#!/usr/bin/env python3
#
# Copyright (C) 2022 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# File: build-vyos-image
# Purpose: builds VyOS images using a fork of Debian's live-build tool

import re
import os
import sys
import uuid
import glob
import shutil
import getpass
import platform
import argparse
import datetime
import functools

import json


try:
    import toml
    import jinja2
    import git
except ModuleNotFoundError as e:
    print("Cannot load a required library: {}".format(e))
    print("Please make sure the following Python3 modules are installed: toml jinja2 git")

import vyos_build_utils as utils
import vyos_build_defaults as defaults

# argparse converts hyphens to underscores,
# so for lookups in the original options hash we have to convert them back
def field_to_option(s):
    return re.sub(r'_', '-', s)

def get_default_build_by():
    return "{user}@{host}".format(user= getpass.getuser(), host=platform.node())

def get_validator(optdict, name):
    try:
        return optdict[name][2]
    except KeyError:
        return None

def merge_dicts(source, destination):
    """ Merge two dictionaries and return a new dict which has the merged key/value pairs.
    Merging logic is as follows:
      Sub-dicts are merged.
      List values are combined.
      Scalar values are set to those from the source dict.
    """
    from copy import deepcopy
    tmp = deepcopy(destination)

    for key, value in source.items():
        if key not in tmp:
            tmp[key] = value
        elif isinstance(source[key], dict):
            tmp[key] = merge_dicts(source[key], tmp[key])
        elif isinstance(source[key], list):
            tmp[key] = source[key] + tmp[key]
        else:
            tmp[key] = source[key]

    return tmp

def has_nonempty_key(config, key):
    if key in config:
        if config[key]:
            return True
    return False

def make_toml_path(dir, file_basename):
    return os.path.join(dir, file_basename + ".toml")


if __name__ == "__main__":
    ## Check if the script is running wirh root permissions
    ## Since live-build requires privileged calls such as chroot(),
    ## there's no real way around it.
    if os.getuid() != 0:
        print("E: this script requires root privileges")
        sys.exit(1)

    ## Check if there are missing build dependencies
    deps = {
        'packages': [
           'sudo',
           'make',
           'live-build',
           'pbuilder',
           'devscripts',
           'python3-pystache',
           'python3-git',
           'qemu-utils'
        ],
       'binaries': []
    }

    print("I: Checking if packages required for VyOS image build are installed")
    try:
        checker = utils.check_system_dependencies(deps)
    except OSError as e:
        print(e)
        sys.exit(1)

    ## Load the file with default build configuration options
    try:
        with open(defaults.DEFAULTS_FILE, 'r') as f:
            build_defaults = toml.load(f)
    except Exception as e:
        print("Failed to open the defaults file {0}: {1}".format(defaults.DEFAULTS_FILE, e))
        sys.exit(1)

    ## Get a list of available build flavors
    build_flavors = list(map(lambda f: os.path.splitext(f)[0], os.listdir(defaults.BUILD_FLAVORS_DIR)))

    ## Set up the option parser
    ## XXX: It uses values from the default configuration file for its option defaults,
    ## which is why it's defined after loading the defaults.toml file data.

    # Options dict format:
    # '$option_name_without_leading_dashes': { ('$help_string', $default_value_generator_thunk, $value_checker_thunk) }
    options = {
       'architecture': ('Image target architecture (amd64 or arm64)',
          lambda: build_defaults['architecture'], lambda x: x in ['amd64', 'arm64']),
       'build-by': ('Builder identifier (e.g. jrandomhacker@example.net)', get_default_build_by, None),
       'debian-mirror': ('Debian repository mirror', lambda: build_defaults['debian_mirror'], None),
       'debian-security-mirror': ('Debian security updates mirror', lambda: build_defaults['debian_security_mirror'], None),
       'pbuilder-debian-mirror': ('Debian repository mirror for pbuilder env bootstrap', lambda: build_defaults['debian_mirror'], None),
       'vyos-mirror': ('VyOS package mirror', lambda: build_defaults["vyos_mirror"], None),
       'build-type': ('Build type, release or development', lambda: 'development', lambda x: x in ['release', 'development']),
       'version': ('Version number (release builds only)', None, None),
       'build-comment': ('Optional build comment', lambda: '', None)
    }

    # Create the option parser
    parser = argparse.ArgumentParser()
    for k, v in options.items():
        help_string, default_value_thunk = v[0], v[1]
        if default_value_thunk is None:
            parser.add_argument('--' + k, type=str, help=help_string)
        else:
            parser.add_argument('--' + k, type=str, help=help_string, default=default_value_thunk())

