drasi-plugin-sdk 0.4.3

// Copyright 2025 The Drasi Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! `#[repr(C)]` vtable structs for the FFI boundary.
//!
//! These structs are the "contracts" between host and plugin. Each vtable
//! holds a `state` pointer (the opaque `self`) plus function pointers that
//! the caller dispatches through.

use std::ffi::c_void;

use super::types::{
    AsyncExecutorFn, FfiChangeOp, FfiComponentStatus, FfiCreateResult, FfiDispatchMode,
    FfiGetResult, FfiOwnedStr, FfiResult, FfiStr, FfiStringArray,
};

// ============================================================================
// Source events — carries SourceChange / SourceEventWrapper across FFI
// ============================================================================

/// Represents a source change event that crosses the FFI boundary.
/// The opaque pointer holds a heap-allocated Rust type (e.g., `SourceEventWrapper`)
/// that the plugin owns. The FFI metadata fields expose key information so the
/// host can route/filter without deserializing.
#[repr(C)]
pub struct FfiSourceEvent {
    pub opaque: *mut c_void,
    pub source_id: FfiStr,
    pub timestamp_us: i64,
    pub op: FfiChangeOp,
    pub label: FfiStr,
    pub entity_id: FfiStr,
    pub drop_fn: extern "C" fn(*mut c_void),
}

/// Bootstrap event — initial state data loaded before streaming begins.
#[repr(C)]
pub struct FfiBootstrapEvent {
    pub opaque: *mut c_void,
    pub source_id: FfiStr,
    pub timestamp_us: i64,
    pub sequence: u64,
    pub label: FfiStr,
    pub entity_id: FfiStr,
    pub drop_fn: extern "C" fn(*mut c_void),
}

// ============================================================================
// Receivers — streaming events from plugin to host
// ============================================================================

/// Callback function type for push-based change delivery.
/// Called by the plugin forwarder for each source event.
/// `ctx` is the host-owned context pointer, `event` is the event to deliver.
/// Returns `true` if the event was accepted, `false` to signal shutdown.
pub type FfiChangePushCallbackFn =
    extern "C" fn(ctx: *mut c_void, event: *mut FfiSourceEvent) -> bool;

/// Change receiver — push-based model.
///
/// Instead of the host polling via `recv_fn`, the host calls `start_push_fn`
/// with a callback. The plugin spawns a forwarder task that reads from the
/// underlying channel and invokes the callback for each event. This avoids
/// the `spawn_blocking` + `dispatch_to_runtime` round-trip per event.
#[repr(C)]
pub struct FfiChangeReceiver {
    pub state: *mut c_void,
    pub executor: AsyncExecutorFn,
    /// Start pushing events to the provided callback.
    /// The plugin spawns a forwarder task on its runtime.
    /// The callback is called once per event until the channel closes
    /// or the callback returns `false`.
    pub start_push_fn: extern "C" fn(
        state: *mut c_void,
        callback: FfiChangePushCallbackFn,
        callback_ctx: *mut c_void,
    ),
    pub drop_fn: extern "C" fn(state: *mut c_void),
}

unsafe impl Send for FfiChangeReceiver {}
unsafe impl Sync for FfiChangeReceiver {}

/// Callback function type for push-based bootstrap delivery.
/// Called by the plugin forwarder for each bootstrap event.
/// `ctx` is the host-owned context pointer, `event` is the event to deliver (null signals end-of-stream).
/// Returns `true` if the event was accepted, `false` to signal shutdown.
pub type FfiBootstrapPushCallbackFn =
    extern "C" fn(ctx: *mut c_void, event: *mut FfiBootstrapEvent) -> bool;

/// Bootstrap receiver — push-based finite stream of bootstrap events.
///
/// Like `FfiChangeReceiver`, uses a push model: the host calls `start_push_fn`
/// with a callback, and the plugin spawns a forwarder that pushes events via
/// the callback until the stream is exhausted (sends null) or the callback
/// returns `false`.
#[repr(C)]
pub struct FfiBootstrapReceiver {
    pub state: *mut c_void,
    pub start_push_fn: extern "C" fn(
        state: *mut c_void,
        callback: FfiBootstrapPushCallbackFn,
        callback_ctx: *mut c_void,
    ),
    pub drop_fn: extern "C" fn(state: *mut c_void),
}

unsafe impl Send for FfiBootstrapReceiver {}
unsafe impl Sync for FfiBootstrapReceiver {}

