#!/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.

'''Download & build Boost.

This script downloads and builds the Boost libraries.  It's main purpose is to:
1) provide a cross-platform way to download & unpack the Boost distribution
archive,
2) set the correct --stagedir parameter value to avoid name clashes.

Please pick a command below.  You can execute `%(prog)s COMMAND --help` to view
its usage message.

A simple usage example:

    $ %(prog)s download 1.71.0
    ...

    $ %(prog)s build -- boost_1_71_0/ --with-filesystem --with-program_options
    ...
'''

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

from project.boost.version import Version
from project.configuration import Configuration
from project.linkage import Linkage
from project.platform import Platform


@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 _on_linux():
    return not _on_windows()


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


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

        urls = version.get_download_urls()

        for url in urls:
            logging.info('Trying URL: %s', url)
            try:
                with urllib.request.urlopen(url, timeout=20) as request:
                    with self.write_archive(version, request.read()) as path:
                        yield BoostArchive(version, path)
                        return
            except urllib.request.URLError as e:
                logging.error("Couldn't download from this mirror, an error occured:")
                logging.exception(e)

        raise RuntimeError("Couldn't download Boost from any of the mirrors")

    @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_args():
            _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 BuildParameters:
    def __init__(self, args):
        self.platforms = args.platforms or Platform.all()
        self.configurations = args.configurations or Configuration.all()
        self.link = args.link or Linkage.all()
        self.runtime_link = args.runtime_link

        self.stage_dir = 'stage'

        self.build_dir = args.build_dir
        self.boost_dir = args.boost_dir

        self.b2_args = args.b2_args

    def enum_b2_args(self):
        with self._create_build_dir() as build_dir:
            for platform in self.platforms:
                for configuration in self.configurations:
                    for link, runtime_link in self._linkage_options():
                        yield self._build_params(build_dir, platform, configuration, link, runtime_link)

    def _linkage_options(self):
        for link in self.link:
            runtime_link = self.runtime_link
            if runtime_link is Linkage.STATIC:
                if link is Linkage.SHARED:
                    logging.warning("Cannot link the runtime statically to a dynamic library, going to link dynamically")
                    runtime_link = Linkage.SHARED
                elif _on_linux():
                    logging.warning("Cannot link to the GNU C Library (which is assumed) statically, going to link dynamically")
                    runtime_link = Linkage.SHARED
            yield link, runtime_link

    @contextmanager
    def _create_build_dir(self):
        if self.build_dir is not None:
            logging.info('Build directory: %s', self.build_dir)
            yield self.build_dir
            return

        with tempfile.TemporaryDirectory(dir=os.path.dirname(self.boost_dir)) as build_dir:
            logging.info('Build directory: %s', build_dir)
            try:
                yield build_dir
            finally:
                logging.info('Removing build directory: %s', build_dir)
            return

    def _build_params(self, build_dir, platform, configuration, link, runtime_link):
        params = []
        params.append(self._build_dir(build_dir))
        params.append(self._stagedir(platform, configuration))
        params.append(self._link(link))
        params.append(self._runtime_link(runtime_link))
        params.append(self._address_model(platform))
        params.append(self._variant(configuration))
        params += self.b2_args
        return params

    @staticmethod
    def _build_dir(build_dir):
        return f'--build-dir={build_dir}'

    def _stagedir(self, platform, configuration):
        # Having different --stagedir values for every configuration/platform
        # combination is unnecessary on Windows.
        # Even for older Boost versions (when the binaries weren't tagged with
        # their target platform) only a single --stagedir for every platform
        # would suffice.
        # For newer versions, just a single --stagedir would do, as the
        # binaries are tagged with the target platform, as well as their
        # configuration (a.k.a. "variant" in Boost's terminology).
        # Still, uniformity helps.
        platform = str(platform)
        configuration = str(configuration)
        return f'--stagedir={os.path.join(self.stage_dir, platform, configuration)}'

    @staticmethod
    def _link(link):
        return f'link={link}'

    @staticmethod
    def _runtime_link(runtime_link):
        return f'runtime-link={runtime_link}'

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

    @staticmethod
    def _variant(configuration):
        return f'variant={configuration.to_boost_variant()}'


def _parse_dir(s):
    return os.path.abspath(os.path.normpath(s))


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

    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter)

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

    download = subparsers.add_parser('download', help='download & bootstrap Boost')

    download.add_argument('--cache', metavar='DIR', dest='cache_dir',
                          type=_parse_dir,
                          help='download directory (temporary file unless specified)')
    download.add_argument('--unpack', metavar='DIR', dest='unpack_dir',
                          type=_parse_dir, default='.',
                          help='directory to unpack the archive to')
    download.add_argument('boost_version', metavar='VERSION',
                          type=Version.from_string,
                          help='Boost version (in the MAJOR.MINOR.PATCH format)')

    build = subparsers.add_parser('build', help='build the libraries')

    # These are used to put the built libraries into proper stage/
    # subdirectories (to avoid name clashes).
    build.add_argument('--platform', metavar='PLATFORM',
                       nargs='*', dest='platforms', default=[],
                       type=Platform.parse,
                       help=f'target platform ({"/".join(map(str, Platform))})')
    build.add_argument('--configuration', metavar='CONFIGURATION',
                       nargs='*', dest='configurations', default=[],
                       type=Configuration.parse,
                       help=f'target configuration ({"/".join(map(str, Configuration))})')
    # This is needed because the default behaviour on Linux and Windows is
    # different: static & dynamic libs are built on Linux, but only static libs
    # are built on Windows by default.
    build.add_argument('--link', metavar='LINKAGE',
                       nargs='*', default=[],
                       type=Linkage.parse,
                       help=f'how the libraries are linked ({"/".join(map(str, Linkage))})')
    # This is used to omit runtime-link=static I'd have to otherwise use a lot,
    # plus the script validates the link= and runtime-link= combinations.
    build.add_argument('--runtime-link', metavar='LINKAGE',
                       type=Linkage.parse, default=Linkage.STATIC,
                       help=f'how the libraries link to the runtime ({"/".join(map(str, Linkage))})')

    build.add_argument('--build', metavar='DIR', dest='build_dir',
                       type=_parse_dir,
                       help='Boost build directory (temporary directory unless specified)')
    build.add_argument('boost_dir', metavar='DIR',
                       type=_parse_dir,
                       help='root Boost directory')

    build.add_argument('b2_args', nargs='*', metavar='B2_ARG', default=[],
                       help='additional b2 arguments, to be passed verbatim')

    args = parser.parse_args(argv)
    if args.command is None:
        parser.error("please specify a command")
    return args


def build(args):
    build_params = BuildParameters(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()