#!/usr/bin/env python
# Copyright (C) 2016  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, see <http://www.gnu.org/licenses/>.

'''Baserock Definitions configuration script.

This generates various .morph files from corresponding .morph.in files. The
.morph.in files should use Jinja2 syntax to use the configuration parameters.

There are predefined configurations you can use, for example 'x86_64-generic':

    ./configure x86_64-generic

Run `./configure --list-configs` for a full list of these.

You can also define your own configuration, but the name must not clash with
any of the built-in ones. For example:

    ./configure jetson-be --arch=armv7b

The generated .morph files are named like `name.{{CONFIG}}.morph`; for example
`build-system.x86_64-generic.morph`. This means you can have as many
configurations set up in parallel as you want, as long as the names don't
clash.

The 'configure' tool saves your configurations to a hidden file, and will
point out when you change an existing configuration.

For information on the Jinja2 templating language, see:

    <http://jinja.pocoo.org/docs/dev/templates/>

To add a new config setting, add it to the PARAMETERS dictionary, and possibly
add a new named configuration that uses it in the NAMED_CONFIGS list.

'''

import jinja2

import argparse
import json
import os
import sys
import tempfile


DEFAULT_ARCH = os.uname()[-1]


# All known configuration parameters. Names should be uppercase with _ to
# separate words. Each one is converted to a commandline option, these will
# be lowercase and use - to separate words. Properties are the same as for
# the 'argparse' module.
PARAMETERS = {
    'ARCH': dict(
        type=str, default=DEFAULT_ARCH,
        help="set architecture (default: %(default)s)",
    ),
    'BSP': dict(
        type=str, default=os.uname()[-1],
        help="set 'board support' stratum (default: %(default)s)",
    ),
    'ENABLE_VAGRANT_BASEBOX': dict(
        type=bool, default=False,
        help="configure systems that support it to work as Vagrant baseboxes",
    ),
}


def compare_configs(a, b):
    '''Compare two configuration dicts.

    Unset values are filled in from the defaults in PARAMETERS.

    '''
    for key in set(a.keys()).union(set(b.keys())):
        default = PARAMETERS[key].get('default')
        if a.get(key, default) != b.get(key, default):
            return False
    return True


# A list of predefined configurations. Users aren't allowed to use these names
# for other configurations. The idea of this is that users can report a failure
# in a specific config ('jetson', for example) and we will know exactly what
# the generated .morph file they are building should contain.
#
# Bear in mind that the Baserock reference systems are examples. Configurations
# listed here probably worked at some point, but they may not work now without
NAMED_CONFIGS = {
    'armv7b-highbank': dict(
        ARCH='armv7b', BSP='armv7b-highbank'),
    'armv7b-vexpress-tc2': dict(
        ARCH='armv7b', BSP='armv7b-vexpress-tc2'),
    'armv7l-altera-socfpga-devkit': dict(
        ARCH='armv7l', BSP='armv7l-altera-socfpga-devkit'),
    'armv7l-versatile': dict(
        ARCH='armv7l', BSP='armv7-versatile'),
    'armv7lhf-chroot': dict(
        ARCH='armv7lhf', BSP=None),
    'armv7lhf-highbank': dict(
        ARCH='armv7lhf', BSP='armv7-highbank'),
    'armv8b64-generic': dict(
        ARCH='armv8b64', BSP='armv8b64-generic'),
    'armv8l64-generic': dict(
        ARCH='armv8l64', BSP='armv8l64-generic'),
    'jetson': dict(
        ARCH='armv7lhf', BSP='jetson'),
    'openbmc-aspeed': dict(
        ARCH='armv5l', BSP='armv5l-openbmc-aspeed'),
    'ppc64-chroot': dict(
        ARCH='ppc64', BSP=None),
    'ppc64-generic': dict(
        ARCH='ppc64', BSP='ppc64-generic'),
    'wandboard': dict(
        ARCH='armv7lhf', BSP='wandboard'),
    'x86_32-chroot': dict(
        ARCH='x86_32', BSP=None),
    'x86_32-generic': dict(
        ARCH='x86_32', BSP='x86_32-generic'),
    'x86_64-chroot': dict(
        ARCH='x86_64', BSP=None),
    'x86_64-generic': dict(
        ARCH='x86_64', BSP='x86_64-generic'),
    'x86_64-vagrant': dict(
        ARCH='x86_64', BSP='x86_64-vagrant', ENABLE_VAGRANT_BASEBOX=True),
}


def argument_parser():
    '''Generate a commandline argument parser for `configure`.

    The values from PARAMETERS are turned into proper commandline arguments.