/// Subscription response — streaming receiver + optional bootstrap receiver.
#[repr(C)]
pub struct FfiSubscriptionResponse {
    pub query_id: FfiOwnedStr,
    pub source_id: FfiOwnedStr,
    pub receiver: *mut FfiChangeReceiver,
    /// Null if no bootstrap data available.
    pub bootstrap_receiver: *mut FfiBootstrapReceiver,
}

// ============================================================================
// Query result events — carries QueryResult across FFI to reactions
// ============================================================================

/// Callback for push-based query result delivery to reactions.
/// The plugin calls this to receive the next QueryResult from the host.
/// Returns a `*mut QueryResult` (ownership transfers to the plugin),
/// or null to signal end-of-stream / shutdown.
/// The `result` parameter is unused (reserved).
pub type FfiResultPushCallbackFn =
    extern "C" fn(ctx: *mut c_void, result: *mut c_void) -> *mut c_void;

// ============================================================================
// Bootstrap sender — callback for sending bootstrap records from provider
// ============================================================================

/// FFI-safe callback for sending bootstrap records from a BootstrapProvider.
/// The host creates this and passes it to the provider.
#[repr(C)]
pub struct FfiBootstrapSender {
    pub state: *mut c_void,
    /// Send a bootstrap record. Returns 0 on success, non-zero if channel closed.
    pub send_fn: extern "C" fn(state: *mut c_void, event: *mut FfiBootstrapEvent) -> i32,
    pub drop_fn: extern "C" fn(state: *mut c_void),
}

unsafe impl Send for FfiBootstrapSender {}
unsafe impl Sync for FfiBootstrapSender {}

// ============================================================================
// Runtime context — host services provided to plugins during initialization
// ============================================================================

/// Runtime context passed from host to plugin during initialization.
/// Contains vtable-based callbacks for host services — no trait objects.
#[repr(C)]
pub struct FfiRuntimeContext {
    pub instance_id: FfiStr,
    pub component_id: FfiStr,
    /// Nullable — not all plugins need state store.
    pub state_store: *const StateStoreVtable,
    /// Per-instance log callback (nullable — falls back to global if null).
    pub log_callback: Option<super::callbacks::LogCallbackFn>,
    /// Opaque context for per-instance log callback.
    pub log_ctx: *mut c_void,
    /// Per-instance lifecycle callback (nullable — falls back to global if null).
    pub lifecycle_callback: Option<super::callbacks::LifecycleCallbackFn>,
    /// Opaque context for per-instance lifecycle callback.
    pub lifecycle_ctx: *mut c_void,
    /// Nullable — identity provider for credential injection.
    pub identity_provider: *const super::identity::IdentityProviderVtable,
}

// Safety: FfiRuntimeContext contains raw pointers that point to thread-safe data.
// The vtables contain only function pointers and Send+Sync state.
// The ctx pointers point to Arc-backed structures that are Send+Sync.
unsafe impl Send for FfiRuntimeContext {}
unsafe impl Sync for FfiRuntimeContext {}

// ============================================================================
// Source vtable
// ============================================================================

drasi_ffi_primitives::ffi_vtable! {
    /// FFI-safe vtable for a Source instance.
    pub struct SourceVtable {
        // Identity
        fn id_fn(state: *const) -> FfiStr,
        fn type_name_fn(state: *const) -> FfiStr,
        fn auto_start_fn(state: *const) -> bool,
        fn dispatch_mode_fn(state: *const) -> FfiDispatchMode,

        // Configuration inspection
        /// Returns the source's configuration properties as a JSON string.
        fn properties_fn(state: *const) -> FfiOwnedStr,

        // Lifecycle
        fn start_fn(state: *mut) -> FfiResult,
        fn stop_fn(state: *mut) -> FfiResult,
        fn status_fn(state: *const) -> FfiComponentStatus,
        fn deprovision_fn(state: *mut) -> FfiResult,

        // Initialization
        fn initialize_fn(state: *mut, ctx: *const FfiRuntimeContext),

