#!/usr/bin/env python3
"""
A web interface for managing htpasswd files.

Copyright 2010 Lars Kruse <devel@sumpfralle.de>

This module 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 module 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 module. If not, see <http://www.gnu.org/licenses/>.
"""

import configparser
import re
import os
import sys

import bottle
import genshi.template
import genshi.filters

import htpasswd


BASE_DIR = os.path.dirname(__file__)
CONFIG_FILE_LOCATIONS = [
    os.path.join(BASE_DIR, "htman.conf"),
    '/etc/htman/htman.conf',
]
TEMPLATES_DIR = os.path.join(BASE_DIR, 'templates')
REGEX = {
    "username": r"[a-zA-Z0-9_\-\.]+$",
    "password": r"[a-zA-Z0-9_\-\.%\$_\;,<>=+\[\]\{\}\(\)#\'\"\/\&\*@]+$",
    "mapping": r"[a-zA-Z0-9_\-\.]+$",
}
# use the environment variable HTMAN_CONFIG as the config file location if the
# variable is defined
if "HTMAN_CONFIG" in os.environ:
    CONFIG_FILE_LOCATIONS = [os.environ["HTMAN_CONFIG"]]


@bottle.route('')
def redirect_frontpage():
    return bottle.redirect(web_defaults["base_url"])


@bottle.route('/')
def show_frontpage():
    values = web_defaults.copy()
    return render("frontpage.html", **values)


@bottle.route('/password')
def change_password_get(zone=None):
    return change_password(zone)


@bottle.route('/password', method='POST')
def change_password(zone=None):
    zone = bottle.request.forms.get('zone')
    username = bottle.request.forms.get('username')
    old_password = bottle.request.forms.get('old_password')
    new_password = bottle.request.forms.get('new_password')
    new_password2 = bottle.request.forms.get('new_password2')
    if zone:
        zone = zone.strip()
    if username:
        username = username.strip()
    if old_password:
        old_password = old_password.strip()
    if new_password:
        new_password = new_password.strip()
    if new_password2:
        new_password2 = new_password2.strip()
    values = web_defaults.copy()
    values["error"] = None
    values["success"] = None
    input_data = {"zone": zone, "username": username}
    verified = False
    if is_zone_valid(zone):
        htdb = get_htpasswd(zone)
        if htdb and username and (username in htdb.get_usernames()) and \
                htdb.verify(username, old_password):
            verified = True
    if old_password is None:
        # first visit of this page: no action, no errors
        pass
    elif new_password != new_password2:
        values["error"] = "New passwords do not match."
    elif not new_password:
        values["error"] = "No new password given."
    elif verified:
        htdb.update(username, new_password)
        htdb.save()
        values["success"] = "Password changed successfully."
    else:
        values["error"] = (
            "Authentication error: zone, username or password is invalid.")
    return render("password_change.html", input_data=input_data, **values)


@bottle.route('/admin')
def show_files():
    values = web_defaults.copy()
    # The template expects a list of tuples: (mapping name, admin-url).
    # We assume, that the admin-url is just below the main admin URL. Thus
    # there is no need for generating a specific URL.
    all_zones = sorted(get_mapping().keys())
    values["mapping"] = [
        (zone_name, "%s%s/%s" % (
            web_defaults["base_url"], "admin/manage", zone_name))
        for zone_name in all_zones
    ]
    return render("list_mappings.html", **values)


def is_zone_valid(zone):
    return (
        zone
        and (zone in get_mapping())
        and re.match(REGEX["mapping"], zone)
    )


@bottle.route('/manage')
def show_htpasswd(zone=None):
    return select_htpasswd(zone)


@bottle.route('/manage', method='POST')
def select_htpasswd(zone=None):
    if not zone:
        zone = bottle.request.forms.get('zone')
    if not is_zone_valid(zone):
        return bottle.redirect(web_defaults["base_url"])
    else:
        # do a redirect: this allows the webserver to check the permissions
        # for this URL
        return bottle.redirect(
            "%smanage/%s" % (web_defaults["base_url"], str(zone)))


def get_htpasswd(zone, auto_create=False):
    htpasswd_file = get_htpasswd_filename(zone)
    do_create_file = auto_create and not os.path.isfile(htpasswd_file)
    try:
        return htpasswd.HtpasswdFile(htpasswd_file, create=do_create_file)
    except IOError:
        return None


@bottle.route('/admin/manage/:zone')
@bottle.route('/manage/:zone')
def mange_htpasswd_get(zone=None):
    return manage_htpasswd(zone)


