#!/usr/bin/env python3

import argparse, sys, shutil, os, hashlib

sys.path.append(os.path.dirname(__file__) + '/lib')

import tamarin, system, rkt

def create_args_parser():
    '''Return a new configured ArgumentParser'''
    profile_names = tamarin.get_available_profile_names()

    parser = argparse.ArgumentParser(description="Generate packages for various GNU/Linux distributions")

    # Define available/required arguments and flags
    parser.add_argument("project_directory", help="The path to your project to package")
    parser.add_argument("-o", "--output", help="The path to the generated packages destination directory", default=".")
    parser.add_argument("-p", "--profile", help="The profile to use to package this project (default: debian)", choices=profile_names, default='debian')
    parser.add_argument("-a", "--architecture", help="The target architecture for the package (default: amd64)", default='amd64')
    parser.add_argument("-b", "--base", help="Use the specified image instead of the profile's one", default='')
    parser.add_argument("--rebuild", help="Ignore cache and rebuild container's image", action="store_true", default=False)
    parser.add_argument("--debug", help="Will add extra output and start the container in interactive mode", action="store_true", default=False)

    return parser

def download_and_extract_rkt(dest_dir, verbose=True):
    '''Download and extract rkt to the given destination directory'''
    rkt_archive_path = tamarin.download_rkt()
    system.extract_tar(rkt_archive_path, workspace_tmp)
    rkt_archive_dir = tamarin.get_rkt_achive_dest_dir()
    shutil.rmtree(local_rkt_dir, ignore_errors=True)
    os.rename(rkt_archive_dir, dest_dir)

def download_and_extract_acbuild(dest_dir, verbose=True):
    '''Download and extract acbuild to the given destination directory'''
    acbuild_archive_path = tamarin.download_acbuild()
    system.extract_tar(acbuild_archive_path, workspace_tmp)
    acbuild_archive_dir = tamarin.get_acbuild_achive_dest_dir()
    shutil.rmtree(local_acbuild_dir, ignore_errors=True)
    os.rename(acbuild_archive_dir, dest_dir)

def get_cached_image_path(profile):
    '''Compute and return the path for an hypothetic cached image for the given profile'''
    containerbuild_hooks = profile['containerbuild']['hooks']
    hasher = hashlib.sha1()
    hasher.update(base_image.encode())
    hasher.update(containerbuild_hooks.encode())
    image_hash = hasher.hexdigest()
    cache_dir = tamarin.get_workspace_subdir('cache')
    return os.path.join(os.sep, cache_dir, '{:s}.aci'.format(image_hash[:12]));

def build_image(build_workspace, aci_file, base_image, profile):

    acbuild_flags = ["--work-path", build_workspace]

    # Find and export base image from rkt' store
    name_pattern = base_image.split('/')[-1] + '$'
    image = rkt.find_image_by_name(name_pattern, rkt_flags=rkt_flags)
    rkt.export_image(image['id'], aci_file, rkt_flags=rkt_flags);

    # Build image
    tamarin.run_acbuild(acbuild_flags+["begin", aci_file])
    tamarin.run_acbuild(acbuild_flags+["set-name", "image_{:d}".format(pid)])
    tamarin.run_acbuild(acbuild_flags+["mount", "add", "src", "/src", "--read-only"])
    tamarin.run_acbuild(acbuild_flags+["mount", "add", "dist", "/dist"])
    tamarin.run_acbuild(acbuild_flags+["mount", "add", "tamarin-hooks", "/tamarin/hooks", "--read-only"])
    tamarin.run_acbuild(acbuild_flags+["mount", "add", "tamarin-lib", "/tamarin/lib", "--read-only"])
    tamarin.run_acbuild(acbuild_flags+["mount", "add", "tamarin-profiles", "/tamarin/profiles", "--read-only"])

    # Configure "containerbuild" hooks environment
    hooks_env = os.environ.copy()
    hooks_env["PATH"] = os.environ['PATH'] + ':' + tamarin.get_workspace_subdir('acbuild')
    hooks_env["TAMARIN_ACBUILD"] = " ".join([system.which('acbuild', local_acbuild_dir)]+acbuild_flags)
    hooks_env["TAMARIN_ACBUILD_ENGINE"] = "chroot" if not system.which('systemctl') else "systemd-nspawn"

