# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

# This script is used to capture the content of config.status-generated
# files and subsequently restore their timestamp if they haven't changed.

import argparse
import errno
import itertools
import os
import re
import subprocess
import sys
import pickle

import mozpack.path as mozpath


class Pool(object):
    def __new__(cls, size):
        try:
            import multiprocessing
            size = min(size, multiprocessing.cpu_count())
            return multiprocessing.Pool(size)
        except:
            return super(Pool, cls).__new__(cls)

    def imap_unordered(self, fn, iterable):
        return itertools.imap(fn, iterable)

    def close(self):
        pass

    def join(self):
        pass


class File(object):
    def __init__(self, path):
        self._path = path
        self._content = open(path, 'rb').read()
        stat = os.stat(path)
        self._times = (stat.st_atime, stat.st_mtime)

    @property
    def path(self):
        return self._path

    @property
    def mtime(self):
        return self._times[1]

    @property
    def modified(self):
        '''Returns whether the file was modified since the instance was
        created. Result is memoized.'''
        if hasattr(self, '_modified'):
            return self._modified

        modified = True
        if os.path.exists(self._path):
            if open(self._path, 'rb').read() == self._content:
                modified = False
        self._modified = modified
        return modified

    def update_time(self):
        '''If the file hasn't changed since the instance was created,
           restore its old modification time.'''
        if not self.modified:
            os.utime(self._path, self._times)


# As defined in the various sub-configures in the tree
PRECIOUS_VARS = set([
    'build_alias',
    'host_alias',
    'target_alias',
    'CC',
    'CFLAGS',
    'LDFLAGS',
    'LIBS',
    'CPPFLAGS',
    'CPP',
    'CCC',
    'CXXFLAGS',
    'CXX',
    'CCASFLAGS',
    'CCAS',
])


CONFIGURE_DATA = 'configure.pkl'


# Autoconf, in some of the sub-configures used in the tree, likes to error
# out when "precious" variables change in value. The solution it gives to
# straighten things is to either run make distclean or remove config.cache.
# There's no reason not to do the latter automatically instead of failing,
# doing the cleanup (which, on buildbots means a full clobber), and
# restarting from scratch.
def maybe_clear_cache(data):
    env = dict(data['env'])
    for kind in ('target', 'host', 'build'):
        arg = data[kind]
        if arg is not None:
            env['%s_alias' % kind] = arg
    # configure can take variables assignments in its arguments, and that
    # overrides whatever is in the environment.
    for arg in data['args']:
        if arg[:1] != '-' and '=' in arg:
            key, value = arg.split('=', 1)
            env[key] = value

    comment = re.compile(r'^\s+#')
    cache = {}
    with open(data['cache-file']) as f:
        for line in f:
            if not comment.match(line) and '=' in line:
                key, value = line.rstrip(os.linesep).split('=', 1)
                # If the value is quoted, unquote it
                if value[:1] == "'":
                    value = value[1:-1].replace("'\\''", "'")
                cache[key] = value
    for precious in PRECIOUS_VARS:
        # If there is no entry at all for that precious variable, then
        # its value is not precious for that particular configure.
        if 'ac_cv_env_%s_set' % precious not in cache:
            continue
        is_set = cache.get('ac_cv_env_%s_set' % precious) == 'set'
        value = cache.get('ac_cv_env_%s_value' % precious) if is_set else None
        if value != env.get(precious):
            print 'Removing %s because of %s value change from:' \
                % (data['cache-file'], precious)
            print '  %s' % (value if value is not None else 'undefined')
            print 'to:'
            print '  %s' % env.get(precious, 'undefined')
            os.remove(data['cache-file'])
            return True
    return False


def split_template(s):
    """Given a "file:template" string, returns "file", "template". If the string
    is of the form "file" (without a template), returns "file", "file.in"."""
    if ':' in s:
        return s.split(':', 1)
    return s, '%s.in' % s


def get_config_files(data):
    config_status = mozpath.join(data['objdir'], 'config.status')
    if not os.path.exists(config_status):
        return [], []

    configure = mozpath.join(data['srcdir'], 'configure')
    config_files = []
    command_files = []

