# 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 versions
from ... import item_infos
from ..simple_dependency_satisfying import compute_payloads, ComputedPayload
from .. import state as st
from .. import policies
from . import base


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 ConcreteMappingRef(st.MappingRef):
    def disable(self, state: st.HaketiloState) -> None:
        raise NotImplementedError()

    def forget_enabled(self, state: st.HaketiloState) -> None:
        raise NotImplementedError()


@dc.dataclass(frozen=True, unsafe_hash=True)
class ConcreteMappingVersionRef(st.MappingVersionRef):
    def enable(self, state: st.HaketiloState) -> None:
        raise NotImplementedError()


@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):
    def get_data(self, state: st.HaketiloState) -> st.PayloadData:
        return t.cast(ConcreteHaketiloState, state).payloads_data[self]

    def get_mapping(self, state: st.HaketiloState) -> st.MappingVersionRef:
        return 'to implement'

    def get_script_paths(self, state: st.HaketiloState) \
        -> t.Iterable[t.Sequence[str]]:
        with t.cast(ConcreteHaketiloState, 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, state: st.HaketiloState, 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 t.cast(ConcreteHaketiloState, 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)

# @dc.dataclass(frozen=True, unsafe_hash=True)
# class ConcretePayloadRef(st.PayloadRef):
#     computed_payload: ComputedPayload = dc.field(hash=False, compare=False)

#     def get_data(self, state: st.HaketiloState) -> st.PayloadData:
#         return t.cast(ConcreteHaketiloState, state).payloads_data[self.id]

#     def get_mapping(self, state: st.HaketiloState) -> st.MappingVersionRef:
#         return 'to implement'

#     def get_script_paths(self, state: st.HaketiloState) \
#         -> t.Iterator[t.Sequence[str]]:
#         for resource_info in self.computed_payload.resources:
#             for file_spec in resource_info.scripts:
#                 yield (resource_info.identifier, *file_spec.name.split('/'))

#     def get_file_data(self, state: st.HaketiloState, 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)

#         script_sha256 = ''

#         matched_resource_info = False

#         for resource_info in self.computed_payload.resources:
#             if resource_info.identifier == resource_identifier:
#                 matched_resource_info = True

#                 for script_spec in resource_info.scripts:
#                     if script_spec.name == file_name:
#                         script_sha256 = script_spec.sha256

#                 break

#         if not matched_resource_info:
#             raise st.MissingItemError(resource_identifier)

#         if script_sha256 == '':
#             return None

#         store_dir_path = t.cast(ConcreteHaketiloState, state).store_dir
#         files_dir_path = store_dir_path / 'temporary_malcontent' / 'file'
#         file_path = files_dir_path / 'sha256' / script_sha256

#         return st.FileData(
#             type     = 'application/javascript',
#             name     = file_name,
#             contents = file_path.read_bytes()
#         )

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

DataById = t.Mapping[str, st.PayloadData]

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

def read_items(malcontent_path: Path, item_class: t.Type[AnyInfoVar]) \
    -> t.Iterator[tuple[AnyInfoVar, str]]:
    item_type_path = malcontent_path / item_class.type_name
    if not item_type_path.is_dir():
        return

    for item_path in item_type_path.iterdir():
        if not item_path.is_dir():
            continue

        for item_version_path in item_path.iterdir():
            definition = item_version_path.read_text()
            item_info = item_class.load(io.StringIO(definition))

            assert item_info.identifier == item_path.name
            assert versions.version_string(item_info.version) == \
                item_version_path.name

            yield item_info, definition

def get_or_make_repo_iteration(cursor: sqlite3.Cursor, repo_name: str) -> int:
    cursor.execute(
        '''
        INSERT OR IGNORE INTO repos(name, url, deleted, next_iteration)
        VALUES(?, '<dummy_url>', TRUE, 2);
        ''',
        (repo_name,)
    )

    cursor.execute(
        '''
        SELECT
                repo_id, next_iteration - 1
        FROM
                repos
        WHERE
                name = ?;
        ''',
        (repo_name,)
    )

    (repo_id, last_iteration), = cursor.fetchall()

    cursor.execute(
        '''
        INSERT OR IGNORE INTO repo_iterations(repo_id, iteration)
        VALUES(?, ?);
        ''',
        (repo_id, last_iteration)
    )

    cursor.execute(
        '''
        SELECT
                repo_iteration_id
        FROM
                repo_iterations
        WHERE
                repo_id = ? AND iteration = ?;
        ''',
        (repo_id, last_iteration)
    )

    (repo_iteration_id,), = cursor.fetchall()

    return repo_iteration_id

def get_or_make_item(cursor: sqlite3.Cursor, type: str, identifier: str) -> int:
    type_letter = {'resource': 'R', 'mapping': 'M'}[type]

    cursor.execute(
        '''
        INSERT OR IGNORE INTO items(type, identifier)
        VALUES(?, ?);
        ''',
        (type_letter, identifier)
    )

    cursor.execute(
        '''
        SELECT
                item_id
        FROM
                items
        WHERE
                type = ? AND identifier = ?;
        ''',
        (type_letter, identifier)
    )

