require 'exa/version'
require 'exa/tree_node'
require 'exa/visitor'

module Exa
  class Process
    def initialize(title)
      @title = title
    end

    def register
      Process.table += [ self ]
    end

    def unregister
      Process.table -= [ self ]
    end

    def run!
      register
      perform!
      unregister
    end

    def self.table
      @table ||= []
    end
  end

  class Copier < Process
    def initialize(source, target)
      @source = source
      @target = target
      super("copy #{source} -> #{target}")
    end

    def perform!
      @target.update @source.value
    end
  end

  class Deleter < Process
    def initialize(target)
      @target = target
      super("delete #{target}")
    end

    def perform!
      @target.parent.remove_child(child_name: @target.name)
    end
  end

  class << self
    def remember(path, value)
      p [ :remember, path: path, value: value ]
      recall(path).update(value)
    end
    alias :[]= :remember

    def recall(path)
      p [ :recall, path: path ]
      visitor.seek(path)
    end
    alias :[] :recall

    def expand(path)
      visitor.query(path)
    end
    alias :call :expand

    def clean_slate!
      @root = TreeNode.new(name: '', value: '(root)')
      # @visitor = Visitor.new(@root)
    end

    private
    def visitor
      Visitor.new(root)
    end

    def root
      @root ||= TreeNode.new(name: '', value: '(system root)')
    end
  end
end