# SPDX-License-Identifier: GPL-3.0-or-later

# Proxy web UI root.
#
# This file is part of Hydrilla&Haketilo.
#
# Copyright (C) 2022 Wojtek Kosior
#
# 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, either version 3 of the License, or
# (at your option) any later version.
#
# 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 <https://www.gnu.org/licenses/>.
#
#
# I, Wojtek Kosior, thereby promise not to sue for violation of this
# file's license. Although I request that you do not make use of this
# code in a proprietary program, I am not going to enforce this in
# court.

"""
This module instantiated Flask apps responsible for the web UI and facilitates
conversion of Flask response objects to the ResponseInfo type used by other
Haketilo code.

In addition, the Haketilo root/settings page and landing page also have their
handlers defined here.
"""

import re
import dataclasses as dc
import typing as t

from threading import Lock
from urllib.parse import urlparse

import jinja2
import flask
import werkzeug

from ... import translations
from ... import versions
from ... import item_infos
from ... import common_jinja_templates
from .. import state as st
from .. import http_messages
from .. import self_doc
from . import rules
from . import repos
from . import items
from . import items_import
from . import prompts
from . import _app


def choose_locale() -> None:
    app = t.cast(WebUIAppImpl, flask.current_app)

    user_chosen_locale = get_settings().locale
    if user_chosen_locale not in translations.supported_locales:
        user_chosen_locale = None

    if user_chosen_locale is None:
        best_locale_match = flask.request.accept_languages.best_match(
            translations.supported_locales,
            default = translations.default_locale
        )
        if best_locale_match is None:
            app._haketilo_request_locale = translations.default_locale
        else:
            app._haketilo_request_locale = best_locale_match
    else:
        app._haketilo_request_locale = user_chosen_locale

    trans = translations.translation(app._haketilo_request_locale)

    app.jinja_env.install_gettext_translations(trans)


def authenticate_by_referrer() -> t.Optional[werkzeug.Response]:
    if flask.request.method == 'GET':
        return None

    parsed_url = urlparse(flask.request.referrer)
    if parsed_url.netloc == 'hkt.mitm.it':
        return None

    flask.abort(403)


def get_current_endpoint() -> str:
    endpoint = flask.request.endpoint
    assert endpoint is not None
    return endpoint

def get_settings() -> st.HaketiloGlobalSettings:
    return _app.get_haketilo_state().get_settings()


@dc.dataclass(init=False)
class WebUIAppImpl(_app.WebUIApp):
    # Flask app is not thread-safe and has to be accompanied by an ugly lock.
    # This can cause slow requests to block other requests, so we might need a
    # better workaround at some later point.
    _haketilo_app_lock: Lock

    _haketilo_blueprints: t.ClassVar[t.Sequence[flask.Blueprint]]
    _haketilo_ui_domain:  t.ClassVar[_app.UIDomain]

    _haketilo_request_locale: str

    def __init__(self):
        super().__init__(__name__)

        self._haketilo_app_lock = Lock()

        loaders = [jinja2.PackageLoader(__package__), self_doc.loader]
        combined_loader = common_jinja_templates.combine_with_loaders(loaders)

        self.jinja_options = {
            **self.jinja_options,
            'loader':        combined_loader,
            'autoescape':    jinja2.select_autoescape(['.jinja']),
            'lstrip_blocks': True,
            'extensions': [
                *self.jinja_options.get('extensions', []),
                'jinja2.ext.i18n',
                'jinja2.ext.do'
            ]
        }

        self.jinja_env.globals['get_current_endpoint'] = get_current_endpoint
        self.jinja_env.globals['get_settings']         = get_settings
        self.jinja_env.globals['EnabledStatus']        = st.EnabledStatus
        self.jinja_env.globals['FrozenStatus']         = st.FrozenStatus
        self.jinja_env.globals['InstalledStatus']      = st.InstalledStatus
        self.jinja_env.globals['ActiveStatus']         = st.ActiveStatus
        self.jinja_env.globals['ItemType']             = item_infos.ItemType
        self.jinja_env.globals['MappingUseMode']       = st.MappingUseMode
        self.jinja_env.globals['versions']             = versions
        self.jinja_env.globals['doc_base_filename']    = 'doc_base.html.jinja'

        self.before_request(authenticate_by_referrer)
        self.before_request(choose_locale)

        for bp in self._haketilo_blueprints:
            self.register_blueprint(bp)


home_bp = flask.Blueprint('home', __package__)