    # Scan the config.status output for information about configuration files
    # it generates.
    config_status_output = subprocess.check_output(
        [data['shell'], '-c', '%s --help' % config_status],
        stderr=subprocess.STDOUT).splitlines()
    state = None
    for line in config_status_output:
        if line.startswith('Configuration') and line.endswith(':'):
            if line.endswith('commands:'):
                state = 'commands'
            else:
                state = 'config'
        elif not line.strip():
            state = None
        elif state:
            for f, t in (split_template(couple) for couple in line.split()):
                f = mozpath.join(data['objdir'], f)
                t = mozpath.join(data['srcdir'], t)
                if state == 'commands':
                    command_files.append(f)
                else:
                    config_files.append((f, t))

    return config_files, command_files


def prepare(srcdir, objdir, shell, args):
    parser = argparse.ArgumentParser()
    parser.add_argument('--target', type=str)
    parser.add_argument('--host', type=str)
    parser.add_argument('--build', type=str)
    parser.add_argument('--cache-file', type=str)
    # The --srcdir argument is simply ignored. It's a useless autoconf feature
    # that we don't support well anyways. This makes it stripped from `others`
    # and allows to skip setting it when calling the subconfigure (configure
    # will take it from the configure path anyways).
    parser.add_argument('--srcdir', type=str)

    data_file = os.path.join(objdir, CONFIGURE_DATA)
    previous_args = None
    if os.path.exists(data_file):
        with open(data_file, 'rb') as f:
            data = pickle.load(f)
            previous_args = data['args']

    # Msys likes to break environment variables and command line arguments,
    # so read those from stdin, as they are passed from the configure script
    # when necessary (on windows).
    # However, for some reason, $PATH is not handled like other environment
    # variables, and msys remangles it even when giving it is already a msys
    # $PATH. Fortunately, the mangling/demangling is just find for $PATH, so
    # we can just take the value from the environment. Msys will convert it
    # back properly when calling subconfigure.
    input = sys.stdin.read()
    if input:
        data = {a: b for [a, b] in eval(input)}
        environ = {a: b for a, b in data['env']}
        environ['PATH'] = os.environ['PATH']
        args = data['args']
    else:
        environ = os.environ

    args, others = parser.parse_known_args(args)

    data = {
        'target': args.target,
        'host': args.host,
        'build': args.build,
        'args': others,
        'shell': shell,
        'srcdir': srcdir,
        'env': environ,
    }

    if args.cache_file:
        data['cache-file'] = mozpath.normpath(mozpath.join(os.getcwd(),
            args.cache_file))
    else:
        data['cache-file'] = mozpath.join(objdir, 'config.cache')

    if previous_args is not None:
        data['previous-args'] = previous_args

    try:
        os.makedirs(objdir)
    except OSError as e:
        if e.errno != errno.EEXIST:
            raise

    with open(data_file, 'wb') as f:
        pickle.dump(data, f)


def prefix_lines(text, prefix):
    return ''.join('%s> %s' % (prefix, line) for line in text.splitlines(True))


def run(objdir):
    ret = 0
    output = ''

    with open(os.path.join(objdir, CONFIGURE_DATA), 'rb') as f:
        data = pickle.load(f)

    data['objdir'] = objdir

    cache_file = data['cache-file']
    cleared_cache = True
    if os.path.exists(cache_file):
        cleared_cache = maybe_clear_cache(data)

    config_files, command_files = get_config_files(data)
    contents = []
    for f, t in config_files:
        contents.append(File(f))

    # AC_CONFIG_COMMANDS actually only registers tags, not file names
    # but most commands are tagged with the file name they create.
    # However, a few don't, or are tagged with a directory name (and their
    # command is just to create that directory)
    for f in command_files:
        if os.path.isfile(f):
            contents.append(File(f))

