defmodule ToweropsWeb.AgentChannel do
  @moduledoc """
  Phoenix channel for bidirectional agent communication.

  Handles WebSocket connections from remote SNMP polling agents, distributing
  polling jobs and collecting metrics via Protocol Buffers binary encoding.

  ## Messages from Server → Agent (binary protobuf)

  - "jobs" - List of SNMP jobs to execute
  - "job" - Single new job (pushed when device added)

  ## Messages from Agent → Server (binary protobuf)

  - "result" - SNMP query results
  - "heartbeat" - Agent metadata (version, hostname, uptime)
  - "error" - Job execution errors

  All messages use Protocol Buffers binary encoding for efficiency.
  """

  use ToweropsWeb, :channel

  alias Towerops.Agent.AgentError
  alias Towerops.Agent.AgentHeartbeat
  alias Towerops.Agent.AgentJob
  alias Towerops.Agent.AgentJobList
  alias Towerops.Agent.CredentialTestResult
  alias Towerops.Agent.MikrotikCommand
  alias Towerops.Agent.MikrotikDevice
  alias Towerops.Agent.MikrotikResult
  alias Towerops.Agent.SnmpDevice
  alias Towerops.Agent.SnmpQuery
  alias Towerops.Agent.SnmpResult
  alias Towerops.Agents
  alias Towerops.Devices
  alias Towerops.Devices.BackupRequests
  alias Towerops.Devices.MikrotikBackups
  alias Towerops.Snmp
  alias Towerops.Snmp.AgentDiscovery

  require Logger

  @impl true
  @spec join(String.t(), map(), Phoenix.Socket.t()) ::
          {:ok, Phoenix.Socket.t()} | {:error, map()}
  def join("agent:" <> agent_id, %{"token" => token} = payload, socket) do
    Logger.info("Agent join attempt",
      topic: "agent:#{agent_id}",
      has_token: not is_nil(token),
      token_length: if(is_binary(token), do: byte_size(token), else: 0),
      payload_keys: Map.keys(payload)
    )

    # Verify agent token from join payload
    case Agents.verify_agent_token(token) do
      {:ok, agent_token} ->
        socket =
          socket
          |> assign(:agent_token_id, agent_token.id)
          |> assign(:organization_id, agent_token.organization_id)
          |> assign(:debug_enabled, agent_token.allow_remote_debug)

        # Log connection with debug info if enabled
        maybe_debug_log(socket, "Agent connected",
          ip: get_remote_ip(socket),
          organization_id: agent_token.organization_id
        )

        # Subscribe to assignment changes for this agent
        _ = Phoenix.PubSub.subscribe(Towerops.PubSub, "agent:#{agent_token.id}:assignments")

        # Subscribe to discovery requests for this agent
        _ = Phoenix.PubSub.subscribe(Towerops.PubSub, "agent:#{agent_token.id}:discovery")

        # Subscribe to backup requests for this agent
        _ = Phoenix.PubSub.subscribe(Towerops.PubSub, "agent:#{agent_token.id}:backup")

        # Subscribe to credential test requests for this agent
        _ = Phoenix.PubSub.subscribe(Towerops.PubSub, "agent:#{agent_token.id}:credential_test")

        # Subscribe to live poll requests for this agent
        _ = Phoenix.PubSub.subscribe(Towerops.PubSub, "agent:#{agent_token.id}:live_poll")

        # Update last_seen_at and IP on join
        remote_ip = get_remote_ip(socket)
        _ = Agents.update_agent_token_heartbeat(agent_token.id, remote_ip, %{})

        # Send initial job list
        send(self(), :send_jobs)

        {:ok, socket}

      {:error, _} ->
        {:error, %{reason: "unauthorized"}}
    end
  end

  def join("agent:" <> _agent_id, _payload, _socket) do
    {:error, %{reason: "missing token"}}
  end

  @impl true
  @spec handle_info(:send_jobs, Phoenix.Socket.t()) :: {:noreply, Phoenix.Socket.t()}
  def handle_info(:send_jobs, socket) do
    jobs = build_jobs_for_agent(socket.assigns.agent_token_id)
    job_list = %AgentJobList{jobs: jobs}
    binary = AgentJobList.encode(job_list)

