#!/usr/bin/python3

import hashlib
import json
import os.path
import pathlib
import re
import ssl
import subprocess
import sys

from debian_linux.config import ConfigCoreDump
from debian_linux.debian import VersionLinux, BinaryPackage
from debian_linux.gencontrol import Gencontrol as Base, \
    iter_flavours, PackagesBundle
from debian_linux.utils import Templates


class Gencontrol(Base):
    def __init__(self, arch):
        super(Gencontrol, self).__init__(
            ConfigCoreDump(fp=open('debian/config.defines.dump', 'rb')),
            Templates(['debian/signing_templates', 'debian/templates']))

        image_binary_version = self.changelog[0].version.complete

        config_entry = self.config[('version',)]
        self.version = VersionLinux(config_entry['source'])

        # Check config version matches changelog version
        assert self.version.complete == re.sub(r'\+b\d+$', r'',
                                               image_binary_version)

        self.abiname = config_entry['abiname']
        self.vars = {
            'upstreamversion': self.version.linux_upstream,
            'version': self.version.linux_version,
            'source_basename': re.sub(r'-[\d.]+$', '',
                                      self.changelog[0].source),
            'source_upstream': self.version.upstream,
            'abiname': self.abiname,
            'imagebinaryversion': image_binary_version,
            'imagesourceversion': self.version.complete,
            'arch': arch,
        }
        self.vars['source_suffix'] = \
            self.changelog[0].source[len(self.vars['source_basename']):]
        self.vars['template'] = \
            'linux-image%(source_suffix)s-%(arch)s-signed-template' % self.vars

        self.package_dir = 'debian/%(template)s' % self.vars
        self.template_top_dir = (self.package_dir
                                 + '/usr/share/code-signing/%(template)s'
                                 % self.vars)
        self.template_debian_dir = (self.template_top_dir
                                    + '/source-template/debian')
        os.makedirs(self.template_debian_dir, exist_ok=True)

        self.image_packages = []

        # We need a separate base dir for now
        self.bundles = {None: PackagesBundle(None, self.templates,
                                             pathlib.Path(self.template_debian_dir))}
        self.packages = self.bundle.packages
        self.makefile = self.bundle.makefile

    def do_main_setup(self, vars, makeflags, extra):
        makeflags['VERSION'] = self.version.linux_version
        makeflags['GENCONTROL_ARGS'] = (
            '-v%(imagebinaryversion)s '
            '-DBuilt-Using="%(source_basename)s%(source_suffix)s (= %(imagesourceversion)s)"' %
            vars)
        makeflags['PACKAGE_VERSION'] = vars['imagebinaryversion']

        self.installer_packages = {}

        if os.getenv('DEBIAN_KERNEL_DISABLE_INSTALLER'):
            if self.changelog[0].distribution == 'UNRELEASED':
                import warnings
                warnings.warn('Disable installer modules on request '
                              '(DEBIAN_KERNEL_DISABLE_INSTALLER set)')
            else:
                raise RuntimeError(
                    'Unable to disable installer modules in release build '
                    '(DEBIAN_KERNEL_DISABLE_INSTALLER set)')
        elif self.config.merge('packages').get('installer', True):
            # Add udebs using kernel-wedge
            kw_env = os.environ.copy()
            kw_env['KW_DEFCONFIG_DIR'] = 'debian/installer'
            kw_env['KW_CONFIG_DIR'] = 'debian/installer'
            kw_proc = subprocess.Popen(
                ['kernel-wedge', 'gen-control', vars['abiname']],
                stdout=subprocess.PIPE,
                text=True,
                env=kw_env)
            udeb_packages = BinaryPackage.read_rfc822(kw_proc.stdout)
            kw_proc.wait()
            if kw_proc.returncode != 0:
                raise RuntimeError('kernel-wedge exited with code %d' %
                                   kw_proc.returncode)

            for package in udeb_packages:
                for arch in package['Architecture']:
                    if self.config.merge('build', arch) \
                                  .get('signed-code', False):
                        self.installer_packages.setdefault(arch, []) \
                                               .append(package)

    def do_main_packages(self, vars, makeflags, extra):
        # Assume that arch:all packages do not get binNMU'd
        self.packages['source']['Build-Depends'].append(
            'linux-support-%(abiname)s (= %(imagesourceversion)s)' % vars)

