions.ClientError as e:
        if e.response['ResponseMetadata']['HTTPStatusCode'] == 404:
            return False
        raise


def get_job_location(service_id, job_id):
    return (
        current_app.config['CSV_UPLOAD_BUCKET_NAME'],
        FILE_LOCATION_STRUCTURE.format(service_id, job_id),
        current_app.config['CSV_UPLOAD_ACCESS_KEY'],
        current_app.config['CSV_UPLOAD_SECRET_KEY'],
        current_app.config['CSV_UPLOAD_REGION'],
    )


def get_contact_list_location(service_id, contact_list_id):
    return (
        current_app.config['CONTACT_LIST_BUCKET_NAME'],
        FILE_LOCATION_STRUCTURE.format(service_id, contact_list_id),
        current_app.config['CONTACT_LIST_ACCESS_KEY'],
        current_app.config['CONTACT_LIST_SECRET_KEY'],
        current_app.config['CONTACT_LIST_REGION'],
    )


def get_job_and_metadata_from_s3(service_id, job_id):
    obj = get_s3_object(*get_job_location(service_id, job_id))
    return obj.get()['Body'].read().decode('utf-8'), obj.get()['Metadata']


def get_job_from_s3(service_id, job_id):
    obj = get_s3_object(*get_job_location(service_id, job_id))
    return obj.get()['Body'].read().decode('utf-8')


def get_job_metadata_from_s3(service_id, job_id):
    obj = get_s3_object(*get_job_location(service_id, job_id))
    return obj.get()['Metadata']


def remove_job_from_s3(service_id, job_id):
    return remove_s3_object(*get_job_location(service_id, job_id))


def remove_contact_list_from_s3(service_id, contact_list_id):
    return remove_s3_object(*get_contact_list_location(service_id, contact_list_id))


def remove_s3_object(bucket_name, object_key, access_key, secret_key, region):
    obj = get_s3_object(bucket_name, object_key, access_key, secret_key, region)
    return obj.delete()


def get_list_of_files_by_suffix(
    bucket_name,
    subfolder='',
    suffix='',
    last_modified=None,
    access_key=default_access_key,
    secret_key=default_secret_key,
    region=default_region
):
    s3_client = client('s3', region, aws_access_key_id=access_key, aws_secret_access_key=secret_key)
    paginator = s3_client.get_paginator('list_objects_v2')

    page_iterator = paginator.paginate(
        Bucket=bucket_name,
        Prefix=subfolder
    )

    for page in page_iterator:
        for obj in page.get('Contents', []):
            key = obj['Key']
            if key.lower().endswith(suffix.lower()):
                if not last_modified or obj['LastModified'] >= last_modified:
                    yield key