require 'bundler'
require 'find'
require 'fileutils'

module Jarbler
  class Builder
    # Execute all functions needed to build the jar file
    # Should be executed in application directory of Rails/Ruby application
    # @return [void]
    def build_jar
      # create a temporary directory for staging
      staging_dir = Dir.mktmpdir

      jarbler_lib_dir = __dir__
      app_root = Dir.pwd
      debug "Project dir: #{app_root}"

      # TODO: transform to internal bundler API call (check if jruby is installed + install if not)
      exec_command  "gem install --no-doc jruby-jars -v #{config.jruby_version}" # Ensure that jruby-jars are installed in the requested version
      gem_search_locations = collect_gem_search_locations(app_root)
      ruby_version = copy_jruby_jars_to_staging(staging_dir, gem_search_locations) # Copy the jruby jars to the staging directory
      exec_command "javac -nowarn -Xlint:deprecation -source 8 -target 8 -d #{staging_dir} #{jarbler_lib_dir}/JarMain.java" # Compile the Java files

      # Copy the application project to the staging directory
      FileUtils.mkdir_p("#{staging_dir}/app_root")
      config.includes.each do |dir|
        file_utils_copy("#{app_root}/#{dir}", "#{staging_dir}/app_root") if File.exist?("#{app_root}/#{dir}")
      end

      # Get the needed Gems
      raise "Gemfile.lock not found in #{app_root}" unless File.exist?("#{app_root}/Gemfile.lock")

      gem_target_location = "#{staging_dir}/gems/jruby/#{ruby_version}"
      FileUtils.mkdir_p("#{gem_target_location}/gems")
      FileUtils.mkdir_p("#{gem_target_location}/specifications")

      needed_gems = gem_dependencies  # get the full names of the dependencies
      needed_gems.each do |gem_full_name|
        copy_gem_to_staging(gem_full_name, gem_target_location, gem_search_locations)
      end

      Dir.chdir(staging_dir) do
        # create the manifest file
        File.open('Manifest.txt', 'w') do |file|
          file.write("Comment: created by Jarbler (https://github.com/rammpeter/jarbler)\n")
          file.write("Main-Class: JarMain\n")
        end

        # Write java properties file for use in JarMain.java
        File.open('jarbler.properties', 'w') do |file|
          file.write("jarbler.executable=#{config.executable}\n")
          # write a list of strings into property file delimited by space
          java_executable_params = ''
          config.executable_params.each do |param|
            java_executable_params += "#{param} "
          end
          file.write("jarbler.executable_params=#{java_executable_params.strip}\n")
        end

        # remove files and directories from excludes, if they exist (after copying the rails project and the gems)
        config.excludes.each do |exclude|
          to_remove = "app_root/#{exclude}"
          if File.exist?(to_remove)
            debug "Removing #{to_remove} from staging directory"
            FileUtils.rm_rf(to_remove)
          else
            debug "Not removing #{to_remove} from staging directory, because it does not exist"
          end
        end

        exec_command "jar cfm #{config.jar_name} Manifest.txt *" # create the jar file

        # place the jar in project directory
        file_utils_copy(config.jar_name, app_root)
        puts "Created jar file #{app_root}/#{config.jar_name}"
      end

      # remove temporary directory staging_dir
      FileUtils.remove_entry staging_dir

    end

    private

    # Find the locations where Gems are installed
    # @param [String] app_root Application root directory
    # @return [Array] Array of Gem locations
    def collect_gem_search_locations(app_root)
      # All active search locations for Gems
      Bundler.setup
      possible_gem_search_locations = Gem.paths.path
      debug "Possible Gem locations: #{possible_gem_search_locations}"
      gem_search_locations = []
      # Check where inside this location the gems may be installed
      possible_gem_search_locations.each do |gem_search_location|
        if File.exist?(gem_search_location) && File.directory?(gem_search_location)
          valid_gem_search_location = nil # No valid path found yet
          Find.find(gem_search_location) do |path|
            if File.directory?(path) && File.exist?("#{path}/specifications") && File.exist?("#{path}/gems")
              valid_gem_search_location = path # Found a valid path
              Find.prune # Do not search deeper
            end
          end
          if valid_gem_search_location
            gem_search_locations << valid_gem_search_location
          else
            debug "No valid gem location found in #{gem_search_location}"
          end
        else
          debug("Gem location #{gem_search_location} does not exist or is not a directory")
        end
      end
      debug "Valid Gem locations: #{gem_search_locations}"
      gem_search_locations
    end

    # Copy the Gem elements to the staging directory
    # @param [String] gem_full_name Full name of the Gem including version and platform
    # @param [String] staging_dir Path to the staging directory
    # @param [Array] gem_search_locations Array of Gem locations
    # @return [void]
    def copy_gem_to_staging(gem_full_name, gem_target_location, gem_search_locations)
      gem_search_locations.each do |gem_search_location|
        gem_dir = "#{gem_search_location}/gems/#{gem_full_name}"
        if File.exist?(gem_dir)
          file_utils_copy(gem_dir, "#{gem_target_location}/gems")
          file_utils_copy("#{gem_search_location}/specifications/#{gem_full_name}.gemspec", "#{gem_target_location}/specifications")
          return
        end
      end
      raise "Gem #{gem_name} (#{gem_version}) not found in any of the following locations:\n#{gem_search_locations.join("\n")}"
    end