    def do_main_recurse(self, vars, makeflags, extra):
        # Each signed source package only covers a single architecture
        self.do_arch(vars['arch'], vars.copy(),
                     makeflags.copy(), extra)

    def do_extra(self):
        pass

    def do_arch_setup(self, vars, makeflags, arch, extra):
        super(Gencontrol, self).do_main_setup(vars, makeflags, extra)

        abiname_part = '-%s' % self.config.merge('abi', arch)['abiname']
        makeflags['ABINAME'] = vars['abiname'] = \
            self.config['version', ]['abiname_base'] + abiname_part

    def do_arch_packages(self, arch, vars, makeflags, extra):
        udeb_packages = self.installer_packages.get(arch, [])

        if udeb_packages:
            makeflags_local = makeflags.copy()
            makeflags_local['PACKAGE_NAMES'] = ' '.join(p['Package'] for p in udeb_packages)

            for package in udeb_packages:
                package.meta['rules-target'] = 'udeb'

            self.bundle.add_packages(
                udeb_packages,
                (arch, 'real'),
                makeflags_local, arch=arch,
            )

    def do_featureset_setup(self, vars, makeflags, arch, featureset, extra):
        self.default_flavour = self.config.merge('base', arch, featureset) \
                                          .get('default-flavour')
        if self.default_flavour is not None:
            if featureset != 'none':
                raise RuntimeError("default-flavour set for %s %s,"
                                   " but must only be set for featureset none"
                                   % (arch, featureset))
            if self.default_flavour \
               not in iter_flavours(self.config, arch, featureset):
                raise RuntimeError("default-flavour %s for %s %s does not exist"
                                   % (self.default_flavour, arch, featureset))

        self.quick_flavour = self.config.merge('base', arch, featureset) \
                                        .get('quick-flavour')

    def do_flavour_setup(self, vars, makeflags, arch, featureset, flavour,
                         extra):
        super(Gencontrol, self).do_flavour_setup(vars, makeflags, arch,
                                                 featureset, flavour, extra)

        config_description = self.config.merge('description', arch, featureset,
                                               flavour)
        config_image = self.config.merge('image', arch, featureset, flavour)

        vars['flavour'] = vars['localversion'][1:]
        vars['class'] = config_description['hardware']
        vars['longclass'] = (config_description.get('hardware-long')
                             or vars['class'])

        vars['image-stem'] = config_image.get('install-stem')
        makeflags['IMAGE_INSTALL_STEM'] = vars['image-stem']

    def do_flavour_packages(self, arch, featureset,
                            flavour, vars, makeflags, extra):
        ruleid = (arch, featureset, flavour, 'real')

        config_build = self.config.merge('build', arch, featureset, flavour)
        if not config_build.get('signed-code', False):
            return

        # In a quick build, only build the quick flavour (if any).
        if 'pkg.linux.quick' in \
           os.environ.get('DEB_BUILD_PROFILES', '').split() \
           and flavour != self.quick_flavour:
            return

        image_suffix = '%(abiname)s%(localversion)s' % vars
        image_package_name = 'linux-image-%s-unsigned' % image_suffix

        # Verify that this flavour is configured to support Secure Boot,
        # and get the trusted certificates filename.
        with open('debian/%s/boot/config-%s' %
                  (image_package_name, image_suffix)) as f:
            kconfig = f.readlines()
        assert 'CONFIG_EFI_STUB=y\n' in kconfig
        assert 'CONFIG_LOCK_DOWN_IN_EFI_SECURE_BOOT=y\n' in kconfig
        cert_file_name = config_build['trusted-certs']
        self.image_packages.append((image_suffix, image_package_name,
                                    cert_file_name))

        self.packages['source']['Build-Depends'].append(
            image_package_name
            + ' (= %(imagebinaryversion)s) [%(arch)s]' % vars)

        packages_own = (
            self.bundle.add('image',
                            ruleid, makeflags, vars, arch=arch)
        )

        if self.config.merge('packages').get('meta', True):
            packages_meta = (
                self.bundle.add('image.meta', ruleid, makeflags, vars, arch=arch)
            )
            assert len(packages_meta) == 1
            packages_meta += (
                self.bundle.add('headers.meta', ruleid, makeflags, vars, arch=arch)
            )
            assert len(packages_meta) == 2

