module Elasticsearch
  module API

    # Generic utility methods
    #
    module Utils

      # URL-escape a string
      #
      # @example
      #     __escape('foo/bar') # => 'foo%2Fbar'
      #     __escape('bar^bam') # => 'bar%5Ebam'
      #
      # @api private
      def __escape(string)
        defined?(EscapeUtils) ? EscapeUtils.escape_url(string.to_s) : CGI.escape(string.to_s)
      end

      # Create a "list" of values from arguments, ignoring nil values and encoding special characters.
      #
      # @example Create a list from array
      #     __listify(['A','B']) # => 'A,B'
      #
      # @example Create a list from arguments
      #     __listify('A','B') # => 'A,B'
      #
      # @example Escape values
      #     __listify('foo','bar^bam') # => 'foo,bar%5Ebam'
      #
      # @api private
      def __listify(*list)
        # require 'pry'
        # binding.pry
        Array(list).flatten.
          map { |e| e.respond_to?(:split) ? e.split(',') : e }.
          flatten.
          compact.
          map { |e| __escape(e) }.
          join(',')
      end

      # Create a path (URL part) from arguments, ignoring nil values and empty strings.
      #
      # @example Create a path from array
      #     __pathify(['foo', '', nil, 'bar']) # => 'foo/bar'
      #
      # @example Create a path from arguments
      #     __pathify('foo', '', nil, 'bar') # => 'foo/bar'
      #
      # # @example Encode special characters
      #     __pathify(['foo', 'bar^bam']) # => 'foo/bar%5Ebam'
      #
      # @api private
      def __pathify(*segments)
        Array(segments).flatten.
          compact.
          reject { |s| s.to_s =~ /^\s*$/ }.
          join('/').
          squeeze('/')
      end

      # Convert an array of payloads into Elasticsearch `header\ndata` format
      #
      #     Elasticsearch::API::Utils.__bulkify [
      #       { :index =>  { :_index => 'myindexA', :_type => 'mytype', :_id => '1', :data => { :title => 'Test' } } },
      #       { :update => { :_index => 'myindexB', :_type => 'mytype', :_id => '2', :data => { :doc => { :title => 'Update' } } } }
      #     ]
      #
      #     # => {"index":{"_index":"myindexA","_type":"mytype","_id":"1"}}
      #     # => {"title":"Test"}
      #     # => {"update":{"_index":"myindexB","_type":"mytype","_id":"2"}}
      #     # => {"doc":{"title":"Update"}}
      #
      def __bulkify(payload)
        case
        # Hashes with `:data`
        when payload.any? { |d| d.is_a?(Hash) && d.values.first.is_a?(Hash) && (d.values.first[:data] || d.values.first['data']) }
          payload = payload.
          inject([]) do |sum, item|
            operation, meta = item.to_a.first
            meta            = meta.clone
            data            = meta.delete(:data) || meta.delete('data')

            sum << { operation => meta }
            sum << data if data
            sum
          end.
          map { |item| MultiJson.dump(item) }
          payload << "" unless payload.empty?
          return payload.join("\n")

        # Array of strings
        when payload.all? { |d| d.is_a? String }
          payload << ''

        # Header/Data pairs
        else
          payload = payload.map { |item| MultiJson.dump(item) }
          payload << ''
        end

        payload = payload.join("\n")
      end

      # Validates the argument Hash against common and valid API parameters
      #
      # @param arguments [Hash]             Hash of arguments to verify and extract, **with symbolized keys**
      # @param valid_params [Array<Symbol>] An array of symbols with valid keys
      #
      # @return [Hash]         Return whitelisted Hash
      # @raise [ArgumentError] If the arguments Hash contains invalid keys
      #
      # @example Extract parameters
      #   __validate_and_extract_params { :foo => 'qux' }, [:foo, :bar]
      #   # => { :foo => 'qux' }
      #
      # @example Raise an exception for invalid parameters
      #   __validate_and_extract_params { :foo => 'qux', :bam => 'mux' }, [:foo, :bar]
      #   # ArgumentError: "URL parameter 'bam' is not supported"
      #
      # @api private
      #
      def __validate_and_extract_params(arguments, valid_params=[])
        arguments.each do |k,v|
          raise ArgumentError, "URL parameter '#{k}' is not supported" \
            unless valid_params.include?(k) || COMMON_PARAMS.include?(k)
        end

        params = arguments.select { |k,v| valid_params.include?(k) }
        params = Hash[params] unless params.is_a?(Hash) # Normalize Ruby 1.8 and Ruby 1.9 Hash#select behaviour
        params
      end

      extend self
    end
  end
end