# frozen_string_literal: true

module Api
  module V1
    ##
    # Controller handling API requests related to grid summons within a party.
    #
    # This controller provides endpoints for creating, updating, resolving conflicts, and deleting grid summons.
    # It ensures that the correct party and summons are found and that the current user (or edit key) is authorized.
    #
    # @see Api::V1::ApiController for shared API behavior.
    class GridSummonsController < Api::V1::ApiController
      include IdResolvable

      attr_reader :party, :incoming_summon

      before_action :find_grid_summon, only: %i[update update_uncap_level update_quick_summon update_position resolve destroy]
      before_action :find_party, only: %i[create update update_uncap_level update_quick_summon update_position swap resolve destroy]
      before_action :find_incoming_summon, only: :create
      before_action :authorize_party_edit!, only: %i[create update update_uncap_level update_quick_summon update_position swap destroy]

      ##
      # Creates a new grid summon.
      #
      # This method builds a new grid summon using the permitted parameters merged
      # with the party and summon IDs. It ensures that the `uncap_level` is set to the
      # maximum allowed level if not provided. Depending on validation, it will either save
      # the summon, handle conflict resolution, or render a validation error response.
      #
      # @return [void]
      def create
        # Build a new grid summon using permitted parameters merged with party and summon IDs.
        # Set the uncap_level to the summon's maximum uncap level regardless of what the client sent.
        grid_summon = build_grid_summon.tap do |gs|
          gs.uncap_level = max_uncap_level(gs.summon)
        end

        # If the grid summon is valid (i.e. it passes all validations), then save it normally.
        if grid_summon.valid?
          save_summon(grid_summon)
          # If it is invalid due to a conflict error, handle the conflict resolution flow.
        elsif conflict_error?(grid_summon)
          handle_conflict(grid_summon)
          # If there's some other kind of validation error, render the validation error response back to the client.
        else
          render_validation_error_response(grid_summon)
        end
      end

      ##
      # Updates an existing grid summon.
      #
      # Updates the grid summon attributes using permitted parameters. If the update is successful,
      # it renders the updated grid summon view; otherwise, it renders a validation error response.
      #
      # @return [void]
      def update
        @grid_summon.attributes = summon_params

        return render json: GridSummonBlueprint.render(@grid_summon, view: :nested, root: :grid_summon) if @grid_summon.save

        render_validation_error_response(@grid_summon)
      end

      ##
      # Updates the uncap level and transcendence step of a grid summon.
      #
      # This action recalculates the maximum allowed uncap level based on the summon attributes
      # and applies business logic to adjust the uncap level and transcendence step accordingly.
      # On success, it renders the updated grid summon view; otherwise, it renders a validation error response.
      #
      # @return [void]
      def update_uncap_level
        summon = @grid_summon.summon
        max_level = max_uncap_level(summon)

        greater_than_max_uncap = summon_params[:uncap_level].to_i > max_level
        can_be_transcended = summon.transcendence &&
          summon_params[:transcendence_step].present? &&
          summon_params[:transcendence_step].to_i.positive?

        new_uncap_level = greater_than_max_uncap || can_be_transcended ? max_level : summon_params[:uncap_level]
        new_transcendence_step = summon.transcendence && summon_params[:transcendence_step].present? ? summon_params[:transcendence_step] : 0

        if @grid_summon.update(uncap_level: new_uncap_level, transcendence_step: new_transcendence_step)
          render json: GridSummonBlueprint.render(@grid_summon, view: :uncap, root: :grid_summon)
        else
          render_validation_error_response(@grid_summon)
        end
      end

      ##
      # Updates the quick summon status for a grid summon.
      #
      # If the grid summon is in positions 4, 5, or 6, no update is performed.
      # Otherwise, it disables quick summon for all other summons in the party,
      # updates the current summon, and renders the updated list of summons.
      #
      # @return [void]
      def update_quick_summon
        return if [4, 5, 6].include?(@grid_summon.position)

        quick_summons = @grid_summon.party.summons.select(&:quick_summon)

        quick_summons.each do |summon|
          summon.update!(quick_summon: false)
        end