    # The debug option is a bit special since it different type is different
    parser.add_argument('--debug', help='Enable debug output', action='store_true')

    parser.add_argument('--dry-run', help='Check build configuration and exit', action='store_true')

    # Custom APT entry and APT key options can be used multiple times
    parser.add_argument('--custom-apt-entry', help="Custom APT entry", action='append', default=[])
    parser.add_argument('--custom-apt-key', help="Custom APT key file", action='append', default=[])
    parser.add_argument('--custom-package', help="Custom package to install from repositories", action='append', default=[])

    # Build flavor is a positional argument
    parser.add_argument('build_flavor', help='Build flavor', nargs='?', action='store')

    args = vars(parser.parse_args())

    debug = args["debug"]

    # Validate options
    for k, v in args.items():
        key = field_to_option(k)
        func = get_validator(options, k)
        if func is not None:
            if not func(v):
                print("{v} is not a valid value for --{o} option".format(o=key, v=v))
                sys.exit(1)

    if not args["build_flavor"]:
        print("E: Build flavor is not specified!")
        print("E: For example, to build the generic ISO, run {} iso".format(sys.argv[0]))
        print("Available build flavors:\n")
        print("\n".join(build_flavors))
        sys.exit(1)

    # Some fixup for mirror settings.
    # The idea is: if --debian-mirror is specified but --pbuilder-debian-mirror is not,
    # use the --debian-mirror value for both lb and pbuilder bootstrap
    if (args['debian_mirror'] != build_defaults["debian_mirror"]) and \
       (args['pbuilder_debian_mirror'] == build_defaults["debian_mirror"]):
        args['pbuilder_debian_mirror'] = args['debian_mirror']

    # Version can only be set for release builds,
    # for dev builds it hardly makes any sense
    if args['build_type'] == 'development':
        if args['version'] is not None:
            print("Version can only be set for release builds")
            print("Use --build-type=release option if you want to set version number")
            sys.exit(1)

    ## Inject some useful hardcoded options
    args['build_dir'] = defaults.BUILD_DIR
    args['pbuilder_config'] = os.path.join(defaults.BUILD_DIR, defaults.PBUILDER_CONFIG)

    ## Combine the arguments with non-configurable defaults
    build_config = merge_dicts(args, build_defaults)

    ## Load the flavor file and mix-ins
    with open(make_toml_path(defaults.BUILD_TYPES_DIR, build_config["build_type"]), 'r') as f:
        build_type_config = toml.load(f)
        build_config = merge_dicts(build_type_config, build_config)

    with open(make_toml_path(defaults.BUILD_ARCHES_DIR, build_config["architecture"]), 'r') as f:
        build_arch_config = toml.load(f)
        build_config = merge_dicts(build_arch_config, build_config)

    with open(make_toml_path(defaults.BUILD_FLAVORS_DIR, build_config["build_flavor"]), 'r') as f:
        flavor_config = toml.load(f)
        build_config = merge_dicts(flavor_config, build_config)

    ## Rename and merge some fields for simplicity
    ## E.g. --custom-packages is for the user, but internally
    ## it's added to the same package list as everything else
    if has_nonempty_key(build_config, "custom_package"):
        build_config["packages"] += build_config["custom_package"]
        del build_config["custom_package"]

    ## Add architecture-dependent packages from the flavor
    if has_nonempty_key(build_config, "architectures"):
        arch = build_config["architecture"]
        if arch in build_config["architectures"]:
            build_config["packages"] += build_config["architectures"][arch]["packages"]

    ## Dump the complete config if the user enabled debug mode
    if debug:
        import json
        print("D: Effective build config:\n")
        print(json.dumps(build_config, indent=4))

    ## Clean up the old build config and set up a fresh copy
    lb_config_dir = os.path.join(defaults.BUILD_DIR, defaults.LB_CONFIG_DIR)
    print(lb_config_dir)
    shutil.rmtree(lb_config_dir, ignore_errors=True)
    shutil.copytree("data/live-build-config/", lb_config_dir)
    os.makedirs(lb_config_dir, exist_ok=True)