    Logger.info("Sending #{length(jobs)} jobs to agent: #{inspect(Enum.map(jobs, & &1.job_id))}")

    push(socket, "jobs", %{binary: Base.encode64(binary)})
    {:noreply, socket}
  end

  # Handle PubSub broadcast when device assignments change
  def handle_info({:assignments_changed, _event}, socket) do
    Logger.info("Agent assignments changed, sending updated job list",
      agent_token_id: socket.assigns.agent_token_id
    )

    send(self(), :send_jobs)
    {:noreply, socket}
  end

  # Handle PubSub broadcast when discovery is requested for a device
  def handle_info({:discovery_requested, device_id}, socket) do
    Logger.info("Discovery requested for device, sending discovery job to agent",
      agent_token_id: socket.assigns.agent_token_id,
      device_id: device_id
    )

    case Devices.get_device_with_details(device_id) do
      nil ->
        Logger.error("Device not found for discovery request", device_id: device_id)
        {:noreply, socket}

      device ->
        # Build and send discovery job to agent
        job = build_discovery_job(device)
        job_list = %AgentJobList{jobs: [job]}
        binary = AgentJobList.encode(job_list)

        push(socket, "discovery_job", %{binary: Base.encode64(binary)})
        {:noreply, socket}
    end
  end

  # Handle PubSub broadcast when backup is requested for a device
  def handle_info({:backup_requested, job}, socket) do
    Logger.info("Backup requested for device, sending backup job to agent",
      agent_token_id: socket.assigns.agent_token_id,
      device_id: job.device_id,
      job_id: job.job_id
    )

    job_list = %AgentJobList{jobs: [job]}
    binary = AgentJobList.encode(job_list)

    push(socket, "backup_job", %{binary: Base.encode64(binary)})
    {:noreply, socket}
  end

  # Handle PubSub broadcast when credential test is requested
  def handle_info({:credential_test_requested, test_id, snmp_config}, socket) do
    Logger.info("Credential test requested, sending test job to agent",
      agent_token_id: socket.assigns.agent_token_id,
      test_id: test_id
    )

    # Build SNMP device from config
    snmp_device = %SnmpDevice{
      ip: snmp_config[:ip],
      port: snmp_config[:port],
      version: snmp_config[:version],
      community: snmp_config[:community],
      v3_security_level: snmp_config[:v3_security_level],
      v3_username: snmp_config[:v3_username],
      v3_auth_protocol: snmp_config[:v3_auth_protocol],
      v3_auth_password: snmp_config[:v3_auth_password],
      v3_priv_protocol: snmp_config[:v3_priv_protocol],
      v3_priv_password: snmp_config[:v3_priv_password]
    }

    # Build test credentials job
    job = %AgentJob{
      job_id: test_id,
      job_type: :TEST_CREDENTIALS,
      device_id: test_id,
      snmp_device: snmp_device,
      queries: [],
      mikrotik_device: nil,
      mikrotik_commands: []
    }

    job_list = %AgentJobList{jobs: [job]}
    binary = AgentJobList.encode(job_list)

    push(socket, "jobs", %{binary: Base.encode64(binary)})
    {:noreply, socket}
  end

  # Handle PubSub broadcast when live polling is requested for a device
  def handle_info({:live_poll_requested, device_id, sensor_oids, reply_topic}, socket) do
    maybe_debug_log(socket, "Live poll requested for device",
      device_id: device_id,
      sensor_count: length(sensor_oids),
      reply_topic: reply_topic
    )

    case Devices.get_device_with_details(device_id) do
      nil ->
        Logger.error("Device not found for live poll request", device_id: device_id)
        {:noreply, socket}

      device ->
        # Build live polling job with only requested sensor OIDs
        job = build_live_polling_job(device, sensor_oids, reply_topic)
        job_list = %AgentJobList{jobs: [job]}
        binary = AgentJobList.encode(job_list)

        maybe_debug_log(socket, "Sending live poll job to agent",
          device_id: device_id,
          device_name: device.name,
          oid_count: length(sensor_oids)
        )

        push(socket, "jobs", %{binary: Base.encode64(binary)})
        {:noreply, socket}
    end
  end

