#!/usr/bin/env python3

"""
Uploads sources and BLOBs to the AlmaLinux sources cache.
"""

import argparse
import hashlib
import os.path
import sys
from typing import Iterator, List, TextIO, Tuple

import boto3 # type: ignore
from botocore.exceptions import ClientError # type: ignore


def init_arg_parser() -> argparse.ArgumentParser:
    """
    Initializes a command line arguments parser.

    Returns:
        Command line arguments parser.
    """
    arg_parser = argparse.ArgumentParser(
        prog="alma_blob_upload",
        description="Uploads sources and BLOBs to the AlmaLinux sources cache"
    )
    group = arg_parser.add_mutually_exclusive_group(required=True)
    group.add_argument('-f', '--file', nargs='+', help='file(s) to upload')
    group.add_argument('-i', '--input-metadata', metavar='INPUT_FILE',
                       help='input metadata file list to upload')
    arg_parser.add_argument('-b', '--bucket', default="sources.almalinux.org",
                            help='Amazon S3 bucket name. Default is '
                                 'sources.almalinux.org')
    arg_parser.add_argument('-o', '--output-metadata', metavar='OUTPUT_FILE',
                            help='output metadata file path')
    arg_parser.add_argument('-p', '--private', action='store_true',
                            help='set uploaded file mode to private. All '
                                 'uploaded files are public by default')
    arg_parser.add_argument('--domain-name', default='sources.almalinux.org',
                            help='AlmaLinux sources server domain name. '
                                 'Default is sources.almalinux.org')
    arg_parser.add_argument('-v', '--verbose', action='store_true',
                            help='enable additional debug output')
    return arg_parser


def get_file_checksum(file_path: str, checksum_type: str = 'sha1',
                      buff_size: int = 1048576) -> str:
    """
    Calculates a file checksum.

    Args:
        file_path: File path.
        checksum_type: Checksum type.
        buff_size: Number of bytes to read at once.

    Returns:
        File checksum.
    """
    hasher = hashlib.new(checksum_type)
    with open(file_path, 'rb') as fd:
        buff = fd.read(buff_size)
        while len(buff):
            hasher.update(buff)
            buff = fd.read(buff_size)
    return hasher.hexdigest()


def normalize_path(path: str) -> str:
    """
    Returns an absolute path with all variables expanded.

    Args:
        path: Path to normalize.

    Returns:
        Normalized path.
    """
    return os.path.abspath(os.path.expanduser(os.path.expandvars(path)))


def iter_metadata(metadata_path: str) -> Iterator[Tuple[str, str]]:
    """
    Iterates over records in a CentOS git repository-compatible metadata file.

    Args:
        metadata_path: Metadata file path.

    Returns:
        Iterator over files and their checksums.
    """
    with open(metadata_path, 'r') as fd:
        for line in fd:
            checksum, file_path = line.split()
            file_path = normalize_path(file_path)
            assert checksum == get_file_checksum(file_path)
            yield file_path, checksum


def iter_files(files: List[str]) -> Iterator[Tuple[str, str]]:
    """
    Iterates over a list of files and calculates checksums for them.

    Args:
        files: List of files.

    Returns:
        Iterator over files and their checksums.
    """
    for file_path in files:
        file_path = normalize_path(file_path)
        checksum = get_file_checksum(file_path)
        yield file_path, checksum


def is_file_exist(s3_client, bucket_name: str, checksum: str) -> bool:
    """
    Checks is a file with a given checksum is already uploaded.
    Args:
        s3_client: Amazon S3 client.
        bucket_name: S3 bucket name.
        checksum: File checksum.

    Returns:
        True if a file is already uploaded, False otherwise.
    """
    try:
        s3_client.head_object(Bucket=bucket_name, Key=checksum)
        return True
    except ClientError:
        return False


def upload_file(s3_client, bucket_name: str, file_path: str,
                checksum: str, private: bool):
    """
    Uploads a file to an Amazon S3 bucket.

    Args:
        s3_client: Amazon S3 client.
        bucket_name: S3 bucket name.
        file_path: File path.
        checksum: File checksum.
        private: False if file should be public, True otherwise.
    """
    acl = 'bucket-owner-full-control' if private else 'public-read'
    s3_client.upload_file(file_path, bucket_name, checksum,
                          ExtraArgs={'ACL': acl})


def add_metadata_record(metadata_fd: TextIO, file_path: str, checksum: str):
    """
    Adds a source file record to a metadata file.

    Args:
        metadata_fd: Metadata file descriptor.
        file_path: Source file path.
        checksum: Source file checksum.
    """
    rel_path = os.path.relpath(file_path)
    metadata_fd.write(f'{checksum} {rel_path}\n')


def main(sys_args):
    arg_parser = init_arg_parser()
    args = arg_parser.parse_args(sys_args)
    s3_client = boto3.client('s3')
    if args.input_metadata:
        iterator = iter_metadata(args.input_metadata)
    else:
        iterator = iter_files(args.file)
    out_fd = None
    if args.output_metadata:
        out_fd = open(args.output_metadata, 'w')
    try:
        for file_path, checksum in iterator:
            file_url = f'https://{args.domain_name}/{checksum}'
            if not is_file_exist(s3_client, args.bucket, checksum):
                upload_file(s3_client, args.bucket, file_path, checksum,
                            args.private)
                print(f'{file_path} uploaded: {file_url}')
            else:
                print(f'{file_path} exists: {file_url}')
            if out_fd:
                add_metadata_record(out_fd, file_path, checksum)
    finally:
        if out_fd:
            out_fd.close()


if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))