# This file is part of Radicale Server - Calendar Server
# Copyright © 2008-2017 Guillaume Ayoub
# Copyright © 2008 Nicolas Kandel
# Copyright © 2008 Pascal Halter
#
# This library 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, either version 3 of the License, or
# (at your option) any later version.
#
# This library 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 Radicale.  If not, see <http://www.gnu.org/licenses/>.

"""
Radicale configuration module.

Give a configparser-like interface to read and write configuration.

"""

import math
import os
from collections import OrderedDict
from configparser import RawConfigParser as ConfigParser

from radicale import auth, rights, storage, web


def positive_int(value):
    value = int(value)
    if value < 0:
        raise ValueError("value is negative: %d" % value)
    return value


def positive_float(value):
    value = float(value)
    if not math.isfinite(value):
        raise ValueError("value is infinite")
    if math.isnan(value):
        raise ValueError("value is not a number")
    if value < 0:
        raise ValueError("value is negative: %f" % value)
    return value


# Default configuration
INITIAL_CONFIG = OrderedDict([
    ("server", OrderedDict([
        ("hosts", {
            "value": "127.0.0.1:5232",
            "help": "set server hostnames including ports",
            "aliases": ["-H", "--hosts"],
            "type": str}),
        ("daemon", {
            "value": "False",
            "help": "launch as daemon",
            "aliases": ["-d", "--daemon"],
            "opposite": ["-f", "--foreground"],
            "type": bool}),
        ("pid", {
            "value": "",
            "help": "set PID filename for daemon mode",
            "aliases": ["-p", "--pid"],
            "type": str}),
        ("max_connections", {
            "value": "20",
            "help": "maximum number of parallel connections",
            "type": positive_int}),
        ("max_content_length", {
            "value": "100000000",
            "help": "maximum size of request body in bytes",
            "type": positive_int}),
        ("timeout", {
            "value": "30",
            "help": "socket timeout",
            "type": positive_int}),
        ("ssl", {
            "value": "False",
            "help": "use SSL connection",
            "aliases": ["-s", "--ssl"],
            "opposite": ["-S", "--no-ssl"],
            "type": bool}),
        ("certificate", {
            "value": "/etc/radicale/server.crt",
            "help": "set certificate file",
            "aliases": ["-c", "--certificate"],
            "type": str}),
        ("key", {
            "value": "/etc/radicale/private/server.key",
            "help": "set private key file",
            "aliases": ["-k", "--key"],
            "type": str}),
        ("certificate_authority", {
            "value": "",
            "help": "set CA certificate for validating clients",
            "aliases": ["--certificate-authority"],
            "type": str}),
        ("protocol", {
            "value": "PROTOCOL_TLSv1_2",
            "help": "SSL protocol used",
            "type": str}),
        ("ciphers", {
            "value": "",
            "help": "available ciphers",
            "type": str}),
        ("dns_lookup", {
            "value": "True",
            "help": "use reverse DNS to resolve client address in logs",
            "type": bool}),
        ("realm", {
            "value": "Radicale - Password Required",
            "help": "message displayed when a password is needed",
            "type": str})])),
    ("encoding", OrderedDict([
        ("request", {
            "value": "utf-8",
            "help": "encoding for responding requests",
            "type": str}),
        ("stock", {
            "value": "utf-8",
            "help": "encoding for storing local collections",
            "type": str})])),
    ("auth", OrderedDict([
        ("type", {
            "value": "none",
            "help": "authentication method",
            "type": str,
            "internal": auth.INTERNAL_TYPES}),
        ("htpasswd_filename", {
            "value": "/etc/radicale/users",
            "help": "htpasswd filename",
            "type": str}),
        ("htpasswd_encryption", {
            "value": "bcrypt",
            "help": "htpasswd encryption method",
            "type": str}),
        ("delay", {
            "value": "1",
            "help": "incorrect authentication delay",
            "type": positive_float})])),
    ("rights", OrderedDict([
        ("type", {
            "value": "owner_only",
            "help": "rights backend",
            "type": str,
            "internal": rights.INTERNAL_TYPES}),
        ("file", {
            "value": "/etc/radicale/rights",
            "help": "file for rights management from_file",
            "type": str})])),
    ("storage", OrderedDict([
        ("type", {
            "value": "multifilesystem",
            "help": "storage backend",
            "type": str,
            "internal": storage.INTERNAL_TYPES}),
        ("filesystem_folder", {
            "value": os.path.expanduser(
                "/var/db/radicale/collections"),
            "help": "path where collections are stored",
            "type": str}),
        ("max_sync_token_age", {
            "value": 2592000,  # 30 days
            "help": "delete sync token that are older",
            "type": int}),
        ("filesystem_fsync", {
            "value": "True",
            "help": "sync all changes to filesystem during requests",
            "type": bool}),
        ("filesystem_locking", {
            "value": "True",
            "help": "lock the storage while accessing it",
            "type": bool}),
        ("filesystem_close_lock_file", {
            "value": "False",
            "help": "close the lock file when no more clients are waiting",
            "type": bool}),
        ("hook", {
            "value": "",
            "help": "command that is run after changes to storage",
            "type": str})])),
    ("web", OrderedDict([
        ("type", {
            "value": "internal",
            "help": "web interface backend",
            "type": str,
            "internal": web.INTERNAL_TYPES})])),
    ("logging", OrderedDict([
        ("config", {
            "value": "",
            "help": "logging configuration file",
            "type": str}),
        ("debug", {
            "value": "False",
            "help": "print debug information",
            "aliases": ["-D", "--debug"],
            "type": bool}),
        ("full_environment", {
            "value": "False",
            "help": "store all environment variables",
            "type": bool}),
        ("mask_passwords", {
            "value": "True",
            "help": "mask passwords in logs",
            "type": bool})]))])


def load(paths=(), extra_config=None, ignore_missing_paths=True):
    config = ConfigParser()
    for section, values in INITIAL_CONFIG.items():
        config.add_section(section)
        for key, data in values.items():
            config.set(section, key, data["value"])
    if extra_config:
        for section, values in extra_config.items():
            for key, value in values.items():
                config.set(section, key, value)
    for path in paths:
        if path or not ignore_missing_paths:
            try:
                if not config.read(path) and not ignore_missing_paths:
                    raise RuntimeError("No such file: %r" % path)
            except Exception as e:
                raise RuntimeError(
                    "Failed to load config file %r: %s" % (path, e)) from e
    # Check the configuration
    for section in config.sections():
        if section == "headers":
            continue
        if section not in INITIAL_CONFIG:
            raise RuntimeError("Invalid section %r in config" % section)
        allow_extra_options = ("type" in INITIAL_CONFIG[section] and
                               config.get(section, "type") not in
                               INITIAL_CONFIG[section]["type"].get("internal",
                                                                   ()))
        for option in config[section]:
            if option not in INITIAL_CONFIG[section]:
                if allow_extra_options:
                    continue
                raise RuntimeError("Invalid option %r in section %r in "
                                   "config" % (option, section))
            type_ = INITIAL_CONFIG[section][option]["type"]
            try:
                if type_ == bool:
                    config.getboolean(section, option)
                else:
                    type_(config.get(section, option))
            except Exception as e:
                raise RuntimeError(
                    "Invalid %s value for option %r in section %r in config: "
                    "%r" % (type_.__name__, option, section,
                            config.get(section, option))) from e
    return config