  @impl true
  @spec handle_in(String.t(), map(), Phoenix.Socket.t()) :: {:noreply, Phoenix.Socket.t()}
  def handle_in("result", %{"binary" => binary_b64}, socket) do
    binary = Base.decode64!(binary_b64)
    result = SnmpResult.decode(binary)

    maybe_debug_log(socket, "Received SNMP result from agent",
      device_id: result.device_id,
      job_type: result.job_type,
      job_id: result.job_id,
      binary_size: byte_size(binary_b64),
      oid_count: map_size(result.oid_values)
    )

    # Check if this is a live poll result
    if String.starts_with?(result.job_id, "live_poll:") do
      handle_live_poll_result(result, socket)
    else
      _ = process_snmp_result(socket.assigns.organization_id, result, socket)
    end

    {:noreply, socket}
  end

  def handle_in("heartbeat", %{"binary" => binary_b64}, socket) do
    binary = Base.decode64!(binary_b64)
    heartbeat = AgentHeartbeat.decode(binary)

    metadata = %{
      "version" => heartbeat.version,
      "hostname" => heartbeat.hostname,
      "uptime_seconds" => heartbeat.uptime_seconds
    }

    _ =
      Agents.update_agent_token_heartbeat(
        socket.assigns.agent_token_id,
        heartbeat.ip_address,
        metadata
      )

    {:noreply, socket}
  end

  @impl true
  def handle_in("error", %{"binary" => binary_b64}, socket) do
    binary = Base.decode64!(binary_b64)
    error = AgentError.decode(binary)

    maybe_debug_log(socket, "Agent job error",
      device_id: error.device_id,
      error_message: error.message,
      binary_size: byte_size(binary_b64)
    )

    Logger.error("Agent job error",
      agent_token_id: socket.assigns.agent_token_id,
      device_id: error.device_id,
      error: error.message
    )

    {:noreply, socket}
  end

  def handle_in("mikrotik_result", %{"binary" => binary_b64}, socket) do
    binary = Base.decode64!(binary_b64)
    result = MikrotikResult.decode(binary)

    maybe_debug_log(socket, "Received MikroTik result from agent",
      device_id: result.device_id,
      job_id: result.job_id,
      has_error: result.error != "",
      sentence_count: length(result.sentences)
    )

    # Check if this is a backup job by the job_id prefix
    if String.starts_with?(result.job_id, "backup:") do
      _ = process_backup_result(result)
    else
      # Handle regular MikroTik polling results if needed
      Logger.debug("Received non-backup MikroTik result", job_id: result.job_id)
    end

    {:noreply, socket}
  end

  def handle_in("credential_test_result", %{"binary" => binary_b64}, socket) do
    binary = Base.decode64!(binary_b64)
    result = CredentialTestResult.decode(binary)

    maybe_debug_log(socket, "Received credential test result from agent",
      test_id: result.test_id,
      success: result.success,
      has_error: result.error_message != ""
    )

    # Broadcast result to the requesting LiveView via PubSub
    # The test_id contains the device_id, so we can broadcast to that topic
    Phoenix.PubSub.broadcast(
      Towerops.PubSub,
      "credential_test:#{result.test_id}",
      {:credential_test_result, result}
    )

    {:noreply, socket}
  end

  # Private helpers

  @spec build_jobs_for_agent(Ecto.UUID.t()) :: [AgentJob.t()]
  defp build_jobs_for_agent(agent_token_id) do
    agent_token_id
    |> Agents.list_agent_polling_targets()
    |> Enum.flat_map(&build_jobs_for_device/1)
  end

  defp build_jobs_for_device(device) do
    # Build SNMP job (discovery or polling)
    snmp_job =
      if needs_discovery?(device) do
        build_discovery_job(device)
      else
        build_polling_job(device)
      end

    # Build MikroTik job only during discovery (not during regular polling)
    # MikroTik commands are discovery-type operations that should run once per 24h
    mikrotik_job =
      if needs_discovery?(device) and mikrotik_device?(device) do
        build_mikrotik_job(device)
      end

    # Return list of jobs (filter out nil)
    Enum.reject([snmp_job, mikrotik_job], &is_nil/1)
  end

  defp needs_discovery?(device) do
    # Need discovery if no SNMP device or last discovery was >24 hours ago
    is_nil(device.snmp_device) or
      is_nil(device.last_discovery_at) or
      DateTime.diff(DateTime.utc_now(), device.last_discovery_at, :hour) > 24
  end

  defp mikrotik_device?(device) do
    # Check if device is MikroTik based on SNMP discovery data
    device.snmp_device &&
      (String.contains?(device.snmp_device.manufacturer || "", "MikroTik") ||
         String.contains?(device.snmp_device.sys_descr || "", "RouterOS"))
  end

