/*
 * Copyright (C) 2016-present ScyllaDB
 *
 * Modified by ScyllaDB
 */

/*
 * SPDX-License-Identifier: (LicenseRef-ScyllaDB-Source-Available-1.0 and Apache-2.0)
 */

#include "client_state.hh"
#include "auth/authenticator.hh"
#include "auth/common.hh"
#include "auth/resource.hh"
#include "exceptions/exceptions.hh"
#include "db/system_keyspace.hh"
#include "db/schema_tables.hh"
#include "tracing/trace_keyspace_helper.hh"
#include "db/system_distributed_keyspace.hh"
#include "replica/database.hh"
#include "utils/overloaded_functor.hh"
#include <seastar/core/coroutine.hh>
#include "service/paxos/paxos_state.hh"

thread_local api::timestamp_type service::client_state::_last_timestamp_micros = 0;

void service::client_state::set_login(auth::authenticated_user user) {
    _user = std::move(user);
}

future<> service::client_state::check_user_can_login() {
    if (auth::is_anonymous(*_user)) {
        co_return;
    }

    auto& role_manager = _auth_service->underlying_role_manager();

    const bool exists = co_await role_manager.exists(*_user->name);

    if (!exists) {
        throw exceptions::authentication_exception(
                format("User {} doesn't exist - create it with CREATE USER query first", *_user->name));
    }

    bool can_login = co_await role_manager.can_login(*_user->name);
    if (!can_login) {
        throw exceptions::authentication_exception(format("{} is not permitted to log in", *_user->name));
    }
}

void service::client_state::validate_login() const {
    if (!_user) {
        throw exceptions::unauthorized_exception("You have not logged in");
    }
}

void service::client_state::ensure_not_anonymous() const {
    validate_login();
    if (auth::is_anonymous(*_user)) {
        throw exceptions::unauthorized_exception("You have to be logged in and not anonymous to perform this request");
    }
}

future<> service::client_state::has_all_keyspaces_access(
                auth::permission p) const {
    if (_is_internal) {
        co_return;
    }
    validate_login();

    auth::resource r{auth::resource_kind::data};
    co_return co_await ensure_has_permission({p, r});
}

future<> service::client_state::has_keyspace_access(const sstring& ks, auth::permission p) const {
    auth::resource r = auth::make_data_resource(ks);
    co_return co_await has_access(ks, {p, r});
}

future<> service::client_state::has_functions_access(auth::permission p) const {
    auth::resource r = auth::make_functions_resource();
    co_return co_await ensure_has_permission({p, r});
}

future<> service::client_state::has_functions_access(const sstring& ks, auth::permission p) const {
    auth::resource r = auth::make_functions_resource(ks);
    co_return co_await has_access(ks, {p, r});
}

future<> service::client_state::has_function_access(const sstring& ks, const sstring& function_signature, auth::permission p) const {
    auth::resource r = auth::make_functions_resource(ks, function_signature);
    co_return co_await has_access(ks, {p, r});
}

future<> service::client_state::has_column_family_access(const sstring& ks,
                const sstring& cf, auth::permission p, auth::command_desc::type t, std::optional<bool> is_vector_indexed) const {
    auto r = auth::make_data_resource(ks, cf);
    co_return co_await has_access(ks, {p, r, t}, is_vector_indexed);
}

future<> service::client_state::has_schema_access(const schema& s, auth::permission p) const {
    auth::resource r = auth::make_data_resource(s.ks_name(), s.cf_name());
    co_return co_await has_access(s.ks_name(), {p, r});
}

future<> service::client_state::has_schema_access(const sstring& ks_name, const sstring& cf_name, auth::permission p) const {
    auth::resource r = auth::make_data_resource(ks_name, cf_name);
    co_return co_await has_access(ks_name, {p, r});
}

future<> service::client_state::check_internal_table_permissions(std::string_view ks, std::string_view table_name, const auth::command_desc& cmd) const {
    // 1. CDC and $paxos tables are managed internally by Scylla. Users are prohibited
    //    from running ALTER or DROP commands on them.
    // 2. Non-superusers are not allowed to access $paxos tables, even if explicit
    //    permissions have been granted.
    // Note: This function is on a hot path; coroutines are avoided to reduce allocations.

