require 'grounds'
require 'json'
require 'rack'
require 'rack-slashenforce'

module Rack::Grounds
  def self.app
    admin_prefix = '!'
    app = Grounds::App.new(Dir.pwd)
    Rack::Builder.app do
      use Rack::AppendTrailingSlash
      map "/#{admin_prefix}/env.json" do
        run Rack::Grounds.json_app { app.env } end
      map "/#{admin_prefix}" do
        run Rack::Grounds.html_app(Grounds::ADMIN_ROOT) end
      map '/' do
        run Rack::Grounds.html_app(app.public_root) end
    end
  end

  def self.json_app(&block)
    headers = { 'Content-Type' => 'application/json' }
    -> (env) { [200, headers, [block[env].to_json]] }
  end

  def self.html_app(root)
    Rack::Builder.app do
      use Rack::Grounds::DynamicIndex, root
      use Rack::Static, urls: [''], index: 'index.html', root: root
      run -> (env) { fail 'should never get here' }
    end
  end

  class DynamicIndex
    def initialize(app, root)
      @app = app
      @root = root
    end

    def call(env)
      path = File.join(@root, env['PATH_INFO'])
      if should_handle? path
        [200, { 'Content-Type' => 'text/html' }, [html_for(path)]]
      else
        @app.call(env)
      end
    end

    def index_for(path) File.join(path, 'index.html') end
    def manifest_for(path) File.join(path, 'index.manifest') end
    def should_handle? path
      %r{/$} === path and not File.exist? index_for(path) and
        File.exist? manifest_for(path)
    end

    def html_for(path)
      manifest = File.read(manifest_for(path))
      open '|grounds', 'w+' do |process|
        parse_manifest(manifest) { |x| process.write "#{x}\n" }
        process.close_write
        process.read
      end
    end

    def parse_manifest(manifest)
      yield 'App-Attrs: manifest="index.manifest"'
      section = :cache
      for line in manifest.lines
        line.chomp!
        yield $1 if line =~ /^#= (.+)$/
        line.sub! /#.*/, ''
        line.sub! /^\s+|\s+$/, ''
        case line
        when 'CACHE MANIFEST', '*', ''
        when 'CACHE:'
          section = :cache
        when 'NETWORK:'
          section = :network
        when 'FALLBACK:'
          section = :fallback
        else
          case section
          when :network
            yield "App-Asset: #{line}"
          when :cache
            yield "Vendor-Asset: #{line}"
          end
        end
      end
    end
  end
end