defmodule ExESDBDashboard.PubSubBridge do
  @moduledoc """
  Bridge that subscribes to ex-esdb-gater PubSub events and translates them
  to dashboard-specific events on ExESDBDashboard.PubSub.
  
  This encapsulates the integration between the gater system and the dashboard,
  allowing the dashboard package to be completely self-contained while still
  receiving real-time updates from the cluster.
  """
  
  use GenServer
  require Logger
  
  @gater_pubsub_instances [
    :ex_esdb_events,      # Core event data (application-specific)
    :ex_esdb_system,      # General system events and configuration
    :ex_esdb_health,      # Health monitoring and cluster status
    :ex_esdb_metrics,     # Performance metrics and analytics
    :ex_esdb_alerts,      # Critical alerts and notifications
    :ex_esdb_lifecycle,   # Process lifecycle events
    :ex_esdb_security,    # Security events and authentication
    :ex_esdb_audit,       # Audit trail and compliance tracking
    :ex_esdb_diagnostics, # Diagnostic information and debugging
    :ex_esdb_logging      # Log aggregation and centralized logging
  ]
  
  def start_link(opts \\ []) do
    GenServer.start_link(__MODULE__, opts, name: __MODULE__)
  end
  
  @impl true
  def init(_opts) do
    Logger.info("[Dashboard.PubSubBridge] Starting PubSub bridge for dashboard events")
    
    # Subscribe to relevant gater PubSub instances
    subscribe_to_gater_events()
    
    {:ok, %{subscriptions: [], last_activity: DateTime.utc_now()}}
  end
  
  # Handle health events from gater
  @impl true
  def handle_info({:health_update, health_data}, state) do
    # Translate to dashboard format
    dashboard_health = translate_health_data(health_data)
    
    # Broadcast to dashboard PubSub
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "cluster_health_updates",
      {:cluster_health_update, dashboard_health}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed health update: #{inspect(dashboard_health)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle system events from gater
  def handle_info({:system_event, event_data}, state) do
    # Broadcast to dashboard PubSub
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "system_events",
      {:system_event, event_data}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed system event: #{inspect(event_data)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle lifecycle events from gater
  def handle_info({:lifecycle_event, event_data}, state) do
    # Broadcast to dashboard PubSub  
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "cluster_lifecycle_events",
      {:cluster_lifecycle, event_data}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed lifecycle event: #{inspect(event_data)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle metrics events from gater
  def handle_info({:metrics_update, metrics_data}, state) do
    # Could translate to performance data or system events
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "system_events",
      {:system_event, %{type: "metrics_update", data: metrics_data}}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed metrics update")
    {:noreply, update_activity(state)}
  end
  
  # Handle alerts from gater
  def handle_info({:alert, alert_data}, state) do
    # Broadcast as system event with enhanced information
    enhanced_alert = %{
      type: "alert", 
      message: alert_data.message, 
      severity: alert_data.severity,
      timestamp: Map.get(alert_data, :timestamp, DateTime.utc_now()),
      node: Map.get(alert_data, :node, :unknown),
      category: Map.get(alert_data, :category, "system")
    }
    
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "system_events",
      {:system_event, enhanced_alert}
    )
    
    # Also broadcast to dedicated alerts channel
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "operational_alerts",
      {:operational_alert, enhanced_alert}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed alert: #{inspect(enhanced_alert)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle connection status changes
  def handle_info({:connection_status_change, status}, state) do
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "connection_status",
      {:connection_status, status}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed connection status: #{inspect(status)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle security events from gater
  def handle_info({:security_event, security_data}, state) do
    enhanced_security = %{
      type: "security",
      event_type: Map.get(security_data, :event_type, "unknown"),
      actor: Map.get(security_data, :actor, "system"),
      resource: Map.get(security_data, :resource, "unknown"),
      timestamp: Map.get(security_data, :timestamp, DateTime.utc_now()),
      node: Map.get(security_data, :node, :unknown),
      details: Map.get(security_data, :details, %{})
    }
    
