# frozen_string_literal: true

# Copyright (c) [2024-2026] SUSE LLC
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# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
# more details.
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require "y2storage/proposal_settings"

module Y2Storage
  module Proposal
    # Class to encapsulate the conversion from Agama config to ProposalSpaceSettings
    class SpaceSettingsBuilder
      # @param config [Agama::Storage::Config]
      def initialize(config)
        @config = config
      end

      # ProposalSpaceSettings corresponding to the Agama configuration
      #
      # @return [ProposalSpaceSettings]
      def space_settings
        Y2Storage::ProposalSpaceSettings.new.tap do |target|
          target.strategy = :bigger_resize
          target.actions = space_actions(config)
        end
      end

    private

      # @return [Agama::Storage::Config]
      attr_reader :config

      # Space actions from the given config.
      #
      # @param config [Agama::Storage::Config]
      # @return [Hash]
      def space_actions(config)
        actions = force_delete_actions(config)
        actions.concat(delete_actions(config))
        actions.concat(resize_actions(config))
      end

      # Space actions for devices that must be deleted.
      #
      # @param config [Agama::Storage::Config]
      # @return [Array<Y2Storage::SpaceActions::Delete>]
      def force_delete_actions(config)
        configs = config_devices(config).select(&:delete?)
        names = device_names(configs)

        names.map { |d| Y2Storage::SpaceActions::Delete.new(d, mandatory: true) }
      end

      # Space actions for devices that might be deleted.
      #
      # @note #delete? takes precedence over #delete_if_needed?.
      #
      # @param config [Agama::Storage::Config]
      # @return [Array<Y2Storage::SpaceActions::Delete>]
      def delete_actions(config)
        configs = config_devices(config).select(&:delete_if_needed?).reject(&:delete?)
        names = device_names(configs)

        names.map { |d| Y2Storage::SpaceActions::Delete.new(d) }
      end

      # Space actions for devices that might be resized
      #
      # @param config [Agama::Storage::Config]
      # @return [Array<Y2Storage::SpaceActions::Resize>]
      def resize_actions(config)
        configs = config_devices(config).select(&:found_device).select(&:size)
        # Resize actions contain information that is potentially useful for the SpaceMaker even
        # when they are only about growing and not shrinking
        configs.map { |c| resize_action(c) }.compact
      end

      # @see #resize_actions
      #
      # @param dev [Agama::Storage::Configs::Partition, Agama::Storage::Configs::LogicalVolume]
      # @return [Y2Storage::SpaceActions::Resize, nil]
      def resize_action(dev)
        min = current_size?(dev, :min) ? nil : dev.size.min
        max = current_size?(dev, :max) ? nil : dev.size.max
        # If both min and max are equal to the current device size, there is nothing to do
        return unless min || max

        Y2Storage::SpaceActions::Resize.new(dev.found_device.name, min_size: min, max_size: max)
      end

      # @see #resize_actions
      def current_size?(dev, attr)
        dev.found_device.size == dev.size.public_send(attr)
      end

      # All partition and logical volume configs from the given config.
      #
      # @param config [Agama::Storage::Config]
      # @return [Array<Agama::Storage::Configs::Partition | Agama::Storage::Configs::LogicalVolume>]
      def config_devices(config)
        config.partitions + config.logical_volumes
      end

      # Device names from the given configs.
      #
      # @param configs [Array<#found_device>]
      # @return [Array<String>]
      def device_names(configs)
        configs
          .map(&:found_device)
          .compact
          .map(&:name)
      end
    end
  end
end