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

# Haketilo proxy data and configuration (instantiatable HaketiloState subtype).
#
# 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 this code
# in a proprietary program, I am not going to enforce this in court.

"""
This module contains logic for keeping track of all settings, rules, mappings
and resources.
"""

# Enable using with Python 3.7.
from __future__ import annotations

import secrets
import io
import hashlib
import typing as t
import dataclasses as dc

from pathlib import Path

import sqlite3

from ...exceptions import HaketiloException
from ...translations import smart_gettext as _
from ... import pattern_tree
from ... import url_patterns
from ... import item_infos
from ..simple_dependency_satisfying import compute_payloads, ComputedPayload
from .. import state as st
from .. import policies
from . import base
from . import mappings
from .load_packages import load_packages


here = Path(__file__).resolve().parent

@dc.dataclass(frozen=True, unsafe_hash=True) # type: ignore[misc]
class ConcreteRepoRef(st.RepoRef):
    def remove(self, state: st.HaketiloState) -> None:
        raise NotImplementedError()

    def update(
            self,
            state: st.HaketiloState,
            *,
            name: t.Optional[str] = None,
            url:  t.Optional[str] = None
    ) -> ConcreteRepoRef:
        raise NotImplementedError()

    def refresh(self, state: st.HaketiloState) -> ConcreteRepoIterationRef:
        raise NotImplementedError()


@dc.dataclass(frozen=True, unsafe_hash=True)
class ConcreteRepoIterationRef(st.RepoIterationRef):
    pass


@dc.dataclass(frozen=True, unsafe_hash=True)
class ConcreteResourceRef(st.ResourceRef):
    pass


@dc.dataclass(frozen=True, unsafe_hash=True)
class ConcreteResourceVersionRef(st.ResourceVersionRef):
    pass


@dc.dataclass(frozen=True, unsafe_hash=True)
class ConcretePayloadRef(st.PayloadRef):
    state: base.HaketiloStateWithFields = dc.field(hash=False, compare=False)

    def get_data(self) -> st.PayloadData:
        try:
            return self.state.payloads_data[self]
        except KeyError:
            raise st.MissingItemError()

    def get_mapping(self) -> st.MappingVersionRef:
        raise NotImplementedError()

    def get_script_paths(self) \
        -> t.Iterable[t.Sequence[str]]:
        with self.state.cursor() as cursor:
            cursor.execute(
                '''
                SELECT
                        i.identifier, fu.name
                FROM
                                  payloads                    AS p
                        LEFT JOIN resolved_depended_resources AS rdd
                                USING (payload_id)
                        LEFT JOIN item_versions               AS iv
                                ON rdd.resource_item_id = iv.item_version_id
                        LEFT JOIN items                       AS i
                                USING (item_id)
                        LEFT JOIN file_uses                   AS fu
                                USING (item_version_id)
                WHERE
                        fu.type = 'W'    AND
                        p.payload_id = ? AND
                        (fu.idx IS NOT NULL OR rdd.idx IS NULL)
                ORDER BY
                        rdd.idx, fu.idx;
                ''',
                (self.id,)
            )

            paths: list[t.Sequence[str]] = []
            for resource_identifier, file_name in cursor.fetchall():
                if resource_identifier is None:
                    # payload found but it had no script files
                    return ()

                paths.append((resource_identifier, *file_name.split('/')))

        if paths == []:
            # payload not found
            raise st.MissingItemError()

        return paths

    def get_file_data(self, path: t.Sequence[str]) \
        -> t.Optional[st.FileData]:
        if len(path) == 0:
            raise st.MissingItemError()

        resource_identifier, *file_name_segments = path

        file_name = '/'.join(file_name_segments)

        with self.state.cursor() as cursor:
            cursor.execute(
                '''
                SELECT
                        f.data, fu.mime_type
                FROM
                             payloads                    AS p
                        JOIN resolved_depended_resources AS rdd
                                USING (payload_id)
                        JOIN item_versions               AS iv
                                ON rdd.resource_item_id = iv.item_version_id
                        JOIN items                       AS i
                                USING (item_id)
                        JOIN file_uses                   AS fu
                                USING (item_version_id)
                        JOIN files                       AS f
                                USING (file_id)
                WHERE
                        p.payload_id = ? AND
                        i.identifier = ? AND
                        fu.name = ?      AND
                        fu.type = 'W';
                ''',
                (self.id, resource_identifier, file_name)
            )

            result = cursor.fetchall()

        if result == []:
            return None

        (data, mime_type), = result

        return st.FileData(type=mime_type, name=file_name, contents=data)

def register_payload(
        policy_tree: base.PolicyTree,
        pattern:     url_patterns.ParsedPattern,
        payload_key: st.PayloadKey,
        token:       str
) -> base.PolicyTree:
    """...."""
    payload_policy_factory = policies.PayloadPolicyFactory(
        builtin     = False,
        payload_key = payload_key
    )

