# 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 ItemsCollection, ComputedPayload
from .. import state as st
from .. import policies
from . import base


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

AnyInfo = t.Union[item_infos.ResourceInfo, item_infos.MappingInfo]

@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):
    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()
        )

PolicyTree = pattern_tree.PatternTree[policies.PolicyFactory]

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

    policy_tree = policy_tree.register(
        payload_key.pattern,
        payload_policy_factory
    )

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

    policy_tree = policy_tree.register(
        payload_key.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 newest_item_path(item_dir: Path) -> t.Optional[Path]:
#     available_versions = tuple(
#         versions.parse_normalize_version(ver_path.name)
#         for ver_path in item_dir.iterdir()
#         if ver_path.is_file()
#     )

#     if available_versions == ():
#         return None

#     newest_version = max(available_versions)

#     version_path = item_dir / versions.version_string(newest_version)

#     assert version_path.is_file()

#     return version_path

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,
        definition:        str,
        info:              AnyInfo
) -> int:
    ver_str = versions.version_string(info.version)

    values = (
        item_id,
        ver_str,
        repo_iteration_id,
        definition,
        info.allows_eval,
        info.allows_cors_bypass
    )

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

    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)
    )

@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() as cursor:
            self.rebuild_structures(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(lock=True, transaction=True) as cursor:
            for info_type in [item_infos.ResourceInfo, item_infos.MappingInfo]:
                info: 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,
                        definition,
                        info
                    )

                    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 rebuild_structures(self, cursor: sqlite3.Cursor) -> None:
        cursor.execute(
            '''
            SELECT
                    item_id, type, version, definition
            FROM
                    item_versions JOIN items USING (item_id);
            '''
        )

        best_versions: dict[int, versions.VerTuple] = {}
        definitions = {}
        types = {}

        for item_id, item_type, ver_str, definition in cursor.fetchall():
            # TODO: what we're doing in this loop does not yet take different
            # repos and different repo iterations into account.
            ver = versions.parse_normalize_version(ver_str)
            if best_versions.get(item_id, (0,)) < ver:
                best_versions[item_id] = ver
                definitions[item_id] = definition
                types[item_id] = item_type

        resources = {}
        mappings = {}

        for item_id, definition in definitions.items():
            if types[item_id] == 'R':
                r_info = item_infos.ResourceInfo.load(io.StringIO(definition))
                resources[r_info.identifier] = r_info
            else:
                m_info = item_infos.MappingInfo.load(io.StringIO(definition))
                mappings[m_info.identifier] = m_info

        items_collection = ItemsCollection(resources, mappings)
        computed_payloads = items_collection.compute_payloads()

        payloads_data = {}

        for mapping_info, by_pattern in computed_payloads.items():
            for num, (pattern, payload) in enumerate(by_pattern.items()):
                payload_id = f'{num}@{mapping_info.identifier}'

                ref = ConcretePayloadRef(payload_id, payload)

                data = st.PayloadData(
                    payload_ref         = ref,
                    mapping_installed   = True,
                    explicitly_enabled  = True,
                    unique_token        = secrets.token_urlsafe(16),
                    pattern             = pattern,
                    eval_allowed        = payload.allows_eval,
                    cors_bypass_allowed = payload.allows_cors_bypass
                )

                payloads_data[payload_id] = data

                key = st.PayloadKey(
                    payload_ref        = ref,
                    mapping_identifier = mapping_info.identifier,
                    pattern            = pattern
                )

                self.policy_tree = register_payload(
                    self.policy_tree,
                    key,
                    data.unique_token
                )

        self.payloads_data = 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':
        return ConcreteHaketiloState(
            store_dir      = store_dir,
            connection     = sqlite3.connect(str(store_dir / 'sqlite3.db'))
        )