#
# Copyright (c) 2006-2012 Hal Brodigan (postmodern.mod3 at gmail.com)
#
# This file is part of Ronin.
#
# Ronin is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ronin is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ronin.  If not, see <http://www.gnu.org/licenses/>.
#

require 'set'

module Ronin
  #
  # The {Installation} module provides methods which help reflect on the
  # installation of Ronin on the system.
  #
  module Installation
    # The loaded gemspecs of all installed ronin libraries
    @gems = {}
    @paths = Set[]

    #
    # Finds the installed Ronin libraries via RubyGems.
    #
    # @return [Hash{String => Gem::Specification}]
    #   The names and gem-specs of the installed Ronin libraries.
    #
    # @since 1.0.0
    #
    # @api semipublic
    #
    def Installation.gems
      load! if @gems.empty?
      return @gems
    end

    #
    # The paths of the installed Ronin libraries.
    #
    # @return [Set<String>]
    #   The paths of the Ronin libraries.
    #
    # @since 1.0.1
    #
    # @api semipublic
    #
    def Installation.paths
      load! if @paths.empty?
      return @paths
    end

    #
    # The names of the additional Ronin libraries installed on the system.
    #
    # @return [Array<String>]
    #   The library names.
    #
    # @since 1.0.0
    #
    # @api semipublic
    #
    def Installation.libraries
      gems.keys
    end

    #
    # Enumerates over all files within a given directory found in any
    # of the installed Ronin libraries.
    #
    # @param [String] pattern
    #   The glob pattern to search for.
    #
    # @yield [file]
    #   The given block will be passed each file found within the directory.
    #
    # @yieldparam [String] file
    #   The sub-path to the file found within the directory.
    #
    # @return [Enumerator]
    #   Returns an Enumerator if no block is given.
    #
    # @since 1.0.0
    #
    # @api semipublic
    #
    def Installation.each_file(pattern)
      return enum_for(:each_file,pattern) unless block_given?

      # query the installed gems
      paths.each do |gem_path|
        slice_index = gem_path.length + 1

        Dir.glob(File.join(gem_path,pattern)) do |path|
          yield path[slice_index..-1]
        end
      end

      return nil
    end

    #
    # Enumerates over every file in a directory.
    #
    # @param [String] directory
    #   The directory to search within.
    #
    # @param [String, Symbol] ext
    #   The optional file extension to search for.
    #
    # @yield [name]
    #   The given block will be passed each matching file-name.
    #
    # @yieldparam [String] name
    #   The basename of the matching path within the directory.
    #
    # @return [Enumerator]
    #   If no block is given, an Enumerator will be returned.
    #
    # @since 1.0.0
    #
    # @api semipublic
    #
    def Installation.each_file_in(directory,ext=nil)
      return enum_for(:each_file_in,directory,ext) unless block_given?

      pattern = File.join(directory,'**','*')
      pattern << ".#{ext}" if ext

      slice_index = directory.length + 1

      each_file(pattern) do |path|
        yield path[slice_index..-1]
      end
    end

    protected

    #
    # Finds the installed Ronin gems.
    #
    # @return [true]
    #   All Ronin libraries were successfully found.
    #
    # @since 1.0.1
    #
    # @api private
    #
    def Installation.load_gems!
      register_gem = lambda { |gem|
        @gems[gem.name] = gem
        @paths << gem.full_gem_path
      }

      ronin_gem = Gem.loaded_specs['ronin']

      # add the main ronin gem
      register_gem[ronin_gem]

      # add any dependent gems
      ronin_gem.dependent_gems.each do |gems|
        register_gem[gems[0]]
      end

      return true
    end

    #
    # Loads the gemspecs of Ronin libraries from the `$LOAD_PATH`.
    #
    # @return [true]
    #   All Ronin gemspecs were successfully found.
    #
    # @since 1.0.0
    #
    # @api private
    #
    def Installation.load_gemspecs!
      $LOAD_PATH.each do |lib_dir|
        root_dir = File.expand_path(File.join(lib_dir,'..'))
        gemspec_path = Dir[File.join(root_dir,'ronin*.gemspec')][0]

        if gemspec_path
          # switch into the gem directory, before loading the gemspec
          gem = Dir.chdir(root_dir) do
            Gem::Specification.load(gemspec_path)
          end

          # do not add duplicate ronin gems
          unless @gems.has_key?(gem.name)
            @gems[gem.name] = gem
            @paths << root_dir
          end
        end
      end

      return true
    end

    #
    # Finds the installed Ronin libraries.
    #
    # @return [true]
    #   All Ronin libraries were successfully found.
    #
    # @since 1.0.1
    #
    # @api private
    #
    def Installation.load!
      if Gem.loaded_specs.has_key?('ronin')
        load_gems!
      else
        load_gemspecs!
      end
    end
  end
end