#
# Copyright (C) 2023 Soleta Networks <info@soleta.eu>
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the
# Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.

import hashlib
import logging
import os
import shlex
import shutil
import subprocess
import urllib.request
from src.log import OgError
from src.utils.cache import *

def _compute_md5(path, bs=2**20):
    m = hashlib.md5()
    with open(path, 'rb') as f:
        while True:
            buf = f.read(bs)
            if not buf:
                break
            m.update(buf)
    return m.hexdigest()


def tip_fetch_csum(tip_addr, image_name):
    """
    """
    url = f'http://{tip_addr}:9999/{image_name}.img.full.sum'
    try:
        with urllib.request.urlopen(f'{url}') as resp:
            r = resp.readline().rstrip().decode('utf-8')
    except urllib.error.URLError as e:
        raise OgError(f'Error fetching checksum file from {url}: {e.reason}') from e
    except urllib.error.HTTPError as e:
        raise OgError(f'Error fetching checksum file via HTTP from {url}: {e.reason}') from e
    return r


def _tip_read_csum(image_checksum_path):
    try:
        with open(image_checksum_path, 'r') as f:
            checksum = f.read().strip("\n")
    except OSError as e:
        return "unavailable"

    return checksum


def tip_write_csum(image_name):
    if not mount_cache():
        raise OgError(f'Failed to checksum {image_name}: cache partition is not available')

    image_path = f'{OG_CACHE_IMAGE_PATH}{image_name}.img'

    if not os.path.exists(image_path):
        raise OgError(f'Invalid image path {image_path} for tiptorrent checksum writing')

    logging.info('Calculating checksum...')
    logging.info('*DO NOT REBOOT OR POWEROFF* the client during this time')

    filename = image_path + ".full.sum"
    csum = _compute_md5(image_path)
    try:
        with open(filename, 'w') as f:
            f.write(csum)
    except OSError as e:
        raise OgError(f'Could not write {filename}, reported: {e}') from e

    return csum


def tip_check_csum(tip_addr, image_name):
    """
    """
    logging.info(f'Verifying checksum for {image_name}.img, please wait...')
    image_path = f'{OG_CACHE_IMAGE_PATH}{image_name}.img'
    if not os.path.exists(image_path):
        logging.error(f'File {image_path} does not exist')
        return False
    if not os.path.exists(f"{image_path}.full.sum"):
        logging.error(f'File {image_path}.full.sum does not exist in repository {tip_addr}')
        return False

    cache_csum = _tip_read_csum(f"{image_path}.full.sum")
    remote_csum = tip_fetch_csum(tip_addr, image_name)

    if cache_csum == remote_csum:
        ret = True
        logging.info(f'Checksum is OK for {image_name}.img')
    else:
        ret = False
        logging.warning(f'Checksum mismatch for {image_name}.img')
        logging.warning(f'Server reports checksum {remote_csum} but local checksum is {cache_csum}')

    return ret


def tip_client_get(tip_addr, image_name):
    """
    """
    image_path = f"{OG_CACHE_IMAGE_PATH}{image_name}.img"
    if os.path.exists(image_path):
        os.unlink(image_path)
    if os.path.exists(f"{image_path}.full.sum"):
        os.unlink(f"{image_path}.full.sum")

    logging.info(f'Fetching image {image_name}.img from tiptorrent server at {tip_addr}')
    logging.info('*DO NOT REBOOT OR POWEROFF* the client during this time')
    cmd = f'tiptorrent-client {tip_addr} {image_name}.img'
    logfile = open('/tmp/command.log', 'wb', 0)

    try:
        proc = subprocess.Popen(shlex.split(cmd),
                                stdout=logfile,
                                cwd=OG_CACHE_IMAGE_PATH)
        proc.communicate()
    except OSError as e:
        raise OgError(f'Unexpected error running tiptorrent subprocess: {e}') from e
    finally:
        logfile.close()

    if proc.returncode != 0:
        raise OgError(f'Error fetching image {image_name} via tiptorrent')
    else:
        tip_write_csum(image_name)