require 'rubygems'
require 'net/http'
require 'open-uri'
require 'json'
 
module ActiveRecord
  module ConnectionAdapters
 
    class DbslayerException < RuntimeError
    end
    
    class DbslayerResult
      def initialize(results_hash)
        @hash = results_hash
      end
 
      def rows
        @hash['ROWS']
      end
 
      def types
        @hash['TYPES']
      end
 
      def header
        @hash['HEADER']
      end
      
      ## Compatibility to the MySQL ones
      def num_rows
        return 0 if rows.nil?
        rows.size
      end
 
      def each
        return if rows.nil?
        rows.each {|r| yield r }
      end
      
      def hash_rows
        return [] if rows.nil?
        rows.map do |row|
          hash = {}
          header.each_with_index do |head, i|
            hash[head] = row[i]
          end
          
          hash
        end
      end
      
      def each_hash
        return if rows.nil?
        hash_rows.each do |row|            
          yield row
        end
      end
    end
 
    class DbslayerConnection
      attr_reader :host, :port
      
      def initialize(host='localhost', port=9090)
        @host = host
        @port = port
      end
 
      ##
      # Executes a SQL query
      def sql_query(sql)
        dbslay_results = cmd_execute(:db, 'SQL' => sql)
                
        # check for an error
        if dbslay_results['MYSQL_ERROR']
          raise DbslayerException, "MySQL Error #{dbslay_results['MYSQL_ERRNO']}: #{dbslay_results['MYSQL_ERROR']}"
        elsif dbslay_results['RESULT']
          result = dbslay_results['RESULT']
          case result
          when Hash
            DbslayerResult.new(result)
          when Array
            result.map {|r| DbslayerResult.new(r) }
          else  
            raise DbslayerException, "Unknown format for SQL results from DBSlayer"
          end
        elsif dbslay_results['SUCCESS']
          return dbslay_results['SUCCESS']
        else  
          raise DbslayerException, "Unknown format for SQL results from DBSlayer"
        end
      end
 
      alias execute sql_query
      alias query sql_query
 
      def mysql_stats
        results = cmd_execute(:db, 'STAT' => true)
        results['STAT']
      end
 
      alias stat mysql_stats
 
      def client_info
        if @client_info.nil?
          @client_info = cmd_execute(:db, 'CLIENT_INFO' => true)["CLIENT_INFO"]
        end
        @client_info
      end
 
      alias server_info client_info
 
      def client_version_num
        if @client_version.nil?
          @client_version = Integer(cmd_execute(:db, 'CLIENT_VERSION' => true)["CLIENT_VERSION"])
        end
        @client_version
      end
 
      def server_version_num
        if @server_version.nil?
          @server_version = Integer(cmd_execute(:db, 'SERVER_VERSION' => true)["SERVER_VERSION"])
        end
        @server_version
      end
 
      def escape_string(str)
        str.gsub(/([\0\n\r\032\'\"\\])/) do
          case $1
          when "\0" then "\\0"
          when "\n" then "\\n"
          when "\r" then "\\r"
          when "\032" then "\\Z"
          else "\\"+$1
          end
        end
      end
      alias :quote :escape_string
      
      private 
      def query_string(commands)
        URI.encode commands.to_json
      end
 
      ##
      # Returns a JSON date
      def cmd_execute(endpoint, commands)
        url = "http://#{host}:#{port}/#{endpoint.to_s}?#{query_string(commands)}"
        open(url) do |file|
          JSON.parse(file.read)
        end
      end
    end
  end
end