module Bond
  # Generates method autocompletions for gems that use {yard}[http://yardoc.org] documentation. Currently
  # generates completions for methods that take a hash of options and have been documented with @option.
  module Yard
    extend self

    # Loads completions for yard gem(s)
    def load_yard_gems(*gems)
      @options = gems[-1].is_a?(Hash) ? gems.pop : {}
      require 'yard'
      raise LoadError unless YARD::VERSION >= '0.5.2'
      gems.select {|e| load_yard_gem(e) }
    rescue LoadError
      $stderr.puts "Bond Error: yard gem (version >= 0.5.2) not installed "
    end

    protected
    def load_yard_gem(rubygem)
      raise("Unable to find gem.") unless (yardoc = find_yardoc(rubygem))
      completion_file = File.join(dir('yard_completions'), rubygem+'.rb')
      create_completion_file(yardoc, completion_file) if !File.exists?(completion_file) || @options[:reload]
      M.load_file completion_file
    rescue
      $stderr.puts "Bond Error: Didn't load yard completions for gem '#{rubygem}'. #{$!.message}"
    end

    def create_completion_file(yardoc, completion_file)
      YARD::Registry.load!(yardoc)
      methods_hash = find_methods_with_options
      body = generate_method_completions(methods_hash)
      File.open(completion_file, 'w') {|e| e.write body }
    end

    def find_yardoc(rubygem)
      (file = YARD::Registry.yardoc_file_for_gem(rubygem) rescue nil) and return(file)
      if (file = M.find_gem_file(rubygem, rubygem+'.rb'))
        output_dir = File.join(dir('.yardocs'), rubygem)
        cmd = ['yardoc', '-n', '-b', output_dir]
        cmd << '-q' unless @options[:verbose]
        cmd += ['-c', output_dir] unless @options[:reload]
        cmd += [file, File.expand_path(file+'/..')+"/#{rubygem}/**/*.rb"]
        puts "Bond: "+cmd.join(' ') if @options[:verbose]
        puts "Bond: Building/loading #{rubygem}'s .yardoc database ..."
        system *cmd
        output_dir
      end
    end

    def dir(subdir)
      (@dirs ||= {})[subdir] ||= begin
        require 'fileutils'
        FileUtils.mkdir_p File.join(M.home, '.bond', subdir)
        File.join(M.home, '.bond', subdir)
      end
    end

    def find_methods_with_options
      YARD::Registry.all(:method).inject({}) {|a,m|
        opts = m.tags.select {|e| e.is_a?(YARD::Tags::OptionTag) }.map {|e| e.pair.name }
        a[m.path] = opts if !opts.empty? && m.path
        a
      }
    end

    def generate_method_completions(methods_hash)
      methods_hash.map do |meth, options|
        options.map! {|e| e.sub(/^:/, '') }
        meth = meth.sub(/#initialize$/, '.new')
        %Q[complete(:method=>'#{meth}') {\n  #{options.inspect}\n}]
      end.join("\n")
    end
  end
end