#!/usr/bin/env python3

# Copyright (c) 2019 Egor Tensin <Egor.Tensin@gmail.com>
# This file is part of the "cmake-common" project.
# For details, see https://github.com/egor-tensin/cmake-common.
# Distributed under the MIT License.

# This script downloads and builds the Boost libraries.
# It's main utility is being able to download & unpack the Boost distribution
# archive in a cross-platform way + setting the correct --stagedir parameter
# value to avoid name clashes.

import abc
import argparse
from contextlib import contextmanager
from enum import Enum
import logging
import os.path
import platform
import re
import shutil
import subprocess
import sys
import tempfile
import urllib.request


@contextmanager
def _chdir(path):
    cwd = os.getcwd()
    os.chdir(path)
    try:
        yield
    finally:
        os.chdir(cwd)


def _setup_logging():
    logging.basicConfig(
        format='%(asctime)s | %(levelname)s | %(message)s',
        level=logging.INFO)


def _on_windows():
    return platform.system() == 'Windows'


def _run_executable(cmd_line):
    logging.info('Running executable: %s', cmd_line)
    return subprocess.run(cmd_line, check=True)


class Platform(Enum):
    X86 = 'x86'
    X64 = 'x64'
    WIN32 = 'Win32'

    def __str__(self):
        return self.value

    @staticmethod
    def all():
        return (Platform.X86, Platform.X64)

    def get_address_model(self):
        if self is Platform.X86:
            return 32
        if self is Platform.X64:
            return 64
        if self is Platform.WIN32:
            return 32
        raise NotImplementedError(f'unsupported platform: {self}')


def _parse_platform(s):
    try:
        return Platform(s)
    except ValueError:
        raise argparse.ArgumentTypeError(f'invalid platform: {s}')


class Configuration(Enum):
    DEBUG = 'Debug'
    RELEASE = 'Release'

    @staticmethod
    def all():
        return tuple(Configuration)

    def __str__(self):
        return self.value


def _parse_configuration(s):
    try:
        return Configuration(s)
    except ValueError:
        raise argparse.ArgumentTypeError(f'invalid configuration: {s}')


class BoostVersion:
    def __init__(self, major, minor, patch):
        self.major = major
        self.minor = minor
        self.patch = patch

    @staticmethod
    def from_string(s):
        result = re.match(r'^(\d+)\.(\d+)\.(\d+)$', s)
        if result is None:
            raise ValueError(f'invalid Boost version: {s}')
        return BoostVersion(result.group(1), result.group(2), result.group(3))

    def __str__(self):
        return f'{self.major}.{self.minor}.{self.patch}'

    @property
    def archive_ext(self):
        return '.tar.gz'

    def dir_path(self, parent_dir):
        return os.path.join(parent_dir, self.dir_name)

    @property
    def dir_name(self):
        return f'boost_{self.major}_{self.minor}_{self.patch}'

    @property
    def archive_name(self):
        return f'{self.dir_name}{self.archive_ext}'

    def get_download_url(self):
        return f'https://dl.bintray.com/boostorg/release/{self}/source/{self.archive_name}'


class BoostArchive:
    def __init__(self, version, path):
        self.version = version
        self.path = path

    @property
    def dir_name(self):
        return self.version.dir_name

    def unpack(self, dest_dir):
        path = os.path.join(dest_dir, self.dir_name)
        if os.path.exists(path):
            raise RuntimeError(f'Boost directory already exists: {path}')
        logging.info('Unpacking Boost to: %s', path)
        shutil.unpack_archive(self.path, dest_dir)
        return BoostDir(path)


class ArchiveStorage(abc.ABC):
    @contextmanager
    def download(self, version):
        path = self.get_archive(version)
        if path is not None:
            logging.info('Using existing Boost archive: %s', path)
            yield BoostArchive(version, path)
            return

        url = version.get_download_url()
        logging.info('Download URL: %s', url)

        with urllib.request.urlopen(url) as request:
            with self.write_archive(version, request.read()) as path:
                yield BoostArchive(version, path)

    @abc.abstractmethod
    def get_archive(self, version):
        pass

    @contextmanager
    @abc.abstractmethod
    def write_archive(self, version, contents):
        pass


class CacheStorage(ArchiveStorage):
    def __init__(self, cache_dir):
        self._dir = cache_dir

    def _archive_path(self, version):
        return os.path.join(self._dir, version.archive_name)

    def get_archive(self, version):
        path = self._archive_path(version)
        if os.path.exists(path):
            return path
        return None

