# RubyRedis is an alternative implementatin of Ruby client library written
# by Salvatore Sanfilippo.
#
# The aim of this library is to create an alternative client library that is
# much simpler and does not implement every command explicitly but uses
# method_missing instead.

require 'socket'

class RedisClient
    BulkCommands = {
        "set"=>true, "setnx"=>true, "rpush"=>true, "lpush"=>true, "lset"=>true,
        "lrem"=>true, "sadd"=>true, "srem"=>true, "sismember"=>true,
        "echo"=>true, "getset"=>true, "smove"=>true
    }

    ConvertToBool = lambda{|r| r == 0 ? false : r}

    ReplyProcessor = {
        "exists" => ConvertToBool,
        "sismember"=> ConvertToBool,
        "sadd"=> ConvertToBool,
        "srem"=> ConvertToBool,
        "smove"=> ConvertToBool,
        "move"=> ConvertToBool,
        "setnx"=> ConvertToBool,
        "del"=> ConvertToBool,
        "renamenx"=> ConvertToBool,
        "expire"=> ConvertToBool,
        "keys" => lambda{|r| r.split(" ")},
        "info" => lambda{|r| 
            info = {}
            r.each_line {|kv|
                k,v = kv.split(':', 2)
                k,v = k.chomp, v = v.chomp
                info[k.to_sym] = v
            }
            info
        }
    }

    def convert_to_bool(r)
        r == 0 ? false : r
    end

    def initialize(opts={})
        opts = {:host => 'localhost', :port => '6379', :db => 0}.merge(opts)
        @host = opts[:host]
        @port = opts[:port]
        @db = opts[:db]
        connect_to_server
    end

    def to_s
        "Redis Client connected to #{@host}:#{@port} against DB #{@db}"
    end

    def connect_to_server
        @sock = TCPSocket.new(@host, @port, 0)
        call_command(["select",@db]) if @db != 0
    end

    def method_missing(*argv)
        call_command(argv)
    end

    def call_command(argv)
        # this wrapper to raw_call_command handle reconnection on socket
        # error. We try to reconnect just one time, otherwise let the error
        # araise.
        begin
            raw_call_command(argv)
        rescue Errno::ECONNRESET
            @sock.close
            connect_to_server
            raw_call_command(argv)
        end
    end

    def raw_call_command(argv)
        bulk = nil
        argv[0] = argv[0].to_s.downcase
        if BulkCommands[argv[0]]
            bulk = argv[-1].to_s
            argv[-1] = bulk.length
        end
        @sock.write(argv.join(" ")+"\r\n")
        @sock.write(bulk+"\r\n") if bulk

        # Post process the reply if needed
        processor = ReplyProcessor[argv[0]]
        processor ? processor.call(read_reply) : read_reply
    end

    def select(*args)
        raise "SELECT not allowed, use the :db option when creating the object"
    end

    def [](key)
        get(key)
    end

    def []=(key,value)
        set(key,value)
    end

    def read_reply
        line = @sock.gets
        raise Errno::ECONNRESET,"Connection lost" if !line
        case line[0..0]
        when "-"
            raise line.strip
        when "+"
            line[1..-1].strip
        when ":"
            line[1..-1].to_i
        when "$"
            bulklen = line[1..-1].to_i
            return nil if bulklen == -1
            data = @sock.read(bulklen)
            @sock.read(2) # CRLF
            data
        when "*"
            objects = line[1..-1].to_i
            return nil if bulklen == -1
            res = []
            objects.times {
                res << read_reply
            }
            res
        end
    end
end