  # Resolves SNMP credentials for a device.
  # For SNMPv3, returns a map with resolved credentials via cascade.
  # For v1/v2c, returns a simple map with community string and version.
  defp resolve_snmp_credentials(device) do
    if device.snmp_version == "3" do
      Devices.get_snmpv3_config(device)
    else
      %{
        community: Devices.resolve_snmp_community(device),
        version: device.snmp_version
      }
    end
  end

  # Checks if SNMP credentials are present (not nil/empty).
  defp credentials_present?(%{community: community}) when is_binary(community) do
    community != ""
  end

  defp credentials_present?(%{username: username}) when is_binary(username) do
    username != ""
  end

  defp credentials_present?(_), do: false

  # Builds the SnmpDevice protobuf message with appropriate credentials.
  # For v1/v2c: Uses community string
  # For v3: Uses SNMPv3 credentials (security_level, username, auth/priv protocols/passwords)
  defp build_snmp_device_message(device, snmp_config) do
    if device.snmp_version == "3" do
      build_v3_snmp_device(device, snmp_config)
    else
      build_v2c_snmp_device(device, snmp_config)
    end
  end

  defp build_v3_snmp_device(device, snmp_config) do
    %SnmpDevice{
      ip: device.ip_address,
      version: device.snmp_version,
      port: device.snmp_port || 161,
      transport: device.snmp_transport || "udp",
      community: "",
      v3_security_level: snmp_config.security_level || "",
      v3_username: snmp_config.username || "",
      v3_auth_protocol: snmp_config.auth_protocol || "",
      v3_auth_password: snmp_config.auth_password || "",
      v3_priv_protocol: snmp_config.priv_protocol || "",
      v3_priv_password: snmp_config.priv_password || ""
    }
  end

  defp build_v2c_snmp_device(device, snmp_config) do
    community = snmp_config.community || ""

    %SnmpDevice{
      ip: device.ip_address,
      version: device.snmp_version,
      port: device.snmp_port || 161,
      transport: device.snmp_transport || "udp",
      community: community
    }
  end

  defp build_discovery_job(device) do
    snmp_credentials = resolve_snmp_credentials(device)

    maybe_debug_log(%{assigns: %{agent_token_id: "system"}}, "Building discovery job",
      device_id: device.id,
      device_name: device.name,
      snmp_version: device.snmp_version,
      credentials_present: credentials_present?(snmp_credentials),
      credential_source:
        if(device.snmp_version == "3",
          do: Map.get(snmp_credentials, :source),
          else: device.snmp_community_source
        )
    )

    %AgentJob{
      job_id: "discover:#{device.id}",
      job_type: :DISCOVER,
      device_id: device.id,
      snmp_device: build_snmp_device_message(device, snmp_credentials),
      queries: build_discovery_queries()
    }
  end

  defp build_polling_job(device) do
    _snmp_device = device.snmp_device
    snmp_credentials = resolve_snmp_credentials(device)

    maybe_debug_log(%{assigns: %{agent_token_id: "system"}}, "Building polling job",
      device_id: device.id,
      device_name: device.name,
      snmp_version: device.snmp_version,
      credentials_present: credentials_present?(snmp_credentials),
      credential_source:
        if(device.snmp_version == "3",
          do: Map.get(snmp_credentials, :source),
          else: device.snmp_community_source
        ),
      site_id: device.site_id,
      site_loaded: not is_nil(Map.get(device, :site))
    )

    %AgentJob{
      job_id: "poll:#{device.id}",
      job_type: :POLL,
      device_id: device.id,
      snmp_device: build_snmp_device_message(device, snmp_credentials),
      queries: build_polling_queries(device)
    }
  end

  defp build_live_polling_job(device, sensor_oids, reply_topic) do
    snmp_credentials = resolve_snmp_credentials(device)

    %AgentJob{
      job_id: "live_poll:#{device.id}:#{reply_topic}",
      job_type: :POLL,
      device_id: device.id,
      snmp_device: build_snmp_device_message(device, snmp_credentials),
      queries: [
        %SnmpQuery{
          query_type: :GET,
          oids: sensor_oids
        }
      ]
    }
  end

