defmodule Odinsea.Game.EventManager do
  @moduledoc """
  Event Manager for scheduling and managing in-game events.
  Ported from Java `server.events` scheduling functionality.

  ## Responsibilities
  - Event scheduling per channel
  - Player registration for events
  - Event state management
  - Event coordination across channels

  ## Event Types
  - Coconut - Team coconut hitting
  - Fitness - Obstacle course
  - OlaOla - Portal guessing
  - OxQuiz - True/False quiz
  - Snowball - Team snowball rolling
  - Survival - Last man standing

  ## Usage
  Event scheduling is typically done by GM commands or automated system:

      # Schedule an event
      EventManager.schedule_event(channel_id, :coconut)

      # Player joins event
      EventManager.join_event(channel_id, character_id, :coconut)

      # Start the event
      EventManager.start_event(channel_id, :coconut)
  """

  use GenServer

  alias Odinsea.Game.Events
  alias Odinsea.Game.Event
  alias Odinsea.Game.Timer.EventTimer

  require Logger

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

  @typedoc "Channel event state"
  @type channel_events :: %{
    optional(Events.t()) => Event.t() | struct()
  }

  @typedoc "Manager state"
  @type state :: %{
    channels: %{optional(non_neg_integer()) => channel_events()},
    schedules: %{optional(reference()) => {:auto_start, non_neg_integer(), Events.t()}}
  }

  # ============================================================================
  # Client API
  # ============================================================================

  @doc """
  Starts the Event Manager.
  """
  def start_link(_opts) do
    GenServer.start_link(__MODULE__, [], name: __MODULE__)
  end

  @doc """
  Schedules an event to run on a specific channel.

  ## Parameters
  - channel_id: Channel to run event on
  - event_type: Type of event (:coconut, :fitness, etc.)

  ## Returns
  - :ok on success
  - {:error, reason} on failure
  """
  def schedule_event(channel_id, event_type) do
    GenServer.call(__MODULE__, {:schedule_event, channel_id, event_type})
  end

  @doc """
  Starts a scheduled event immediately.

  ## Parameters
  - channel_id: Channel running the event
  - event_type: Type of event
  """
  def start_event(channel_id, event_type) do
    GenServer.call(__MODULE__, {:start_event, channel_id, event_type})
  end

  @doc """
  Cancels a scheduled event.

  ## Parameters
  - channel_id: Channel with the event
  - event_type: Type of event
  """
  def cancel_event(channel_id, event_type) do
    GenServer.call(__MODULE__, {:cancel_event, channel_id, event_type})
  end

  @doc """
  Registers a player for an event.

  ## Parameters
  - channel_id: Channel with the event
  - character_id: Character joining
  - event_type: Type of event
  """
  def join_event(channel_id, character_id, event_type) do
    GenServer.call(__MODULE__, {:join_event, channel_id, character_id, event_type})
  end

  @doc """
  Unregisters a player from an event.

  ## Parameters
  - channel_id: Channel with the event
  - character_id: Character leaving
  - event_type: Type of event
  """
  def leave_event(channel_id, character_id, event_type) do
    GenServer.call(__MODULE__, {:leave_event, channel_id, character_id, event_type})
  end

  @doc """
  Handles a player loading into an event map.
  Called by map load handlers.

  ## Parameters
  - channel_id: Channel the player is on
  - character: Character struct
  - map_id: Map ID player loaded into
  """
  def on_map_load(channel_id, character, map_id) do
    GenServer.cast(__MODULE__, {:on_map_load, channel_id, character, map_id})
  end

  @doc """
  Handles a GM manually starting an event.
  """
  def on_start_event(channel_id, character, map_id) do
    GenServer.cast(__MODULE__, {:on_start_event, channel_id, character, map_id})
  end

  @doc """
  Gets the active event on a channel.
  """
  def get_active_event(channel_id) do
    GenServer.call(__MODULE__, {:get_active_event, channel_id})
  end

  @doc """
  Gets all events for a channel.
  """
  def get_channel_events(channel_id) do
    GenServer.call(__MODULE__, {:get_channel_events, channel_id})
  end

