use plc_platform_core::model::EventRecord;
use plc_platform_core::{
    event::EventEnvelope,
    websocket::{WebSocketManager, WsMessage},
};
use tokio::sync::mpsc;
use uuid::Uuid;

const CONTROL_EVENT_CHANNEL_CAPACITY: usize = 1024;

/// Feeder-specific business events only.
/// Platform events (source/point lifecycle) are handled by core's emit_event().
#[derive(Debug, Clone)]
pub enum AppEvent {
    EquipmentStartCommandSent {
        equipment_id: Uuid,
        unit_id: Option<Uuid>,
        point_id: Uuid,
    },
    EquipmentStopCommandSent {
        equipment_id: Uuid,
        unit_id: Option<Uuid>,
        point_id: Uuid,
    },
    AutoControlStarted {
        unit_id: Uuid,
    },
    AutoControlStopped {
        unit_id: Uuid,
    },
    FaultLocked {
        unit_id: Uuid,
        equipment_id: Uuid,
    },
    FaultAcked {
        unit_id: Uuid,
    },
    CommLocked {
        unit_id: Uuid,
    },
    CommRecovered {
        unit_id: Uuid,
    },
    RemLocal {
        unit_id: Uuid,
        equipment_id: Uuid,
    },
    RemRecovered {
        unit_id: Uuid,
    },
    UnitStateChanged {
        unit_id: Uuid,
        from_state: String,
        to_state: String,
    },
}

pub struct EventManager {
    control_sender: mpsc::Sender<AppEvent>,
}

impl EventManager {
    pub fn new(pool: sqlx::PgPool, ws_manager: Option<std::sync::Arc<WebSocketManager>>) -> Self {
        let (control_sender, mut control_receiver) =
            mpsc::channel::<AppEvent>(CONTROL_EVENT_CHANNEL_CAPACITY);

        let control_pool = pool.clone();
        let control_ws_manager = ws_manager.clone();
        tokio::spawn(async move {
            while let Some(event) = control_receiver.recv().await {
                handle_control_event(event, &control_pool, control_ws_manager.as_ref()).await;
            }
        });

        Self { control_sender }
    }

    pub fn send(&self, event: AppEvent) -> Result<(), String> {
        match self.control_sender.try_send(event) {
            Ok(()) => Ok(()),
            Err(mpsc::error::TrySendError::Closed(e)) => Err(format!(
                "Failed to send control event: channel closed ({e:?})"
            )),
            Err(mpsc::error::TrySendError::Full(e)) => {
                Err(format!("Failed to send control event: queue full ({e:?})"))
            }
        }
    }
}

/// Bridges platform events to feeder-specific side effects.
/// Connection management and telemetry are handled by core automatically.
pub struct FeederPlatformEventSink {
    control_runtime: std::sync::Arc<crate::control::runtime::ControlRuntimeStore>,
}

impl FeederPlatformEventSink {
    pub fn new(
        control_runtime: std::sync::Arc<crate::control::runtime::ControlRuntimeStore>,
    ) -> Self {
        Self { control_runtime }
    }
}

impl plc_platform_core::platform_context::PlatformEventSink for FeederPlatformEventSink {
    fn on_event(&self, event: &plc_platform_core::event::PlatformEvent) {
        match event {
            plc_platform_core::event::PlatformEvent::UnitsChanged { unit_ids } => {
                let runtime = self.control_runtime.clone();
                let ids = unit_ids.clone();
                tokio::spawn(async move {
                    for unit_id in ids {
                        runtime.notify_unit(unit_id).await;
                    }
                });
            }
            // Other platform events: connection management handled by core.
            _ => {}
        }
    }
}

async fn handle_control_event(
    event: AppEvent,
    pool: &sqlx::PgPool,
    ws_manager: Option<&std::sync::Arc<WebSocketManager>>,
) {
    persist_event_if_needed(&event, pool, ws_manager).await;

