module Berkshelf
  # @author Jamie Winsor <jamie@vialstudios.com>
  module Location
    OPSCODE_COMMUNITY_API = 'http://cookbooks.opscode.com/api/v1/cookbooks'.freeze

    module ClassMethods
      # Returns the location identifier key for the class
      #
      # @return [Symbol]
      attr_reader :location_key

      # Register the location key for the including source location with CookbookSource
      #
      # @param [Symbol] key
      def set_location_key(key)
        CookbookSource.add_location_key(key, self)
        @location_key = key
      end

      # Register a valid option or multiple options with the CookbookSource class
      #
      # @param [Symbol] opts
      def set_valid_options(*opts)
        Array(opts).each do |opt|
          CookbookSource.add_valid_option(opt)
        end
      end

      # Returns an array where the first element is string representing the best version
      # for the given constraint and the second element is the URI to where the corresponding
      # version of the Cookbook can be downloaded from
      #
      # @example:
      #   constraint = Solve::Constraint.new("~> 0.101.2")
      #   versions = {
      #     "1.0.0" => "http://cookbooks.opscode.com/api/v1/cookbooks/nginx/versions/1_0_0",
      #     "2.0.0" => "http://cookbooks.opscode.com/api/v1/cookbooks/nginx/versions/2_0_0"
      #   }
      #
      #   subject.solve_for_constraint(versions, constraint) =>
      #     [ "2.0.0", "http://cookbooks.opscode.com/api/v1/cookbooks/nginx/versions/2_0_0" ]
      #
      # @param [String, Solve::Constraint] constraint
      #   version constraint to solve for
      #
      # @param [Hash] versions
      #   a hash where the keys are a string representing a cookbook version and the values
      #   are the download URL for the cookbook version.
      #
      # @return [Array, nil]
      def solve_for_constraint(constraint, versions)
        version = Solve::Solver.satisfy_best(constraint, versions.keys).to_s

        [ version, versions[version] ]
      rescue Solve::Errors::NoSolutionError
        nil
      end
    end

    class << self
      def included(base)
        base.send :extend, ClassMethods
      end

      # Creates a new instance of a Class implementing Location with the given name and
      # constraint. Which Class to instantiated is determined by the values in the given
      # options Hash. Source Locations have an associated location_key registered with
      # CookbookSource. If your options Hash contains a key matching one of these location_keys
      # then the Class who registered that location_key will be instantiated. If you do not
      # provide an option with a matching location_key a SiteLocation class will be
      # instantiated.
      #
      # @example
      #   Location.init("nginx", ">= 0.0.0", git: "git://github.com/RiotGames/artifact-cookbook.git") =>
      #     instantiates a GitLocation
      #
      #   Location.init("nginx", ">= 0.0.0", path: "/Users/reset/code/nginx-cookbook") =>
      #     instantiates a PathLocation
      #
      #   Location.init("nginx", ">= 0.0.0", site: "http://cookbooks.opscode.com/api/v1/cookbooks") =>
      #     instantiates a SiteLocation
      #
      #   Location.init("nginx", ">= 0.0.0", chef_api: "https://api.opscode.com/organizations/vialstudios") =>
      #     instantiates a ChefAPILocation
      #
      #   Location.init("nginx", ">= 0.0.0") =>
      #     instantiates a SiteLocation
      #
      # @param [String] name
      # @param [String, Solve::Constraint] constraint
      # @param [Hash] options
      #
      # @return [SiteLocation, PathLocation, GitLocation, ChefAPILocation]
      def init(name, constraint, options = {})
        klass = klass_from_options(options)

        klass.new(name, constraint, options)
      end

      private

        def klass_from_options(options)
          location_keys = (options.keys & CookbookSource.location_keys.keys)
          if location_keys.length > 1
            location_keys.collect! { |opt| "'#{opt}'" }
            raise InternalError, "Only one location key (#{CookbookSource.location_keys.keys.join(', ')}) may be specified. You gave #{location_keys.join(', ')}."
          end

          if location_keys.empty?
            SiteLocation
          else
            CookbookSource.location_keys[location_keys.first]
          end
        end
    end

    attr_reader :name
    attr_reader :version_constraint

    # @param [#to_s] name
    # @param [Solve::Constraint] version_constraint
    # @param [Hash] options
    def initialize(name, version_constraint, options = {})
      @name               = name
      @version_constraint = version_constraint
      @downloaded_status  = false
    end

    # @param [#to_s] destination
    #
    # @return [Berkshelf::CachedCookbook]
    def download(destination)
      raise AbstractFunction
    end

    # @return [Boolean]
    def downloaded?
      @downloaded_status
    end

    # Ensure the retrieved CachedCookbook is valid
    #
    # @param [CachedCookbook] cached_cookbook
    #
    # @raise [ConstraintNotSatisfied] if the CachedCookbook does not satisfy the version constraint of
    #   this instance of Location.
    #
    # @raise [AmbiguousCookbookName] if the CachedCookbook's name does not match the locations's name attribute
    #
    # @return [Boolean]
    def validate_cached(cached_cookbook)
      unless version_constraint.satisfies?(cached_cookbook.version)
        raise ConstraintNotSatisfied, "A cookbook satisfying '#{self.name}' (#{self.version_constraint}) not found at #{self}"
      end

      # JW TODO: Safe to uncomment when when Opscode makes the 'name' a required attribute in Cookbook metadata
      # unless self.name == cached_cookbook.cookbook_name
      #   raise AmbiguousCookbookName, "Expected a cookbook at #{self} to be named '#{self.name}'. Did you set the 'name' attribute in your Cookbooks metadata? If you didn't, the name of the directory will be used as the name of your Cookbook (awful, right?)."
      # end

      true
    end

    def to_hash
      {
        type: self.class.location_key
      }
    end

    def to_json
      MultiJson.dump(self.to_hash, pretty: true)
    end

    private

      def set_downloaded_status(state)
        @downloaded_status = state
      end
  end
end

Dir["#{File.dirname(__FILE__)}/locations/*.rb"].sort.each do |path|
  require "berkshelf/locations/#{File.basename(path, '.rb')}"
end