# SPDX-License-Identifier: AGPL-3.0-or-later
# lint: pylint
"""Searx preferences implementation.
"""

# pylint: disable=useless-object-inheritance

from base64 import urlsafe_b64encode, urlsafe_b64decode
from zlib import compress, decompress
from urllib.parse import parse_qs, urlencode
from typing import Iterable, Dict, List, Set
from dataclasses import dataclass

import flask

from searx import settings, autocomplete
from searx.engines import Engine
from searx.plugins import Plugin
from searx.locales import LOCALE_NAMES
from searx.webutils import VALID_LANGUAGE_CODE
from searx.engines import OTHER_CATEGORY


COOKIE_MAX_AGE = 60 * 60 * 24 * 365 * 5  # 5 years
DISABLED = 0
ENABLED = 1
DOI_RESOLVERS = list(settings['doi_resolvers'])


class ValidationException(Exception):

    """Exption from ``cls.__init__`` when configuration value is invalid."""


class Setting:
    """Base class of user settings"""

    def __init__(self, default_value, locked: bool = False):
        super().__init__()
        self.value = default_value
        self.locked = locked

    def parse(self, data: str):
        """Parse ``data`` and store the result at ``self.value``

        If needed, its overwritten in the inheritance.
        """
        self.value = data

    def get_value(self):
        """Returns the value of the setting

        If needed, its overwritten in the inheritance.
        """
        return self.value

    def save(self, name: str, resp: flask.Response):
        """Save cookie ``name`` in the HTTP reponse obect

        If needed, its overwritten in the inheritance."""
        resp.set_cookie(name, self.value, max_age=COOKIE_MAX_AGE)


class StringSetting(Setting):
    """Setting of plain string values"""


class EnumStringSetting(Setting):
    """Setting of a value which can only come from the given choices"""

    def __init__(self, default_value: str, choices: Iterable[str], locked=False):
        super().__init__(default_value, locked)
        self.choices = choices
        self._validate_selection(self.value)

    def _validate_selection(self, selection: str):
        if selection not in self.choices:
            raise ValidationException('Invalid value: "{0}"'.format(selection))

    def parse(self, data: str):
        """Parse and validate ``data`` and store the result at ``self.value``"""
        self._validate_selection(data)
        self.value = data


class MultipleChoiceSetting(Setting):
    """Setting of values which can only come from the given choices"""

    def __init__(self, default_value: List[str], choices: Iterable[str], locked=False):
        super().__init__(default_value, locked)
        self.choices = choices
        self._validate_selections(self.value)

    def _validate_selections(self, selections: List[str]):
        for item in selections:
            if item not in self.choices:
                raise ValidationException('Invalid value: "{0}"'.format(selections))

    def parse(self, data: str):
        """Parse and validate ``data`` and store the result at ``self.value``"""
        if data == '':
            self.value = []
            return

        elements = data.split(',')
        self._validate_selections(elements)
        self.value = elements

    def parse_form(self, data: List[str]):
        if self.locked:
            return

        self.value = []
        for choice in data:
            if choice in self.choices and choice not in self.value:
                self.value.append(choice)

    def save(self, name: str, resp: flask.Response):
        """Save cookie ``name`` in the HTTP reponse obect"""
        resp.set_cookie(name, ','.join(self.value), max_age=COOKIE_MAX_AGE)


class SetSetting(Setting):
    """Setting of values of type ``set`` (comma separated string)"""

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.values = set()

    def get_value(self):
        """Returns a string with comma separated values."""
        return ','.join(self.values)

    def parse(self, data: str):
        """Parse and validate ``data`` and store the result at ``self.value``"""
        if data == '':
            self.values = set()
            return

        elements = data.split(',')
        for element in elements:
            self.values.add(element)

    def parse_form(self, data: str):
        if self.locked:
            return

        elements = data.split(',')
        self.values = set(elements)

    def save(self, name: str, resp: flask.Response):
        """Save cookie ``name`` in the HTTP reponse obect"""
        resp.set_cookie(name, ','.join(self.values), max_age=COOKIE_MAX_AGE)


class SearchLanguageSetting(EnumStringSetting):
    """Available choices may change, so user's value may not be in choices anymore"""