    (item_id,), = cursor.fetchall()

    return item_id

def get_or_make_item_version(
        cursor:            sqlite3.Cursor,
        item_id:           int,
        repo_iteration_id: int,
        version:           versions.VerTuple,
        definition:        str
) -> int:
    ver_str = versions.version_string(version)

    cursor.execute(
        '''
        INSERT OR IGNORE INTO item_versions(
    	        item_id,
                version,
	        repo_iteration_id,
                definition
        )
        VALUES(?, ?, ?, ?);
        ''',
        (item_id, ver_str, repo_iteration_id, definition)
    )

    cursor.execute(
        '''
        SELECT
                item_version_id
        FROM
                item_versions
        WHERE
                item_id = ? AND version = ? AND repo_iteration_id = ?;
        ''',
        (item_id, ver_str, repo_iteration_id)
    )

    (item_version_id,), = cursor.fetchall()

    return item_version_id

def make_mapping_status(cursor: sqlite3.Cursor, item_id: int) -> None:
    cursor.execute(
        '''
        INSERT OR IGNORE INTO mapping_statuses(item_id, enabled)
        VALUES(?, 'N');
        ''',
        (item_id,)
    )

def get_or_make_file(cursor: sqlite3.Cursor, sha256: str, file_bytes: bytes) \
    -> int:
    cursor.execute(
        '''
        INSERT OR IGNORE INTO files(sha256, data)
        VALUES(?, ?)
        ''',
        (sha256, file_bytes)
    )

    cursor.execute(
        '''
        SELECT
                file_id
        FROM
                files
        WHERE
                sha256 = ?;
        ''',
        (sha256,)
    )

    (file_id,), = cursor.fetchall()

    return file_id

def make_file_use(
        cursor:          sqlite3.Cursor,
        item_version_id: int,
        file_id:         int,
        name:            str,
        type:            str,
        mime_type:       str,
        idx:             int
) -> None:
    cursor.execute(
        '''
        INSERT OR IGNORE INTO file_uses(
                item_version_id,
                file_id,
                name,
                type,
                mime_type,
                idx
        )
        VALUES(?, ?, ?, ?, ?, ?);
        ''',
        (item_version_id, file_id, name, type, mime_type, idx)
    )

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._populate_database_with_stuff_from_temporary_malcontent_dir()

        with self.cursor(transaction=True) as cursor:
            self.recompute_payloads(cursor)

    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.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 _populate_database_with_stuff_from_temporary_malcontent_dir(self) \
        -> None:
        malcontent_dir_path = self.store_dir / 'temporary_malcontent'
        files_by_sha256_path = malcontent_dir_path / 'file' / 'sha256'

        with self.cursor(transaction=True) as cursor:
            for info_type in [item_infos.ResourceInfo, item_infos.MappingInfo]:
                info: item_infos.AnyInfo
                for info, definition in read_items(
                        malcontent_dir_path,
                        info_type # type: ignore
                ):
                    repo_iteration_id = get_or_make_repo_iteration(
                        cursor,
                        info.repo
                    )

                    item_id = get_or_make_item(
                        cursor,
                        info.type_name,
                        info.identifier
                    )

                    item_version_id = get_or_make_item_version(
                        cursor,
                        item_id,
                        repo_iteration_id,
                        info.version,
                        definition
                    )

                    if info_type is item_infos.MappingInfo:
                        make_mapping_status(cursor, item_id)

                    file_ids_bytes = {}

                    file_specifiers = [*info.source_copyright]
                    if isinstance(info, item_infos.ResourceInfo):
                        file_specifiers.extend(info.scripts)
                    
                    for file_spec in file_specifiers:
                        file_path = files_by_sha256_path / file_spec.sha256
                        file_bytes = file_path.read_bytes()

                        sha256 = hashlib.sha256(file_bytes).digest().hex()
                        assert sha256 == file_spec.sha256

                        file_id = get_or_make_file(cursor, sha256, file_bytes)

                        file_ids_bytes[sha256] = (file_id, file_bytes)

                    for idx, file_spec in enumerate(info.source_copyright):
                        file_id, file_bytes = file_ids_bytes[file_spec.sha256]
                        if file_bytes.isascii():
                            mime = 'text/plain'
                        else:
                            mime = 'application/octet-stream'

                        make_file_use(
                            cursor,
                            item_version_id = item_version_id,
                            file_id         = file_id,
                            name            = file_spec.name,
                            type            = 'L',
                            mime_type       = mime,
                            idx             = idx
                        )

                    if isinstance(info, item_infos.MappingInfo):
                        continue

                    for idx, file_spec in enumerate(info.scripts):
                        file_id, _ = file_ids_bytes[file_spec.sha256]
                        make_file_use(
                            cursor,
                            item_version_id = item_version_id,
                            file_id         = file_id,
                            name            = file_spec.name,
                            type            = 'W',
                            mime_type       = 'application/javascript',
                            idx             = idx
                        )

    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: sqlite3.Cursor) -> None:
        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()
        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))

            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 get_mapping(self, mapping_id: str) -> st.MappingRef:
        return ConcreteMappingRef(mapping_id)

    def get_mapping_version(self, mapping_version_id: str) \
        -> st.MappingVersionRef:
        return ConcreteMappingVersionRef(mapping_version_id)

    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:
        return 'not implemented'

    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
        )