# the alternative "/admin" URL allows to define super-user htaccess rules via
# Apache's "Location" directive
@bottle.route('/admin/manage/:zone', method='POST')
@bottle.route('/manage/:zone', method='POST')
def manage_htpasswd(zone=None):
    action = bottle.request.forms.get('action')
    username = bottle.request.forms.get('username')
    password = bottle.request.forms.get('password')
    values = web_defaults.copy()
    values["error"] = None
    values["success"] = None
    if not is_zone_valid(zone):
        return bottle.redirect(web_defaults["base_url"])
    values["zone"] = zone
    htdb = get_htpasswd(zone, auto_create=True)
    if not htdb:
        values["error"] = "Failed to read htpasswd file"
        values["usernames"] = []
    else:
        if action is None:
            # just show the current state
            pass
        elif not username:
            values["error"] = "The username may not be empty!"
        elif not re.match(REGEX["username"], username):
            values["error"] = "The username contains invalid characters!"
        elif action == "del":
            if username in htdb.get_usernames():
                htdb.delete(username)
                htdb.save()
                values["success"] = "User removed"
            else:
                values["error"] = "The user does not exist!"
        elif not password:
            values["error"] = "The password may not be empty!"
        elif not re.match(REGEX["password"], password):
            values["error"] = "The password contains invalid characters!"
        elif action == "update":
            if username in htdb.get_usernames():
                htdb.update(username, password)
                htdb.save()
                values["success"] = "Password changed"
            else:
                values["error"] = "The user does not exist!"
        elif action == "new":
            if username not in htdb.get_usernames():
                htdb.update(username, password)
                htdb.save()
                values["success"] = "User added"
            else:
                values["error"] = "The user exists already!"
        else:
            values["error"] = "Invalid action"
        values["usernames"] = htdb.get_usernames()
    # show the current htpasswd file
    return render("manage_users.html", **values)


def get_config():
    config = configparser.ConfigParser()
    for filename in CONFIG_FILE_LOCATIONS:
        if os.path.isfile(filename):
            try:
                config.read(filename)
            except IOError:
                # ignore errors
                pass
            else:
                return config
    print(
        "Failed to load config file from %s" % str(CONFIG_FILE_LOCATIONS),
        file=sys.stderr
    )
    sys.exit(1)


def get_mapping():
    try:
        mapping_file = config.get("Locations", "mapping")
    except configparser.NoOptionError:
        print >>sys.stderr, "The location of the mapping file is not " \
                "defined in the config file: [Locations] -> mapping"
        sys.exit(2)
    if not os.path.isfile(mapping_file):
        print >>sys.stderr, "The mapping file does not exist: %s" \
                % str(mapping_file)
        sys.exit(2)
    # read the mapping file
    try:
        input_data = open(mapping_file, "r").readlines()
    except IOError:
        print >>sys.stderr, "Failed to open mapping file: %s" % mapping_file
        sys.exit(4)
    mapping = {}
    for line in input_data:
        if line.startswith("#"):
            continue
        if "=" in line:
            name, location = line.split("=", 1)
            name = name.strip()
            location = location.strip()
            # ignore invalid mapping names
            if re.match(REGEX["mapping"], name):
                mapping[name] = location
    return mapping


def get_htpasswd_filename(zone):
    basename = mapping[zone]
    if basename and (basename != os.path.abspath(basename)):
        # relative filename in mapping file
        # let's try the htpasswd_directory setting
        try:
            htpasswd_directory = config.get("Locations", "htpasswd_directory")
            return os.path.join(htpasswd_directory, basename)
        except configparser.NoOptionError:
            return os.path.abspath(basename)
    else:
        return basename


def get_templates_dir(config):
    try:
        templates_dir = config.get("Locations", "templates")
    except configparser.NoOptionError:
        # use the default
        templates_dir = TEMPLATES_DIR
    if not os.path.isdir(templates_dir):
        print >>sys.stderr, "Templates directory not found: %s" % templates_dir
        sys.exit(3)
    return os.path.abspath(templates_dir)


def render(filename, input_data=None, **values):
    stream = loader.load(filename).generate(**values)
    if input_data is not None:
        stream |= genshi.filters.HTMLFormFiller(data=input_data)
    return stream.render("html", doctype="html")


# *** Initialization ***
config = get_config()
# defaults to the standard TEMPLATES_DIR
mapping = get_mapping()
templates_dir = get_templates_dir(config)
web_defaults = dict(config.items("Web"))
if not web_defaults["base_url"].endswith("/"):
    web_defaults["base_url"] += "/"
loader = genshi.template.TemplateLoader([templates_dir], auto_reload=False)