    match event {
        AppEvent::EquipmentStartCommandSent {
            equipment_id,
            unit_id,
            point_id,
        } => {
            tracing::info!(
                "Equipment start command sent: equipment={}, unit={:?}, point={}",
                equipment_id,
                unit_id,
                point_id
            );
        }
        AppEvent::EquipmentStopCommandSent {
            equipment_id,
            unit_id,
            point_id,
        } => {
            tracing::info!(
                "Equipment stop command sent: equipment={}, unit={:?}, point={}",
                equipment_id,
                unit_id,
                point_id
            );
        }
        AppEvent::AutoControlStarted { unit_id } => {
            tracing::info!("Auto control started for unit {}", unit_id);
        }
        AppEvent::AutoControlStopped { unit_id } => {
            tracing::info!("Auto control stopped for unit {}", unit_id);
        }
        AppEvent::FaultLocked {
            unit_id,
            equipment_id,
        } => {
            tracing::warn!("Fault locked: unit={}, equipment={}", unit_id, equipment_id);
        }
        AppEvent::FaultAcked { unit_id } => {
            tracing::info!("Fault acked for unit {}", unit_id);
        }
        AppEvent::CommLocked { unit_id } => {
            tracing::warn!("Comm locked for unit {}", unit_id);
        }
        AppEvent::CommRecovered { unit_id } => {
            tracing::info!("Comm recovered for unit {}", unit_id);
        }
        AppEvent::RemLocal {
            unit_id,
            equipment_id,
        } => {
            tracing::warn!("REM local: unit={}, equipment={}", unit_id, equipment_id);
        }
        AppEvent::RemRecovered { unit_id } => {
            tracing::info!("REM recovered for unit {}", unit_id);
        }
        AppEvent::UnitStateChanged {
            unit_id,
            from_state,
            to_state,
        } => {
            tracing::info!("Unit {} state: {} -> {}", unit_id, from_state, to_state);
        }
    }
}

async fn fetch_unit_code(pool: &sqlx::PgPool, id: Uuid) -> String {
    sqlx::query_scalar::<_, String>("SELECT code FROM unit WHERE id = $1")
        .bind(id)
        .fetch_optional(pool)
        .await
        .ok()
        .flatten()
        .unwrap_or_else(|| id.to_string())
}

async fn fetch_equipment_code(pool: &sqlx::PgPool, id: Uuid) -> String {
    sqlx::query_scalar::<_, String>("SELECT code FROM equipment WHERE id = $1")
        .bind(id)
        .fetch_optional(pool)
        .await
        .ok()
        .flatten()
        .unwrap_or_else(|| id.to_string())
}

