# -*- coding: utf-8 -*-
# Copyright 2014, 2015 OpenMarket Ltd
#
# 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.

import argparse
import errno
import os
import yaml
import sys
from textwrap import dedent


class ConfigError(Exception):
    pass


MISSING_REPORT_STATS_CONFIG_INSTRUCTIONS = """\
Please opt in or out of reporting anonymized homeserver usage statistics, by
setting the `report_stats` key in your config file to either True or False.
"""

MISSING_REPORT_STATS_SPIEL = """\
We would really appreciate it if you could help our project out by reporting
anonymized usage statistics from your homeserver. Only very basic aggregate
data (e.g. number of users) will be reported, but it helps us to track the
growth of the Matrix community, and helps us to make Matrix a success, as well
as to convince other networks that they should peer with us.

Thank you.
"""

MISSING_SERVER_NAME = """\
Missing mandatory `server_name` config option.
"""


class Config(object):
    @staticmethod
    def parse_size(value):
        if isinstance(value, int) or isinstance(value, long):
            return value
        sizes = {"K": 1024, "M": 1024 * 1024}
        size = 1
        suffix = value[-1]
        if suffix in sizes:
            value = value[:-1]
            size = sizes[suffix]
        return int(value) * size

    @staticmethod
    def parse_duration(value):
        if isinstance(value, int) or isinstance(value, long):
            return value
        second = 1000
        hour = 60 * 60 * second
        day = 24 * hour
        week = 7 * day
        year = 365 * day
        sizes = {"s": second, "h": hour, "d": day, "w": week, "y": year}
        size = 1
        suffix = value[-1]
        if suffix in sizes:
            value = value[:-1]
            size = sizes[suffix]
        return int(value) * size

    @staticmethod
    def abspath(file_path):
        return os.path.abspath(file_path) if file_path else file_path

    @classmethod
    def check_file(cls, file_path, config_name):
        if file_path is None:
            raise ConfigError(
                "Missing config for %s."
                " You must specify a path for the config file. You can "
                "do this with the -c or --config-path option. "
                "Adding --generate-config along with --server-name "
                "<server name> will generate a config file at the given path."
                % (config_name,)
            )
        if not os.path.exists(file_path):
            raise ConfigError(
                "File %s config for %s doesn't exist."
                " Try running again with --generate-config"
                % (file_path, config_name,)
            )
        return cls.abspath(file_path)

    @classmethod
    def ensure_directory(cls, dir_path):
        dir_path = cls.abspath(dir_path)
        try:
            os.makedirs(dir_path)
        except OSError, e:
            if e.errno != errno.EEXIST:
                raise
        if not os.path.isdir(dir_path):
            raise ConfigError(
                "%s is not a directory" % (dir_path,)
            )
        return dir_path

    @classmethod
    def read_file(cls, file_path, config_name):
        cls.check_file(file_path, config_name)
        with open(file_path) as file_stream:
            return file_stream.read()

    @staticmethod
    def default_path(name):
        return os.path.abspath(os.path.join(os.path.curdir, name))

    @staticmethod
    def read_config_file(file_path):
        with open(file_path) as file_stream:
            return yaml.load(file_stream)

    def invoke_all(self, name, *args, **kargs):
        results = []
        for cls in type(self).mro():
            if name in cls.__dict__:
                results.append(getattr(cls, name)(self, *args, **kargs))
        return results

    def generate_config(self, config_dir_path, server_name, report_stats=None):
        default_config = "# vim:ft=yaml\n"

        default_config += "\n\n".join(dedent(conf) for conf in self.invoke_all(
            "default_config",
            config_dir_path=config_dir_path,
            server_name=server_name,
            report_stats=report_stats,
        ))

        config = yaml.load(default_config)

        return default_config, config

    @classmethod
    def load_config(cls, description, argv, generate_section=None):
        obj = cls()

        config_parser = argparse.ArgumentParser(add_help=False)
        config_parser.add_argument(
            "-c", "--config-path",
            action="append",
            metavar="CONFIG_FILE",
            help="Specify config file. Can be given multiple times and"
                 " may specify directories containing *.yaml files."
        )
        config_parser.add_argument(
            "--generate-config",
            action="store_true",
            help="Generate a config file for the server name"
        )
        config_parser.add_argument(
            "--report-stats",
            action="store",
            help="Stuff",
            choices=["yes", "no"]
        )
        config_parser.add_argument(
            "--generate-keys",
            action="store_true",
            help="Generate any missing key files then exit"
        )
        config_parser.add_argument(
            "--keys-directory",
            metavar="DIRECTORY",
            help="Used with 'generate-*' options to specify where files such as"
                 " certs and signing keys should be stored in, unless explicitly"
                 " specified in the config."
        )
        config_parser.add_argument(
            "-H", "--server-name",
            help="The server name to generate a config file for"
        )
        config_args, remaining_args = config_parser.parse_known_args(argv)

