#!/usr/bin/env python

# Copyright 2015 Red Hat Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

from collections import defaultdict
import errno
import os
import sys
import yaml


_PARAM_FORMAT = u"""%(indent_space)s  # %(description)s
  %(mandatory)s%(indent_space)s# Type: %(type)s
  %(indent_space)s%(name)s:%(default)s
"""
_STATIC_MESSAGE_START = (
    '%(indent_space)s  # ******************************************************\n'
    '%(indent_space)s  # Static parameters - these are values that must be\n'
    '%(indent_space)s  # included in the environment but should not be changed.\n'
    '%(indent_space)s  # ******************************************************\n'
    )
_STATIC_MESSAGE_END = ('%(indent_space)s  # *********************\n'
                       '%(indent_space)s  # End static parameters\n'
                       '%(indent_space)s  # *********************\n'
                       )
_FILE_HEADER = (
    '# *******************************************************************\n'
    '# This file was created automatically by the sample environment\n'
    '# generator. Developers should use `tox -e genconfig` to update it.\n'
    '# Users are recommended to make changes to a copy of the file instead\n'
    '# of the original, if any customizations are needed.\n'
    '# *******************************************************************\n'
    )
_PARAMETERS = "parameters"
# Certain parameter names can't be changed, but shouldn't be shown because
# they are never intended for direct user input.
_PRIVATE_OVERRIDES = ['server', 'servers', 'NodeIndex']
# Hidden params are not included by default when the 'all' option is used,
# but can be explicitly included by referencing them in sample_defaults or
# static.  This allows us to generate sample environments using them when
# necessary, but they won't be improperly included by accident.
_HIDDEN_PARAMS = ['EndpointMap', 'RoleName', 'RoleParameters',
                  'ServiceNetMap', 'ServiceData',
                  ]


def _initialize_params_dict(params_dict, k, v):
    for role, param_name in params_dict.items():
        if k in param_name:
            params_dict[role][k]['sample'] = v


def _create_output_dir(target_file):
    try:
        os.makedirs(os.path.dirname(target_file))
    except OSError as e:
        if e.errno == errno.EEXIST:
            pass
        else:
            raise


def _generate_environment(input_env, output_path, parent_env=None):
    if parent_env is None:
        parent_env = {}
    env = dict(parent_env)
    env.pop('children', None)
    env.update(input_env)
    f_parameter_defaults = {}
    param_names = defaultdict(list)
    sample_values = env.get('sample_values', {})
    static_names = env.get('static', [])
    for template_file, template_data in env.get('files', {}).items():
        with open(template_file) as f:
            f_data = yaml.safe_load(f)
            f_params = f_data['parameters']
            f_parameter_defaults.update(f_params)
        for t_param_role, t_params in template_data.items():
            if t_params == 'all':
                new_names = [k for k, v in f_params.items()]
                for hidden in _HIDDEN_PARAMS:
                    if (hidden not in (static_names + list(sample_values)) and
                            hidden in new_names):
                        new_names.remove(hidden)
            else:
                new_names = t_params
            missing_params = [name for name in new_names
                              if name not in f_params]
            if missing_params:
                raise RuntimeError('Did not find specified parameter names %s '
                                   'in file %s for environment %s' %
                                   (missing_params, template_file,
                                    env['name']))
            param_names[t_param_role] += new_names

    static_defaults = defaultdict(dict)
    parameter_defaults = defaultdict(dict)
    for role, params in param_names.items():
        static_defaults[role] = {name: f_parameter_defaults[name]
                                 for name in params
                                 if name in f_parameter_defaults and
                                 name in static_names}
        parameter_defaults[role] = {name: f_parameter_defaults[name]
                                    for name in params
                                    if name in f_parameter_defaults and
                                    name not in _PRIVATE_OVERRIDES and
                                    not name.startswith('_') and
                                    name not in static_names}

    for k, v in sample_values.items():
        _initialize_params_dict(parameter_defaults, k, v)
        _initialize_params_dict(static_defaults, k, v)