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "operational_security",
      {:security_event, enhanced_security}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed security event: #{inspect(enhanced_security)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle audit events from gater
  def handle_info({:audit_event, audit_data}, state) do
    enhanced_audit = %{
      type: "audit",
      actor: Map.get(audit_data, :actor, "system"),
      action: Map.get(audit_data, :action, "unknown"),
      resource: Map.get(audit_data, :resource, "unknown"),
      timestamp: Map.get(audit_data, :timestamp, DateTime.utc_now()),
      node: Map.get(audit_data, :node, :unknown),
      result: Map.get(audit_data, :result, "success"),
      details: Map.get(audit_data, :details, %{})
    }
    
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "operational_audit",
      {:audit_event, enhanced_audit}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed audit event: #{inspect(enhanced_audit)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle diagnostic events from gater
  def handle_info({:diagnostic_event, diagnostic_data}, state) do
    enhanced_diagnostic = %{
      type: "diagnostic",
      component: Map.get(diagnostic_data, :component, "system"),
      diagnostic_type: Map.get(diagnostic_data, :diagnostic_type, "trace"),
      data: Map.get(diagnostic_data, :data, %{}),
      timestamp: Map.get(diagnostic_data, :timestamp, DateTime.utc_now()),
      node: Map.get(diagnostic_data, :node, :unknown)
    }
    
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "operational_diagnostics",
      {:diagnostic_event, enhanced_diagnostic}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed diagnostic event: #{inspect(enhanced_diagnostic)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle logging events from gater
  def handle_info({:log_event, log_data}, state) do
    enhanced_log = %{
      type: "log",
      level: Map.get(log_data, :level, "info"),
      message: Map.get(log_data, :message, ""),
      component: Map.get(log_data, :component, "system"),
      timestamp: Map.get(log_data, :timestamp, DateTime.utc_now()),
      node: Map.get(log_data, :node, :unknown),
      metadata: Map.get(log_data, :metadata, %{})
    }
    
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "operational_logging",
      {:log_event, enhanced_log}
    )
    
    # Also add to system events for general dashboard updates
    if log_data.level in ["error", "warn"] do
      Phoenix.PubSub.broadcast(
        ExESDBDashboard.PubSub,
        "system_events",
        {:system_event, %{type: "log_#{log_data.level}", message: log_data.message}}
      )
    end
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed log event: #{inspect(enhanced_log)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle enhanced metrics with operational patterns
  def handle_info({:operational_metrics, metrics_data}, state) do
    enhanced_metrics = %{
      type: "operational_metrics",
      component: Map.get(metrics_data, :component, "system"),
      metrics: Map.get(metrics_data, :metrics, %{}),
      timestamp: Map.get(metrics_data, :timestamp, DateTime.utc_now()),
      node: Map.get(metrics_data, :node, :unknown),
      metric_type: Map.get(metrics_data, :metric_type, "performance")
    }
    
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "operational_metrics",
      {:operational_metrics, enhanced_metrics}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed operational metrics: #{inspect(enhanced_metrics)}")
    {:noreply, update_activity(state)}
  end
  
  # Handle configuration changes
  def handle_info({:config_change, config_data}, state) do
    enhanced_config = %{
      type: "config_change",
      component: Map.get(config_data, :component, "system"),
      changes: Map.get(config_data, :changes, %{}),
      timestamp: Map.get(config_data, :timestamp, DateTime.utc_now()),
      node: Map.get(config_data, :node, :unknown),
      changed_by: Map.get(config_data, :changed_by, "system")
    }
    
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "operational_config",
      {:config_change, enhanced_config}
    )
    
    # Also broadcast to system events for general awareness
    Phoenix.PubSub.broadcast(
      ExESDBDashboard.PubSub,
      "system_events",
      {:system_event, %{type: "config_change", component: config_data.component}}
    )
    
    Logger.debug("[Dashboard.PubSubBridge] Relayed config change: #{inspect(enhanced_config)}")
    {:noreply, update_activity(state)}
  end
  