    # Run hooks
    tamarin.run_profile_hooks(profile, 'containerbuild', cwd=build_workspace, env=hooks_env)

    tamarin.run_acbuild(acbuild_flags+["write", "--overwrite", aci_file])
    tamarin.run_acbuild(acbuild_flags+["end"])

    return aci_file

def cleanup(build_workspace, rkt_flags):

    # Nettoyage des conteneurs
    rkt.run([
        "gc",
        "--grace-period=0"
    ] + rkt_flags, as_root=True)

    # Nettoyage des images obsolètes du store
    rkt.run([
        "image",
        "gc"
    ] + rkt_flags, as_root=True)

    # Suppression de l'espace de travail de build
    shutil.rmtree(build_workspace, ignore_errors=True)

def validate_args(args):
    '''TODO'''

if __name__ == "__main__":

    parser = create_args_parser()
    args = parser.parse_args()

    validate_args(args)

    # Verify project directory
    project_dir = os.path.abspath(args.project_directory)
    output_dir = os.path.abspath(args.output)

    # Load build profile
    profile = tamarin.load_profile(args.profile)

    workspace = tamarin.get_workspace_dir()
    workspace_tmp = tamarin.get_workspace_subdir('tmp')

    local_rkt_dir = tamarin.get_workspace_subdir('rkt')
    if not system.which('rkt', local_rkt_dir):
        download_and_extract_rkt(local_rkt_dir)

    local_acbuild_dir = tamarin.get_workspace_subdir('acbuild')
    if not system.which('acbuild', local_acbuild_dir):
        download_and_extract_acbuild(local_acbuild_dir)

    pid = os.getpid()
    build_workspace = tamarin.get_workspace_subdir('tmp/build_{:d}'.format(pid))

    rkt_store = tamarin.get_workspace_subdir('store')
    rkt_flags = ["--dir={:s}".format(rkt_store)]

    base_image = args.base if args.base != '' else profile['profile']['default_image']

    # If the base image is Docker-based, download it
    if base_image.startswith('docker://'):
        rkt.run([
            "fetch",
            "--insecure-options=image",
            base_image
        ] + rkt_flags)

    aci_file = os.path.join(os.sep, build_workspace, 'image.aci')
    cached_image_file = get_cached_image_path(profile)

    if not args.rebuild and os.path.exists(cached_image_file):
        # Copy cached image
        shutil.copyfile(cached_image_file, aci_file)
    else:
        build_image(build_workspace, aci_file, base_image, profile)
        # Cache image
        shutil.copyfile(aci_file, cached_image_file)

    # rkt run arguments
    rkt_args = [
      "run",
      "--insecure-options=image",
      aci_file, "--net=host",
      "--volume=src,kind=host,source={:s}".format(project_dir),
      "--volume=dist,kind=host,source={:s}".format(output_dir),
      "--volume=tamarin-hooks,kind=host,source={:s}".format(tamarin.get_hooks_dir()),
      "--volume=tamarin-lib,kind=host,source={:s}".format(tamarin.get_lib_dir()),
      "--volume=tamarin-profiles,kind=host,source={:s}".format(tamarin.get_profiles_dir())
    ]

    # Use environment proxy if defined
    for proxy_var in ['HTTP_PROXY', 'HTTPS_PROXY', 'http_proxy', 'https_proxy']:
      if proxy_var in os.environ:
        rkt_args += ["--set-env={:s}={:s}".format(proxy_var, os.environ[proxy_var])]

    if args.debug:
      rkt_args += ["--interactive", "--exec", "/bin/bash"]
    else:
      rkt_args += ["--exec", "/usr/bin/python3", "--", "/tamarin/lib/build.py", args.profile, args.architecture]

    # Start container
    rkt.run(rkt_flags+rkt_args, as_root=True)

    # Cleanup
    cleanup(build_workspace, rkt_flags)