#!/usr/bin/env python3

# This file is part of Cockpit.
#
# Copyright (C) 2013 Red Hat, Inc.
#
# Cockpit is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# Cockpit is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Cockpit; If not, see <http://www.gnu.org/licenses/>.

#
# Download images or other state
#
# Images usually have a name specific link committed to git. These
# are referred to as 'committed'
#
# Other state is simply referenced by name without a link in git
# This is referred to as 'state'
#
# The stores are places to look for images or other state
#

import argparse
import email
import io
import os
import shutil
import socket
import stat
import subprocess
import sys
import tempfile
import time
import fcntl
import urllib.parse

from machine import testvm
from task import REDHAT_STORE

CONFIG = "~/.config/image-stores"
DEFAULT = [
    "http://cockpit-images.verify.svc.cluster.local",
    "https://images-cockpit.apps.ci.centos.org/",
    "https://209.132.184.41:8493/",
    REDHAT_STORE
]

BOTS = os.path.dirname(os.path.realpath(__file__))

DEVNULL = open("/dev/null", "r+")
EPOCH = "Thu, 1 Jan 1970 00:00:00 GMT"

def find(name, stores, latest, quiet):
    found = [ ]
    ca = os.path.join(testvm.IMAGES_DIR, "files", "ca.pem")

    for store in stores:
        url = urllib.parse.urlparse(store)

        defport = url.scheme == 'http' and 80 or 443

        try:
            ai = socket.getaddrinfo(url.hostname, url.port or defport, socket.AF_INET, 0, socket.IPPROTO_TCP)
        except socket.gaierror:
            ai = [ ]
            message = store

        for (family, socktype, proto, canonname, sockaddr) in ai:
            message = "{scheme}://{0}:{1}{path}".format(*sockaddr, scheme=url.scheme, path=url.path)

            def curl(*args):
                try:
                    cmd = ["curl"] + list(args) + ["--head", "--silent", "--fail", "--cacert", ca, source]
                    start = time.time()
                    output = subprocess.check_output(cmd, universal_newlines=True)
                    found.append((cmd, output, message, time.time() - start))
                    if not quiet:
                        sys.stderr.write(" > {0}\n".format(message))
                    return True
                except subprocess.CalledProcessError:
                    return False

            # first try with stores that accept the "cockpit-tests" host name
            resolve = "cockpit-tests:{1}:{0}".format(*sockaddr)
            source = urllib.parse.urljoin("{0}://cockpit-tests:{1}{2}".format(url.scheme, sockaddr[1], url.path), name)
            if curl("--resolve", resolve):
                continue

            # fall back for OpenShift proxied stores which send their own SSL cert initially; host name has to match that
            source = urllib.parse.urljoin(store, name)
            if curl():
                continue

            if not quiet:
                sys.stderr.write(" x {0}\n".format(message))

    # If we couldn't find the file, but it exists, we're good
    if not found:
        return None, None

    # Find the most recent version of this file
    def header_date(args):
        cmd, output, message, latency = args
        try:
            reply_line, headers_alone = output.split('\n', 1)
            last_modified = email.message_from_file(io.StringIO(headers_alone)).get("Last-Modified", "")
            return time.mktime(time.strptime(last_modified, '%a, %d %b %Y %H:%M:%S %Z'))
        except ValueError:
            return ""

    if latest:
        found.sort(reverse=True, key=header_date)
    else:
        found.sort(reverse=False, key=lambda x: x[3])

    # Return the command and message
    return found[0][0], found[0][2]

def download(dest, force, state, quiet, stores):
    if not stores:
        config = os.path.expanduser(CONFIG)
        if os.path.exists(config):
            with open(config, 'r') as fp:
                stores = fp.read().strip().split("\n")
        else:
            stores = []
        stores += DEFAULT

    # The time condition for If-Modified-Since
    exists = not force and os.path.exists(dest)
    if exists:
        since = dest
    else:
        since = EPOCH

    name = os.path.basename(dest)
    cmd, message = find(name, stores, latest=state, quiet=quiet)

    # If we couldn't find the file, but it exists, we're good
    if not cmd:
        if exists:
            return
        raise RuntimeError("image-download: couldn't find file anywhere: {0}".format(name))

    # Choose the first found item after sorting by date
    if not quiet:
        sys.stderr.write(" > {0}\n".format(urllib.parse.urljoin(message, name)))

    temp = dest + ".partial"