    def _validate_selection(self, selection):
        if selection != '' and not VALID_LANGUAGE_CODE.match(selection):
            raise ValidationException('Invalid language code: "{0}"'.format(selection))

    def parse(self, data: str):
        """Parse and validate ``data`` and store the result at ``self.value``"""
        if data not in self.choices and data != self.value:
            # hack to give some backwards compatibility with old language cookies
            data = str(data).replace('_', '-')
            lang = data.split('-', maxsplit=1)[0]

            if data in self.choices:
                pass
            elif lang in self.choices:
                data = lang
            else:
                data = self.value
        self._validate_selection(data)
        self.value = data


class MapSetting(Setting):
    """Setting of a value that has to be translated in order to be storable"""

    def __init__(self, default_value, map: Dict[str, object], locked=False):  # pylint: disable=redefined-builtin
        super().__init__(default_value, locked)
        self.map = map

        if self.value not in self.map.values():
            raise ValidationException('Invalid default value')

    def parse(self, data: str):
        """Parse and validate ``data`` and store the result at ``self.value``"""

        if data not in self.map:
            raise ValidationException('Invalid choice: {0}'.format(data))
        self.value = self.map[data]
        self.key = data  # pylint: disable=attribute-defined-outside-init

    def save(self, name: str, resp: flask.Response):
        """Save cookie ``name`` in the HTTP reponse obect"""
        if hasattr(self, 'key'):
            resp.set_cookie(name, self.key, max_age=COOKIE_MAX_AGE)


@dataclass
class Choice:
    """A choice for a ``SwitchableSetting``."""

    default_on: bool
    id: str


class SwitchableSetting(Setting):
    """Base class for settings that can be turned on && off"""

    def __init__(self, default_value, locked: bool, choices: Iterable[Choice]):
        super().__init__(default_value, locked)
        self.choices = choices
        self.enabled: Set[str] = set()
        self.disabled: Set[str] = set()

    def transform_form_items(self, items):
        # pylint: disable=no-self-use
        return items

    def transform_values(self, values):
        # pylint: disable=no-self-use
        return values

    def parse_cookie(self, data):
        if data[DISABLED] != '':
            self.disabled = set(data[DISABLED].split(','))
        if data[ENABLED] != '':
            self.enabled = set(data[ENABLED].split(','))

    def parse_form(self, items: List[str]):
        if self.locked:
            return

        items = self.transform_form_items(items)
        self.disabled = set()
        self.enabled = set()
        for choice in self.choices:
            if choice.default_on:
                if choice.id in items:
                    self.disabled.add(choice.id)
            else:
                if choice.id not in items:
                    self.enabled.add(choice.id)

    def save(self, resp: flask.Response):  # pylint: disable=arguments-differ
        """Save cookie in the HTTP reponse obect"""
        resp.set_cookie('disabled_{0}'.format(self.value), ','.join(self.disabled), max_age=COOKIE_MAX_AGE)
        resp.set_cookie('enabled_{0}'.format(self.value), ','.join(self.enabled), max_age=COOKIE_MAX_AGE)

    def get_disabled(self):
        disabled = self.disabled
        for choice in self.choices:
            if not choice.default_on and choice.id not in self.enabled:
                disabled.add(choice.id)
        return self.transform_values(disabled)

    def get_enabled(self):
        enabled = self.enabled
        for choice in self.choices:
            if choice.default_on and choice.id not in self.disabled:
                enabled.add(choice.id)
        return self.transform_values(enabled)


class EnginesSetting(SwitchableSetting):
    """Engine settings"""

    def __init__(self, default_value, engines: Iterable[Engine]):
        choices = []
        for engine in engines:
            for category in engine.categories:
                if not category in list(settings['categories_as_tabs'].keys()) + [OTHER_CATEGORY]:
                    continue
                choices.append(Choice(default_on=not engine.disabled, id='{}__{}'.format(engine.name, category)))
        super().__init__(default_value, False, choices)

    def transform_form_items(self, items):
        return [item[len('engine_') :].replace('_', ' ').replace('  ', '__') for item in items]

    def transform_values(self, values):
        if len(values) == 1 and next(iter(values)) == '':
            return []
        transformed_values = []
        for value in values:
            engine, category = value.split('__')
            transformed_values.append((engine, category))
        return transformed_values