    '''
    parser = argparse.ArgumentParser(
        description="Baserock Definitions configure script")

    parser.add_argument(
        'name', nargs='?',
        help="name of this configuration")

    class list_all_configs_and_exit(argparse.Action):
        def __call__(*args, **kwargs):
            sys.stdout.write('Built-in configurations:\n  ')
            sys.stdout.write('\n  '.join(sorted(name for name in NAMED_CONFIGS)))
            sys.stdout.write('\n')
            sys.exit(0)

    parser.add_argument(
        '--list-configs', '-l', nargs=0, action=list_all_configs_and_exit,
        help="list all named configurations")

    parser.add_argument(
        '--output-dir', '-o',
        help="directory to output generated files to (default: current dir)",
        default='.', metavar='DIR')

    def config_var_to_arg(name):
        return '--' + name.lower().replace('_', '-')

    for name, settings in PARAMETERS.iteritems():
        if settings['type'] == bool:
            # argparse handles true/false parameters in a 'special' way.
            argparse_settings = settings.copy()
            del argparse_settings['type']
            if settings['default'] == True:
                argparse_settings['action'] = 'store_false'
            elif settings['default'] == False:
                argparse_settings['action'] = 'store_true'
            parser.add_argument(
                config_var_to_arg(name), **argparse_settings)
        else:
            parser.add_argument(
                config_var_to_arg(name), **settings)

    return parser


class SaveFile(file):
    '''Save files with a temporary name and rename when they're ready.'''

    def __init__(self, filename, *args, **kwargs):
        self.real_filename = filename
        dirname = os.path.dirname(filename)
        fd, self._savefile_tempname = tempfile.mkstemp(dir=dirname)
        os.close(fd)
        file.__init__(self, self._savefile_tempname, *args, **kwargs)

    def abort(self):
        os.remove(self._savefile_tempname)
        return file.close(self)

    def close(self):
        ret = file.close(self)
        os.rename(self._savefile_tempname, self.real_filename)
        return ret


def status(message, *args):
    print(message % args)


def get_jinja_vars(args):
    '''Work out the actual configuration values we should be using.

    If a named configuration was specified, we use that.

    '''
    if args.name and args.name in NAMED_CONFIGS:
        jinja_vars = NAMED_CONFIGS[args.name]

        # We don't allow customising these configurations.
        for param_name, param_settings in PARAMETERS.items():
            value = getattr(args, param_name.lower())
            expected_value = param_settings.get('default')
            if value != expected_value:
                raise RuntimeError(
                    "Please specify a custom name for this configuration, or "
                    "use the expected value for %s: %s" % (
                        param_name, NAMED_CONFIGS[args.name][param_name]))
            if param_name not in jinja_vars:
                jinja_vars[param_name] = expected_value

        jinja_vars['CONFIG'] = args.name
    else:
        jinja_vars = {}

        for param_name, param_settings in PARAMETERS.items():
            value = getattr(args, param_name.lower())
            jinja_vars[param_name] = value

        if args.name:
            jinja_vars['CONFIG'] = args.name
        else:
            # If this config matches a built-in one, use that name
            for name, config in NAMED_CONFIGS.items():
                if jinja_vars == config:
                    jinja_vars['CONFIG'] = name
                    break
            else:
                raise RuntimeError(
                    "Please specify a name for this configuration, or use one of "
                    "the built-in configurations (use `-l` to get a list).")

    return jinja_vars


def generate(environment, input_path, output_dir, jinja_vars):
    '''Generate a .morph file from a .morph.in file, using Jinja2.'''
    base_name = os.path.basename(input_path[:-len('.morph.in')])
    output_name = base_name + '.' + jinja_vars['CONFIG'] + '.morph'
    output_path = os.path.join(output_dir, output_name)

    try:
        input_file = environment.get_template(input_path)
    except jinja2.exceptions.TemplateSyntaxError as e:
        raise RuntimeError("%s:%i: %s" % (e.filename, e.lineno, e))

    with SaveFile(output_path, 'w') as f:
        f.write('# Generated from %s\n' % input_path)
        f.write(input_file.render(**jinja_vars) + '\n')
        f.write('# Generated from %s\n' % input_path)


def main():
    args = argument_parser().parse_args()

    output_dir = args.output_dir or '.'

    jinja_vars = get_jinja_vars(args)
    config_name = jinja_vars['CONFIG']

    if not os.path.isdir(output_dir):
        os.mkdir(output_dir)

    configs_file = os.path.join(output_dir, '.configurations')
    try:
        with open(configs_file, 'r') as f:
            existing_configs = json.load(f)
    except (IOError, ValueError) as e:
        existing_configs = dict()

    loader = jinja2.FileSystemLoader('.')
    environment = jinja2.Environment(loader=loader)

    if config_name in existing_configs:
        status("Regenerating '%s' configuration:" % config_name)
        existing_config = existing_configs[config_name]
    else:
        status("Generating '%s' configuration:" % config_name)
        existing_configs = None

    for var, value in jinja_vars.items():
        if var != 'CONFIG':
            if var in existing_config and existing_config[var] != value:
                status("  %s: %s (was: %s)" % (var, value,
                                               existing_config[var]))
            else:
                status("  %s: %s" % (var, value))

    for dirpath, dirnames, filenames in os.walk('.'):
        for f in filenames:
            if f.endswith('.morph.in'):
                input_path = os.path.join(dirpath, f)

                generate (environment, input_path,
                          os.path.join(output_dir, dirpath), jinja_vars)

    existing_configs[config_name] = jinja_vars
    with SaveFile(configs_file, 'w') as f:
        json.dump(existing_configs, f)


try:
    main()
except RuntimeError as e:
    sys.stderr.write("%s\n" % e)
    sys.exit(1)