    # Adjust the command above that worked to make it visible and download real stuff
    cmd.remove("--head")
    cmd.append("--show-error")
    if not quiet and os.isatty(sys.stdout.fileno()):
        cmd.remove("--silent")
        cmd.insert(1, "--progress-bar")
    cmd.append("--remote-time")
    cmd.append("--time-cond")
    cmd.append(since)
    cmd.append("--output")
    cmd.append(temp)
    if os.path.exists(temp):
        if force:
            os.remove(temp)
        else:
            cmd.append("-C")
            cmd.append("-")

    # Always create the destination file (because --state)
    else:
        open(temp, 'a').close()

    curl = subprocess.Popen(cmd)
    ret = curl.wait()
    if ret != 0:
        raise RuntimeError("curl: unable to download %s (returned: %s)" % (message, ret))

    os.chmod(temp, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)

    # Due to time-cond the file size may be zero
    # A new file downloaded, put it in place
    if not exists or os.path.getsize(temp) > 0:
        shutil.move(temp, dest)

# Calculate a place to put images where links are not committed in git
def state_target(path):
    data_dir = testvm.get_images_data_dir()
    os.makedirs(data_dir, mode=0o775, exist_ok=True)
    return os.path.join(data_dir, path)

# Calculate a place to put images where links are committed in git
def committed_target(image):
    link = os.path.join(testvm.IMAGES_DIR, image)
    if not os.path.islink(link):
        raise RuntimeError("image link does not exist: " + image)

    dest = os.readlink(link)
    relative_dir = os.path.dirname(os.path.abspath(link))
    full_dest = os.path.join(relative_dir, dest)
    while os.path.islink(full_dest):
        link = full_dest
        dest = os.readlink(link)
        relative_dir = os.path.dirname(os.path.abspath(link))
        full_dest = os.path.join(relative_dir, dest)

    dest = os.path.join(testvm.get_images_data_dir(), dest)

    # We have the file but there is not valid link
    if os.path.exists(dest):
        try:
            os.symlink(dest, os.path.join(testvm.IMAGES_DIR, os.readlink(link)))
        except FileExistsError:
            pass

    # The image file in the images directory, may be same as dest
    image_file = os.path.join(testvm.IMAGES_DIR, os.readlink(link))

    # Double check that symlink in place but never make a cycle.
    if os.path.abspath(dest) != os.path.abspath(image_file):
        try:
            os.symlink(os.path.abspath(dest), image_file)
        except FileExistsError:
            pass

    return dest

def wait_lock(target):
    lockfile = os.path.join(tempfile.gettempdir(), ".cockpit-test-resources", os.path.basename(target) + ".lock")
    os.makedirs(os.path.dirname(lockfile), exist_ok=True)

    # we need to keep the lock fd open throughout the entire runtime, so remember it in a global-scoped variable
    wait_lock.f = open(lockfile, "w")
    for retry in range(360):
        try:
            fcntl.flock(wait_lock.f, fcntl.LOCK_NB | fcntl.LOCK_EX)
            return
        except BlockingIOError:
            if retry == 0:
                print("Waiting for concurrent image-download of %s..." % os.path.basename(target))
            time.sleep(10)
    else:
        raise TimeoutError("timed out waiting for concurrent downloads of %s\n" % target)

def download_images(image_list, force, quiet, state, store):
    data_dir = testvm.get_images_data_dir()
    os.makedirs(data_dir, exist_ok=True)

    # A default set of images are all links in git.  These links have
    # no directory part.  Other links might exist, such as the
    # auxiliary links created by committed_target above, and we ignore
    # them.
    if not image_list:
        image_list = []
        if not state:
            for filename in os.listdir(testvm.IMAGES_DIR):
                link = os.path.join(testvm.IMAGES_DIR, filename)
                if os.path.islink(link) and os.path.dirname(os.readlink(link)) == "":
                    image_list.append(filename)

    success = True

    for image in image_list:
        image = testvm.get_test_image(image)
        try:
            if state:
                target = state_target(image)
            else:
                target = committed_target(image)

            # don't download the same thing multiple times in parallel
            wait_lock(target)

            if force or state or not os.path.exists(target):
                download(target, force, state, quiet, store)
        except Exception as ex:
            success = False
            sys.stderr.write("image-download: {0}\n".format(str(ex)))

    return success

def main():
    parser = argparse.ArgumentParser(description='Download a bot state or images')
    parser.add_argument("--force", action="store_true", help="Force unnecessary downloads")
    parser.add_argument("--store", action="append", help="Where to find state or images")
    parser.add_argument("--quiet", action="store_true", help="Make downloading quieter")
    parser.add_argument("--state", action="store_true", help="Images or state not recorded in git")
    parser.add_argument('image', nargs='*')
    args = parser.parse_args()

    if not download_images(args.image, args.force, args.quiet, args.state, args.store):
        return 1

    return 0

if __name__ == '__main__':
    sys.exit(main())