            # Don't pretend to support build-profiles
            for package in packages_meta:
                del package['Build-Profiles']

            if flavour == self.default_flavour \
               and not self.vars['source_suffix']:
                packages_meta[0].setdefault('Provides') \
                                .append('linux-image-generic')
                packages_meta[1].setdefault('Provides') \
                                .append('linux-headers-generic')

            packages_own.extend(packages_meta)

    def write(self):
        self.bundle.extract_makefile()
        self.write_changelog()
        self.write_control(name=(self.template_debian_dir + '/control'))
        self.write_makefile(name=(self.template_debian_dir + '/rules.gen'))
        self.write_files_json()
        self.write_source_lintian_overrides()

    def write_changelog(self):
        # Copy the linux changelog, but:
        # * Change the source package name and version
        # * Insert a line to refer to refer to the linux source version
        vars = self.vars.copy()
        vars['source'] = self.changelog[0].source
        vars['distribution'] = self.changelog[0].distribution
        vars['urgency'] = self.changelog[0].urgency
        vars['signedsourceversion'] = \
            re.sub(r'\+b(\d+)$', r'.b\1',
                   re.sub(r'-', r'+', vars['imagebinaryversion']))

        with open(self.template_debian_dir + '/changelog', 'w',
                  encoding='utf-8') as f:
            f.write(self.substitute('''\
linux-signed@source_suffix@-@arch@ (@signedsourceversion@) @distribution@; urgency=@urgency@

  * Sign kernel from @source@ @imagebinaryversion@

''',
                                    vars))

            with open('debian/changelog', 'r', encoding='utf-8') \
                 as changelog_in:
                # Ignore first two header lines
                changelog_in.readline()
                changelog_in.readline()

                for d in changelog_in.read():
                    f.write(d)

    def write_files_json(self):
        # Can't raise from a lambda function :-(
        def raise_func(e):
            raise e

        # Some functions in openssl work with multiple concatenated
        # PEM-format certificates, but others do not.
        def get_certs(file_name):
            certs = []
            BEGIN, MIDDLE = 0, 1
            state = BEGIN
            with open(file_name) as f:
                for line in f:
                    if line == '-----BEGIN CERTIFICATE-----\n':
                        assert state == BEGIN
                        certs.append([])
                        state = MIDDLE
                    elif line == '-----END CERTIFICATE-----\n':
                        assert state == MIDDLE
                        state = BEGIN
                    else:
                        assert line[0] != '-'
                        assert state == MIDDLE
                    certs[-1].append(line)
            assert state == BEGIN
            return [''.join(cert_lines) for cert_lines in certs]

        def get_cert_fingerprint(cert, algo):
            hasher = hashlib.new(algo)
            hasher.update(ssl.PEM_cert_to_DER_cert(cert))
            return hasher.hexdigest()

        all_files = {'packages': {}}

        for image_suffix, image_package_name, cert_file_name in \
                self.image_packages:
            package_dir = 'debian/%s' % image_package_name
            package_files = []
            package_modules = []
            package_files.append({'sig_type': 'efi',
                                  'file': 'boot/vmlinuz-%s' % image_suffix})
            for root, dirs, files in os.walk('%s/lib/modules' % package_dir,
                                             onerror=raise_func):
                for name in files:
                    if name.endswith('.ko'):
                        package_modules.append(
                            '%s/%s' %
                            (root[(len(package_dir) + 1):], name))
            package_modules.sort()
            for module in package_modules:
                package_files.append(
                    {'sig_type': 'linux-module',
                     'file': module})
            package_certs = [get_cert_fingerprint(cert, 'sha256')
                             for cert in get_certs(cert_file_name)]
            assert len(package_certs) >= 1
            all_files['packages'][image_package_name] = {
                'trusted_certs': package_certs,
                'files': package_files
            }

        with open(self.template_top_dir + '/files.json', 'w') as f:
            json.dump(all_files, f)

    def write_source_lintian_overrides(self):
        os.makedirs(os.path.join(self.template_debian_dir, 'source'),
                    exist_ok=True)
        with open(os.path.join(self.template_debian_dir,
                               'source/lintian-overrides'), 'w') as f:
            f.write(self.substitute(self.templates.get('source.lintian-overrides'),
                                    self.vars))


if __name__ == '__main__':
    Gencontrol(sys.argv[1])()