@home_bp.route('/', methods=['GET'])
def home(errors: t.Mapping[str, bool] = {}) -> werkzeug.Response:
    state = _app.get_haketilo_state()

    html = flask.render_template(
        'index.html.jinja',
        orphan_item_stats = state.count_orphan_items(),
        **errors
    )
    return flask.make_response(html, 200)

popup_toggle_action_re = re.compile(
    r'^popup_(yes|no)_when_(jsallowed|jsblocked|payloadon)$'
)

@home_bp.route('/', methods=['POST'])
def home_post() -> werkzeug.Response:
    action = flask.request.form['action']

    state = _app.get_haketilo_state()

    if action == 'set_lang':
        new_locale = flask.request.form['locale']
        assert new_locale in translations.supported_locales
        state.update_settings(locale=new_locale)
    elif action == 'use_enabled':
        state.update_settings(mapping_use_mode=st.MappingUseMode.WHEN_ENABLED)
    elif action == 'use_auto':
        state.update_settings(mapping_use_mode=st.MappingUseMode.AUTO)
    elif action == 'use_question':
        state.update_settings(mapping_use_mode=st.MappingUseMode.QUESTION)
    elif action == 'allow_scripts':
        state.update_settings(default_allow_scripts=True)
    elif action == 'block_scripts':
        state.update_settings(default_allow_scripts=False)
    elif action == 'user_make_advanced':
        state.update_settings(advanced_user=True)
    elif action == 'user_make_simple':
        state.update_settings(advanced_user=False)
    elif action == 'prune_orphans':
        state.prune_orphan_items()
    else:
        match = popup_toggle_action_re.match(action)
        if match is None:
            raise ValueError()

        popup_enable = match.group(1) == 'yes'
        page_type    = match.group(2)

        settings_prop = f'default_popup_{page_type}'
        old_settings = getattr(state.get_settings(), settings_prop)

        new_settings = dc.replace(old_settings, keyboard_trigger=popup_enable)

        state.update_settings(default_popup_settings={page_type: new_settings})

    return flask.redirect(flask.url_for('.home'), 303)

@home_bp.route('/doc/<path:page>', methods=['GET'])
def home_doc(page: str) -> str:
    if page not in self_doc.page_names:
        flask.abort(404)

    locale = t.cast(WebUIAppImpl, flask.current_app)._haketilo_request_locale
    if locale not in self_doc.available_locales:
        locale = translations.default_locale

    return flask.render_template(
        f'{locale}/{page}.html.jinja',
        doc_output = 'html_hkt_mitm_it'
    )

blueprints_main = \
    (rules.bp, repos.bp, items.bp, items_import.bp, prompts.bp, home_bp)

@dc.dataclass(init=False)
class AppMain(WebUIAppImpl):
    _haketilo_blueprints = blueprints_main
    _haketilo_ui_domain  = _app.UIDomain.MAIN


landing_bp = flask.Blueprint('landing_page', __package__)

@landing_bp.route('/', methods=['GET'])
def landing(errors: t.Mapping[str, bool] = {}) -> werkzeug.Response:
    state = _app.get_haketilo_state()

    html = flask.render_template(
        'landing.html.jinja',
        listen_host = state.listen_host,
        listen_port = state.listen_port
    )
    return flask.make_response(html, 200)

@dc.dataclass(init=False)
class AppLandingPage(WebUIAppImpl):
    _haketilo_blueprints = (landing_bp,)
    _haketilo_ui_domain  = _app.UIDomain.LANDING_PAGE


apps_seq = [AppMain(), AppLandingPage()]
apps = dict((app._haketilo_ui_domain, app) for app in apps_seq)


def process_request(
        request_info: http_messages.RequestInfo,
        state:        st.HaketiloState,
        ui_domain:    _app.UIDomain = _app.UIDomain.MAIN
) -> http_messages.ResponseInfo:
    path = '/'.join(('', *request_info.url.path_segments))
    if (request_info.url.has_trailing_slash):
        path += '/'

    app = apps[ui_domain]

    with app._haketilo_app_lock:
        app._haketilo_state = state

        flask_response = app.test_client().open(
            path         = path,
            base_url     = request_info.url.url_without_path,
            method       = request_info.method,
            query_string = request_info.url.query,
            headers      = [*request_info.headers.items()],
            data         = request_info.body
        )

        headers_bytes = [
            (key.encode(), val.encode())
            for key, val
            in flask_response.headers
        ]

        return http_messages.ResponseInfo.make(
            status_code = flask_response.status_code,
            headers     = headers_bytes,
            body        = flask_response.data
        )