# frozen_string_literal: true

# Copyright (c) [2017-2025] SUSE LLC
#
# All Rights Reserved.
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# This program is free software; you can redistribute it and/or modify it
# under the terms of version 2 of the GNU General Public License as published
# by the Free Software Foundation.
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# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
# more details.
#
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require "y2storage/exceptions"
require "y2storage/proposal/lvm_creator"
require "y2storage/proposal/agama_md_creator"
require "y2storage/proposal/partition_creator"

module Y2Storage
  module Proposal
    # Class to create and reuse devices during the Agama proposal
    class AgamaDevicesCreator
      include Yast::Logger

      # @return [Array<Agama::Issue>] List of found issues
      attr_reader :issues_list

      # Constructor
      #
      # @param original_graph [Devicegraph] Devicegraph to be used as starting point
      # @param issues_list [Array<Agama::Issue>] List of issues to register the problems
      #    found during devices creation
      def initialize(original_graph, issues_list)
        @original_graph = original_graph
        @issues_list = issues_list
      end

      # Devicegraph including all the specified planned devices
      #
      # @param planned_devices [Planned::DevicesCollection] Devices to create/reuse
      # @param space_maker [SpaceMaker]
      #
      # @return [CreatorResult] Result with new devicegraph in which all the
      #   planned devices have been allocated
      def populated_devicegraph(planned_devices, space_maker)
        # Process planned partitions
        log.info "planned devices = #{planned_devices.to_a.inspect}"

        reset

        @planned_devices = planned_devices
        @space_maker = space_maker

        process_devices
      end

    protected

      # @return [Devicegraph] Original devicegraph
      attr_reader :original_graph

      # @return [Planned::DevicesCollection] Devices to create/reuse
      attr_reader :planned_devices

      # @return [SpaceMaker] space maker to use during operation
      attr_reader :space_maker

      # @return [Proposal::CreatorResult] Current result containing the devices that have been
      #   created
      attr_reader :creator_result

      # @return [Devicegraph] Current devicegraph
      attr_accessor :devicegraph

    private

      # Sets the current creator result
      #
      # The current devicegraph is properly updated.
      #
      # @param result [Proposal::CreatorResult]
      def creator_result=(result)
        @creator_result = result
        @devicegraph = result.devicegraph
      end

      # Resets values before create devices
      #
      # @see #populated_devicegraph
      def reset
        @creator_result = nil
        @devicegraph = original_graph.duplicate
      end

      # Reuses and creates planned devices
      #
      # @return [CreatorResult] Result with new devicegraph in which all the
      #   planned devices have been allocated
      def process_devices
        process_existing_partitionables
        mds = process_new_mds
        process_new_partitionables(mds)
        process_volume_groups

        # This may be unexpected if the storage configuration provided by the user includes
        # carefully crafted mount options but may be needed in weird situations for more automated
        # proposals. Let's re-evaluate over time.
        devicegraph.mount_points.each(&:adjust_mount_options)

        creator_result
      end

      # @see #process_devices
      def process_existing_partitionables
        partitions = partitions_for_existing(planned_devices)
        vgs = resolved_candidate_devices(automatic_vgs_for_existing)

        begin
          # Check whether there is any chance of getting an unwanted order for the planned
          # partitions within a disk
          space_result = space_maker.provide_space(
            original_graph, partitions: partitions, volume_groups: vgs
          )
        rescue Error => e
          log.info "SpaceMaker was not able to find enough space: #{e}"
          raise NoDiskSpaceError
        end

        self.devicegraph = space_result[:devicegraph]
        distribution = space_result[:partitions_distribution]

        grow_and_reuse_devices(distribution)
        self.creator_result = PartitionCreator.new(devicegraph).create_partitions(distribution)
      end

      # @see #process_devices
      def process_new_mds
        creator = AgamaMdCreator.new(devicegraph, planned_devices, creator_result)
        planned_devices.mds.reject(&:reuse?).map do |planned_md|
          creator.create(planned_md)
        end
      end

      # @see #process_devices
      def process_new_partitionables(devices)
        planned_devices = creator_result.devices_map.fetch_values(*devices.map(&:name))
        partitions = planned_devices.flat_map(&:partitions)
        vgs = resolved_candidate_devices(automatic_vgs - automatic_vgs_for_existing)

        spaces = devices.flat_map(&:free_spaces)
        calculator = Proposal::PartitionsDistributionCalculator.new(partitions, vgs)
        distribution = calculator.best_distribution(spaces)

        if distribution.nil?
          log.error "Partitions cannot be allocated:"
          log.error "  devices: #{devices}"
          log.error "  automatic volume groups: #{vgs}"
          log.error "  partitions: #{partitions}"
          raise NoDiskSpaceError, "Partitions cannot be allocated into #{devices.map(&:name)}"
        end

        new_result = PartitionCreator.new(devicegraph).create_partitions(distribution)
        self.creator_result = creator_result.merge(new_result)
      end

