# frozen_string_literal: true

require_relative "../worker"
require_relative "gem_installer"

module Bundler
  class ParallelInstaller
    class SpecInstallation
      attr_accessor :spec, :name, :full_name, :post_install_message, :state, :error
      def initialize(spec)
        @spec = spec
        @name = spec.name
        @full_name = spec.full_name
        @state = :none
        @post_install_message = ""
        @error = nil
      end

      def installed?
        state == :installed
      end

      def enqueued?
        state == :enqueued
      end

      def enqueue_with_priority?
        state == :installable && spec.extensions.any?
      end

      def failed?
        state == :failed
      end

      def ready_to_enqueue?
        state == :none
      end

      def ready_to_install?(installed_specs)
        return false unless state == :downloaded

        spec.extensions.none? || dependencies_installed?(installed_specs)
      end

      def has_post_install_message?
        !post_install_message.empty?
      end

      def ignorable_dependency?(dep)
        dep.type == :development || dep.name == @name
      end

      # Checks installed dependencies against spec's dependencies to make
      # sure needed dependencies have been installed.
      def dependencies_installed?(installed_specs)
        dependencies.all? {|d| installed_specs.include? d.name }
      end

      # Represents only the non-development dependencies, the ones that are
      # itself and are in the total list.
      def dependencies
        @dependencies ||= all_dependencies.reject {|dep| ignorable_dependency? dep }
      end

      # Represents all dependencies
      def all_dependencies
        @spec.dependencies
      end

      def to_s
        "#<#{self.class} #{full_name} (#{state})>"
      end
    end

    def self.call(*args, **kwargs)
      new(*args, **kwargs).call
    end

    attr_reader :size

    def initialize(installer, all_specs, size, standalone, force, local: false, skip: nil)
      @installer = installer
      @size = size
      @standalone = standalone
      @force = force
      @local = local
      @specs = all_specs.map {|s| SpecInstallation.new(s) }
      @specs.each do |spec_install|
        spec_install.state = :installed if skip.include?(spec_install.name)
      end if skip
      @spec_set = all_specs
      @rake = @specs.find {|s| s.name == "rake" unless s.installed? }
    end

    def call
      if @rake
        do_download(@rake, 0)
        do_install(@rake, 0)
        Gem::Specification.reset
      end

      if @size > 1
        install_with_worker
      else
        install_serially
      end

      handle_error if failed_specs.any?
      @specs
    ensure
      worker_pool&.stop
    end

    private

    def failed_specs
      @specs.select(&:failed?)
    end

    def install_with_worker
      installed_specs = {}
      enqueue_specs(installed_specs)

      process_specs(installed_specs) until finished_installing?
    end

    def install_serially
      until finished_installing?
        raise "failed to find a spec to enqueue while installing serially" unless spec_install = @specs.find(&:ready_to_enqueue?)
        spec_install.state = :enqueued
        do_download(spec_install, 0)
        do_install(spec_install, 0)
      end
    end

    def worker_pool
      @worker_pool ||= Bundler::Worker.new @size, "Parallel Installer", lambda {|spec_install, worker_num|
        case spec_install.state
        when :enqueued
          do_download(spec_install, worker_num)
        when :installable
          do_install(spec_install, worker_num)
        else
          spec_install
        end
      }
    end

    def do_download(spec_install, worker_num)
      Plugin.hook(Plugin::Events::GEM_BEFORE_INSTALL, spec_install)

      gem_installer = Bundler::GemInstaller.new(
        spec_install.spec, @installer, @standalone, worker_num, @force, @local
      )

      success, message = gem_installer.download

      if success
        spec_install.state = :downloaded
      else
        spec_install.error = "#{message}\n\n#{require_tree_for_spec(spec_install.spec)}"
        spec_install.state = :failed
      end

      spec_install
    end

    def do_install(spec_install, worker_num)
      gem_installer = Bundler::GemInstaller.new(
        spec_install.spec, @installer, @standalone, worker_num, @force, @local
      )
      success, message = gem_installer.install_from_spec
      if success
        spec_install.state = :installed
        spec_install.post_install_message = message unless message.nil?
      else
        spec_install.error = "#{message}\n\n#{require_tree_for_spec(spec_install.spec)}"
        spec_install.state = :failed
      end
      Plugin.hook(Plugin::Events::GEM_AFTER_INSTALL, spec_install)
      spec_install
    end

    # Dequeue a spec and save its post-install message and then enqueue the
    # remaining specs.
    # Some specs might've had to wait til this spec was installed to be
    # processed so the call to `enqueue_specs` is important after every
    # dequeue.
    def process_specs(installed_specs)
      spec = worker_pool.deq

      if spec.installed?
        installed_specs[spec.name] = true
        return
      elsif spec.failed?
        return
      elsif spec.ready_to_install?(installed_specs)
        spec.state = :installable
      end

      worker_pool.enq(spec, priority: spec.enqueue_with_priority?)
    end

    def finished_installing?
      @specs.all? do |spec|
        return true if spec.failed?
        spec.installed?
      end
    end

    def handle_error
      errors = failed_specs.map(&:error)
      if exception = errors.find {|e| e.is_a?(Bundler::BundlerError) }
        raise exception
      end
      raise Bundler::InstallError, errors.join("\n\n")
    end

    def require_tree_for_spec(spec)
      tree = @spec_set.what_required(spec)
      t = String.new("In #{File.basename(SharedHelpers.default_gemfile)}:\n")
      tree.each_with_index do |s, depth|
        t << "  " * depth.succ << s.name
        unless tree.last == s
          t << %( was resolved to #{s.version}, which depends on)
        end
        t << %(\n)
      end
      t
    end

    # Keys in the remains hash represent uninstalled gems specs.
    # We enqueue all gem specs that do not have any dependencies.
    # Later we call this lambda again to install specs that depended on
    # previously installed specifications. We continue until all specs
    # are installed.
    def enqueue_specs(installed_specs)
      @specs.each do |spec|
        if spec.installed?
          installed_specs[spec.name] = true
          next
        end

        spec.state = :enqueued
        worker_pool.enq spec
      end
    end
  end
end