# Copyright (C) 2012  Codethink Limited
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

import os

import morphlib


class BuildEnvironment():

    def __init__(self, settings, arch=None):
        self.arch = morphlib.util.arch() if arch is None else arch
        self.env = self._clean_env(settings)

    _osenv = os.environ
    _default_path = '/sbin:/usr/sbin:/bin:/usr/bin'
    _override_term = 'dumb'
    _override_shell = '/bin/sh'
    _override_username = 'tomjon'
    _override_locale = 'C'
    _override_home = '/tmp'
    _ccache_path = '/usr/lib/ccache'

    def _clean_env(self, settings):
        '''Create a fresh set of environment variables for a clean build.

        Return a dict with the new environment.

        '''

        path = self._osenv['PATH']

        # copy a set of white-listed variables from the original env
        copied_vars = dict.fromkeys([
            'BOOTSTRAP_TOOLS',
            'DISTCC_HOSTS',
            'LD_PRELOAD',
            'LD_LIBRARY_PATH',
            'FAKEROOTKEY',
            'FAKED_MODE',
            'FAKEROOT_FD_BASE',
        ])
        for name in copied_vars:
            copied_vars[name] = self._osenv.get(name, None)

        env = {}

        # apply the copied variables to the clean env
        for name in copied_vars:
            if copied_vars[name] is not None:
                env[name] = copied_vars[name]

        if settings['bootstrap'] or not settings['staging-chroot']:
            if 'TMPDIR' in self._osenv:
                env['TMPDIR'] = self._osenv['TMPDIR']

        env['TERM'] = self._override_term
        env['SHELL'] = self._override_shell
        env['USER'] = \
            env['USERNAME'] = \
            env['LOGNAME'] = self._override_username
        env['LC_ALL'] = self._override_locale
        env['HOME'] = self._override_home

        if settings['keep-path'] or settings['bootstrap']:
            env['PATH'] = path
        else:
            env['PATH'] = self._default_path

        env['TOOLCHAIN_TARGET'] = settings['toolchain-target']
        env['CFLAGS'] = settings['target-cflags']
        env['PREFIX'] = settings['prefix']
        env['BOOTSTRAP'] = 'true' if settings['bootstrap'] else 'false'
        if not settings['no-ccache']:
            env['PATH'] = ('%s:%s' % (self._ccache_path, env['PATH']))
# FIXME: we should set CCACHE_BASEDIR so any objects that refer to their
#        current directory get corrected. This improve the cache hit rate
#            env['CCACHE_BASEDIR'] = self.tempdir.dirname
            env['CCACHE_DIR'] = '/tmp/ccache'
            env['CCACHE_EXTRAFILES'] = ':'.join(
                f for f in ('/baserock/binutils.meta',
                            '/baserock/eglibc.meta',
                            '/baserock/gcc.meta') if os.path.exists(f)
            )
            if not settings['no-distcc']:
                env['CCACHE_PREFIX'] = 'distcc'

        return env