defmodule Odinsea.Channel.Handler.Party do
  @moduledoc """
  Handles party operations.
  Ported from src/handling/channel/handler/PartyHandler.java
  
  Manages party create, join, leave, expel, and leader change.
  """

  require Logger

  alias Odinsea.Net.Packet.In
  alias Odinsea.Channel.Packets
  alias Odinsea.Game.Character
  alias Odinsea.World.Party

  @party_invite_quest_id 1000  # TODO: Get actual quest ID
  @party_request_quest_id 1001  # TODO: Get actual quest ID

  @doc """
  Handles party operations (CP_PARTY_OPERATION).
  Ported from PartyHandler.PartyOperation()
  
  Operation:
  - 1: Create party
  - 2: Leave party
  - 3: Accept invitation
  - 4: Invite player
  - 5: Expel member
  - 6: Change leader
  - 7: Request to join party
  - 8: Toggle party requests
  """
  def handle_party_operation(packet, client_state) do
    with {:ok, character_pid} <- get_character(client_state),
         {:ok, character} <- Character.get_state(character_pid) do
      
      {operation, packet} = In.decode_byte(packet)
      
      Logger.debug("Party operation: #{operation} from #{character.name}")
      
      case operation do
        1 -> handle_create_party(character, client_state)
        2 -> handle_leave_party(character, client_state)
        3 -> handle_accept_invitation(packet, character, client_state)
        4 -> handle_invite_player(packet, character, client_state)
        5 -> handle_expel_member(packet, character, client_state)
        6 -> handle_change_leader(packet, character, client_state)
        7 -> handle_request_join(packet, character, client_state)
        8 -> handle_toggle_requests(packet, character, client_state)
        _ -> 
          Logger.warning("Unknown party operation: #{operation}")
          {:ok, client_state}
      end
    else
      {:error, reason} ->
        Logger.warning("Party operation failed: #{inspect(reason)}")
        {:ok, client_state}
    end
  end

  @doc """
  Handles party request denial (CP_DENY_PARTY_REQUEST).
  Ported from PartyHandler.DenyPartyRequest()
  """
  def handle_deny_party_request(packet, client_state) do
    with {:ok, _character_pid} <- get_character(client_state),
         {:ok, character} <- Character.get_state(client_state.character_id) do
      
      {action, packet} = In.decode_byte(packet)
      
      # Check for GMS-specific action
      if action == 0x32 do
        # TODO: GMS-specific party join
        {:ok, client_state}
      else
        {party_id, _packet} = In.decode_int(packet)
        
        if action == 0x1D || action == 0x1B do
          # Accept - handled by PartyOperation(3)
          {:ok, client_state}
        else
          # Deny - notify inviter
          case Party.get_party(party_id) do
            nil -> :ok
            party ->
              # Find leader and notify
              notify_party_denied(party.leader_id, character.name)
          end
          {:ok, client_state}
        end
      end
    else
      _ -> {:ok, client_state}
    end
  end

  @doc """
  Handles party invite settings (CP_ALLOW_PARTY_INVITE).
  Ported from PartyHandler.AllowPartyInvite()
  """
  def handle_allow_party_invite(packet, character) do
    {enabled, _packet} = In.decode_byte(packet)
    
    # Update quest status for party invite blocking
    if enabled > 0 do
      Character.remove_quest(character.id, @party_invite_quest_id)
    else
      Character.start_quest(character.id, @party_invite_quest_id)
    end
    
    :ok
  end

  # ============================================================================
  # Party Operation Handlers
  # ============================================================================

  defp handle_create_party(character, client_state) do
    if character.party_id && character.party_id > 0 do
      # Already in a party
      case Party.get_party(character.party_id) do
        nil ->
          # Invalid party, create new
          create_new_party(character, client_state)
          
        party ->
          # Check if leader of single-member party
          if party.leader_id == character.id && length(party.members) == 1 do
            # Re-send party created
            party_created_packet = Packets.party_created(party.id)
            send_packet(client_state, party_created_packet)
          else
            Character.send_message(character.id, "You can't create a party as you are already in one", 5)
          end
      end
    else
      create_new_party(character, client_state)
    end
    
    {:ok, client_state}
  end

  defp create_new_party(character, client_state) do
    party_character = create_party_character(character, client_state.channel_id)
    
    case Party.create_party(party_character) do
      {:ok, party} ->
        # Update character's party
        Character.set_party(character.id, party.id)
        
        # Send party created packet
        party_created_packet = Packets.party_created(party.id)
        send_packet(client_state, party_created_packet)
        
        Logger.info("Party #{party.id} created by #{character.name}")
        