        // Subscriptions
        /// Subscribe with query_id, node_labels JSON, relation_labels JSON.
        fn subscribe_fn(state: *mut, source_id: FfiStr, enable_bootstrap: bool, query_id: FfiStr, nodes_json: FfiStr, relations_json: FfiStr) -> *mut FfiSubscriptionResponse,

        /// Host calls this to inject an external bootstrap provider (from another plugin).
        fn set_bootstrap_provider_fn(state: *mut, provider: *mut BootstrapProviderVtable),
    }
}

// ============================================================================
// Reaction vtable
// ============================================================================

drasi_ffi_primitives::ffi_vtable! {
    /// FFI-safe vtable for a Reaction instance.
    pub struct ReactionVtable {
        // Identity
        fn id_fn(state: *const) -> FfiStr,
        fn type_name_fn(state: *const) -> FfiStr,
        fn auto_start_fn(state: *const) -> bool,
        fn query_ids_fn(state: *const) -> FfiStringArray,

        // Configuration inspection
        /// Returns the reaction's configuration properties as a JSON string.
        fn properties_fn(state: *const) -> FfiOwnedStr,

        // Lifecycle
        fn start_fn(state: *mut) -> FfiResult,
        fn stop_fn(state: *mut) -> FfiResult,
        fn status_fn(state: *const) -> FfiComponentStatus,
        fn deprovision_fn(state: *mut) -> FfiResult,

        // Initialization
        fn initialize_fn(state: *mut, ctx: *const FfiRuntimeContext),

        // Host-managed query subscription forwarding (push-based)
        /// The host calls this once to start push-based delivery.
        /// The plugin spawns a forwarder task that reads from an internal channel
        /// and calls `reaction.enqueue_query_result()` for each item.
        fn start_result_push_fn(state: *mut, callback: FfiResultPushCallbackFn, callback_ctx: *mut c_void),
    }
}

// ============================================================================
// Bootstrap provider vtable
// ============================================================================

drasi_ffi_primitives::ffi_vtable! {
    /// FFI-safe vtable for a BootstrapProvider.
    /// The bootstrap plugin creates this; the host wraps it and passes it to the source plugin.
    pub struct BootstrapProviderVtable {
        /// Perform bootstrap. Sends records via the FfiBootstrapSender.
        /// Returns the count of records sent (>= 0), or negative on error.
        fn bootstrap_fn(state: *mut, query_id: FfiStr, node_labels: *const FfiStr, node_labels_count: usize, relation_labels: *const FfiStr, relation_labels_count: usize, request_id: FfiStr, server_id: FfiStr, source_id: FfiStr, sender: *mut FfiBootstrapSender) -> i64,
    }
}

// ============================================================================
// Plugin descriptor vtables — factories that create Source/Reaction instances
// ============================================================================

drasi_ffi_primitives::ffi_vtable! {
    /// FFI-safe vtable for a SourcePluginDescriptor (factory).
    /// The host calls `create_source_fn` to construct a SourceVtable from config.
    pub struct SourcePluginVtable {
        fn kind_fn(state: *const) -> FfiStr,
        fn config_version_fn(state: *const) -> FfiStr,
        fn config_schema_json_fn(state: *const) -> FfiOwnedStr,
        fn config_schema_name_fn(state: *const) -> FfiStr,

        fn create_source_fn(state: *mut, id: FfiStr, config_json: FfiStr, auto_start: bool) -> FfiCreateResult,
    }
}

drasi_ffi_primitives::ffi_vtable! {
    /// FFI-safe vtable for a ReactionPluginDescriptor (factory).
    pub struct ReactionPluginVtable {
        fn kind_fn(state: *const) -> FfiStr,
        fn config_version_fn(state: *const) -> FfiStr,
        fn config_schema_json_fn(state: *const) -> FfiOwnedStr,
        fn config_schema_name_fn(state: *const) -> FfiStr,