      # @see #process_devices
      def process_volume_groups
        planned_devices.vgs.map { |v| create_volume_group(v) }
      end

      # Planned volume groups for which the proposal must automatically create the needed physical
      # volumes
      #
      # @return [Array<Planned::LvmVg>]
      def automatic_vgs
        planned_devices.select do |dev|
          dev.is_a?(Planned::LvmVg) && dev.pvs_candidate_devices.any?
        end
      end

      # Filters {#automatic_vgs} to include only those that target pre-existing devices
      #
      # @return [Array<Planned::LvmVg>]
      def automatic_vgs_for_existing
        # Use #any? because we know for sure that all candidate devices are of the same type
        # (either found or created).
        automatic_vgs.select { |vg| vg.pvs_candidate_devices.any? { |i| find_planned(i).reuse? } }
      end

      # Creates a volume group for the the given planned device.
      #
      # @param planned [Planned::LvmVg]
      def create_volume_group(planned)
        pv_names = physical_volumes_for(planned.volume_group_name)
        # TODO: Generate issue if there are no physical volumes for a new VG.
        return if pv_names.empty? && !planned.reuse?

        creator = Proposal::LvmCreator.new(creator_result.devicegraph, space_maker.settings)
        new_result = creator.create_volumes(planned, pv_names)
        self.creator_result = creator_result.merge(new_result)
      end

      # Physical volumes (new partitions and reused devices) for a new volume group.
      #
      # @param vg_name [String]
      # @return [Array<String>]
      def physical_volumes_for(vg_name)
        pv_condition = proc { |d| d.respond_to?(:pv_for?) && d.pv_for?(vg_name) }

        new_pvs = creator_result.created_names(&pv_condition)
        reused_pvs = reused_planned_devices
          .select(&pv_condition)
          .map(&:reuse_name)

        new_pvs + reused_pvs
      end

      # Turns the values of {Planned::LvmVg#pvs_candidate_devices} into real device names
      #
      # This is needed because Agama uses the field to store ids referencing devices that may (or
      # may not) exist at the beginning of the proposal process.
      #
      # @param vgs [Array<Planned::LvmVg>] original list of VGs containing references
      # @return [Array<Planned::LvmVg>] a copy of the original list in which references has been
      #   converted into device names
      def resolved_candidate_devices(vgs)
        vgs.map do |volume_group|
          volume_group.dup.tap do |vg|
            vg.pvs_candidate_devices = volume_group.pvs_candidate_devices.map do |pv|
              device_name(pv)
            end
          end
        end
      end

      # Planned device corresponding to the given planned ID
      #
      # @param id [String]
      # @return [Planned::Device]
      def find_planned(id)
        planned_devices.find { |d| d.planned_id == id }
      end

      # Final device name corresponding to the planned device with the given ID
      #
      # @param id [String]
      # @return [String]
      def device_name(id)
        planned = find_planned(id)
        return devicegraph.find_device(planned.reuse_sid).name if planned.reuse?

        creator_result.created_names { |d| d.planned_id == id }.first
      end

      # @see #process_existing_partitionables
      def grow_and_reuse_devices(distribution)
        planned_devices.select(&:reuse?).each do |planned|
          space = assigned_space_next_to(planned, distribution)

          planned.limit_grow(space.disposable_size, devicegraph) if space
          planned.reuse!(devicegraph)
          # TODO: Check if the final size is smaller than the min and... abort? register issue?
          space&.update_disk_space
        end
      end

      # Assigned space that is located next to the given planned device, only if that device
      # points to an existing partition that needs to grow
      #
      # @return [Y2Storage::Planned::AssignedSpace]
      def assigned_space_next_to(planned, distribution)
        return unless planned.respond_to?(:subsequent_slot?)
        return unless planned.resize?

        distribution.spaces.find { |s| planned.subsequent_slot?(s) }
      end

      # @see #process_existing_partitionables
      def partitions_for_existing(planned_devices)
        planned_devices.disk_partitions.reject(&:reuse?) +
          planned_devices.mds.select(&:reuse?).flat_map(&:partitions).reject(&:reuse?)
      end

      # Planned devices configured to be reused.
      #
      # @return [Array<Planned::Device>]
      def reused_planned_devices
        planned_devices.disks.select(&:reuse?) +
          planned_devices.mds.select(&:reuse?) +
          planned_devices.partitions.select(&:reuse?)
      end

      # Formats and/or mounts the disk-like block devices
      #
      # XEN partitions (StrayBlkDevice) are intentionally left out for now
      #
      # Add planned disks to reuse list so they can be considered for lvm and raids later on.
      def process_disk_like_devs
        # Do we do something about SpaceMaker here? I assume it was already done as mandatory
        planned_devs = planned_devices.select { |d| d.is_a?(Planned::Disk) }
        planned_devs.each { |d| d.reuse!(devicegraph) }
      end
    end
  end
end