#!/usr/bin/env python3

# Build the Debian packages using Docker images.
#
# This script builds the Docker images and then executes them sequentially, each
# one building a Debian package for the targeted operating system. It is
# designed to be a "single command" to produce all the images.
#
# By default, builds for all known distributions, but a list of distributions
# can be passed on the commandline for debugging.

import argparse
import os
import signal
import subprocess
import sys
import threading
from concurrent.futures import ThreadPoolExecutor

DISTS = (
    "debian:stretch",
    "debian:buster",
    "debian:sid",
    "ubuntu:xenial",
    "ubuntu:bionic",
    "ubuntu:cosmic",
    "ubuntu:disco",
)

DESC = '''\
Builds .debs for synapse, using a Docker image for the build environment.

By default, builds for all known distributions, but a list of distributions
can be passed on the commandline for debugging.
'''


class Builder(object):
    def __init__(self, redirect_stdout=False):
        self.redirect_stdout = redirect_stdout
        self.active_containers = set()
        self._lock = threading.Lock()
        self._failed = False

    def run_build(self, dist):
        """Build deb for a single distribution"""

        if self._failed:
            print("not building %s due to earlier failure" % (dist, ))
            raise Exception("failed")

        try:
            self._inner_build(dist)
        except Exception as e:
            print("build of %s failed: %s" % (dist, e), file=sys.stderr)
            self._failed = True
            raise

    def _inner_build(self, dist):
        projdir = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
        os.chdir(projdir)

        tag = dist.split(":", 1)[1]

        # Make the dir where the debs will live.
        #
        # Note that we deliberately put this outside the source tree, otherwise
        # we tend to get source packages which are full of debs. (We could hack
        # around that with more magic in the build_debian.sh script, but that
        # doesn't solve the problem for natively-run dpkg-buildpakage).
        debsdir = os.path.join(projdir, '../debs')
        os.makedirs(debsdir, exist_ok=True)

        if self.redirect_stdout:
            logfile = os.path.join(debsdir, "%s.buildlog" % (tag, ))
            print("building %s: directing output to %s" % (dist, logfile))
            stdout = open(logfile, "w")
        else:
            stdout = None

        # first build a docker image for the build environment
        subprocess.check_call([
            "docker", "build",
            "--tag", "dh-venv-builder:" + tag,
            "--build-arg", "distro=" + dist,
            "-f", "docker/Dockerfile-dhvirtualenv",
            "docker",
        ], stdout=stdout, stderr=subprocess.STDOUT)

        container_name = "synapse_build_" + tag
        with self._lock:
            self.active_containers.add(container_name)

        # then run the build itself
        subprocess.check_call([
            "docker", "run",
            "--rm",
            "--name", container_name,
            "--volume=" + projdir + ":/synapse/source:ro",
            "--volume=" + debsdir + ":/debs",
            "-e", "TARGET_USERID=%i" % (os.getuid(), ),
            "-e", "TARGET_GROUPID=%i" % (os.getgid(), ),
            "dh-venv-builder:" + tag,
        ], stdout=stdout, stderr=subprocess.STDOUT)

        with self._lock:
            self.active_containers.remove(container_name)

        if stdout is not None:
            stdout.close()
            print("Completed build of %s" % (dist, ))

    def kill_containers(self):
        with self._lock:
            active = list(self.active_containers)

        for c in active:
            print("killing container %s" % (c,))
            subprocess.run([
                "docker", "kill", c,
            ], stdout=subprocess.DEVNULL)
            with self._lock:
                self.active_containers.remove(c)


def run_builds(dists, jobs=1):
    builder = Builder(redirect_stdout=(jobs > 1))

    def sig(signum, _frame):
        print("Caught SIGINT")
        builder.kill_containers()
    signal.signal(signal.SIGINT, sig)

    with ThreadPoolExecutor(max_workers=jobs) as e:
        res = e.map(builder.run_build, dists)

    # make sure we consume the iterable so that exceptions are raised.
    for r in res:
        pass


if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description=DESC,
    )
    parser.add_argument(
        '-j', '--jobs', type=int, default=1,
        help='specify the number of builds to run in parallel',
    )
    parser.add_argument(
        'dist', nargs='*', default=DISTS,
        help='a list of distributions to build for. Default: %(default)s',
    )
    args = parser.parse_args()
    run_builds(dists=args.dist, jobs=args.jobs)