        /// Factory: create a ReactionVtable from JSON config.
        fn create_reaction_fn(state: *mut, id: FfiStr, query_ids_json: FfiStr, config_json: FfiStr, auto_start: bool) -> FfiCreateResult,
    }
}

drasi_ffi_primitives::ffi_vtable! {
    /// FFI-safe vtable for a BootstrapPluginDescriptor (factory).
    pub struct BootstrapPluginVtable {
        fn kind_fn(state: *const) -> FfiStr,
        fn config_version_fn(state: *const) -> FfiStr,
        fn config_schema_json_fn(state: *const) -> FfiOwnedStr,
        fn config_schema_name_fn(state: *const) -> FfiStr,

        /// Factory: create a BootstrapProviderVtable from JSON config.
        fn create_bootstrap_provider_fn(state: *mut, config_json: FfiStr, source_config_json: FfiStr) -> FfiCreateResult,
    }
}

// ============================================================================
// State store vtable — reverse direction (host → plugin)
// ============================================================================

/// State store vtable — host creates and provides to plugins.
/// Plugins call these function pointers to access persistent state.
#[repr(C)]
pub struct StateStoreVtable {
    pub state: *mut c_void,
    // Basic operations
    pub get_fn: extern "C" fn(state: *mut c_void, store_id: FfiStr, key: FfiStr) -> FfiGetResult,
    pub set_fn: extern "C" fn(
        state: *mut c_void,
        store_id: FfiStr,
        key: FfiStr,
        value: *const u8,
        value_len: usize,
    ) -> FfiResult,
    pub delete_fn: extern "C" fn(state: *mut c_void, store_id: FfiStr, key: FfiStr) -> FfiResult,
    pub contains_key_fn:
        extern "C" fn(state: *mut c_void, store_id: FfiStr, key: FfiStr) -> FfiResult,
    // Batch operations (keys passed as FfiStr arrays)
    pub get_many_fn: extern "C" fn(
        state: *mut c_void,
        store_id: FfiStr,
        keys: *const FfiStr,
        keys_count: usize,
        out_values: *mut FfiGetResult,
    ) -> FfiResult,
    pub set_many_fn: extern "C" fn(
        state: *mut c_void,
        store_id: FfiStr,
        keys: *const FfiStr,
        values: *const *const u8,
        value_lens: *const usize,
        count: usize,
    ) -> FfiResult,
    pub delete_many_fn: extern "C" fn(
        state: *mut c_void,
        store_id: FfiStr,
        keys: *const FfiStr,
        keys_count: usize,
    ) -> i64,
    // Store-level operations
    pub clear_store_fn: extern "C" fn(state: *mut c_void, store_id: FfiStr) -> i64,
    pub list_keys_fn: extern "C" fn(state: *mut c_void, store_id: FfiStr) -> FfiStringArray,
    pub store_exists_fn: extern "C" fn(state: *mut c_void, store_id: FfiStr) -> FfiResult,
    pub key_count_fn: extern "C" fn(state: *mut c_void, store_id: FfiStr) -> i64,
    pub sync_fn: extern "C" fn(state: *mut c_void) -> FfiResult,
    // Cleanup
    pub drop_fn: extern "C" fn(state: *mut c_void),
}

unsafe impl Send for StateStoreVtable {}
unsafe impl Sync for StateStoreVtable {}

// ============================================================================
// Plugin registration — returned by drasi_plugin_init() for cdylib builds
// ============================================================================

/// FFI-safe plugin registration returned by `drasi_plugin_init()`.
/// Contains factory vtables for all plugin types this shared library provides.
#[repr(C)]
pub struct FfiPluginRegistration {
    pub source_plugins: *mut SourcePluginVtable,
    pub source_plugin_count: usize,
    pub reaction_plugins: *mut ReactionPluginVtable,
    pub reaction_plugin_count: usize,
    pub bootstrap_plugins: *mut BootstrapPluginVtable,
    pub bootstrap_plugin_count: usize,
    /// Host calls this to provide a log callback with an opaque context pointer.
    /// The plugin stores both the callback and context, passing context back on every call.
    pub set_log_callback:
        extern "C" fn(ctx: *mut ::std::ffi::c_void, callback: super::callbacks::LogCallbackFn),
    /// Host calls this to provide a lifecycle event callback with an opaque context pointer.
    pub set_lifecycle_callback: extern "C" fn(
        ctx: *mut ::std::ffi::c_void,
        callback: super::callbacks::LifecycleCallbackFn,
    ),
}