require 'readline'
require 'shellwords'

# @author John Mair (banisterfiend)
class Pry

  # class accessors
  class << self

    # Get nesting data.
    # This method should not need to be accessed directly.
    # @return [Array] The unparsed nesting information.
    attr_reader :nesting

    # Get last value evaluated by Pry.
    # This method should not need to be accessed directly.
    # @return [Object] The last result.
    attr_accessor :last_result

    # Get the active Pry instance that manages the active Pry session.
    # This method should not need to be accessed directly.
    # @return [Pry] The active Pry instance.
    attr_accessor :active_instance

    # Get/Set the object to use for input by default by all Pry instances.
    # @return [#readline] The object to use for input by default by all
    #   Pry instances.
    attr_accessor :input

    # Get/Set the object to use for output by default by all Pry instances.
    # @return [#puts] The object to use for output by default by all
    #   Pry instances.
    attr_accessor :output

    # Get/Set the object to use for commands by default by all Pry instances.
    # @return [Pry::CommandBase] The object to use for commands by default by all
    #   Pry instances.
    attr_accessor :commands

    # Get/Set the Proc to use for printing by default by all Pry
    # instances.
    # This is the 'print' component of the REPL.
    # @return [Proc] The Proc to use for printing by default by all
    #   Pry instances.
    attr_accessor :print

    # Get/Set the Hash that defines Pry hooks used by default by all Pry
    # instances.
    # @return [Hash] The hooks used by default by all Pry instances.
    # @example
    #   Pry.hooks :before_session => proc { puts "hello" },
    #     :after_session => proc { puts "goodbye" }
    attr_accessor :hooks

    # Get the array of Procs to be used for the prompts by default by
    # all Pry instances.
    # @return [Array<Proc>] The array of Procs to be used for the
    #   prompts by default by all Pry instances.
    attr_accessor :prompt
  end
  
  # Start a Pry REPL.
  # @param [Object, Binding] target The receiver of the Pry session
  # @param [Hash] options
  # @option options (see Pry#initialize)
  # @example
  #   Pry.start(Object.new, :input => MyInput.new)
  def self.start(target=TOPLEVEL_BINDING, options={})
    new(options).repl(target)
  end

  # A custom version of `Kernel#inspect`.
  # This method should not need to be accessed directly.
  # @param obj The object to view.
  # @return [String] The string representation of `obj`.
  def self.view(obj)
    case obj
    when String, Hash, Array, Symbol, nil
      obj.inspect
    else
      obj.to_s
    end
  end

  # A version of `Pry.view` that clips the output to `max_size` chars.
  # In case of > `max_size` chars the `#<Object...> notation is used.
  # @param obj The object to view.
  # @param max_size The maximum number of chars before clipping occurs.
  # @return [String] The string representation of `obj`.
  def self.view_clip(obj, max_size=60)
    if Pry.view(obj).size < max_size
      Pry.view(obj)
    else
      "#<#{obj.class}:%#x>" % (obj.object_id << 1)
    end
  end

  # Run a Pry command from outside a session. The commands available are
  # those referenced by `Pry.commands` (the default command set).
  # Command output is suppresed by default, this is because the return
  # value (if there is one) is likely to be more useful.
  # @param [String] arg_string The Pry command (including arguments,
  #   if any).
  # @param [Hash] options Optional named parameters.
  # @return [Object] The return value of the Pry command.
  # @option options [Object, Binding] :context The object context to run the
  #   command under. Defaults to `TOPLEVEL_BINDING` (main).
  # @option options [Boolean] :show_output Whether to show command
  #   output. Defaults to false.
  # @example Run at top-level with no output.
  #   Pry.run_command "ls"
  # @example Run under Pry class, returning only public methods.
  #   Pry.run_command "ls -m", :context => Pry
  # @example Display command output.
  #   Pry.run_command "ls -av", :show_output => true
  def self.run_command(arg_string, options={})
    name, arg_string = arg_string.split(/\s+/, 2)
    arg_string = "" if !arg_string
    
    options = {
      :context => TOPLEVEL_BINDING,
      :show_output => false
    }.merge!(options)
    
    null_output = Object.new.tap { |v| v.instance_eval { def puts(*) end } }
    
    commands = Pry.commands.dup
    commands.output = options[:show_output] ? Pry.output : null_output
    commands.target = Pry.binding_for(options[:context])

    cmd = commands.commands[name]
    if cmd
      action = cmd[:action]
      commands.instance_exec(*Shellwords.shellwords(arg_string), &action)
    else
      raise "No such command: #{name}"
    end
  end

  # Set all the configurable options back to their default values
  def self.reset_defaults
    @input = Readline
    @output = $stdout
    @commands = Pry::Commands
    @prompt = DEFAULT_PROMPT
    @print = DEFAULT_PRINT
    @hooks = DEFAULT_HOOKS
  end

  self.reset_defaults

  @nesting = []
  def @nesting.level
    last.is_a?(Array) ? last.first : nil
  end

  # Return all active Pry sessions.
  # @return [Array<Pry>] Active Pry sessions.
  def self.sessions
    # last element in nesting array is the pry instance
    nesting.map(&:last)
  end

  # Return a `Binding` object for `target` or return `target` if it is
  # already a `Binding`.
  # In the case where `target` is top-level then return `TOPLEVEL_BINDING`
  # @param [Object] target The object to get a `Binding` object for.
  # @return [Binding] The `Binding` object.
  def self.binding_for(target)
    if target.is_a?(Binding)
      target
    else
      if target == TOPLEVEL_BINDING.eval('self')
        TOPLEVEL_BINDING
      else
        target.__binding__
      end
    end
  end
end