    def write_sample_entry(f, name, value, indent_space_count=0):
        indent_space = " " * indent_space_count
        default = value.get('default')
        mandatory = ''
        if default is None:
            mandatory = ('# Mandatory. This parameter must be set by the '
                         'user.\n  ')
            default = '<None>'
        if value.get('sample') is not None:
            default = value['sample']
        # We ultimately cast this to str for output anyway
        default = str(default)
        if default == '':
            default = "''"
        # If the default value is something like %index%, yaml won't
        # parse the output correctly unless we wrap it in quotes.
        # However, not all default values can be wrapped so we need to
        # do it conditionally.
        if default.startswith('%'):
            default = "'%s'" % default
        if not default.startswith('\n'):
            default = ' ' + default

        values = {'name': name,
                  'type': value['type'],
                  'description':
                      value.get('description', '').rstrip().
                      replace('\n', '\n%s  # ' % indent_space).rstrip(),
                  'default': default,
                  'mandatory': mandatory,
                  'indent_space': indent_space,
                  }
        f.write(_PARAM_FORMAT % values + '\n')

    target_file = os.path.join(output_path, env['name'] + '.yaml')
    _create_output_dir(target_file)

    def write_params_entry(f, parameter_defaults_tuple, static_defaults_tuple, indent_space_count):
        for param_name, param_value in sorted(parameter_defaults_tuple.items()):
            write_sample_entry(f, param_name,
                               param_value, indent_space_count)
        if static_defaults_tuple:
            f.write(_STATIC_MESSAGE_START % {"indent_space": " " * indent_space_count})
            for param_name, param_value in sorted(static_defaults_tuple.items()):
                write_sample_entry(f, param_name,
                                   param_value, indent_space_count)
            f.write(_STATIC_MESSAGE_END % {"indent_space": " " * indent_space_count})

    with open(target_file, 'w') as env_file:
        env_file.write(_FILE_HEADER)
        # TODO(bnemec): Once Heat allows the title and description to live in
        # the environment itself, uncomment these entries and make them
        # top-level keys in the YAML.
        env_title = env.get('title', '')
        env_file.write(u'# title: %s\n' % env_title)
        env_desc = env.get('description', '')
        env_file.write(u'# description: |\n')
        for line in env_desc.splitlines():
            if line:
                env_file.write(u'#   %s\n' % line)
            else:
                env_file.write('#\n')
        if parameter_defaults or static_defaults:
            env_file.write(u'parameter_defaults:\n')
            write_params_entry(env_file, parameter_defaults[_PARAMETERS],
                               static_defaults[_PARAMETERS], 0)
            param_names.pop(_PARAMETERS, None)
            for name in param_names:
                env_file.write(u'  %s:\n' % name)
                write_params_entry(env_file, parameter_defaults[name],
                                   static_defaults[name], 2)
        if env.get('resource_registry'):
            env_file.write(u'resource_registry:\n')
        for res, value in sorted(env.get('resource_registry', {}).items()):
            env_file.write(u'  %s: %s\n' % (res, value))
        if env.get('parameter_merge_strategies'):
            env_file.write(u'parameter_merge_strategies:\n')
        for res, value in sorted(env.get('parameter_merge_strategies', {}).items()):
            env_file.write(u'  %s: %s\n' % (res, value))
        print('Wrote sample environment "%s"' % target_file)

    for e in env.get('children', []):
        _generate_environment(e, output_path, env)


def generate_environments(config_path, output_path):
    if os.path.isdir(config_path):
        config_files = os.listdir(config_path)
        config_files = [os.path.join(config_path, i) for i in config_files
                        if os.path.splitext(i)[1] == '.yaml']
    else:
        config_files = [config_path]
    for config_file in config_files:
        print('Reading environment definitions from %s' % config_file)
        with open(config_file) as f:
            config = yaml.safe_load(f)
        for env in config['environments']:
            _generate_environment(env, output_path)


def usage(exit_code=1):
    print('Usage: %s [<filename.yaml> | <directory>] [output path]' % sys.argv[0])
    print('Output path is optional and defaults to "environments"')
    sys.exit(exit_code)


def main():
    try:
        config_path = sys.argv[1]
    except IndexError:
        usage()
    if len(sys.argv) > 2:
        output_path = sys.argv[2]
    else:
        output_path = 'environments'
    print('Writing output to %s' % output_path)
    generate_environments(config_path, output_path)


if __name__ == '__main__':
    main()