        @grid_summon.update!(quick_summon: summon_params[:quick_summon])
        return unless @grid_summon.persisted?

        quick_summons -= [@grid_summon]
        summons = [@grid_summon] + quick_summons

        render json: GridSummonBlueprint.render(summons, view: :nested, root: :summons)
      end

      ##
      # Updates the position of a GridSummon.
      #
      # Moves a grid summon to a new position, optionally changing its container.
      # Validates that the target position is empty and within allowed bounds.
      #
      # @return [void]
      def update_position
        new_position = position_params[:position].to_i
        new_container = position_params[:container]

        # Validate position bounds (-1 main, 0-3 sub, 4-5 subaura, 6 friend)
        unless valid_summon_position?(new_position)
          return render_unprocessable_entity_response(
            Api::V1::InvalidPositionError.new("Invalid position #{new_position} for summon")
          )
        end

        # Check if position is restricted (main summon, friend)
        if restricted_summon_position?(new_position)
          return render_unprocessable_entity_response(
            Api::V1::InvalidPositionError.new("Cannot move summon to restricted position #{new_position}")
          )
        end

        # Check if target position is occupied
        if GridSummon.exists?(party_id: @party.id, position: new_position)
          return render_unprocessable_entity_response(
            Api::V1::PositionOccupiedError.new("Position #{new_position} is already occupied")
          )
        end

        @grid_summon.position = new_position

        if @grid_summon.save
          render json: {
            party: PartyBlueprint.render_as_hash(@party.reload, view: :full),
            grid_summon: GridSummonBlueprint.render_as_hash(@grid_summon.reload, view: :nested)
          }, status: :ok
        else
          render_validation_error_response(@grid_summon)
        end
      end

      ##
      # Swaps positions between two GridSummons.
      #
      # Exchanges the positions of two grid summons within the same party.
      # Both summons must belong to the same party and not be in restricted positions.
      #
      # @return [void]
      def swap
        source_id = swap_params[:source_id]
        target_id = swap_params[:target_id]

        source = GridSummon.find_by(id: source_id, party_id: @party.id)
        target = GridSummon.find_by(id: target_id, party_id: @party.id)

        unless source && target
          return render_not_found_response('grid_summon')
        end

        # Check if either position is restricted
        if restricted_summon_position?(source.position) || restricted_summon_position?(target.position)
          return render_unprocessable_entity_response(
            Api::V1::InvalidPositionError.new("Cannot swap summons in restricted positions")
          )
        end

        # Perform the swap
        ActiveRecord::Base.transaction do
          temp_position = -999
          source_pos = source.position
          target_pos = target.position

          source.update!(position: temp_position)
          target.update!(position: source_pos)
          source.update!(position: target_pos)
        end

        render json: {
          party: PartyBlueprint.render_as_hash(@party.reload, view: :full),
          swapped: {
            source: GridSummonBlueprint.render_as_hash(source.reload, view: :nested),
            target: GridSummonBlueprint.render_as_hash(target.reload, view: :nested)
          }
        }, status: :ok
      rescue ActiveRecord::RecordInvalid => e
        render_validation_error_response(e.record)
      end

      #
      # Destroys a grid summon.
      #
      # Finds the grid summon by ID. If not found, renders a not-found response.
      # If the current user is not authorized to perform the deletion, renders an unauthorized response.
      # On successful destruction, renders the destroyed grid summon view.
      #
      # @return [void]
      def destroy
        grid_summon = GridSummon.find_by('id = ?', params[:id])

        return render_not_found_response('grid_summon') if grid_summon.nil?

        if grid_summon.destroy
          render json: GridSummonBlueprint.render(grid_summon, view: :destroyed), status: :ok
        else
          render_unprocessable_entity_response(
            Api::V1::GranblueError.new(grid_summon.errors.full_messages.join(', '))
          )
        end
      end