    static constexpr auto forbidden_permissions = auth::permission_set::of<
                    auth::permission::ALTER, auth::permission::DROP>();

    if (forbidden_permissions.contains(cmd.permission)) {
        if ((ks == db::system_distributed_keyspace::NAME || ks == db::system_distributed_keyspace::NAME_EVERYWHERE)
                && (table_name == db::system_distributed_keyspace::CDC_DESC_V2
                || table_name == db::system_distributed_keyspace::CDC_TOPOLOGY_DESCRIPTION
                || table_name == db::system_distributed_keyspace::CDC_TIMESTAMPS
                || table_name == db::system_distributed_keyspace::CDC_GENERATIONS_V2)) {
            return make_exception_future(exceptions::unauthorized_exception(
                    format("Cannot {} {}", auth::permissions::to_string(cmd.permission), cmd.resource)));
        }
    }

    if (service::paxos::paxos_store::try_get_base_table(table_name)) {
        if (forbidden_permissions.contains(cmd.permission)) {
            return make_exception_future(exceptions::unauthorized_exception(
                    format("Cannot {} {}", auth::permissions::to_string(cmd.permission), cmd.resource)));
        }

        return _auth_service->underlying_role_manager().is_superuser(*_user->name)
            .then([&cmd](bool is_superuser) {
                return is_superuser
                    ? make_ready_future<>()
                    : make_exception_future(exceptions::unauthorized_exception(
                        format("Only superusers are allowed to {} {}", 
                            auth::permissions::to_string(cmd.permission), cmd.resource)));
            });
    }

    return make_ready_future<>();
}

future<> service::client_state::has_access(const sstring& ks, auth::command_desc cmd, std::optional<bool> is_vector_indexed) const {
    if (ks.empty()) {
        throw exceptions::invalid_request_exception("You have not set a keyspace for this session");
    }
    if (_is_internal) {
        co_return;
    }

    validate_login();

    static const auto alteration_permissions = auth::permission_set::of<
            auth::permission::CREATE, auth::permission::ALTER, auth::permission::DROP>();

    // we only care about schema modification.
    if (alteration_permissions.contains(cmd.permission)) {
        // prevent system keyspace modification
        auto name = ks;
        std::transform(name.begin(), name.end(), name.begin(), ::tolower);
        if (is_system_keyspace(name) && cmd.type_ != auth::command_desc::type::ALTER_SYSTEM_WITH_ALLOWED_OPTS) {
            throw exceptions::unauthorized_exception(ks + " keyspace is not user-modifiable.");
        }

        //
        // we want to disallow dropping any contents of TRACING_KS and disallow dropping the `auth::meta::legacy::AUTH_KS`
        // keyspace.
        //

        const bool dropping_anything_in_tracing = (name == tracing::trace_keyspace_helper::KEYSPACE_NAME)
                && (cmd.permission == auth::permission::DROP);

        const bool dropping_auth_keyspace = (cmd.resource == auth::make_data_resource(auth::meta::legacy::AUTH_KS))
                && (cmd.permission == auth::permission::DROP);

        if (dropping_anything_in_tracing || dropping_auth_keyspace) {
            throw exceptions::unauthorized_exception(
                    format("Cannot {} {}", auth::permissions::to_string(cmd.permission), cmd.resource));
        }
    }

    static thread_local std::unordered_set<auth::resource> readable_system_resources = [] {
        std::unordered_set<auth::resource> tmp;
        for (auto cf : { db::system_keyspace::LOCAL, db::system_keyspace::PEERS }) {
            tmp.insert(auth::make_data_resource(db::system_keyspace::NAME, cf));
        }
        for (const auto& cf : db::schema_tables::all_table_infos(db::schema_features::full())) {
            tmp.insert(auth::make_data_resource(db::schema_tables::NAME, cf.name));
        }
        return tmp;
    }();

    if (cmd.permission == auth::permission::SELECT && readable_system_resources.contains(cmd.resource)) {
        co_return;
    }
    if (alteration_permissions.contains(cmd.permission)) {
        if (auth::is_protected(*_auth_service, cmd)) {
            throw exceptions::unauthorized_exception(format("{} is protected", cmd.resource));
        }
    }

    if (cmd.resource.kind() == auth::resource_kind::data) {
        const auto resource_view = auth::data_resource_view(cmd.resource);
        if (resource_view.table()) {
            co_await check_internal_table_permissions(ks, *resource_view.table(), cmd);
        }
    }

    if (cmd.resource.kind() == auth::resource_kind::data
            && !(cmd.permission == auth::permission::SELECT || cmd.permission == auth::permission::DESCRIBE)
            && is_system_keyspace(ks)
            && _user
            && !auth::is_anonymous(*_user)
            && !co_await _auth_service->underlying_role_manager().is_superuser(*_user->name)) [[unlikely]] {
        throw exceptions::unauthorized_exception(
                ks + " can be granted only SELECT or DESCRIBE permissions to a non-superuser.");
    }

    if (cmd.resource.kind() == auth::resource_kind::data && cmd.permission == auth::permission::SELECT && is_vector_indexed.has_value() && is_vector_indexed.value()) {

        co_return co_await ensure_has_permission<auth::command_desc_with_permission_set>({auth::permission_set::of<auth::permission::SELECT, auth::permission::VECTOR_SEARCH_INDEXING>(), cmd.resource});