  @doc """
  Checks if an event is running on a channel.
  """
  def event_running?(channel_id, event_type) do
    GenServer.call(__MODULE__, {:event_running?, channel_id, event_type})
  end

  @doc """
  Sets the active event map for a channel.
  This is the map where players should go to join.
  """
  def set_event_map(channel_id, map_id) do
    GenServer.cast(__MODULE__, {:set_event_map, channel_id, map_id})
  end

  @doc """
  Gets the event map for a channel (where players join).
  """
  def get_event_map(channel_id) do
    GenServer.call(__MODULE__, {:get_event_map, channel_id})
  end

  @doc """
  Lists all available event types.
  """
  def list_event_types do
    Events.all()
  end

  @doc """
  Gets event info for a type.
  """
  def event_info(event_type) do
    %{
      type: event_type,
      name: Events.display_name(event_type),
      map_ids: Events.map_ids(event_type),
      entry_map: Events.entry_map_id(event_type),
      stages: Events.stage_count(event_type),
      is_race: Events.race_event?(event_type),
      is_team: Events.team_event?(event_type)
    }
  end

  # ============================================================================
  # Server Callbacks
  # ============================================================================

  @impl true
  def init(_) do
    Logger.info("EventManager started")

    state = %{
      channels: %{},
      schedules: %{},
      event_maps: %{}  # channel_id => map_id
    }

    {:ok, state}
  end

  @impl true
  def handle_call({:schedule_event, channel_id, event_type}, _from, state) do
    case do_schedule_event(state, channel_id, event_type) do
      {:ok, new_state} ->
        broadcast_event_notice(channel_id, event_type)
        {:reply, :ok, new_state}

      {:error, reason} ->
        {:reply, {:error, reason}, state}
    end
  end

  @impl true
  def handle_call({:start_event, channel_id, event_type}, _from, state) do
    case do_start_event(state, channel_id, event_type) do
      {:ok, new_state} ->
        {:reply, :ok, new_state}

      {:error, reason} ->
        {:reply, {:error, reason}, state}
    end
  end

  @impl true
  def handle_call({:cancel_event, channel_id, event_type}, _from, state) do
    new_state = do_cancel_event(state, channel_id, event_type)
    {:reply, :ok, new_state}
  end

  @impl true
  def handle_call({:join_event, channel_id, character_id, event_type}, _from, state) do
    {reply, new_state} = do_join_event(state, channel_id, character_id, event_type)
    {:reply, reply, new_state}
  end

  @impl true
  def handle_call({:leave_event, channel_id, character_id, event_type}, _from, state) do
    {reply, new_state} = do_leave_event(state, channel_id, character_id, event_type)
    {:reply, reply, new_state}
  end

  @impl true
  def handle_call({:get_active_event, channel_id}, _from, state) do
    event = get_active_event_impl(state, channel_id)
    {:reply, event, state}
  end

  @impl true
  def handle_call({:get_channel_events, channel_id}, _from, state) do
    events = Map.get(state.channels, channel_id, %{})
    {:reply, events, state}
  end

  @impl true
  def handle_call({:event_running?, channel_id, event_type}, _from, state) do
    running = event_running_impl?(state, channel_id, event_type)
    {:reply, running, state}
  end

  @impl true
  def handle_call({:get_event_map, channel_id}, _from, state) do
    map_id = Map.get(state.event_maps, channel_id)
    {:reply, map_id, state}
  end

  @impl true
  def handle_cast({:on_map_load, channel_id, character, map_id}, state) do
    new_state = do_on_map_load(state, channel_id, character, map_id)
    {:noreply, new_state}
  end

  @impl true
  def handle_cast({:on_start_event, channel_id, character, map_id}, state) do
    new_state = do_on_start_event(state, channel_id, character, map_id)
    {:noreply, new_state}
  end

  @impl true
  def handle_cast({:set_event_map, channel_id, map_id}, state) do
    new_maps = Map.put(state.event_maps, channel_id, map_id)
    {:noreply, %{state | event_maps: new_maps}}
  end