    ## Create the version file

    # Create a build timestamp
    now = datetime.datetime.today()
    build_timestamp = now.strftime("%Y%m%d%H%M")

    # FIXME: use aware rather than naive object
    build_date = now.strftime("%a %d %b %Y %H:%M UTC")

    # Assign a (hopefully) unique identifier to the build (UUID)
    build_uuid = str(uuid.uuid4())

    # Initialize Git object from our repository
    try:
        repo = git.Repo('.')

        # Retrieve the Git commit ID of the repository, 14 charaters will be sufficient
        build_git = repo.head.object.hexsha[:14]
        # If somone played around with the source tree and the build is "dirty", mark it
        if repo.is_dirty():
            build_git += "-dirty"

        # Retrieve git branch name
        git_branch = repo.active_branch.name
    except Exception as e:
      print("Could not retrieve information from git: {0}".format(str(e)))
      build_git = ""
      git_branch = ""
      git_commit = ""

    # Create the build version string
    if build_config['build_type'] == 'development':
        try:
            if not git_branch:
                raise ValueError("git branch could not be determined")

            # Load the branch to version mapping file
            with open('data/versions') as f:
                version_mapping = json.load(f)

            branch_version = version_mapping[git_branch]

            version = "{0}-rolling-{1}".format(branch_version, build_timestamp)
        except Exception as e:
            print("Could not build a version string specific to git branch, falling back to default: {0}".format(str(e)))
            version = "999.{0}".format(build_timestamp)
    else:
        # Release build, use the version from ./configure arguments
        version = build_config['version']

    if build_config['build_type'] == 'development':
        lts_build = False
    else:
        lts_build = True

    version_data = {
        'version': version,
        'built_by': build_config['build_by'],
        'built_on': build_date,
        'build_uuid': build_uuid,
        'build_git': build_git,
        'build_branch': git_branch,
        'release_train': build_config['release_train'],
        'lts_build': lts_build,
        'build_comment': build_config['build_comment']
    }

    os_release = f"""
    PRETTY_NAME="VyOS {version} ({build_config['release_train']})"
    NAME="VyOS"
    VERSION_ID="{version}"
    VERSION="{version} ({build_config['release_train']})"
    VERSION_CODENAME={build_defaults['debian_distribution']}
    ID=vyos
    HOME_URL="{build_defaults['website_url']}"
    SUPPORT_URL="{build_defaults['support_url']}"
    BUG_REPORT_URL="{build_defaults['bugtracker_url']}"
    """

    chroot_includes_dir = os.path.join(defaults.BUILD_DIR, defaults.CHROOT_INCLUDES_DIR)
    vyos_data_dir = os.path.join(chroot_includes_dir, "usr/share/vyos")
    os.makedirs(vyos_data_dir, exist_ok=True)
    with open(os.path.join(vyos_data_dir, 'version.json'), 'w') as f:
        json.dump(version_data, f)

    # For backwards compatibility with 'add system image' script from older versions
    # we need a file in the old format so that script can find out the version of the image
    # for upgrade
    os.makedirs(os.path.join(chroot_includes_dir, 'opt/vyatta/etc/'), exist_ok=True)
    with open(os.path.join(chroot_includes_dir, 'opt/vyatta/etc/version'), 'w') as f:
        print("Version: {0}".format(version), file=f)


    # Define variables that influence to welcome message on boot
    os.makedirs(os.path.join(chroot_includes_dir, 'usr/lib/'), exist_ok=True)
    with open(os.path.join(chroot_includes_dir, 'usr/lib//os-release'), 'w') as f:
        print(os_release, file=f)


    ## Switch to the build directory, this is crucial for the live-build work work
    ## because the efective build config files etc. are there
    os.chdir(defaults.BUILD_DIR)

    ## Clean up earlier build state and artifacts
    print("I: Cleaning the build workspace")
    os.system("lb clean")
    #iter(lambda p: shutil.rmtree(p, ignore_errors=True),
    #  ['config/binary', 'config/bootstrap', 'config/chroot', 'config/common', 'config/source'])
    artifacts = functools.reduce(
      lambda x, y: x + y,
      map(glob.glob, ['*.iso', '*.raw', '*.img', '*.xz', '*.ova', '*.ovf']))
    iter(os.remove, artifacts)

    ## Create live-build configuration files

    # Add the additional repositories to package lists
    print("I: Setting up additional APT entries")
    vyos_repo_entry = "deb {0} {1} main\n".format(build_config['vyos_mirror'], build_config['vyos_branch'])

    apt_file = defaults.VYOS_REPO_FILE

    if debug:
        print("D: Adding these entries to {0}:".format(apt_file))
        print("\t", vyos_repo_entry)

    with open(apt_file, 'w') as f:
        f.write(vyos_repo_entry)