      {:error, reason} ->
        Logger.error("Failed to create party: #{inspect(reason)}")
        Character.send_message(character.id, "Failed to create party", 5)
    end
  end

  defp handle_leave_party(character, client_state) do
    if character.party_id && character.party_id > 0 do
      party_character = create_party_character(character, client_state.channel_id)
      
      case Party.update_party(character.party_id, :leave, party_character) do
        {:ok, _} ->
          # Update character
          Character.set_party(character.id, nil)
          
          # If in Dojo or Pyramid, fail those
          # TODO: Implement Dojo/Pyramid fail
          
          # If in event instance, handle leave
          # TODO: Implement event instance leftParty
          
          Logger.info("#{character.name} left party #{character.party_id}")
          
        {:error, reason} ->
          Logger.error("Failed to leave party: #{inspect(reason)}")
      end
    end
    
    {:ok, client_state}
  end

  defp handle_accept_invitation(packet, character, client_state) do
    {party_id, _packet} = In.decode_int(packet)
    
    if character.party_id && character.party_id > 0 do
      Character.send_message(character.id, "You can't join the party as you are already in one", 5)
    else
      # Check if accepting party invites
      if Character.has_quest(character.id, @party_invite_quest_id) do
        {:ok, client_state}
      else
        case Party.get_party(party_id) do
          nil ->
            Character.send_message(character.id, "The party you are trying to join does not exist", 5)
            
          party ->
            if length(party.members) >= 6 do
              send_party_status_message(client_state, 17)
            else
              # Join party
              party_character = create_party_character(character, client_state.channel_id)
              
              case Party.update_party(party_id, :join, party_character) do
                {:ok, _} ->
                  Character.set_party(character.id, party_id)
                  
                  # Request party member HP updates
                  # TODO: Implement receivePartyMemberHP / updatePartyMemberHP
                  
                  Logger.info("#{character.name} joined party #{party_id}")
                  
                {:error, :party_full} ->
                  send_party_status_message(client_state, 17)
                  
                {:error, reason} ->
                  Logger.error("Failed to join party: #{inspect(reason)}")
              end
            end
        end
      end
    end
    
    {:ok, client_state}
  end

  defp handle_invite_player(packet, character, client_state) do
    # Create party if not in one
    party = if not (character.party_id && character.party_id > 0) do
      party_character = create_party_character(character, client_state.channel_id)
      {:ok, new_party} = Party.create_party(party_character)
      Character.set_party(character.id, new_party.id)
      
      party_created_packet = Packets.party_created(new_party.id)
      send_packet(client_state, party_created_packet)
      
      new_party
    else
      Party.get_party(character.party_id)
    end
    
    {target_name, _packet} = In.decode_string(packet)
    target_name = String.downcase(target_name)
    
    cond do
      party && party.expedition_id > 0 ->
        Character.send_message(character.id, "You may not do party operations while in a raid.", 5)
        
      party && length(party.members) >= 6 ->
        send_party_status_message(client_state, 16)
        
      true ->
        # Find target character
        case Odinsea.Channel.Players.find_by_name(client_state.channel_id, target_name) do
          {:ok, target} ->
            # Check if can invite
            if can_invite_to_party?(character, target) do
              # Send invite
              send_party_invite(target, character)
              
              send_party_status_message(client_state, 22, target.name)
              
              Logger.info("#{character.name} invited #{target.name} to party")
            else
              send_party_status_message(client_state, 17)
            end
            
          {:error, :not_found} ->
            send_party_status_message(client_state, 19)
        end
    end
    
    {:ok, client_state}
  end

  defp handle_expel_member(packet, character, client_state) do
    {target_id, _packet} = In.decode_int(packet)
    
    if character.party_id && character.party_id > 0 do
      case Party.get_party(character.party_id) do
        nil ->
          :ok
          
        party ->
          # Check if leader
          if party.leader_id == character.id do
            # Check expedition
            if party.expedition_id > 0 do
              Character.send_message(character.id, "You may not do party operations while in a raid.", 5)
            else
              # Find member to expel
              target = Enum.find(party.members, fn m -> m.id == target_id end)
              
              if target do
                party_character = %{create_party_character(character, client_state.channel_id) | id: target_id}
                
                case Party.update_party(character.party_id, :expel, party_character) do
                  {:ok, _} ->
                    # Update expelled character
                    Character.set_party(target_id, nil)
                    
                    # Handle event instance
                    # TODO: disbandParty if leader wants to boot
                    
                    Logger.info("#{target.name} expelled from party by #{character.name}")
                    
                  {:error, reason} ->
                    Logger.error("Failed to expel member: #{inspect(reason)}")
                end
              end
            end
          end
      end
    end
    