  @impl true
  def handle_info({:auto_start, channel_id, event_type}, state) do
    Logger.info("Auto-starting event #{event_type} on channel #{channel_id}")

    # Start the event
    case do_start_event(state, channel_id, event_type) do
      {:ok, new_state} ->
        # Clear event map
        new_maps = Map.delete(new_state.event_maps, channel_id)
        {:noreply, %{new_state | event_maps: new_maps}}

      {:error, _} ->
        {:noreply, state}
    end
  end

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

  defp do_schedule_event(state, channel_id, event_type) do
    # Check if event type is valid
    if event_type not in Events.all() do
      {:error, "Invalid event type"}
    else
      # Check if event is already running
      if event_running_impl?(state, channel_id, event_type) do
        {:error, "Event already running"}
      else
        # Create event instance
        event = create_event(event_type, channel_id)

        # Reset event
        event = reset_event(event, event_type)

        # Store event
        channel_events = Map.get(state.channels, channel_id, %{})
        channel_events = Map.put(channel_events, event_type, event)
        channels = Map.put(state.channels, channel_id, channel_events)

        # Set event map (entry map)
        entry_map = Events.entry_map_id(event_type)
        event_maps = Map.put(state.event_maps, channel_id, entry_map)

        {:ok, %{state | channels: channels, event_maps: event_maps}}
      end
    end
  end

  defp do_start_event(state, channel_id, event_type) do
    with {:ok, event} <- get_event(state, channel_id, event_type) do
      # Start the event
      new_event = start_event_impl(event, event_type)

      # Update state
      channel_events = Map.get(state.channels, channel_id, %{})
      channel_events = Map.put(channel_events, event_type, new_event)
      channels = Map.put(state.channels, channel_id, channel_events)

      # Clear event map
      event_maps = Map.delete(state.event_maps, channel_id)

      {:ok, %{state | channels: channels, event_maps: event_maps}}
    else
      nil -> {:error, "Event not found"}
    end
  end

  defp do_cancel_event(state, channel_id, event_type) do
    with {:ok, event} <- get_event(state, channel_id, event_type) do
      # Unreset event (cleanup)
      unreset_event(event, event_type)

      # Remove from state
      channel_events = Map.get(state.channels, channel_id, %{})
      channel_events = Map.delete(channel_events, event_type)
      channels = Map.put(state.channels, channel_id, channel_events)

      # Clear event map
      event_maps = Map.delete(state.event_maps, channel_id)

      %{state | channels: channels, event_maps: event_maps}
    else
      nil -> state
    end
  end

  defp do_join_event(state, channel_id, character_id, event_type) do
    with {:ok, event} <- get_event(state, channel_id, event_type) do
      if event.base.is_running do
        # Register player
        new_event = Event.register_player(event.base, character_id)
        new_event = %{event | base: new_event}

        # Check if we should auto-start (250 players)
        new_event = Event.increment_player_count(new_event.base)
        new_event = %{event | base: new_event}

        # Update state
        channel_events = Map.get(state.channels, channel_id, %{})
        channel_events = Map.put(channel_events, event_type, new_event)
        channels = Map.put(state.channels, channel_id, channel_events)

        {{:ok, :joined}, %{state | channels: channels}}
      else
        {{:error, "Event not running"}, state}
      end
    else
      nil -> {{:error, "Event not found"}, state}
    end
  end

  defp do_leave_event(state, channel_id, character_id, event_type) do
    with {:ok, event} <- get_event(state, channel_id, event_type) do
      # Unregister player
      new_base = Event.unregister_player(event.base, character_id)
      new_event = %{event | base: new_base}

      # Update state
      channel_events = Map.get(state.channels, channel_id, %{})
      channel_events = Map.put(channel_events, event_type, new_event)
      channels = Map.put(state.channels, channel_id, channel_events)

      {{:ok, :left}, %{state | channels: channels}}
    else
      nil -> {{:error, "Event not found"}, state}
    end
  end

  defp do_on_map_load(state, channel_id, character, map_id) do
    # Check if any event is running on this channel
    channel_events = Map.get(state.channels, channel_id, %{})