    # Only run configure if one of the following is true:
    # - config.status doesn't exist
    # - config.status is older than configure
    # - the configure arguments changed
    # - the environment changed in a way that requires a cache clear.
    configure = mozpath.join(data['srcdir'], 'configure')
    config_status_path = mozpath.join(objdir, 'config.status')
    skip_configure = True
    if not os.path.exists(config_status_path):
        skip_configure = False
        config_status = None
    else:
        config_status = File(config_status_path)
        if config_status.mtime < os.path.getmtime(configure) or \
                data.get('previous-args', data['args']) != data['args'] or \
                cleared_cache:
            skip_configure = False

    relobjdir = os.path.relpath(objdir, os.getcwd())

    if not skip_configure:
        command = [data['shell'], configure]
        for kind in ('target', 'build', 'host'):
            if data.get(kind) is not None:
                command += ['--%s=%s' % (kind, data[kind])]
        command += data['args']
        command += ['--cache-file=%s' % cache_file]

        # Pass --no-create to configure so that it doesn't run config.status.
        # We're going to run it ourselves.
        command += ['--no-create']

        print prefix_lines('configuring', relobjdir)
        print prefix_lines('running %s' % ' '.join(command[:-1]), relobjdir)
        sys.stdout.flush()
        try:
            output += subprocess.check_output(command,
                stderr=subprocess.STDOUT, cwd=objdir, env=data['env'])
        except subprocess.CalledProcessError as e:
            return relobjdir, e.returncode, e.output

        # Leave config.status with a new timestamp if configure is newer than
        # its original mtime.
        if config_status and os.path.getmtime(configure) <= config_status.mtime:
            config_status.update_time()

    # Only run config.status if one of the following is true:
    # - config.status changed or did not exist
    # - one of the templates for config files is newer than the corresponding
    #   config file.
    skip_config_status = True
    if not config_status or config_status.modified:
        # If config.status doesn't exist after configure (because it's not
        # an autoconf configure), skip it.
        if os.path.exists(config_status_path):
            skip_config_status = False
    else:
        # config.status changed or was created, so we need to update the
        # list of config and command files.
        config_files, command_files = get_config_files(data)
        for f, t in config_files:
            if not os.path.exists(t) or \
                    os.path.getmtime(f) < os.path.getmtime(t):
                skip_config_status = False

    if not skip_config_status:
        if skip_configure:
            print prefix_lines('running config.status', relobjdir)
            sys.stdout.flush()
        try:
            output += subprocess.check_output([data['shell'], '-c',
                './config.status'], stderr=subprocess.STDOUT, cwd=objdir,
                env=data['env'])
        except subprocess.CalledProcessError as e:
            ret = e.returncode
            output += e.output

        for f in contents:
            f.update_time()

    return relobjdir, ret, output


def subconfigure(args):
    parser = argparse.ArgumentParser()
    parser.add_argument('--list', type=str,
        help='File containing a list of subconfigures to run')
    parser.add_argument('--skip', type=str,
        help='File containing a list of Subconfigures to skip')
    parser.add_argument('subconfigures', type=str, nargs='*',
        help='Subconfigures to run if no list file is given')
    args, others = parser.parse_known_args(args)
    subconfigures = args.subconfigures
    if args.list:
        subconfigures.extend(open(args.list, 'rb').read().splitlines())
    if args.skip:
        skips = set(open(args.skip, 'rb').read().splitlines())
        subconfigures = [s for s in subconfigures if s not in skips]

    if not subconfigures:
        return 0

    ret = 0
    # One would think using a ThreadPool would be faster, considering
    # everything happens in subprocesses anyways, but no, it's actually
    # slower on Windows. (20s difference overall!)
    pool = Pool(len(subconfigures))
    for relobjdir, returncode, output in \
            pool.imap_unordered(run, subconfigures):
        print prefix_lines(output, relobjdir)
        sys.stdout.flush()
        ret = max(returncode, ret)
        if ret:
            break
    pool.close()
    pool.join()
    return ret


def main(args):
    if args[0] != '--prepare':
        return subconfigure(args)

    topsrcdir = os.path.abspath(args[1])
    subdir = args[2]
    # subdir can be of the form srcdir:objdir
    if ':' in subdir:
        srcdir, subdir = subdir.split(':', 1)
    else:
        srcdir = subdir
    srcdir = os.path.join(topsrcdir, srcdir)
    objdir = os.path.abspath(subdir)

    return prepare(srcdir, objdir, args[3], args[4:])


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