    policy_tree = policy_tree.register(pattern, payload_policy_factory)

    resource_policy_factory = policies.PayloadResourcePolicyFactory(
        builtin     = False,
        payload_key = payload_key
    )

    policy_tree = policy_tree.register(
        pattern.path_append(token, '***'),
        resource_policy_factory
    )

    return policy_tree

AnyInfoVar = t.TypeVar(
    'AnyInfoVar',
    item_infos.ResourceInfo,
    item_infos.MappingInfo
)

def get_infos_of_type(cursor: sqlite3.Cursor, info_type: t.Type[AnyInfoVar],) \
    -> t.Mapping[AnyInfoVar, int]:
    cursor.execute(
        '''
        SELECT
                i.item_id, iv.definition, r.name, ri.iteration
        FROM
                     item_versions   AS iv
                JOIN items           AS i  USING (item_id)
                JOIN repo_iterations AS ri USING (repo_iteration_id)
                JOIN repos           AS r  USING (repo_id)
        WHERE
                i.type = ?;
        ''',
        (info_type.type_name[0].upper(),)
    )

    result: dict[AnyInfoVar, int] = {}

    for item_id, definition, repo_name, repo_iteration in cursor.fetchall():
        definition_io = io.StringIO(definition)
        info = info_type.load(definition_io, repo_name, repo_iteration)
        result[info] = item_id

    return result

@dc.dataclass
class ConcreteHaketiloState(base.HaketiloStateWithFields):
    def __post_init__(self) -> None:
        self._prepare_database()

        self._rebuild_structures()

    def _prepare_database(self) -> None:
        """...."""
        cursor = self.connection.cursor()

        try:
            cursor.execute(
                '''
                SELECT
                        COUNT(name)
                FROM
                        sqlite_master
                WHERE
                        name = 'general' AND type = 'table';
                '''
            )

            (db_initialized,), = cursor.fetchall()

            if not db_initialized:
                cursor.executescript((here.parent / 'tables.sql').read_text())
 
            else:
                cursor.execute(
                    '''
                    SELECT
                            haketilo_version
                    FROM
                            general;
                    '''
                )

                (db_haketilo_version,) = cursor.fetchone()
                if db_haketilo_version != '3.0b1':
                    raise HaketiloException(_('err.proxy.unknown_db_schema'))

            cursor.execute('PRAGMA FOREIGN_KEYS;')
            if cursor.fetchall() == []:
                raise HaketiloException(_('err.proxy.no_sqlite_foreign_keys'))

            cursor.execute('PRAGMA FOREIGN_KEYS=ON;')
        finally:
            cursor.close()

    def import_packages(self, malcontent_path: Path) -> None:
        with self.cursor(transaction=True) as cursor:
            load_packages(self, cursor, malcontent_path)
            self.recompute_payloads(cursor)

    def recompute_payloads(self, cursor: sqlite3.Cursor) -> None:
        assert self.connection.in_transaction

        resources = get_infos_of_type(cursor, item_infos.ResourceInfo)
        mappings  = get_infos_of_type(cursor, item_infos.MappingInfo)

        payloads = compute_payloads(resources.keys(), mappings.keys())

        payloads_data: dict[st.PayloadRef, st.PayloadData] = {}

        cursor.execute('DELETE FROM payloads;')

        for mapping_info, by_pattern in payloads.items():
            for num, (pattern, payload) in enumerate(by_pattern.items()):
                cursor.execute(
                    '''
                    INSERT INTO payloads(
                            mapping_item_id,
                            pattern,
	                    eval_allowed,
                            cors_bypass_allowed
                    )
                    VALUES (?, ?, ?, ?);
                    ''',
                    (
                        mappings[mapping_info],
                        pattern.orig_url,
                        payload.allows_eval,
                        payload.allows_cors_bypass
                    )
                )

                cursor.execute(
                    '''
                    SELECT
                            payload_id
                    FROM
                            payloads
                    WHERE
                            mapping_item_id = ? AND pattern = ?;
                    ''',
                    (mappings[mapping_info], pattern.orig_url)
                )

                (payload_id_int,), = cursor.fetchall()

                for res_num, resource_info in enumerate(payload.resources):
                    cursor.execute(
                        '''
                        INSERT INTO resolved_depended_resources(
                                payload_id,
                                resource_item_id,
                                idx
                        )
                        VALUES(?, ?, ?);
                        ''',
                        (payload_id_int, resources[resource_info], res_num)
                    )

        self._rebuild_structures(cursor)

    def _rebuild_structures(self, cursor: t.Optional[sqlite3.Cursor] = None) \
        -> None:
        """
        Recreation of data structures as done after every recomputation of
        dependencies as well as at startup.
        """
        if cursor is None:
            with self.cursor() as new_cursor:
                return self._rebuild_structures(new_cursor)