    }

    co_return co_await ensure_has_permission(cmd);
}

static bool intersects_permissions(const auth::permission_set& permissions, const auth::command_desc_with_permission_set& cmd) {
    return permissions.intersects(cmd.permission);
}

static bool intersects_permissions(const auth::permission_set& permissions, const auth::command_desc& cmd) {
    return permissions.contains(cmd.permission);
}

sstring service::client_state::generate_authorization_error_msg(const auth::command_desc& cmd) const {
    return format("User {} has no {} permission on {} or any of its parents",
            *_user,
            auth::permissions::to_string(cmd.permission),
            cmd.resource);
}

sstring service::client_state::generate_authorization_error_msg(const auth::command_desc_with_permission_set& cmd) const {
    sstring perm_names = fmt::format("{}", fmt::join(auth::permissions::to_strings(cmd.permission), ", "));
    return format("User {} has none of the permissions ({}) on {} or any of its parents",
            *_user,
            perm_names,
            cmd.resource);
}

template <typename Cmd>
future<bool> service::client_state::check_has_permission(Cmd cmd) const {
    if (_is_internal) {
        co_return true;
    }

    std::optional<auth::resource> parent_r = cmd.resource.parent();

    auth::permission_set set = co_await auth::get_permissions(*_auth_service, *_user, cmd.resource);
    if (intersects_permissions(set, cmd)) {
        co_return true;
    }
    if (parent_r) {
        co_return co_await check_has_permission<Cmd>({cmd.permission, *parent_r});
    }
    co_return false;
}
template future<bool> service::client_state::check_has_permission(auth::command_desc) const;
template future<bool> service::client_state::check_has_permission<auth::command_desc_with_permission_set>(auth::command_desc_with_permission_set) const;

template <typename Cmd>
future<> service::client_state::ensure_has_permission(Cmd cmd) const {
    return check_has_permission(cmd).then([this, cmd](bool ok) {
        if (!ok) {
            return make_exception_future<>(exceptions::unauthorized_exception(
                generate_authorization_error_msg(cmd)));
        }
        return make_ready_future<>();
    });
}
template future<> service::client_state::ensure_has_permission(auth::command_desc) const;
template future<> service::client_state::ensure_has_permission<auth::command_desc_with_permission_set>(auth::command_desc_with_permission_set) const;

void service::client_state::set_keyspace(replica::database& db, std::string_view keyspace) {
    // Skip keyspace validation for non-authenticated users. Apparently, some client libraries
    // call set_keyspace() before calling login(), and we have to handle that.
    if (_user && !db.has_keyspace(keyspace)) {
        throw exceptions::invalid_request_exception(seastar::format("Keyspace '{}' does not exist", keyspace));
    }
    _keyspace = sstring(keyspace);
}

future<> service::client_state::ensure_exists(const auth::resource& r) const {
    return _auth_service->exists(r).then([&r](bool exists) {
        if (!exists) {
            return make_exception_future<>(exceptions::invalid_request_exception(format("{} doesn't exist.", r)));
        }

        return make_ready_future<>();
    });
}

future<> service::client_state::maybe_update_per_service_level_params() {
    if (_sl_controller && _user && _user->name) {
        auto slo_opt = co_await _sl_controller->find_effective_service_level(_user->name.value());
        if (!slo_opt) {
            co_return;
        }
        
        update_per_service_level_params(*slo_opt);
    }
}

void service::client_state::update_per_service_level_params(qos::service_level_options& slo) {
    auto slo_timeout_or = [&] (const lowres_clock::duration& default_timeout) {
        return std::visit(overloaded_functor{
            [&] (const qos::service_level_options::unset_marker&) -> lowres_clock::duration {
                return default_timeout;
            },
            [&] (const qos::service_level_options::delete_marker&) -> lowres_clock::duration {
                return default_timeout;
            },
            [&] (const lowres_clock::duration& d) -> lowres_clock::duration {
                return d;
            },
        }, slo.timeout);
    };

    _timeout_config.read_timeout = slo_timeout_or(_default_timeout_config.read_timeout);
    _timeout_config.write_timeout = slo_timeout_or(_default_timeout_config.write_timeout);
    _timeout_config.range_read_timeout = slo_timeout_or(_default_timeout_config.range_read_timeout);
    _timeout_config.counter_write_timeout = slo_timeout_or(_default_timeout_config.counter_write_timeout);
    _timeout_config.truncate_timeout = slo_timeout_or(_default_timeout_config.truncate_timeout);
    _timeout_config.cas_timeout = slo_timeout_or(_default_timeout_config.cas_timeout);
    _timeout_config.other_timeout = slo_timeout_or(_default_timeout_config.other_timeout);

    _workload_type = slo.workload;
}