  # Handle live poll result - broadcast to reply topic instead of saving
  defp handle_live_poll_result(result, socket) do
    # Extract reply topic from job_id: "live_poll:device_id:reply_topic"
    case String.split(result.job_id, ":", parts: 3) do
      ["live_poll", _device_id, reply_topic] ->
        maybe_debug_log(socket, "Broadcasting live poll result",
          reply_topic: reply_topic,
          oid_count: map_size(result.oid_values)
        )

        # Broadcast OID values directly to the waiting LiveView
        Phoenix.PubSub.broadcast(
          Towerops.PubSub,
          reply_topic,
          {:live_poll_result, result.oid_values}
        )

      _ ->
        Logger.warning("Invalid live poll job_id format: #{result.job_id}")
    end
  end

  defp build_discovery_queries do
    [
      # System info (GET)
      %SnmpQuery{
        query_type: :GET,
        oids: [
          # sysDescr
          "1.3.6.1.2.1.1.1.0",
          # sysObjectID
          "1.3.6.1.2.1.1.2.0",
          # sysUpTime
          "1.3.6.1.2.1.1.3.0",
          # sysContact
          "1.3.6.1.2.1.1.4.0",
          # sysName
          "1.3.6.1.2.1.1.5.0",
          # sysLocation
          "1.3.6.1.2.1.1.6.0"
        ]
      },
      # Interface table (WALK)
      %SnmpQuery{
        query_type: :WALK,
        # ifTable
        oids: ["1.3.6.1.2.1.2.2.1"]
      },
      # Interface extensions (WALK)
      %SnmpQuery{
        query_type: :WALK,
        # ifXTable
        oids: ["1.3.6.1.2.1.31.1.1.1"]
      },
      # Sensor discovery - ENTITY-SENSOR-MIB (WALK)
      %SnmpQuery{
        query_type: :WALK,
        oids: [
          # ENTITY-SENSOR-MIB - sensor tables
          "1.3.6.1.2.1.99.1.1.1",
          # ENTITY-MIB - physical entity descriptions (needed for sensor names)
          "1.3.6.1.2.1.47.1.1.1.1.2",
          # entPhysicalName
          "1.3.6.1.2.1.47.1.1.1.1.7",
          # entPhysicalClass
          "1.3.6.1.2.1.47.1.1.1.1.5"
        ]
      },
      # Vendor-specific MIBs (WALK)
      %SnmpQuery{
        query_type: :WALK,
        oids: [
          # Cisco
          "1.3.6.1.4.1.9",
          # MikroTik
          "1.3.6.1.4.1.14988",
          # Ubiquiti
          "1.3.6.1.4.1.41112"
        ]
      },
      # Neighbor discovery (WALK)
      %SnmpQuery{
        query_type: :WALK,
        oids: [
          # LLDP
          "1.0.8802.1.1.2.1.4.1.1",
          # Cisco CDP
          "1.3.6.1.4.1.9.9.23"
        ]
      }
    ]
  end

  defp build_polling_queries(device) do
    sensor_oids = Enum.map(device.snmp_device.sensors, & &1.sensor_oid)

    interface_oids =
      Enum.flat_map(device.snmp_device.interfaces, fn iface ->
        idx = iface.if_index

        [
          # ifInOctets
          "1.3.6.1.2.1.2.2.1.10.#{idx}",
          # ifOutOctets
          "1.3.6.1.2.1.2.2.1.16.#{idx}",
          # ifInErrors
          "1.3.6.1.2.1.2.2.1.14.#{idx}",
          # ifOutErrors
          "1.3.6.1.2.1.2.2.1.20.#{idx}",
          # ifInDiscards
          "1.3.6.1.2.1.2.2.1.13.#{idx}",
          # ifOutDiscards
          "1.3.6.1.2.1.2.2.1.19.#{idx}"
        ]
      end)

    # Neighbor discovery OIDs
    neighbor_oids = [
      # LLDP
      "1.0.8802.1.1.2.1.4.1.1",
      # Cisco CDP
      "1.3.6.1.4.1.9.9.23"
    ]

