require 'cgi'

module Evrythng
  # Wrapper for the Evrythng Search API
  class Search < API
    include Enumerable

    # @private
    attr_reader :query

    # Creates a new search
    #
    # @example Initialize an Evrythng search
    #   search = Evrythng::Search.new
    def initialize(*)
      clear
      super
    end

    # Clears all query filters and cached results
    #
    # @return [Evrythng::Search] self
    # @example Clear a search for "evrythng"
    #   search = Evrythng::Search.new
    #   search.containing("bike").fetch
    #   search.clear
    #   search.fetch_next_page #=> 403 Forbidden: You must enter a query.
    def clear
      @cache = nil
      @query = {}
      @query[:q] = []
      self
    end

    # @group Generic filters

    # Search query
    #
    # @param query [String] The search query.
    # @return [Evrythng::Search] self
    # @example Return an array of thngs containing "bike"
    #   Evrythng::Search.new.containing("bike").fetch
    def containing(query)
      @query[:q] << query
      self
    end

    # Negative search query
    #
    # @param query [String] The negative search query.
    # @return [Evrythng::Search] self
    # @example Return an array of thngs containing "bike" but not "mountain"
    #   Evrythng::Search.new.containing("bike").not_containing("mountain").fetch
    def not_containing(query)
      @query[:q] << "-#{query}"
      self
    end

    # Only include thngs from users in a given radius of a given location
    #
    # @param lat [Float] A latitude.
    # @param long [Float] A longitude.
    # @param radius [String] A search radius, specified in either 'mi' (miles) or 'km' (kilometers).
    # @return [Evrythng::Search] self
    # @example Return an array of thngs within a 1-kilometer radius of Barcelona
    #   Evrythng::Search.new.containing("bike").geocode(41.38, 2.18, "1km").fetch
    def geocode(lat, long, radius)
      @query[:geocode] = [lat, long, radius].join(",")
      self
    end

    # @group User filters

    # Only include thngs owned by a given user, specified by screen_name
    #
    # @param screen_name [String] A Evrythng user name.
    # @return [Evrythng::Search] self
    # @example Return an array of thngs containing "bike" from "mike"
    #   Evrythng::Search.new.containing("bike").from("mike").fetch
    def from(screen_name)
      @query[:q] << "from:#{screen_name}"
      self
    end

    # Exclude thngs from a given user, specified by screen_name
    #
    # @param screen_name [String] A Evrythng user name.
    # @return [Evrythng::Search] self
    # @example Return an array of thngs containing "bike" from everyone except "mike"
    #   Evrythng::Search.new.containing("bike").not_from("mike").fetch
    def not_from(screen_name)
      @query[:q] << "-from:#{screen_name}"
      self
    end

    # @group Paging

    # Specify the number of thngs to return per page
    #
    # @param number [Integer] The number of thngs to return per page, up to a max of 100.
    # @return [Evrythng::Search] self
    # @example Return an array of 100 thngs containing "bike"
    #   Evrythng::Search.new.containing("bike").per_page(100).fetch
    def per_page(number=15)
      @query[:per_page] = number
      self
    end

    # Specify the page number to return, up to a maximum of roughly 500 results
    #
    # @param number [Integer] The page number (starting at 1) to return, up to a max of roughly 500 results (based on {Evrythng::Client::Search#per_page} * {Evrythng::Client::Search#page}).
    # @return [Evrythng::Search] self
    # @example Return the second page of thngs containing "bike"
    #   Evrythng::Search.new.containing("bike").page(2).fetch
    def page(number)
      @query[:page] = number
      self
    end

    # Indicates if there are additional results to be fetched
    #
    # @return [Boolean]
    # @example
    #   search = Evrythng::Search.new.containing("bike").fetch
    #   search.next_page? #=> true
    def next_page?
      fetch if @cache.nil?
      !!@cache["next_page"]
    end

    # @group Fetching

    # Fetch the next page of results of the query
    #
    # @return [Array] Thngs that match specified query.
    # @example Return the first two pages of results
    #   search = Evrythng::Search.new.containing("bike").fetch
    #   search.fetch_next_page
    def fetch_next_page
      if next_page?
        @cache = get("search", CGI.parse(@cache["next_page"][1..-1]), :json)
        @cache.results
      end
    end

    # Fetch the results of the query
    #
    # @param force [Boolean] Ignore the cache and hit the API again.
    # @return [Array] Thngs that match specified query.
    # @example Return an array of thngs containing "bike"
    #   search = Evrythng::Search.new.containing("bike").fetch
    def fetch(force=false)
      if @cache.nil? || force
        options = query.dup
        options[:q] = options[:q].join(" ")
        @cache = get("search", options, :json)
      end
      @cache.results
    end

    # Calls block once for each element in self, passing that element as a parameter
    #
    # @yieldparam [Hashie::Mash] result Thngs that matches specified query.
    # @return [Array] Thngs that match specified query.
    # @example
    #   Evrythng::Search.new.containing('cafe del mar').each do |result|
    #     puts "#{result.identifier} by #{result.owner}"
    #   end
    def each
      fetch.each{|result| yield result}
    end
  end
end