    @contextmanager
    def write_archive(self, version, contents):
        path = self._archive_path(version)
        logging.info('Writing Boost archive: %s', path)
        if os.path.exists(path):
            raise RuntimeError(f'cannot download Boost, file already exists: {path}')
        with open(path, mode='w+b') as dest:
            dest.write(contents)
        yield path


class TempStorage(ArchiveStorage):
    def __init__(self, temp_dir):
        self._dir = temp_dir

    def get_archive(self, version):
        return None

    @contextmanager
    def write_archive(self, version, contents):
        with tempfile.NamedTemporaryFile(prefix=f'boost_{version}_', suffix=version.archive_ext, dir=self._dir, delete=False) as dest:
            path = dest.name
            logging.info('Writing Boost archive: %s', path)
            dest.write(contents)
        try:
            yield path
        finally:
            logging.info('Removing temporary Boost archive: %s', path)
            os.remove(path)


class BoostDir:
    def __init__(self, path):
        if not os.path.isdir(path):
            raise RuntimeError(f"Boost directory doesn't exist: {path}")
        self.path = path

    def _go(self):
        return _chdir(self.path)

    def build(self, params):
        with self._go():
            self._bootstrap_if_required()
            self._b2(params)

    def _bootstrap_if_required(self):
        if os.path.isfile(self._b2_path()):
            logging.info('Not going to bootstrap, b2 is already there')
            return
        self.bootstrap()

    def bootstrap(self):
        with self._go():
            _run_executable(self._bootstrap_path())

    def _b2(self, params):
        for b2_params in params.enum_b2_params():
            _run_executable([self._b2_path()] + b2_params)

    @staticmethod
    def _bootstrap_path():
        return os.path.join('.', BoostDir._bootstrap_name())

    @staticmethod
    def _bootstrap_name():
        ext = '.sh'
        if _on_windows():
            ext = '.bat'
        return f'bootstrap{ext}'

    @staticmethod
    def _b2_path():
        return os.path.join('.', BoostDir._b2_name())

    @staticmethod
    def _b2_name():
        ext = ''
        if _on_windows():
            ext = '.exe'
        return f'b2{ext}'


class BoostBuild:
    def __init__(self, args):
        self.platforms = args.platforms or Platform.all()
        self.configurations = args.configurations or Configuration.all()
        self.b2_args = args.b2_args

    def enum_b2_params(self):
        for platform in self.platforms:
            platform_params = []
            platform_params.append(self._address_model(platform))
            platform_params += self.b2_args
            if _on_windows():
                platform_params.append(self._windows_stagedir(platform))
                platform_params.append(self._windows_variant(self.configurations))
                yield platform_params
            else:
                for configuration in self.configurations:
                    variant_params = list(platform_params)
                    variant_params.append(self._unix_stagedir(platform, configuration))
                    variant_params.append(self._unix_variant(configuration))
                    yield variant_params

    @staticmethod
    def _address_model(platform):
        return f'address-model={platform.get_address_model()}'

    @staticmethod
    def _windows_stagedir(platform):
        return f'--stagedir=stage/{platform}'

    @staticmethod
    def _unix_stagedir(platform, configuration):
        return f'--stagedir=stage/{platform}/{configuration}'

    @staticmethod
    def _windows_variant(configurations):
        variant = ','.join((str(config).lower() for config in configurations))
        return f'variant={variant}'

    @staticmethod
    def _unix_variant(configuration):
        return f'variant={str(configuration).lower()}'


def _parse_args(argv=None):
    if argv is None:
        argv = sys.argv[1:]
    logging.info('Command line arguments: %s', argv)

    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers(dest='command')

    download = subparsers.add_parser('download', help='download & bootstrap Boost')
    download.add_argument('boost_version', metavar='VERSION',
                          type=BoostVersion.from_string,
                          help='Boost version (in the MAJOR.MINOR.PATCH format)')
    download.add_argument('--cache', metavar='DIR', dest='cache_dir',
                          type=os.path.abspath,
                          help='download directory (will download Boost to a temporary file and delete it unless specified)')
    download.add_argument('--unpack', metavar='DIR', dest='unpack_dir',
                          type=os.path.abspath, default='.',
                          help='directory to unpack Boost to')

    build = subparsers.add_parser('build', help='build Boost libraries')
    build.add_argument('--platform', metavar='PLATFORM',
                       nargs='*', dest='platforms', default=[],
                       type=_parse_platform,
                       help='target platform (e.g. x86/x64)')
    build.add_argument('--configuration', metavar='CONFIGURATION',
                       nargs='*', dest='configurations', default=[],
                       type=_parse_configuration,
                       help='target configuration (e.g. Debug/Release)')
    build.add_argument('boost_dir', metavar='DIR',
                       help='Boost root directory')
    build.add_argument('b2_args', nargs='*', metavar='B2_ARG', default=[],
                       help='additional b2 arguments, to be passed verbatim')

    return parser.parse_args(argv)


def build(args):
    build_params = BoostBuild(args)
    boost_dir = BoostDir(args.boost_dir)
    boost_dir.build(build_params)


def download(args):
    storage = TempStorage(args.unpack_dir)
    if args.cache_dir is not None:
        storage = CacheStorage(args.cache_dir)
    with storage.download(args.boost_version) as archive:
        boost_dir = archive.unpack(args.unpack_dir)
        boost_dir.bootstrap()


def main(argv=None):
    args = _parse_args(argv)
    if args.command == 'download':
        download(args)
    elif args.command == 'build':
        build(args)
    else:
        raise NotImplementedError(f'unsupported command: {args.command}')


def _main(argv=None):
    _setup_logging()
    try:
        main(argv)
    except Exception as e:
        logging.exception(e)
        raise


if __name__ == '__main__':
    _main()