        generate_keys = config_args.generate_keys

        config_files = []
        if config_args.config_path:
            for config_path in config_args.config_path:
                if os.path.isdir(config_path):
                    # We accept specifying directories as config paths, we search
                    # inside that directory for all files matching *.yaml, and then
                    # we apply them in *sorted* order.
                    files = []
                    for entry in os.listdir(config_path):
                        entry_path = os.path.join(config_path, entry)
                        if not os.path.isfile(entry_path):
                            print (
                                "Found subdirectory in config directory: %r. IGNORING."
                            ) % (entry_path, )
                            continue

                        if not entry.endswith(".yaml"):
                            print (
                                "Found file in config directory that does not"
                                " end in '.yaml': %r. IGNORING."
                            ) % (entry_path, )
                            continue

                        files.append(entry_path)

                    config_files.extend(sorted(files))
                else:
                    config_files.append(config_path)

        if config_args.generate_config:
            if config_args.report_stats is None:
                config_parser.error(
                    "Please specify either --report-stats=yes or --report-stats=no\n\n" +
                    MISSING_REPORT_STATS_SPIEL
                )
            if not config_files:
                config_parser.error(
                    "Must supply a config file.\nA config file can be automatically"
                    " generated using \"--generate-config -H SERVER_NAME"
                    " -c CONFIG-FILE\""
                )
            (config_path,) = config_files
            if not os.path.exists(config_path):
                if config_args.keys_directory:
                    config_dir_path = config_args.keys_directory
                else:
                    config_dir_path = os.path.dirname(config_path)
                config_dir_path = os.path.abspath(config_dir_path)

                server_name = config_args.server_name
                if not server_name:
                    print "Must specify a server_name to a generate config for."
                    sys.exit(1)
                if not os.path.exists(config_dir_path):
                    os.makedirs(config_dir_path)
                with open(config_path, "wb") as config_file:
                    config_bytes, config = obj.generate_config(
                        config_dir_path=config_dir_path,
                        server_name=server_name,
                        report_stats=(config_args.report_stats == "yes"),
                    )
                    obj.invoke_all("generate_files", config)
                    config_file.write(config_bytes)
                print (
                    "A config file has been generated in %r for server name"
                    " %r with corresponding SSL keys and self-signed"
                    " certificates. Please review this file and customise it"
                    " to your needs."
                ) % (config_path, server_name)
                print (
                    "If this server name is incorrect, you will need to"
                    " regenerate the SSL certificates"
                )
                sys.exit(0)
            else:
                print (
                    "Config file %r already exists. Generating any missing key"
                    " files."
                ) % (config_path,)
                generate_keys = True

        parser = argparse.ArgumentParser(
            parents=[config_parser],
            description=description,
            formatter_class=argparse.RawDescriptionHelpFormatter,
        )

        obj.invoke_all("add_arguments", parser)
        args = parser.parse_args(remaining_args)

        if not config_files:
            config_parser.error(
                "Must supply a config file.\nA config file can be automatically"
                " generated using \"--generate-config -H SERVER_NAME"
                " -c CONFIG-FILE\""
            )

        if config_args.keys_directory:
            config_dir_path = config_args.keys_directory
        else:
            config_dir_path = os.path.dirname(config_args.config_path[-1])
        config_dir_path = os.path.abspath(config_dir_path)

        specified_config = {}
        for config_file in config_files:
            yaml_config = cls.read_config_file(config_file)
            specified_config.update(yaml_config)

        if "server_name" not in specified_config:
            sys.stderr.write("\n" + MISSING_SERVER_NAME + "\n")
            sys.exit(1)

        server_name = specified_config["server_name"]
        _, config = obj.generate_config(
            config_dir_path=config_dir_path,
            server_name=server_name
        )
        config.pop("log_config")
        config.update(specified_config)
        if "report_stats" not in config:
            sys.stderr.write(
                "\n" + MISSING_REPORT_STATS_CONFIG_INSTRUCTIONS + "\n" +
                MISSING_REPORT_STATS_SPIEL + "\n")
            sys.exit(1)

        if generate_keys:
            obj.invoke_all("generate_files", config)
            sys.exit(0)

        obj.invoke_all("read_config", config)

        obj.invoke_all("read_arguments", args)

        return obj