module Berkshelf
  # @author Jamie Winsor <jamie@vialstudios.com>
  class SiteLocation
    include Location

    location_key :site

    attr_reader :api_uri
    attr_accessor :version_constraint

    class << self
      # @param [String] target
      #   file path to the tar.gz archive on disk
      # @param [String] destination
      #   file path to extract the contents of the target to
      def unpack(target, destination)
        Archive::Tar::Minitar.unpack(Zlib::GzipReader.new(File.open(target, 'rb')), destination)
      end
    end

    # @param [#to_s] name
    # @param [Solve::Constraint] version_constraint
    # @param [Hash] options
    #
    # @option options [String, Symbol] :site
    #   a URL pointing to a community API endpoint. Alternatively the symbol :opscode can
    #   be provided to initialize a SiteLocation pointing to the Opscode Community Site.
    def initialize(name, version_constraint, options = {})
      @name = name
      @version_constraint = version_constraint

      @api_uri = if options[:site].nil? || options[:site] == :opscode
        Location::OPSCODE_COMMUNITY_API
      else
        options[:site]
      end

      @rest = Chef::REST.new(api_uri, false, false)
    end

    # @param [#to_s] destination
    #
    # @return [Berkshelf::CachedCookbook]
    def download(destination)
      version, uri = target_version
      remote_file = rest.get_rest(uri)['file']

      downloaded_tf = rest.get_rest(remote_file, true)

      dir = Dir.mktmpdir
      cb_path = File.join(destination, "#{name}-#{version}")

      self.class.unpack(downloaded_tf.path, dir)
      FileUtils.mv(File.join(dir, name), cb_path, force: true)

      cached = CachedCookbook.from_store_path(cb_path)
      validate_cached(cached)
      
      set_downloaded_status(true)
      cached
    end

    # Returns a hash of all the cookbook versions found at communite site URL for the cookbook
    # name of this location.
    #
    # @example
    #   { 
    #     "0.101.2" => "http://cookbooks.opscode.com/api/v1/cookbooks/nginx/versions/0_101_2",
    #     "0.101.0" => "http://cookbooks.opscode.com/api/v1/cookbooks/nginx/versions/0_101_0"
    #   }
    #
    # @return [Hash]
    #   a hash representing the cookbook versions on at a Chef API for location's cookbook.
    #   The keys are version strings and the values are URLs to download the cookbook version.
    def versions
      {}.tap do |versions|
        rest.get_rest(name)['versions'].each do |uri|
          version = version_from_uri(File.basename(uri))

          versions[version] = uri
        end
      end
    rescue Net::HTTPServerException => e
      if e.response.code == "404"
        raise CookbookNotFound, "Cookbook '#{name}' not found at site: '#{api_uri}'"
      else
        raise
      end
    end

    # Returns the latest version of the cookbook and it's download link.
    #
    # @example
    #   [ "0.101.2" => "https://api.opscode.com/organizations/vialstudios/cookbooks/nginx/0.101.2" ]
    #
    # @return [Array]
    #   an array containing the version and download URL for the cookbook version that
    #   should be downloaded for this location.
    def latest_version
      quietly {
        uri = rest.get_rest(name)['latest_version']

        [ version_from_uri(uri), uri ]
      }
    rescue Net::HTTPServerException => e
      if e.response.code == "404"
        raise CookbookNotFound, "Cookbook '#{name}' not found at site: '#{api_uri}'"
      else
        raise
      end
    end

    def to_s
      "site: '#{api_uri}'"
    end

    private

      attr_reader :rest

      def uri_escape_version(version)
        version.gsub('.', '_')
      end

      def version_from_uri(latest_version)
        File.basename(latest_version).gsub('_', '.')
      end

      # Returns an array containing the version and download URL for the cookbook version that
      # should be downloaded for this location.
      #
      # @example
      #   [ "0.101.2" => "https://api.opscode.com/organizations/vialstudios/cookbooks/nginx/0.101.2" ]
      #
      # @return [Array]
      def target_version
        if version_constraint
          solution = self.class.solve_for_constraint(version_constraint, versions)
          
          unless solution
            raise NoSolution, "No cookbook version of '#{name}' found at #{self} that would satisfy constraint (#{version_constraint})."
          end

          solution
        else
          latest_version
        end
      end
  end
end