    # Add custom APT entries
    if build_config.get('additional_repositories', False):
        build_config['custom_apt_entry'] += build_config['additional_repositories']

    if build_config.get('custom_apt_entry', False):
        custom_apt_file = defaults.CUSTOM_REPO_FILE
        entries = "\n".join(build_config['custom_apt_entry'])
        if debug:
            print("D: Adding custom APT entries:")
            print(entries)
        with open(custom_apt_file, 'w') as f:
            f.write(entries)
            f.write("\n")

    # Add custom APT keys
    if has_nonempty_key(build_config, 'custom_apt_key'):
        key_dir = defaults.ARCHIVES_DIR
        for k in build_config['custom_apt_key']:
            dst_name = '{0}.key.chroot'.format(os.path.basename(k))
            shutil.copy(k, os.path.join(key_dir, dst_name))

    # Add custom packages
    if has_nonempty_key(build_config, 'packages'):
        package_list_file = defaults.PACKAGE_LIST_FILE
        packages = "\n".join(build_config['packages'])
        with open (package_list_file, 'w') as f:
            f.write(packages)

    ## Create includes
    if has_nonempty_key(build_config, "includes_chroot"):
        for i in build_config["includes_chroot"]:
            file_path = os.path.join(chroot_includes_dir, i["path"])
            os.makedirs(os.path.dirname(file_path), exist_ok=True)
            with open(file_path, 'w') as f:
                f.write(i["data"])


    ## Configure live-build
    lb_config_tmpl = jinja2.Template("""
    lb config noauto \
            --architectures {{architecture}} \
            --bootappend-live "boot=live components hostname=vyos username=live nopersistence noautologin nonetworking union=overlay console=ttyS0,115200 console=tty0 net.ifnames=0 biosdevname=0" \
            --bootappend-live-failsafe "live components memtest noapic noapm nodma nomce nolapic nomodeset nosmp nosplash vga=normal console=ttyS0,115200 console=tty0 net.ifnames=0 biosdevname=0" \
            --linux-flavours {{kernel_flavor}} \
            --linux-packages linux-image-{{kernel_version}} \
            --bootloader {{ bootloaders }} \
            --binary-images iso-hybrid \
            --checksums 'sha256 md5' \
            --debian-installer none \
            --distribution {{debian_distribution}} \
            --iso-application "VyOS" \
            --iso-publisher "{{build_by}}" \
            --iso-volume "VyOS" \
            --debootstrap-options "--variant=minbase --exclude=isc-dhcp-client,isc-dhcp-common,ifupdown --include=apt-utils,ca-certificates,gnupg2" \
            --mirror-bootstrap {{debian_mirror}} \
            --mirror-chroot {{debian_mirror}} \
            --mirror-chroot-security {{debian_security_mirror}} \
            --mirror-binary {{debian_mirror}} \
            --mirror-binary-security {{debian_security_mirror}} \
            --archive-areas {{debian_archive_areas}} \
            --firmware-chroot false \
            --firmware-binary false \
            --updates true \
            --security true \
            --backports true \
            --apt-recommends false \
            --apt-options "--yes -oAPT::Get::allow-downgrades=true" \
            --apt-indices false
            "${@}"
    """)

    lb_config_command = lb_config_tmpl.render(build_config)

    ## Pin release for VyOS packages
    apt_pin = f"""Package: *
Pin: release n={build_config['release_train']}
Pin-Priority: 600
"""

    with open(defaults.VYOS_PIN_FILE, 'w') as f:
        f.write(apt_pin)

    print("I: Configuring live-build")

    if debug:
        print("D: live-build configuration command")
        print(lb_config_command)

    result = os.system(lb_config_command)
    if result > 0:
        print("E: live-build config failed")
        sys.exit(1)

    ## In dry-run mode, exit at this point
    if build_config["dry_run"]:
        print("I: dry-run, not starting image build")
        sys.exit(0)

    ## Add local packages
    local_packages = glob.glob('../packages/*.deb')
    if local_packages:
        for f in local_packages:
            shutil.copy(f, os.path.join(defaults.LOCAL_PACKAGES_PATH, os.path.basename(f)))

    ## Build the image
    print("I: Starting image build")
    if debug:
        print("D: It's not like I'm building this specially for you or anything!")
    res = os.system("lb build 2>&1")
    if res > 0:
        sys.exit(res)

    # Copy the image
    shutil.copy("live-image-{0}.hybrid.iso".format(build_config["architecture"]),
      "vyos-{0}-{1}.iso".format(version_data["version"], build_config["architecture"]))