  # Generic event handler for unknown events
  def handle_info(event, state) do
    Logger.debug("[Dashboard.PubSubBridge] Received unknown event: #{inspect(event)}")
    {:noreply, state}
  end
  
  # Private functions
  
  defp subscribe_to_gater_events do
    # Subscribe to relevant topics on each gater PubSub instance
    subscriptions = [
      # Health monitoring
      {:ex_esdb_health, "cluster.health"},
      {:ex_esdb_health, "store.health"},
      {:ex_esdb_health, "component_health"},
      {:ex_esdb_health, "node_health"},
      
      # System events and configuration
      {:ex_esdb_system, "cluster.lifecycle"},
      {:ex_esdb_system, "store.lifecycle"},
      {:ex_esdb_system, "config"},
      {:ex_esdb_system, "lifecycle"},
      
      # Alerts and notifications
      {:ex_esdb_alerts, "cluster.alerts"},
      {:ex_esdb_alerts, "system.alerts"},
      {:ex_esdb_alerts, "critical_alerts"},
      
      # Performance metrics
      {:ex_esdb_metrics, "performance"},
      {:ex_esdb_metrics, "system.metrics"},
      {:ex_esdb_metrics, "persistence"},
      {:ex_esdb_metrics, "emitter"},
      
      # Process lifecycle
      {:ex_esdb_lifecycle, "process.lifecycle"},
      {:ex_esdb_lifecycle, "cluster_membership"},
      {:ex_esdb_lifecycle, "node_lifecycle"},
      
      # Security events
      {:ex_esdb_security, "authentication"},
      {:ex_esdb_security, "authorization"},
      {:ex_esdb_security, "security_events"},
      
      # Audit trail
      {:ex_esdb_audit, "data_change"},
      {:ex_esdb_audit, "access_log"},
      {:ex_esdb_audit, "audit_trail"},
      
      # Diagnostic information
      {:ex_esdb_diagnostics, "debug_trace"},
      {:ex_esdb_diagnostics, "diagnostics"},
      {:ex_esdb_diagnostics, "system_info"},
      
      # Log aggregation
      {:ex_esdb_logging, "system_logs"},
      {:ex_esdb_logging, "error_logs"},
      {:ex_esdb_logging, "log_aggregation"}
    ]
    
    successful_subs = 
      Enum.reduce(subscriptions, [], fn {pubsub_instance, topic}, acc ->
        try do
          Phoenix.PubSub.subscribe(pubsub_instance, topic)
          Logger.debug("[Dashboard.PubSubBridge] Subscribed to #{topic} on #{pubsub_instance}")
          [{pubsub_instance, topic} | acc]
        rescue
          error ->
            Logger.debug("[Dashboard.PubSubBridge] Failed to subscribe to #{topic} on #{pubsub_instance}: #{inspect(error)}")
            acc
        end
      end)
    
    Logger.info("[Dashboard.PubSubBridge] Successfully subscribed to #{length(successful_subs)} gater PubSub topics")
    successful_subs
  end
  
  defp translate_health_data(health_data) when is_map(health_data) do
    # Convert gater health format to dashboard format
    status = case Map.get(health_data, :status) do
      :healthy -> :healthy
      :ok -> :healthy
      :degraded -> :degraded  
      :warning -> :degraded
      :unhealthy -> :unhealthy
      :error -> :unhealthy
      :critical -> :unhealthy
      _ -> :unknown
    end
    
    %{
      status: status,
      message: Map.get(health_data, :message, "System status update"),
      timestamp: Map.get(health_data, :timestamp, DateTime.utc_now()),
      source: Map.get(health_data, :source, "gater")
    }
  end
  
  defp translate_health_data(health_atom) when is_atom(health_atom) do
    translate_health_data(%{status: health_atom})
  end
  
  defp translate_health_data(health_data) do
    Logger.warning("[Dashboard.PubSubBridge] Unknown health data format: #{inspect(health_data)}")
    %{status: :unknown, message: "Unknown health status", timestamp: DateTime.utc_now()}
  end
  
  defp update_activity(state) do
    Map.put(state, :last_activity, DateTime.utc_now())
  end
end