    Enum.reduce(channel_events, state, fn {event_type, event}, acc_state ->
      if event.base.is_running do
        # Check if this is the finish map
        if map_id == 109050000 do
          # Call finished callback
          finished_event(event, event_type, character)
        end

        # Check if this is an event map
        if Event.event_map?(event.base, map_id) do
          # Call on_map_load callback
          on_map_load_event(event, event_type, character)

          # If first map, increment player count
          if Event.map_index(event.base, map_id) == 0 do
            new_base = Event.increment_player_count(event.base)

            # Check if we hit 250 players
            if new_base.player_count >= 250 do
              # Auto-start
              schedule_auto_start(channel_id, event_type)
            end

            # Update event in state
            new_event = put_event_base(event, event_type, new_base)
            channel_events = Map.put(acc_state.channels[channel_id], event_type, new_event)
            channels = Map.put(acc_state.channels, channel_id, channel_events)
            %{acc_state | channels: channels}
          else
            acc_state
          end
        else
          acc_state
        end
      else
        acc_state
      end
    end)
  end

  defp do_on_start_event(state, channel_id, character, map_id) do
    channel_events = Map.get(state.channels, channel_id, %{})

    Enum.find_value(channel_events, state, fn {event_type, event} ->
      if event.base.is_running and Event.event_map?(event.base, map_id) do
        # Start the event
        new_event = start_event_impl(event, event_type)

        # Update state
        channel_events = Map.put(channel_events, event_type, new_event)
        channels = Map.put(state.channels, channel_id, channel_events)

        # Clear event map
        event_maps = Map.delete(state.event_maps, channel_id)

        %{state | channels: channels, event_maps: event_maps}
      end
    end) || state
  end

  defp get_event(state, channel_id, event_type) do
    channel_events = Map.get(state.channels, channel_id, %{})

    case Map.get(channel_events, event_type) do
      nil -> nil
      event -> {:ok, event}
    end
  end

  defp get_active_event_impl(state, channel_id) do
    channel_events = Map.get(state.channels, channel_id, %{})

    Enum.find_value(channel_events, fn {event_type, event} ->
      if event.base.is_running do
        {event_type, event}
      end
    end)
  end

  defp event_running_impl?(state, channel_id, event_type) do
    case get_event(state, channel_id, event_type) do
      {:ok, event} -> event.base.is_running
      nil -> false
    end
  end

  defp create_event(:coconut, channel_id), do: Odinsea.Game.Events.Coconut.new(channel_id)
  defp create_event(:fitness, channel_id), do: Odinsea.Game.Events.Fitness.new(channel_id)
  defp create_event(:ola_ola, channel_id), do: Odinsea.Game.Events.OlaOla.new(channel_id)
  defp create_event(:ox_quiz, channel_id), do: Odinsea.Game.Events.OxQuiz.new(channel_id)
  defp create_event(:snowball, channel_id), do: Odinsea.Game.Events.Snowball.new(channel_id)
  defp create_event(:survival, channel_id), do: Odinsea.Game.Events.Survival.new(channel_id)
  defp create_event(_, _), do: nil

  defp reset_event(event, :coconut), do: Odinsea.Game.Events.Coconut.reset(event)
  defp reset_event(event, :fitness), do: Odinsea.Game.Events.Fitness.reset(event)
  defp reset_event(event, :ola_ola), do: Odinsea.Game.Events.OlaOla.reset(event)
  defp reset_event(event, :ox_quiz), do: Odinsea.Game.Events.OxQuiz.reset(event)
  defp reset_event(event, :snowball), do: Odinsea.Game.Events.Snowball.reset(event)
  defp reset_event(event, :survival), do: Odinsea.Game.Events.Survival.reset(event)
  defp reset_event(event, _), do: event