    # Read the default/production dependencies from Gemfile.lock and Gemfile
    # @return [Array] Array with full names of dependencies
    def gem_dependencies
      needed_gems = []
      lockfile_specs = Bundler::LockfileParser.new(Bundler.read_file(Bundler.default_lockfile)).specs

      Bundler.setup # Load Gems specified in Gemfile
      # filter Gems needed for production
      gemfile_specs = Bundler.definition.dependencies.select do |d|
        d.groups.include?(:default) || d.groups.include?(:production)
      end

      debug "Gems from Gemfile needed for production:"
      gemfile_specs.each do |gemfile_spec|
        # find lockfile record for Gemfile spec
        lockfile_spec = lockfile_specs.find { |lockfile_spec| lockfile_spec.name == gemfile_spec.name }
        if lockfile_spec
          needed_gems << lockfile_spec.full_name unless needed_gems.include?(lockfile_spec.full_name)
          debug "Direct Gem dependency: #{lockfile_spec.full_name}"
          add_indirect_dependencies(lockfile_specs, lockfile_spec, needed_gems)
        else
          debug "Gem #{gemfile_spec.name} not found in Gemfile.lock"
        end
      end
      needed_gems.uniq.sort
    end

    # recurively find all indirect dependencies
    # @param [Array] lockfile_specs Array of Bundler::LockfileParser::Spec objects
    # @param [Bundler::LockfileParser::Spec] lockfile_spec current lockfile spec to check for their dependencies
    # @param [Array] needed_gems Array with full names of already found dependencies, add findings here
    # @return [void]
    def add_indirect_dependencies(lockfile_specs, lockfile_spec, needed_gems)
      lockfile_spec.dependencies.each do |lockfile_spec_dep|
        lockfile_spec_found = lockfile_specs.find { |lockfile_spec| lockfile_spec.name == lockfile_spec_dep.name }
        if lockfile_spec_found
          debug "Indirect Gem dependency from #{lockfile_spec.full_name}: #{lockfile_spec_found.full_name}"
          unless needed_gems.include?(lockfile_spec_found.full_name)
            needed_gems << lockfile_spec_found.full_name
            add_indirect_dependencies(lockfile_specs, lockfile_spec_found, needed_gems)
          end
        else
          debug "Gem #{lockfile_spec_dep.name} not found in Gemfile.lock"
        end
      end
    end
    def debug(msg)
      puts msg if ENV['DEBUG']
    end

    def config
      unless defined? @config
       @config = Config.create
       debug("Config attributes:")
       @config.instance_variables.each do |var|
         debug("#{var}: #{@config.instance_variable_get(var)}")
       end
       debug ""
      end
      @config
    end

    # Copy the jruby-jars to the staging directory
    # @param [String] staging_dir Path to the staging directory
    # @param [Array] gem_search_locations Array of Gem locations to look for jRuby jars
    # @return [String] the ruby version of the jRuby jars
    def copy_jruby_jars_to_staging(staging_dir, gem_search_locations)
      jruby_jars_location = nil
      gem_search_locations.each do |gem_search_location|
        gem_dir = "#{gem_search_location}/gems/jruby-jars-#{config.jruby_version}"
        if File.exist?(gem_dir)
          jruby_jars_location = gem_dir
          break
        end
      end
      raise "Could not determine location of jRuby jars for release '#{config.jruby_version}' in the following locations:\n#{gem_search_locations}" unless jruby_jars_location
      file_utils_copy("#{jruby_jars_location}/lib/jruby-core-#{config.jruby_version}-complete.jar", staging_dir)
      file_utils_copy("#{jruby_jars_location}/lib/jruby-stdlib-#{config.jruby_version}.jar", staging_dir)

      # Get the according Ruby version for the current jRuby version
      lines = exec_command "java -cp #{jruby_jars_location}/lib/jruby-core-#{config.jruby_version}-complete.jar org.jruby.Main --version"
      match_result = lines.match(/\(.*\)/)
      raise "Could not determine Ruby version for jRuby #{config.jruby_version} in following output:\n#{lines}" unless match_result
      ruby_version = match_result[0].tr('()', '')
      debug "Corresponding Ruby version for jRuby (#{config.jruby_version}): #{ruby_version}"
      ruby_version
    end

    # Execute the command and return the output
    def exec_command(command)
      lines = `#{command}`
      raise "Command \"#{command}\"failed with return code #{$?} and output:\n#{lines}" unless $?.success?
      debug "Command \"#{command}\" executed successfully with following output:\n#{lines}"
      lines
    end

    # Copy file or directory with error handling
    def file_utils_copy(source, destination)
      if File.exist?(source) && File.directory?(source)
        FileUtils.cp_r(source, destination)
      else
        FileUtils.cp(source, destination)
      end
    rescue Exception
      puts "Error copying #{source} to #{destination}"
      raise
    end
  end

end