# typed: strict
# frozen_string_literal: true

require "os/linux/glibc"

module OS
  module Linux
    module DependencyCollector
      sig { params(related_formula_names: T::Set[String]).returns(T.nilable(Dependency)) }
      def gcc_dep_if_needed(related_formula_names)
        # gcc is required for libgcc_s.so.1 if glibc or gcc are too old
        return unless ::DevelopmentTools.needs_build_formulae?
        return if building_global_dep_tree?
        return if related_formula_names.include?(GCC)
        return if global_dep_tree[GCC]&.intersect?(related_formula_names)
        return unless formula_for(GCC)

        Dependency.new(GCC, [:implicit])
      end

      sig { params(related_formula_names: T::Set[String]).returns(T.nilable(Dependency)) }
      def glibc_dep_if_needed(related_formula_names)
        return unless ::DevelopmentTools.needs_libc_formula?
        return if building_global_dep_tree?
        return if related_formula_names.include?(GLIBC)
        return if global_dep_tree[GLIBC]&.intersect?(related_formula_names)
        return unless formula_for(GLIBC)

        Dependency.new(GLIBC, [:implicit])
      end

      private

      GLIBC = "glibc"
      GCC = OS::LINUX_PREFERRED_GCC_RUNTIME_FORMULA

      sig { void }
      def init_global_dep_tree_if_needed!
        return unless ::DevelopmentTools.needs_build_formulae?
        return if building_global_dep_tree?
        return unless global_dep_tree.empty?

        building_global_dep_tree!
        global_dep_tree[GLIBC] = Set.new(global_deps_for(GLIBC))
        # gcc depends on glibc
        global_dep_tree[GCC] = Set.new([*global_deps_for(GCC), GLIBC, *@@global_dep_tree[GLIBC]])
        built_global_dep_tree!
      end

      sig { params(name: String).returns(T.nilable(Formula)) }
      def formula_for(name)
        @formula_for ||= T.let({}, T.nilable(T::Hash[String, Formula]))
        @formula_for[name] ||= ::Formula[name]
      rescue FormulaUnavailableError
        nil
      end

      sig { params(name: String).returns(T::Array[String]) }
      def global_deps_for(name)
        @global_deps_for ||= T.let({}, T.nilable(T::Hash[String, T::Array[String]]))
        # Always strip out glibc and gcc from all parts of dependency tree when
        # we're calculating their dependency trees. Other parts of Homebrew will
        # catch any circular dependencies.
        @global_deps_for[name] ||= if (formula = formula_for(name))
          formula.deps.map(&:name).flat_map do |dep|
            [dep, *global_deps_for(dep)].compact
          end.uniq
        else
          []
        end
      end

      # Use class variables to avoid this expensive logic needing to be done more
      # than once.
      # rubocop:disable Style/ClassVars
      @@global_dep_tree = T.let({}, T::Hash[String, T::Set[String]])
      @@building_global_dep_tree = T.let(false, T::Boolean)

      sig { returns(T::Hash[String, T::Set[String]]) }
      def global_dep_tree
        @@global_dep_tree
      end

      sig { void }
      def building_global_dep_tree!
        @@building_global_dep_tree = true
      end

      sig { void }
      def built_global_dep_tree!
        @@building_global_dep_tree = false
      end

      sig { returns(T::Boolean) }
      def building_global_dep_tree?
        @@building_global_dep_tree.present?
      end
      # rubocop:enable Style/ClassVars
    end
  end
end

DependencyCollector.prepend(OS::Linux::DependencyCollector)