    [
      %SnmpQuery{
        query_type: :GET,
        oids: sensor_oids ++ interface_oids
      },
      %SnmpQuery{
        query_type: :WALK,
        oids: neighbor_oids
      }
    ]
  end

  defp build_mikrotik_job(device) do
    mikrotik_config = Devices.get_mikrotik_config(device)

    # Only build job if MikroTik API is enabled and has credentials
    if mikrotik_config.enabled && mikrotik_config.username do
      %AgentJob{
        job_id: "mikrotik:#{device.id}",
        job_type: :MIKROTIK,
        device_id: device.id,
        mikrotik_device: %MikrotikDevice{
          ip: device.ip_address,
          username: mikrotik_config.username,
          password: mikrotik_config.password,
          port: mikrotik_config.port,
          use_ssl: mikrotik_config.use_ssl
        },
        mikrotik_commands: build_mikrotik_commands()
      }
    end
  end

  defp build_mikrotik_commands do
    [
      # System identity
      %MikrotikCommand{
        command: "/system/identity/print",
        args: %{}
      },
      # System resources
      %MikrotikCommand{
        command: "/system/resource/print",
        args: %{}
      }
    ]
  end

  defp process_snmp_result(organization_id, result, socket) do
    with {:ok, device} <- fetch_device(result.device_id),
         :ok <- verify_device_organization(device, organization_id) do
      process_job_result(device, result, socket)
    else
      {:error, :device_not_found} ->
        Logger.error("Device not found: #{result.device_id}")

      {:error, :wrong_organization} ->
        Logger.error("Device #{result.device_id} not in agent's organization")
    end
  end

  defp fetch_device(device_id) do
    case Devices.get_device_with_details(device_id) do
      nil -> {:error, :device_not_found}
      device -> {:ok, device}
    end
  end

  defp verify_device_organization(device, organization_id) do
    # Cloud pollers (organization_id = nil) can access any device
    if is_nil(organization_id) or device.organization_id == organization_id do
      :ok
    else
      {:error, :wrong_organization}
    end
  end

  defp process_job_result(device, %{job_type: :DISCOVER} = result, socket) do
    process_discovery_result(device, result, socket)
  end

  defp process_job_result(device, %{job_type: :POLL} = result, socket) do
    process_polling_result(device, result, socket)
  end

  defp process_discovery_result(device, result, socket) do
    # Agent has completed discovery and sent back SNMP data
    # Update last_discovery_at to signal completion to DiscoveryWorker
    Logger.info("Discovery results received from agent for #{device.name}, processing data")

    # Update device timestamp to mark discovery as complete
    case Devices.update_device(device, %{last_discovery_at: DateTime.utc_now()}) do
      {:ok, updated_device} ->
        Logger.info("Updated last_discovery_at for device #{device.name}")

        # Process the SNMP data from agent's discovery queries
        # The agent sends back oid_values map with all the collected data
        process_discovery_data(updated_device, result, socket)

      {:error, changeset} ->
        Logger.error("Failed to update last_discovery_at for device #{device.name}: #{inspect(changeset)}")
    end
  end

  defp process_discovery_data(device, result, socket) do
    oid_values = Map.new(result.oid_values)

    Logger.info("Processing discovery with #{map_size(oid_values)} OIDs",
      device_id: device.id,
      device_name: device.name
    )

    # Debug log full OID values if debug is enabled
    maybe_debug_log(socket, "Discovery OID values received",
      device_id: device.id,
      device_name: device.name,
      oid_count: map_size(oid_values),
      sample_oids: oid_values |> Enum.take(10) |> Map.new(),
      all_oids: if(socket.assigns[:debug_enabled], do: oid_values, else: :redacted)
    )

    # Process full discovery using agent data
    case AgentDiscovery.process_agent_discovery(device, oid_values) do
      {:ok, _discovered_device} ->
        Logger.info("Agent discovery completed",
          device_id: device.id,
          device_name: device.name
        )

        maybe_debug_log(socket, "Discovery processing succeeded",
          device_id: device.id,
          device_name: device.name
        )

        # Broadcast for real-time UI updates
        _ =
          Phoenix.PubSub.broadcast(
            Towerops.PubSub,
            "device:#{device.id}",
            {:discovery_completed, device.id}
          )