  defp unreset_event(event, :coconut), do: Odinsea.Game.Events.Coconut.unreset(event)
  defp unreset_event(event, :fitness), do: Odinsea.Game.Events.Fitness.unreset(event)
  defp unreset_event(event, :ola_ola), do: Odinsea.Game.Events.OlaOla.unreset(event)
  defp unreset_event(event, :ox_quiz), do: Odinsea.Game.Events.OxQuiz.unreset(event)
  defp unreset_event(event, :snowball), do: Odinsea.Game.Events.Snowball.unreset(event)
  defp unreset_event(event, :survival), do: Odinsea.Game.Events.Survival.unreset(event)
  defp unreset_event(event, _), do: event

  defp start_event_impl(event, :coconut), do: Odinsea.Game.Events.Coconut.start_event(event)
  defp start_event_impl(event, :fitness), do: Odinsea.Game.Events.Fitness.start_event(event)
  defp start_event_impl(event, :ola_ola), do: Odinsea.Game.Events.OlaOla.start_event(event)
  defp start_event_impl(event, :ox_quiz), do: Odinsea.Game.Events.OxQuiz.start_event(event)
  defp start_event_impl(event, :snowball), do: Odinsea.Game.Events.Snowball.start_event(event)
  defp start_event_impl(event, :survival), do: Odinsea.Game.Events.Survival.start_event(event)
  defp start_event_impl(event, _), do: event

  defp finished_event(event, :coconut, character), do: Odinsea.Game.Events.Coconut.finished(event, character)
  defp finished_event(event, :fitness, character), do: Odinsea.Game.Events.Fitness.finished(event, character)
  defp finished_event(event, :ola_ola, character), do: Odinsea.Game.Events.OlaOla.finished(event, character)
  defp finished_event(event, :ox_quiz, character), do: Odinsea.Game.Events.OxQuiz.finished(event, character)
  defp finished_event(event, :snowball, character), do: Odinsea.Game.Events.Snowball.finished(event, character)
  defp finished_event(event, :survival, character), do: Odinsea.Game.Events.Survival.finished(event, character)
  defp finished_event(_, _, _), do: :ok

  defp on_map_load_event(event, :coconut, character), do: Odinsea.Game.Events.Coconut.on_map_load(event, character)
  defp on_map_load_event(event, :fitness, character), do: Odinsea.Game.Events.Fitness.on_map_load(event, character)
  defp on_map_load_event(event, :ola_ola, character), do: Odinsea.Game.Events.OlaOla.on_map_load(event, character)
  defp on_map_load_event(event, :ox_quiz, character), do: Odinsea.Game.Events.OxQuiz.on_map_load(event, character)
  defp on_map_load_event(event, :snowball, character), do: Odinsea.Game.Events.Snowball.on_map_load(event, character)
  defp on_map_load_event(event, :survival, character), do: Odinsea.Game.Events.Survival.on_map_load(event, character)
  defp on_map_load_event(_, _, _), do: :ok

  defp put_event_base(event, :coconut, base), do: %{event | base: base}
  defp put_event_base(event, :fitness, base), do: %{event | base: base}
  defp put_event_base(event, :ola_ola, base), do: %{event | base: base}
  defp put_event_base(event, :ox_quiz, base), do: %{event | base: base}
  defp put_event_base(event, :snowball, base), do: %{event | base: base}
  defp put_event_base(event, :survival, base), do: %{event | base: base}
  defp put_event_base(event, _, _), do: event

  defp schedule_auto_start(channel_id, event_type) do
    EventTimer.schedule(
      fn ->
        send(__MODULE__, {:auto_start, channel_id, event_type})
      end,
      30_000  # 30 seconds
    )

    broadcast_server_notice(channel_id, "The event will start in 30 seconds!")
  end

  defp broadcast_event_notice(channel_id, event_type) do
    event_name = Events.display_name(event_type)

    broadcast_server_notice(
      channel_id,
      "Hello! Let's play a #{event_name} event in channel #{channel_id}! " <>
      "Change to channel #{channel_id} and use @event command!"
    )
  end

  defp broadcast_server_notice(channel_id, message) do
    # In real implementation, broadcast to channel
    Logger.info("[Channel #{channel_id}] #{message}")
  end
end