class PluginsSetting(SwitchableSetting):
    """Plugin settings"""

    def __init__(self, default_value, plugins: Iterable[Plugin]):
        choices = []
        for plugin in plugins:
            choices.append(Choice(default_on=plugin.default_on, id=plugin.id))
        super().__init__(default_value, False, choices)

    def transform_form_items(self, items):
        return [item[len('plugin_') :] for item in items]


class Preferences:
    """Validates and saves preferences to cookies"""

    def __init__(self, themes: List[str], categories: List[str], engines: Dict[str, Engine], plugins: Iterable[Plugin]):
        super().__init__()

        self.key_value_settings: Dict[str, Setting] = {
            # fmt: off
            'categories': MultipleChoiceSetting(
                ['general'],
                locked=is_locked('categories'),
                choices=categories + ['none']
            ),
            'language': SearchLanguageSetting(
                settings['search']['default_lang'],
                locked=is_locked('language'),
                choices=settings['search']['languages'] + ['']
            ),
            'locale': EnumStringSetting(
                settings['ui']['default_locale'],
                locked=is_locked('locale'),
                choices=list(LOCALE_NAMES.keys()) + ['']
            ),
            'autocomplete': EnumStringSetting(
                settings['search']['autocomplete'],
                locked=is_locked('autocomplete'),
                choices=list(autocomplete.backends.keys()) + ['']
            ),
            'image_proxy': MapSetting(
                settings['server']['image_proxy'],
                locked=is_locked('image_proxy'),
                map={
                    '': settings['server']['image_proxy'],
                    '0': False,
                    '1': True,
                    'True': True,
                    'False': False
                }
            ),
            'method': EnumStringSetting(
                settings['server']['method'],
                locked=is_locked('method'),
                choices=('GET', 'POST')
            ),
            'safesearch': MapSetting(
                settings['search']['safe_search'],
                locked=is_locked('safesearch'),
                map={
                    '0': 0,
                    '1': 1,
                    '2': 2
                }
            ),
            'theme': EnumStringSetting(
                settings['ui']['default_theme'],
                locked=is_locked('theme'),
                choices=themes
            ),
            'results_on_new_tab': MapSetting(
                settings['ui']['results_on_new_tab'],
                locked=is_locked('results_on_new_tab'),
                map={
                    '0': False,
                    '1': True,
                    'False': False,
                    'True': True
                }
            ),
            'doi_resolver': MultipleChoiceSetting(
                [settings['default_doi_resolver'], ],
                locked=is_locked('doi_resolver'),
                choices=DOI_RESOLVERS
            ),
            'oscar-style': EnumStringSetting(
                settings['ui']['theme_args']['oscar_style'],
                locked=is_locked('oscar-style'),
                choices=['', 'logicodev', 'logicodev-dark', 'pointhi']
            ),
            'simple_style': EnumStringSetting(
                settings['ui']['theme_args']['simple_style'],
                locked=is_locked('simple_style'),
                choices=['', 'auto', 'light', 'dark']
            ),
            'advanced_search': MapSetting(
                settings['ui']['advanced_search'],
                locked=is_locked('advanced_search'),
                map={
                    '0': False,
                    '1': True,
                    'False': False,
                    'True': True,
                    'on': True,
                }
            ),
            'query_in_title': MapSetting(
                settings['ui']['query_in_title'],
                locked=is_locked('query_in_title'),
                map={
                    '': settings['ui']['query_in_title'],
                    '0': False,
                    '1': True,
                    'True': True,
                    'False': False
                }
            ),
            # fmt: on
        }

        self.engines = EnginesSetting('engines', engines=engines.values())
        self.plugins = PluginsSetting('plugins', plugins=plugins)
        self.tokens = SetSetting('tokens')
        self.unknown_params: Dict[str, str] = {}

    def get_as_url_params(self):
        """Return preferences as URL parameters"""
        settings_kv = {}
        for k, v in self.key_value_settings.items():
            if v.locked:
                continue
            if isinstance(v, MultipleChoiceSetting):
                settings_kv[k] = ','.join(v.get_value())
            else:
                settings_kv[k] = v.get_value()