        :ok

      {:error, reason} ->
        Logger.error("Agent discovery failed: #{inspect(reason)}",
          device_id: device.id,
          device_name: device.name
        )

        maybe_debug_log(socket, "Discovery processing failed",
          device_id: device.id,
          device_name: device.name,
          error_reason: inspect(reason)
        )

        # Don't update last_discovery_at - DiscoveryWorker will retry
        # with direct discovery as fallback
        {:error, reason}
    end
  end

  defp process_polling_result(device, result, _socket) do
    snmp_device = device.snmp_device
    oid_values = Map.new(result.oid_values)
    timestamp = DateTime.from_unix!(result.timestamp, :second)

    Logger.info(
      "Processing polling result for #{device.name}: #{map_size(oid_values)} OIDs, #{length(snmp_device.sensors)} sensors"
    )

    # Process sensor readings
    Enum.each(snmp_device.sensors, &process_sensor_reading(&1, oid_values, timestamp))

    # Process interface stats
    Enum.each(device.snmp_device.interfaces, &process_interface_stats(&1, oid_values, timestamp))

    # Note: Neighbor discovery is handled by separate polling worker
    # since it requires complex LLDP/CDP parsing
  end

  defp process_sensor_reading(sensor, oid_values, timestamp) do
    case Map.get(oid_values, sensor.sensor_oid) do
      nil ->
        :ok

      value ->
        with parsed_value when not is_nil(parsed_value) <- parse_float(value) do
          final_value = parsed_value / sensor.sensor_divisor

          Snmp.create_sensor_reading(%{
            sensor_id: sensor.id,
            value: final_value,
            status: "ok",
            checked_at: timestamp
          })
        end
    end
  end

  defp process_interface_stats(iface, oid_values, timestamp) do
    idx = iface.if_index

    Snmp.create_interface_stat(%{
      interface_id: iface.id,
      if_in_octets: parse_integer(Map.get(oid_values, "1.3.6.1.2.1.2.2.1.10.#{idx}")),
      if_out_octets: parse_integer(Map.get(oid_values, "1.3.6.1.2.1.2.2.1.16.#{idx}")),
      if_in_errors: parse_integer(Map.get(oid_values, "1.3.6.1.2.1.2.2.1.14.#{idx}")),
      if_out_errors: parse_integer(Map.get(oid_values, "1.3.6.1.2.1.2.2.1.20.#{idx}")),
      if_in_discards: parse_integer(Map.get(oid_values, "1.3.6.1.2.1.2.2.1.13.#{idx}")),
      if_out_discards: parse_integer(Map.get(oid_values, "1.3.6.1.2.1.2.2.1.19.#{idx}")),
      checked_at: timestamp
    })
  end

  defp parse_integer(nil), do: nil
  defp parse_integer(value) when is_integer(value), do: value

  defp parse_integer(value) when is_binary(value) do
    case Integer.parse(value) do
      {int, _} -> int
      :error -> nil
    end
  end

  defp parse_integer(_), do: nil

  defp parse_float(value) when is_float(value), do: value
  defp parse_float(value) when is_integer(value), do: value / 1.0

  defp parse_float(value) when is_binary(value) do
    case Float.parse(value) do
      {float, _} -> float
      :error -> nil
    end
  end

  defp parse_float(_), do: nil

  defp get_remote_ip(socket) do
    case socket.transport_pid do
      nil ->
        nil

      pid when is_pid(pid) ->
        case :ranch.get_addr(pid) do
          {ip, _port} when is_tuple(ip) -> format_ip(ip)
          _ -> nil
        end
    end
  rescue
    _ -> nil
  end

  defp format_ip({a, b, c, d}), do: "#{a}.#{b}.#{c}.#{d}"

  defp format_ip({a, b, c, d, e, f, g, h}),
    do:
      "#{Integer.to_string(a, 16)}:#{Integer.to_string(b, 16)}:#{Integer.to_string(c, 16)}:#{Integer.to_string(d, 16)}:#{Integer.to_string(e, 16)}:#{Integer.to_string(f, 16)}:#{Integer.to_string(g, 16)}:#{Integer.to_string(h, 16)}"