    {:ok, client_state}
  end

  defp handle_change_leader(packet, character, client_state) do
    {new_leader_id, _packet} = In.decode_int(packet)
    
    if character.party_id && character.party_id > 0 do
      case Party.get_party(character.party_id) do
        nil ->
          :ok
          
        party ->
          # Check expedition
          if party.expedition_id > 0 do
            Character.send_message(character.id, "You may not do party operations while in a raid.", 5)
          else
            # Check if leader
            if party.leader_id == character.id do
              # Check if new leader is in party
              if Enum.any?(party.members, fn m -> m.id == new_leader_id end) do
                case Party.change_leader(character.party_id, new_leader_id, character.id) do
                  :ok ->
                    Logger.info("Party #{character.party_id} leader changed to #{new_leader_id}")
                    
                  {:error, reason} ->
                    Logger.error("Failed to change leader: #{inspect(reason)}")
                end
              end
            end
          end
      end
    end
    
    {:ok, client_state}
  end

  defp handle_request_join(packet, character, client_state) do
    {party_id, _packet} = In.decode_int(packet)
    
    # Leave current party if any
    if character.party_id && character.party_id > 0 do
      handle_leave_party(character, client_state)
    end
    
    # Request to join party
    case Party.get_party(party_id) do
      nil ->
        :ok
        
      party ->
        # Check restrictions
        # TODO: Check event instance, pyramid, dojo, expedition
        
        # Find leader
        case Registry.lookup(Odinsea.CharacterRegistry, party.leader_id) do
          [{leader_pid, _}] ->
            case Character.get_state(leader_pid) do
              {:ok, leader} ->
                # Check if leader accepts party requests
                unless Character.has_quest(leader.id, @party_request_quest_id) do
                  # Check blacklist
                  unless Enum.member?(leader.blacklist, String.downcase(character.name)) do
                    # Send request to leader
                    send_party_request(leader, character)
                    
                    send_party_status_message(client_state, 50, character.name)
                  else
                    Character.send_message(character.id, "Player was not found or player is not accepting party requests.", 5)
                  end
                else
                  Character.send_message(character.id, "Player was not found or player is not accepting party requests.", 5)
                end
                
              _ ->
                Character.send_message(character.id, "Player was not found or player is not accepting party requests.", 5)
            end
            
          [] ->
            Character.send_message(character.id, "Player was not found or player is not accepting party requests.", 5)
        end
    end
    
    {:ok, client_state}
  end

  defp handle_toggle_requests(packet, character, client_state) do
    {enabled, _packet} = In.decode_byte(packet)
    
    if enabled > 0 do
      Character.remove_quest(character.id, @party_request_quest_id)
    else
      Character.start_quest(character.id, @party_request_quest_id)
    end
    
    {:ok, client_state}
  end

  # ============================================================================
  # Helper Functions
  # ============================================================================

  defp get_character(client_state) do
    case client_state.character_id do
      nil -> {:error, :no_character}
      character_id -> 
        case Registry.lookup(Odinsea.CharacterRegistry, character_id) do
          [{pid, _}] -> {:ok, pid}
          [] -> {:error, :character_not_found}
        end
    end
  end

  defp create_party_character(character, channel_id) do
    %{
      id: character.id,
      name: character.name,
      level: character.level,
      job: character.job,
      channel_id: channel_id,
      map_id: character.map_id,
      # Door info (for mystic door skill)
      door_town: 999999999,
      door_target: 999999999,
      door_skill: 0,
      door_x: 0,
      door_y: 0
    }
  end

  defp can_invite_to_party?(inviter, target) do
    cond do
      # Target has blocked inventory
      target.has_blocked_inventory ->
        false
        
      # Target already in party
      target.party_id && target.party_id > 0 ->
        false
        
      # Target has blocked invites
      Character.has_quest(target.id, @party_invite_quest_id) ->
        false
        
      # Target has inviter blacklisted
      Enum.member?(target.blacklist, String.downcase(inviter.name)) ->
        false
        
      true ->
        true
    end
  end

  defp send_party_invite(target, inviter) do
    case Registry.lookup(Odinsea.CharacterRegistry, target.id) do
      [{pid, _}] ->
        invite_packet = Packets.party_invite(inviter)
        send(pid, {:send_packet, invite_packet})
      [] -> :ok
    end
  end

  defp send_party_request(leader, requester) do
    case Registry.lookup(Odinsea.CharacterRegistry, leader.id) do
      [{pid, _}] ->
        request_packet = Packets.party_request(requester)
        send(pid, {:send_packet, request_packet})
      [] -> :ok
    end
  end

  defp notify_party_denied(leader_id, denier_name) do
    case Registry.lookup(Odinsea.CharacterRegistry, leader_id) do
      [{pid, _}] ->
        message_packet = Packets.party_status_message(23, denier_name)
        send(pid, {:send_packet, message_packet})
      [] -> :ok
    end
  end

  defp send_party_status_message(client_state, code, name \\ "") do
    packet = Packets.party_status_message(code, name)
    send_packet(client_state, packet)
  end

  defp send_packet(client_state, packet) do
    if client_state.socket do
      :gen_tcp.send(client_state.socket, packet)
    end
  end
end