        settings_kv['disabled_engines'] = ','.join(self.engines.disabled)
        settings_kv['enabled_engines'] = ','.join(self.engines.enabled)

        settings_kv['disabled_plugins'] = ','.join(self.plugins.disabled)
        settings_kv['enabled_plugins'] = ','.join(self.plugins.enabled)

        settings_kv['tokens'] = ','.join(self.tokens.values)

        return urlsafe_b64encode(compress(urlencode(settings_kv).encode())).decode()

    def parse_encoded_data(self, input_data: str):
        """parse (base64) preferences from request (``flask.request.form['preferences']``)"""
        bin_data = decompress(urlsafe_b64decode(input_data))
        dict_data = {}
        for x, y in parse_qs(bin_data.decode('ascii')).items():
            dict_data[x] = y[0]
        self.parse_dict(dict_data)

    def parse_dict(self, input_data: Dict[str, str]):
        """parse preferences from request (``flask.request.form``)"""
        for user_setting_name, user_setting in input_data.items():
            if user_setting_name in self.key_value_settings:
                if self.key_value_settings[user_setting_name].locked:
                    continue
                self.key_value_settings[user_setting_name].parse(user_setting)
            elif user_setting_name == 'disabled_engines':
                self.engines.parse_cookie(
                    (input_data.get('disabled_engines', ''), input_data.get('enabled_engines', ''))
                )
            elif user_setting_name == 'disabled_plugins':
                self.plugins.parse_cookie(
                    (input_data.get('disabled_plugins', ''), input_data.get('enabled_plugins', ''))
                )
            elif user_setting_name == 'tokens':
                self.tokens.parse(user_setting)
            elif not any(
                user_setting_name.startswith(x) for x in ['enabled_', 'disabled_', 'engine_', 'category_', 'plugin_']
            ):
                self.unknown_params[user_setting_name] = user_setting

    def parse_form(self, input_data: Dict[str, str]):
        """Parse formular (``<input>``) data from a ``flask.request.form``"""
        disabled_engines = []
        enabled_categories = []
        disabled_plugins = []
        for user_setting_name, user_setting in input_data.items():
            if user_setting_name in self.key_value_settings:
                self.key_value_settings[user_setting_name].parse(user_setting)
            elif user_setting_name.startswith('engine_'):
                disabled_engines.append(user_setting_name)
            elif user_setting_name.startswith('category_'):
                enabled_categories.append(user_setting_name[len('category_') :])
            elif user_setting_name.startswith('plugin_'):
                disabled_plugins.append(user_setting_name)
            elif user_setting_name == 'tokens':
                self.tokens.parse_form(user_setting)
            else:
                self.unknown_params[user_setting_name] = user_setting
        self.key_value_settings['categories'].parse_form(enabled_categories)
        self.engines.parse_form(disabled_engines)
        self.plugins.parse_form(disabled_plugins)

    # cannot be used in case of engines or plugins
    def get_value(self, user_setting_name: str):
        """Returns the value for ``user_setting_name``"""
        ret_val = None
        if user_setting_name in self.key_value_settings:
            ret_val = self.key_value_settings[user_setting_name].get_value()
        if user_setting_name in self.unknown_params:
            ret_val = self.unknown_params[user_setting_name]
        return ret_val

    def save(self, resp: flask.Response):
        """Save cookie in the HTTP reponse obect"""
        for user_setting_name, user_setting in self.key_value_settings.items():
            # pylint: disable=unnecessary-dict-index-lookup
            if self.key_value_settings[user_setting_name].locked:
                continue
            user_setting.save(user_setting_name, resp)
        self.engines.save(resp)
        self.plugins.save(resp)
        self.tokens.save('tokens', resp)
        for k, v in self.unknown_params.items():
            resp.set_cookie(k, v, max_age=COOKIE_MAX_AGE)
        return resp

    def validate_token(self, engine):
        valid = True
        if hasattr(engine, 'tokens') and engine.tokens:
            valid = False
            for token in self.tokens.values:
                if token in engine.tokens:
                    valid = True
                    break

        return valid


def is_locked(setting_name: str):
    """Checks if a given setting name is locked by settings.yml"""
    if 'preferences' not in settings:
        return False
    if 'lock' not in settings['preferences']:
        return False
    return setting_name in settings['preferences']['lock']