defmodule Odinsea.Game.Events.Survival do
  @moduledoc """
  Survival Event - Last-man-standing platform challenge.
  Ported from Java `server.events.MapleSurvival`.

  ## Gameplay
  - Players must navigate platforms without falling
  - Fall once = elimination
  - Last players to survive win

  ## Maps
  - Stage 1: 809040000
  - Stage 2: 809040100

  ## Win Condition
  - Survive until time runs out
  - Last players standing win
  """

  alias Odinsea.Game.Event
  alias Odinsea.Game.Timer.EventTimer
  alias Odinsea.Game.Character

  require Logger

  # ============================================================================
  # Types
  # ============================================================================

  @typedoc "Survival event state"
  @type t :: %__MODULE__{
    base: Event.t(),
    time_started: integer() | nil,
    event_duration: non_neg_integer(),
    schedules: [reference()]
  }

  defstruct [
    :base,
    time_started: nil,
    event_duration: 360_000,  # 6 minutes default
    schedules: []
  ]

  # ============================================================================
  # Constants
  # ============================================================================

  @map_ids [809040000, 809040100]
  @default_duration 360_000  # 6 minutes in ms

  # ============================================================================
  # Event Implementation
  # ============================================================================

  @doc """
  Creates a new Survival event for the given channel.
  """
  def new(channel_id) do
    base = Event.new(:survival, channel_id, @map_ids)

    %__MODULE__{
      base: base,
      time_started: nil,
      event_duration: @default_duration,
      schedules: []
    }
  end

  @doc """
  Returns the map IDs for this event type.
  """
  def map_ids, do: @map_ids

  @doc """
  Resets the event state for a new game.
  """
  def reset(%__MODULE__{} = event) do
    # Cancel existing schedules
    cancel_schedules(event)

    # Close entry portal
    set_portal_state(event, "join00", false)

    base = %{event.base | is_running: true, player_count: 0}

    %__MODULE__{
      event |
      base: base,
      time_started: nil,
      schedules: []
    }
  end

  @doc """
  Cleans up the event after it ends.
  """
  def unreset(%__MODULE__{} = event) do
    cancel_schedules(event)

    # Open entry portal
    set_portal_state(event, "join00", true)

    base = %{event.base | is_running: false, player_count: 0}

    %__MODULE__{
      event |
      base: base,
      time_started: nil,
      schedules: []
    }
  end

  @doc """
  Called when a player finishes (reaches end map).
  Gives prize and achievement.
  """
  def finished(%__MODULE__{} = event, character) do
    Logger.info("Player #{character.name} finished Survival event!")

    # Give prize
    Event.give_prize(character)

    # Give achievement (ID 25)
    Character.finish_achievement(character, 25)

    :ok
  end

  @doc """
  Called when a player loads into an event map.
  Sends clock if timer is running.
  """
  def on_map_load(%__MODULE__{} = event, character) do
    if is_timer_started(event) do
      time_left = get_time_left(event)
      Logger.debug("Sending Survival clock to #{character.name}: #{div(time_left, 1000)}s remaining")
      # Send clock packet
    end

    :ok
  end

  @doc """
  Starts the Survival event gameplay.
  """
  def start_event(%__MODULE__{} = event) do
    Logger.info("Starting Survival event on channel #{event.base.channel_id}")

    now = System.system_time(:millisecond)

    # Close entry portal
    set_portal_state(event, "join00", false)

    # Broadcast start
    Event.broadcast_to_event(event.base, :event_started)
    Event.broadcast_to_event(event.base, {:clock, div(event.event_duration, 1000)})
    Event.broadcast_to_event(event.base, {:server_notice, "The portal has now opened. Press the up arrow key at the portal to enter."})
    Event.broadcast_to_event(event.base, {:server_notice, "Fall down once, and never get back up again! Get to the top without falling down!"})

    # Schedule event end
    end_ref = EventTimer.schedule(
      fn -> end_event(event) end,
      event.event_duration
    )

    %__MODULE__{
      event |
      time_started: now,
      schedules: [end_ref]
    }
  end

  @doc """
  Checks if the timer has started.
  """
  def is_timer_started(%__MODULE__{time_started: nil}), do: false
  def is_timer_started(%__MODULE__{}), do: true

  @doc """
  Gets the total event duration in milliseconds.
  """
  def get_time(%__MODULE__{event_duration: duration}), do: duration

  @doc """
  Gets the time remaining in milliseconds.
  """
  def get_time_left(%__MODULE__{time_started: nil, event_duration: duration}), do: duration
  def get_time_left(%__MODULE__{time_started: started, event_duration: duration}) do
    elapsed = System.system_time(:millisecond) - started
    max(0, duration - elapsed)
  end

  @doc """
  Handles a player falling (elimination).
  """
  def player_fell(%__MODULE__{} = event, character) do
    Logger.info("Player #{character.name} fell and was eliminated from Survival event")

    # Warp player out
    Event.warp_back(character)

    # Unregister from event
    base = Event.unregister_player(event.base, character.id)

    %{event | base: base}
  end

  @doc """
  Checks if a player position is valid (on platform).
  Falling below a certain Y coordinate = elimination.
  """
  def valid_position?(%__MODULE__{}, %{y: y}) do
    # Y threshold for falling (map-specific)
    y > -500  # Example threshold
  end

  # ============================================================================
  # Private Functions
  # ============================================================================

  defp cancel_schedules(%__MODULE__{schedules: schedules} = event) do
    Enum.each(schedules, fn ref ->
      EventTimer.cancel(ref)
    end)

    %{event | schedules: []}
  end

  defp set_portal_state(%__MODULE__{}, _portal_name, _state) do
    # In real implementation, update map portal state
    :ok
  end

  defp end_event(%__MODULE__{} = event) do
    Logger.info("Survival event ended on channel #{event.base.channel_id}")

    # Warp out all remaining players
    # In real implementation:
    # - Get all players on event maps
    # - Give prizes to survivors
    # - Warp each back to saved location

    # Unreset event
    unreset(event)
  end
end