        cursor.execute(
            '''
            SELECT
                    p.payload_id, p.pattern, p.eval_allowed,
                            p.cors_bypass_allowed,
                    ms.enabled,
                    i.identifier
            FROM
                         payloads         AS p
                    JOIN item_versions    AS iv
                            ON p.mapping_item_id = iv.item_version_id
                    JOIN items            AS i  USING (item_id)
                    JOIN mapping_statuses AS ms USING (item_id);
            '''
        )

        new_policy_tree = base.PolicyTree()

        ui_factory = policies.WebUIPolicyFactory(builtin=True)
        web_ui_pattern = 'http*://hkt.mitm.it/***'
        for parsed_pattern in url_patterns.parse_pattern(web_ui_pattern):
            new_policy_tree = new_policy_tree.register(
                parsed_pattern,
                ui_factory
            )

        new_payloads_data: dict[st.PayloadRef, st.PayloadData] = {}

        for row in cursor.fetchall():
            (payload_id_int, pattern, eval_allowed, cors_bypass_allowed,
             enabled_status,
             identifier) = row

            payload_ref = ConcretePayloadRef(str(payload_id_int), self)

            previous_data = self.payloads_data.get(payload_ref)
            if previous_data is not None:
                token = previous_data.unique_token
            else:
                token = secrets.token_urlsafe(8)

            payload_key = st.PayloadKey(payload_ref, identifier)

            for parsed_pattern in url_patterns.parse_pattern(pattern):
                new_policy_tree = register_payload(
                    new_policy_tree,
                    parsed_pattern,
                    payload_key,
                    token
                )

                pattern_path_segments = parsed_pattern.path_segments

            payload_data = st.PayloadData(
                payload_ref           = payload_ref,
                #explicitly_enabled  = enabled_status == 'E',
                explicitly_enabled    = True,
                unique_token          = token,
                pattern_path_segments = pattern_path_segments,
                eval_allowed          = eval_allowed,
                cors_bypass_allowed   = cors_bypass_allowed
            )

            new_payloads_data[payload_ref] = payload_data

        self.policy_tree   = new_policy_tree
        self.payloads_data = new_payloads_data

    def get_repo(self, repo_id: str) -> st.RepoRef:
        return ConcreteRepoRef(repo_id)

    def get_repo_iteration(self, repo_iteration_id: str) -> st.RepoIterationRef:
        return ConcreteRepoIterationRef(repo_iteration_id)

    def mapping_store(self) -> st.MappingStore:
        raise NotImplementedError()

    def mapping_version_store(self) -> st.MappingVersionStore:
        return mappings.ConcreteMappingVersionStore(self)

    def get_resource(self, resource_id: str) -> st.ResourceRef:
        return ConcreteResourceRef(resource_id)

    def get_resource_version(self, resource_version_id: str) \
        -> st.ResourceVersionRef:
        return ConcreteResourceVersionRef(resource_version_id)

    def get_payload(self, payload_id: str) -> st.PayloadRef:
        raise NotImplementedError()

    def add_repo(self, name: t.Optional[str], url: t.Optional[str]) \
        -> st.RepoRef:
        raise NotImplementedError()

    def get_settings(self) -> st.HaketiloGlobalSettings:
        return st.HaketiloGlobalSettings(
            mapping_use_mode       = st.MappingUseMode.AUTO,
            default_allow_scripts  = True,
            repo_refresh_seconds   = 0
        )

    def update_settings(
            self,
            *,
            mapping_use_mode:      t.Optional[st.MappingUseMode] = None,
            default_allow_scripts: t.Optional[bool]              = None,
            repo_refresh_seconds:  t.Optional[int]               = None
    ) -> None:
        raise NotImplementedError()

    def select_policy(self, url: url_patterns.ParsedUrl) -> policies.Policy:
        """...."""
        with self.lock:
            policy_tree = self.policy_tree

        try:
            best_priority: int                         = 0
            best_policy:   t.Optional[policies.Policy] = None

            for factories_set in policy_tree.search(url):
                for stored_factory in sorted(factories_set):
                    factory = stored_factory.item

                    policy = factory.make_policy(self)

                    if policy.priority > best_priority:
                        best_priority = policy.priority
                        best_policy   = policy
        except Exception as e:
            return policies.ErrorBlockPolicy(
                builtin = True,
                error   = e
            )

        if best_policy is not None:
            return best_policy

        if self.get_settings().default_allow_scripts:
            return policies.FallbackAllowPolicy()
        else:
            return policies.FallbackBlockPolicy()

    @staticmethod
    def make(store_dir: Path) -> 'ConcreteHaketiloState':
        connection = sqlite3.connect(
            str(store_dir / 'sqlite3.db'),
            isolation_level   = None,
            check_same_thread = False
        )
        return ConcreteHaketiloState(
            store_dir      = store_dir,
            connection     = connection
        )