class Pry
  class Command::FindMethod < Pry::ClassCommand
    extend Pry::Helpers::BaseHelpers

    match 'find-method'
    group 'Context'
    options :requires_gem => 'ruby18_source_location' if mri_18?
    options :shellwords => false

    description 'Recursively search for a method within a Class/Module or the current namespace. find-method [-n | -c] METHOD [NAMESPACE]'

    banner <<-BANNER
      Usage: find-method  [-n | -c] METHOD [NAMESPACE]

      Recursively search for a method within a Class/Module or the current namespace.
      Use the `-n` switch (the default) to search for methods whose name matches the given regex.
      Use the `-c` switch to search for methods that contain the given code.

      e.g find-method re Pry                # find all methods whose name match /re/ inside the Pry namespace. Matches Pry#repl, etc.
      e.g find-method -c 'output.puts' Pry  # find all methods that contain the code: output.puts inside the Pry namepsace.
    BANNER

    def setup
      require 'ruby18_source_location' if mri_18?
    end

    def options(opti)
      opti.on :n, :name, "Search for a method by name"
      opti.on :c, :content, "Search for a method based on content in Regex form"
    end

    def process
      return if args.size < 1
      pattern = ::Regexp.new args[0]
      if args[1]
        klass = target.eval(args[1])
        if !klass.is_a?(Module)
          klass = klass.class
        end
      else
        klass = (target_self.is_a?(Module)) ? target_self : target_self.class
      end

      matches = if opts.content?
                  content_search(pattern, klass)
                else
                  name_search(pattern, klass)
                end

      if matches.empty?
        output.puts text.bold("No Methods Matched")
      else
        print_matches(matches, pattern)
      end

    end

    private

    # pretty-print a list of matching methods.
    #
    # @param Array[Method]
    def print_matches(matches, pattern)
      grouped = matches.group_by(&:owner)
      order = grouped.keys.sort_by{ |x| x.name || x.to_s }

      order.each do |klass|
        output.puts text.bold(klass.name)
        grouped[klass].each do |method|
          header = method.name_with_owner

          extra = if opts.content?
                    header += ": "
                    colorize_code((method.source.split(/\n/).select {|x| x =~ pattern }).join("\n#{' ' * header.length}"))
                  else
                    ""
                  end

          output.puts header + extra
        end
      end
    end

    # Run the given block against every constant in the provided namespace.
    #
    # @param Module  The namespace in which to start the search.
    # @param Hash[Module,Boolean]  The namespaces we've already visited (private)
    # @yieldparam klazz  Each class/module in the namespace.
    #
    def recurse_namespace(klass, done={}, &block)
      return if !(Module === klass) || done[klass]

      done[klass] = true

      yield klass

      klass.constants.each do |name|
        next if klass.autoload?(name)
        begin
          const = klass.const_get(name)
        rescue RescuableException
          # constant loading is an inexact science at the best of times,
          # this often happens when a constant was .autoload? but someone
          # tried to load it. It's now not .autoload? but will still raise
          # a NameError when you access it.
        else
          recurse_namespace(const, done, &block)
        end
      end
    end

    # Gather all the methods in a namespace that pass the given block.
    #
    # @param Module  The namespace in which to search.
    # @yieldparam Method  The method to test
    # @yieldreturn Boolean
    # @return Array[Method]
    #
    def search_all_methods(namespace)
      done = Hash.new{ |h,k| h[k] = {} }
      matches = []

      recurse_namespace(namespace) do |klass|
        (Pry::Method.all_from_class(klass) + Pry::Method.all_from_obj(klass)).each do |method|
          next if done[method.owner][method.name]
          done[method.owner][method.name] = true

          matches << method if yield method
        end
      end

      matches
    end

    # Search for all methods with a name that matches the given regex
    # within a namespace.
    #
    # @param Regex  The regex to search for
    # @param Module  The namespace to search
    # @return Array[Method]
    #
    def name_search(regex, namespace)
      search_all_methods(namespace) do |meth|
        meth.name =~ regex
      end
    end

    # Search for all methods who's implementation matches the given regex
    # within a namespace.
    #
    # @param Regex  The regex to search for
    # @param Module  The namespace to search
    # @return Array[Method]
    #
    def content_search(regex, namespace)
      search_all_methods(namespace) do |meth|
        begin
          meth.source =~ regex
        rescue RescuableException
          false
        end
      end
    end
  end

  Pry::Commands.add_command(Pry::Command::FindMethod)
end