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

# Haketilo proxy data and configuration (definition of fields of a class that
# will implement HaketiloState).
#
# 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 defines fields that will later be part of a concrete HaketiloState
subtype.
"""

# Enable using with Python 3.7.
from __future__ import annotations

import sqlite3
import secrets
import threading
import dataclasses as dc
import typing as t

from pathlib import Path
from contextlib import contextmanager
from abc import abstractmethod

from immutables import Map

from ... import url_patterns
from ... import pattern_tree
from .. import simple_dependency_satisfying as sds
from .. import state as st
from .. import policies


PolicyTree = pattern_tree.PatternTree[policies.PolicyFactory]
PayloadsData = t.Mapping[st.PayloadRef, st.PayloadData]

@dc.dataclass(frozen=True, unsafe_hash=True)
class ConcretePayloadRef(st.PayloadRef):
    state: '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: PolicyTree,
        pattern:     url_patterns.ParsedPattern,
        payload_key: st.PayloadKey,
        token:       str
) -> 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

# mypy needs to be corrected:
# https://stackoverflow.com/questions/70999513/conflict-between-mix-ins-for-abstract-dataclasses/70999704#70999704
@dc.dataclass # type: ignore[misc]
class HaketiloStateWithFields(st.HaketiloState):
    """...."""
    store_dir:      Path
    connection:     sqlite3.Connection
    current_cursor: t.Optional[sqlite3.Cursor] = None
    #settings:       st.HaketiloGlobalSettings

    policy_tree:   PolicyTree   = PolicyTree()
    payloads_data: PayloadsData = dc.field(default_factory=dict)

    lock: threading.RLock = dc.field(default_factory=threading.RLock)

    @contextmanager
    def cursor(self, transaction: bool = False) \
        -> t.Iterator[sqlite3.Cursor]:
        """...."""
        start_transaction = transaction and not self.connection.in_transaction

        with self.lock:
            if self.current_cursor is not None:
                yield self.current_cursor
                return

            try:
                self.current_cursor = self.connection.cursor()

                if start_transaction:
                    self.current_cursor.execute('BEGIN TRANSACTION;')

                try:
                    yield self.current_cursor

                    if start_transaction:
                        assert self.connection.in_transaction
                        self.current_cursor.execute('COMMIT TRANSACTION;')
                except:
                    if start_transaction:
                        self.current_cursor.execute('ROLLBACK TRANSACTION;')
                    raise
            finally:
                self.current_cursor = None

    def rebuild_structures(self) -> None:
        """
        Recreation of data structures as done after every recomputation of
        dependencies as well as at startup.
        """
        with self.cursor(transaction=True) as 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);
                '''
            )

        rows = cursor.fetchall()

        new_policy_tree = 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 rows:
            (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',
                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

    @abstractmethod
    def recompute_dependencies(
            self,
            requirements: t.Iterable[sds.MappingRequirement] = []
    ) -> None:
        """...."""
        ...