  # Debug logging helper - only logs when debug is enabled for this agent
  # Uses :info level since production logger filters out :debug
  defp maybe_debug_log(socket, message, metadata) do
    if socket.assigns[:debug_enabled] do
      Logger.info(
        message,
        Keyword.merge(
          [
            agent_token_id: socket.assigns.agent_token_id,
            debug_enabled: true
          ],
          metadata
        )
      )
    end
  end

  defp process_backup_result(result) do
    case BackupRequests.get_request_by_job_id(result.job_id) do
      nil ->
        Logger.warning("Backup request not found for job_id", job_id: result.job_id)

      request ->
        handle_backup_request(request, result)
    end
  end

  defp handle_backup_request(request, %{error: ""} = result) do
    case extract_config_from_result(result) do
      {:ok, config_text} ->
        # Manual backups always create a snapshot, even if config unchanged
        # Automated backups (daily_cron) use deduplication to save storage
        should_create_backup =
          request.source == "manual" || backup_needed?(result.device_id, config_text)

        if should_create_backup do
          create_and_save_backup(request, result, config_text)
        else
          mark_backup_skipped(request, result)
        end

      {:error, reason} ->
        mark_backup_failed(request, result, "Failed to extract config: #{reason}")
    end
  end

  defp handle_backup_request(request, result) do
    mark_backup_failed(request, result, result.error)
  end

  defp create_and_save_backup(request, result, config_text) do
    case MikrotikBackups.create_backup(result.device_id, config_text, request.source) do
      {:ok, _backup} ->
        BackupRequests.update_request_status(request.id, "success", nil)
        Logger.info("Backup created", device_id: result.device_id, source: request.source)

      {:error, reason} ->
        mark_backup_failed(request, result, "Failed to create backup: #{inspect(reason)}")
    end
  end

  defp backup_needed?(device_id, config_text) do
    {:ok, needs_backup?} = MikrotikBackups.needs_backup?(device_id, config_text)
    needs_backup?
  end

  defp mark_backup_skipped(request, result) do
    BackupRequests.update_request_status(request.id, "success", nil)
    Logger.info("Backup skipped (no changes)", device_id: result.device_id)
  end

  defp mark_backup_failed(request, result, error_message) do
    BackupRequests.update_request_status(request.id, "failed", error_message)
    Logger.error("Backup failed", device_id: result.device_id, error: error_message)
  end

  defp extract_config_from_result(result) do
    # SSH backups return a single sentence with "config" attribute (new method)
    # API backups use /file/read which returns chunks with "data" attribute (old method)

    # Try SSH backup format first (single sentence with "config" attribute)
    config_direct =
      Enum.find_value(result.sentences, fn sentence -> Map.get(sentence.attributes, "config") end)

    case config_direct do
      nil ->
        # Try chunked API backup format
        extract_config_from_chunked_data(result)

      config_text when is_binary(config_text) and config_text != "" ->
        {:ok, config_text}

      _ ->
        {:error, "Config attribute found but empty or invalid"}
    end
  end

  defp extract_config_from_chunked_data(result) do
    # The old API backup workflow uses /file/read which returns chunks with "data" attribute
    data_chunks =
      result.sentences
      |> Enum.filter(fn sentence -> Map.has_key?(sentence.attributes, "data") end)
      |> Enum.map(fn sentence -> Map.get(sentence.attributes, "data") end)

    case data_chunks do
      [] ->
        # Fallback: try other methods
        extract_config_from_fallback(result)

      chunks ->
        # Combine all chunks in order
        config_text = Enum.join(chunks, "")

        if config_text == "" do
          {:error, "No config data in result - all chunks were empty"}
        else
          {:ok, config_text}
        end
    end
  end

  defp extract_config_from_fallback(result) do
    # Fallback: try to find any sentence with configuration-like content
    # Look for sentences with common RouterOS config markers
    config_text =
      Enum.find_value(result.sentences, fn sentence ->
        find_config_in_attributes(sentence.attributes)
      end)

    case config_text do
      nil -> {:error, "No config data in result - received #{length(result.sentences)} sentences"}
      text -> {:ok, text}
    end
  end

  defp find_config_in_attributes(attributes) do
    Enum.find_value(attributes, fn {_key, value} ->
      if routeros_config?(value), do: value
    end)
  end

  defp routeros_config?(value) when is_binary(value) do
    String.contains?(value, ["# ", "/", "set "]) and String.length(value) > 100
  end

  defp routeros_config?(_), do: false
end