      ##
      # Saves the provided grid summon.
      #
      # If an existing grid summon is found at the specified position for the party, it is replaced.
      # On successful save, renders the grid summon view with a created status.
      #
      # @param summon [GridSummon] The grid summon instance to be saved.
      # @return [void]
      def save_summon(summon)
        if (grid_summon = GridSummon.where(
          party_id: party.id,
          position: summon_params[:position]
        ).first)
          GridSummon.destroy(grid_summon.id)
        end

        return unless summon.save

        output = render_grid_summon_view(summon)
        render json: output, status: :created
      end

      ##
      # Handles conflict resolution for a grid summon.
      #
      # If a conflict is detected and the conflicting summon matches the incoming summon,
      # the method updates the conflicting summon’s position with the new position.
      # On a successful update, renders the updated grid summon view.
      #
      # @param summon [GridSummon] The grid summon instance that encountered a conflict.
      # @return [void]
      def handle_conflict(summon)
        conflict_summon = summon.conflicts(party)
        return unless conflict_summon.summon.id == incoming_summon.id

        old_position = conflict_summon.position
        conflict_summon.position = summon_params[:position]

        return unless conflict_summon.save

        output = render_grid_summon_view(conflict_summon, old_position)
        render json: output
      end

      private

      ##
      # Finds the party based on the provided party_id parameter.
      #
      # Sets the @party instance variable and renders an unauthorized response if the current
      # user is not the owner of the party.
      #
      # @return [void]

      ##
      # Finds and sets the party based on parameters.
      #
      # Renders an unauthorized response if the current user is not the owner.
      #
      # @return [void]
      def find_party
        @party = Party.find_by(id: params.dig(:summon, :party_id)) || Party.find_by(id: params[:party_id]) || @grid_summon&.party
        render_not_found_response('party') unless @party
      end

      ##
      # Finds and sets the GridSummon based on the provided parameters.
      #
      # Searches for a grid summon using various parameter keys and renders a not found response if it is absent.
      #
      # @return [void]
      def find_grid_summon
        grid_summon_id = params[:id] || params.dig(:summon, :id) || params.dig(:resolve, :conflicting)
        @grid_summon = GridSummon.find_by(id: grid_summon_id)
        render_not_found_response('grid_summon') unless @grid_summon
      end

      ##
      # Finds the incoming summon based on the provided parameters.
      #
      # Sets the @incoming_summon instance variable.
      #
      # @return [void]
      def find_incoming_summon
        @incoming_summon = find_by_any_id(Summon, summon_params[:summon_id])
      end

      ##
      # Builds a new GridSummon instance using permitted parameters.
      #
      # Merges the party id and the incoming summon id into the parameters.
      #
      # @return [GridSummon] A new grid summon instance.
      def build_grid_summon
        GridSummon.new(summon_params.merge(party_id: party.id, summon_id: incoming_summon.id))
      end

      ##
      # Checks whether the grid summon error is solely due to a conflict.
      #
      # Verifies if the errors on the :series attribute include the specific conflict message
      # and confirms that a conflict exists for the current party.
      #
      # @param grid_summon [GridSummon] The grid summon instance to check.
      # @return [Boolean] True if the error is due solely to a conflict, false otherwise.
      def conflict_error?(grid_summon)
        grid_summon.errors[:series].include?('must not conflict with existing summons') &&
          grid_summon.conflicts(party).present?
      end

      ##
      # Renders the grid summon view with additional metadata.
      #
      # @param grid_summon [GridSummon] The grid summon instance to render.
      # @param conflict_position [Integer, nil] The position of a conflicting summon, if applicable.
      # @return [String] The rendered grid summon view as JSON.
      def render_grid_summon_view(grid_summon, conflict_position = nil)
        GridSummonBlueprint.render(grid_summon,
                                   view: :nested,
                                   root: :grid_summon,
                                   meta: { replaced: conflict_position })
      end

