defmodule Object.ResourceManager do
  @moduledoc """
  Manages system resources including memory, CPU, network, and storage limits.
  Provides graceful degradation and emergency shutdown capabilities.
  """

  defstruct [
    :memory_limit,
    :cpu_limit,
    :network_limit,
    :storage_limit,
    :graceful_degradation,
    :emergency_shutdown_threshold,
    current_usage: %{memory: 0, cpu: 0.0, network: 0, storage: 0},
    alerts: [],
    emergency_mode: false
  ]

  def new(opts) do
    %__MODULE__{
      memory_limit: opts[:memory_limit] || 1000,
      cpu_limit: opts[:cpu_limit] || 100.0,
      network_limit: opts[:network_limit] || 10000,
      storage_limit: opts[:storage_limit] || 5000,
      graceful_degradation: opts[:graceful_degradation] || true,
      emergency_shutdown_threshold: opts[:emergency_shutdown_threshold] || 0.95
    }
  end

  def check_resource_usage(resource_manager) do
    memory_usage = :erlang.memory(:total) / 1024 / 1024
    cpu_usage = get_cpu_usage()
    
    current_usage = %{
      memory: memory_usage,
      cpu: cpu_usage,
      network: 0,
      storage: 0
    }
    
    resource_manager = %{resource_manager | current_usage: current_usage}
    
    memory_pressure = memory_usage / resource_manager.memory_limit
    cpu_pressure = cpu_usage / resource_manager.cpu_limit
    
    pressure = max(memory_pressure, cpu_pressure)
    
    cond do
      pressure >= resource_manager.emergency_shutdown_threshold ->
        trigger_emergency_shutdown(resource_manager)
      pressure >= 0.8 ->
        trigger_graceful_degradation(resource_manager)
      true ->
        {resource_manager, :normal}
    end
  end

  defp get_cpu_usage do
    case :cpu_sup.avg1() / 256 do
      usage when usage >= 0 -> usage
      _ -> 0.0
    end
  rescue
    _ -> 0.0
  end

  defp trigger_emergency_shutdown(resource_manager) do
    resource_manager = %{resource_manager | 
      emergency_mode: true,
      alerts: ["Emergency shutdown triggered" | resource_manager.alerts]
    }
    {resource_manager, :emergency_shutdown}
  end

  defp trigger_graceful_degradation(resource_manager) do
    resource_manager = %{resource_manager | 
      alerts: ["Graceful degradation activated" | resource_manager.alerts]
    }
    {resource_manager, :graceful_degradation}
  end

  def get_memory_pressure(resource_manager) do
    resource_manager.current_usage.memory / resource_manager.memory_limit
  end

  def allocate_resource(resource_manager, resource_type, amount) do
    current = resource_manager.current_usage[resource_type] || 0
    limit = Map.get(resource_manager, :"#{resource_type}_limit", 1000)
    
    if current + amount <= limit do
      new_usage = Map.put(resource_manager.current_usage, resource_type, current + amount)
      {:ok, %{resource_manager | current_usage: new_usage}}
    else
      {:error, :resource_limit_exceeded}
    end
  end

  def deallocate_resource(resource_manager, resource_type, amount) do
    current = resource_manager.current_usage[resource_type] || 0
    new_amount = max(0, current - amount)
    new_usage = Map.put(resource_manager.current_usage, resource_type, new_amount)
    %{resource_manager | current_usage: new_usage}
  end
end