# -*- coding: utf-8 -*-

import string

valid_bucket_charset: set = set(string.ascii_lowercase + string.digits + ".-")
letter_and_number: set = set(string.ascii_lowercase + string.digits)

safe_key_charset: set = set(string.ascii_letters + string.digits + "/!-_.*'()")
req_special_handling_key_charset: set = set("&$@=;:+ ,?")
to_avoid_key_charset: set = set("\\{}^&`[]\"<>#|~%")
valid_key_charset: set = set.union(safe_key_charset, req_special_handling_key_charset)


class S3BucketValidationError(Exception): pass

class S3KeyValidationError(Exception): pass


def validate_s3_bucket(bucket: str) -> None:
    """
    Raise exception if validation not passed.

    Ref:

    - `Bucket naming rules <https://docs.aws.amazon.com/AmazonS3/latest/userguide/bucketnamingrules.html>`_
    """
    if not (3 <= len(bucket) <= 63):
        raise ValueError("Bucket names must be between 3 and 63 characters long.")

    invalid_chars = set(bucket).difference(valid_bucket_charset)
    if len(invalid_chars) != 0:
        raise ValueError(
            (
                "Bucket names can consist only of lowercase letters, numbers, "
                "dots (.), and hyphens (-). invalid char found {}"
            ).format(invalid_chars)
        )

    if (bucket[0] not in letter_and_number) or (bucket[-1] not in letter_and_number):
        raise ValueError("Bucket names must begin and end with a letter or number.")

    try:
        parts = [int(part) for part in bucket.split(".")]
        assert len(parts) == 4
        for p in parts:
            assert 0 <= p <= 255
        raise S3BucketValidationError("Bucket names must not be formatted as an IP address (for example, 192.168.5.4).")
    except S3BucketValidationError as e:
        raise e
    except:
        pass

    if bucket.startswith("xn--"):
        raise ValueError("Bucket names must not start with the prefix xn--.")
    if bucket.endswith("-s3alias"):
        raise ValueError("Bucket names must not end with the suffix -s3alias. This suffix is reserved for access point alias names.")
    # raise ValueError("Buckets used with Amazon S3 Transfer Acceleration can't have dots (.) in their names.")


def validate_s3_key(key: str) -> None:
    """
    Raise exception if validation not passed.

    Ref:

    - `Key naming rules <https://docs.aws.amazon.com/AmazonS3/latest/userguide/object-keys.html#object-key-guidelines>`_
    """
    if len(key) > 1024:
        raise ValueError(
            "S3 key must be less that 1024 chars "
            "to construct the S3 console url!"
        )

    invalid_chars = set(key).difference(valid_key_charset)
    if len(invalid_chars) != 0:
        doc_url = "https://docs.aws.amazon.com/AmazonS3/latest/userguide/object-keys.html#object-key-guidelines"
        raise ValueError(
            (
                "Invalid char found {}, "
                "read {} "
                "for more info"
            ).format(invalid_chars, doc_url)
        )


def validate_s3_uri(uri: str) -> None:
    """
    Raise exception if validation not passed.

    S3 URI is just ``s3://{bucket}/{key}``
    """
    if not uri.startswith("s3://"):
        raise ValueError("S3 URI must starts with 's3://'")

    if uri.count("/") < 3:
        raise ValueError(
            "S3 URI must have at least three '/', "
            "for example: s3://bucket/"
        )

    parts = uri.split("/", 3)
    bucket = parts[2]
    key = parts[3]
    validate_s3_bucket(bucket)
    validate_s3_key(key)


def validate_s3_arn(arn: str) -> None:
    """
    Raise exception if validation not passed.

    S3 ARN is just:

    - for bucket: ``arn:aws:s3:::{bucket}``
    - for object: ``arn:aws:s3:::{bucket}/{key}``
    - for directory: ``arn:aws:s3:::{bucket}/{prefix}/``
    """
    if not arn.startswith("arn:aws:s3:::"):
        raise ValueError("S3 ARN must starts with 'arn:aws:s3:::'")

    path = arn.replace("arn:aws:s3:::", "", 1)

    if "/" not in path:  # path is the bucket
        validate_s3_bucket(path)
    else:
        bucket, key = path.split("/", 1)
        validate_s3_bucket(bucket)
        validate_s3_key(key)