      ##
      # Determines the maximum uncap level for a given summon.
      #
      # The maximum uncap level is determined based on the attributes of the summon:
      # - Returns 4 if the summon has FLB but not ULB and is not transcended.
      # - Returns 5 if the summon has ULB and is not transcended.
      # - Returns 6 if the summon has transcendence.
      # - Otherwise, returns 3.
      #
      # @param summon [Summon] The summon for which to determine the maximum uncap level.
      # @return [Integer] The maximum uncap level.
      def max_uncap_level(summon)
        if summon.flb && !summon.ulb && !summon.transcendence
          4
        elsif summon.ulb && !summon.transcendence
          5
        elsif summon.transcendence
          6
        else
          3
        end
      end

      ##
      # Authorizes the current action by ensuring that the current user or provided edit key matches the party's owner.
      #
      # For parties associated with a user, it verifies that the current_user is the owner.
      # For anonymous parties, it checks that the provided edit key matches the party's edit key.
      #
      # @return [void]
      def authorize_party_edit!
        if @party.user.present?
          authorize_user_party
        else
          authorize_anonymous_party
        end
      end

      ##
      # Authorizes an action for a party that belongs to a user.
      #
      # Renders an unauthorized response unless the current user is present and
      # matches the party's user.
      #
      # @return [void]
      def authorize_user_party
        return if current_user.present? && @party.user == current_user

        render_unauthorized_response
      end

      ##
      # Authorizes an action for an anonymous party using an edit key.
      #
      # Retrieves and normalizes the provided edit key and compares it with the party's edit key.
      # Renders an unauthorized response unless the keys are valid.
      #
      # @return [void]
      def authorize_anonymous_party
        provided_edit_key = edit_key.to_s.strip.force_encoding('UTF-8')
        party_edit_key = @party.edit_key.to_s.strip.force_encoding('UTF-8')
        return if valid_edit_key?(provided_edit_key, party_edit_key)

        render_unauthorized_response
      end

      ##
      # Validates that the provided edit key matches the party's edit key.
      #
      # @param provided_edit_key [String] the edit key provided in the request.
      # @param party_edit_key [String] the edit key associated with the party.
      # @return [Boolean] true if the edit keys match; false otherwise.
      def valid_edit_key?(provided_edit_key, party_edit_key)
        provided_edit_key.present? &&
          provided_edit_key.bytesize == party_edit_key.bytesize &&
          ActiveSupport::SecurityUtils.secure_compare(provided_edit_key, party_edit_key)
      end

      ##
      # Validates if a summon position is valid.
      #
      # @param position [Integer] the position to validate.
      # @return [Boolean] true if the position is valid; false otherwise.
      def valid_summon_position?(position)
        # Main (-1), sub slots (0-3), subaura (4-5), friend (6)
        position == -1 || (0..6).cover?(position)
      end

      ##
      # Checks if a summon position is restricted (cannot be drag-drop target).
      #
      # @param position [Integer] the position to check.
      # @return [Boolean] true if the position is restricted; false otherwise.
      def restricted_summon_position?(position)
        # Main summon (-1) and friend summon (6) are restricted
        position == -1 || position == 6
      end

      ##
      # Defines and permits the whitelisted parameters for a grid summon.
      #
      # @return [ActionController::Parameters] The permitted parameters.
      def summon_params
        params.require(:summon).permit(:id, :party_id, :summon_id, :position, :main, :friend,
                                       :quick_summon, :uncap_level, :transcendence_step)
      end

      ##
      # Specifies and permits the position update parameters.
      #
      # @return [ActionController::Parameters] the permitted parameters.
      def position_params
        params.permit(:position, :container)
      end

      ##
      # Specifies and permits the swap parameters.
      #
      # @return [ActionController::Parameters] the permitted parameters.
      def swap_params
        params.permit(:source_id, :target_id)
      end
    end
  end
end