async fn persist_event_if_needed(
    event: &AppEvent,
    pool: &sqlx::PgPool,
    ws_manager: Option<&std::sync::Arc<WebSocketManager>>,
) {
    let record: Option<(
        &str,
        &str,
        Option<Uuid>,
        Option<Uuid>,
        Option<Uuid>,
        String,
        serde_json::Value,
    )> = match event {
        AppEvent::EquipmentStartCommandSent {
            equipment_id,
            unit_id,
            point_id,
        } => {
            let code = fetch_equipment_code(pool, *equipment_id).await;
            Some((
                "feeder.equipment.start_command_sent",
                "info",
                *unit_id,
                Some(*equipment_id),
                None,
                format!("Start command sent to equipment {}", code),
                serde_json::json!({
                    "equipment_id": equipment_id,
                    "unit_id": unit_id,
                    "point_id": point_id
                }),
            ))
        }
        AppEvent::EquipmentStopCommandSent {
            equipment_id,
            unit_id,
            point_id,
        } => {
            let code = fetch_equipment_code(pool, *equipment_id).await;
            Some((
                "feeder.equipment.stop_command_sent",
                "info",
                *unit_id,
                Some(*equipment_id),
                None,
                format!("Stop command sent to equipment {}", code),
                serde_json::json!({
                    "equipment_id": equipment_id,
                    "unit_id": unit_id,
                    "point_id": point_id
                }),
            ))
        }
        AppEvent::AutoControlStarted { unit_id } => {
            let code = fetch_unit_code(pool, *unit_id).await;
            Some((
                "feeder.unit.auto_control_started",
                "info",
                Some(*unit_id),
                None,
                None,
                format!("Auto control started for unit {}", code),
                serde_json::json!({ "unit_id": unit_id }),
            ))
        }
        AppEvent::AutoControlStopped { unit_id } => {
            let code = fetch_unit_code(pool, *unit_id).await;
            Some((
                "feeder.unit.auto_control_stopped",
                "info",
                Some(*unit_id),
                None,
                None,
                format!("Auto control stopped for unit {}", code),
                serde_json::json!({ "unit_id": unit_id }),
            ))
        }
        AppEvent::FaultLocked {
            unit_id,
            equipment_id,
        } => {
            let unit_code = fetch_unit_code(pool, *unit_id).await;
            let eq_code = fetch_equipment_code(pool, *equipment_id).await;
            Some((
                "feeder.unit.fault_locked",
                "error",
                Some(*unit_id),
                Some(*equipment_id),
                None,
                format!(
                    "Fault locked for unit {} by equipment {}",
                    unit_code, eq_code
                ),
                serde_json::json!({ "unit_id": unit_id, "equipment_id": equipment_id }),
            ))
        }
        AppEvent::FaultAcked { unit_id } => {
            let code = fetch_unit_code(pool, *unit_id).await;
            Some((
                "feeder.unit.fault_acked",
                "info",
                Some(*unit_id),
                None,
                None,
                format!("Fault acknowledged for unit {}", code),
                serde_json::json!({ "unit_id": unit_id }),
            ))
        }
        AppEvent::CommLocked { unit_id } => {
            let code = fetch_unit_code(pool, *unit_id).await;
            Some((
                "feeder.unit.comm_locked",
                "warn",
                Some(*unit_id),
                None,
                None,
                format!("Communication locked for unit {}", code),
                serde_json::json!({ "unit_id": unit_id }),
            ))
        }
        AppEvent::CommRecovered { unit_id } => {
            let code = fetch_unit_code(pool, *unit_id).await;
            Some((
                "feeder.unit.comm_recovered",
                "info",
                Some(*unit_id),
                None,
                None,
                format!("Communication recovered for unit {}", code),
                serde_json::json!({ "unit_id": unit_id }),
            ))
        }
        AppEvent::RemLocal {
            unit_id,
            equipment_id,
        } => {
            let unit_code = fetch_unit_code(pool, *unit_id).await;
            let eq_code = fetch_equipment_code(pool, *equipment_id).await;
            Some((
                "feeder.unit.rem_local",
                "warn",
                Some(*unit_id),
                Some(*equipment_id),
                None,
                format!(
                    "Unit {} switched to local control via equipment {}",
                    unit_code, eq_code
                ),
                serde_json::json!({ "unit_id": unit_id, "equipment_id": equipment_id }),
            ))
        }
        AppEvent::RemRecovered { unit_id } => {
            let code = fetch_unit_code(pool, *unit_id).await;
            Some((
                "feeder.unit.rem_recovered",
                "warn",
                Some(*unit_id),
                None,
                None,
                format!(
                    "Unit {} returned to remote control; auto control requires manual restart",
                    code
                ),
                serde_json::json!({ "unit_id": unit_id }),
            ))
        }
        AppEvent::UnitStateChanged { .. } => None,
    };

    let Some((event_type, level, unit_id, equipment_id, source_id, message, payload)) = record
    else {
        return;
    };
    let envelope = EventEnvelope::new(event_type, payload);

    let inserted = sqlx::query_as::<_, EventRecord>(
        r#"
        INSERT INTO event (event_type, level, unit_id, equipment_id, source_id, message, payload)
        VALUES ($1, $2, $3, $4, $5, $6, $7)
        RETURNING *
        "#,
    )
    .bind(envelope.event_type)
    .bind(level)
    .bind(unit_id as Option<Uuid>)
    .bind(equipment_id as Option<Uuid>)
    .bind(source_id)
    .bind(message)
    .bind(sqlx::types::Json(envelope.payload))
    .fetch_one(pool)
    .await;

    match inserted {
        Ok(record) => {
            if let Some(ws_manager) = ws_manager {
                let ws_message = WsMessage::EventCreated(record);
                if let Err(err) = ws_manager.send_to_public(ws_message).await {
                    tracing::warn!("Failed to broadcast event websocket message: {}", err);
                }
            }
        }
        Err(err) => {
            tracing::warn!("Failed to persist event: {}", err);
        }
    }
}