require 'rubygems'
require 'redis'

$redis = Redis.new()
$redis.select(3)

# do a zdiffstore only on scores that match
# ie [23:12345] will only be removed by [23:12345], not [23:12350]
def zdiffstore(x, y)
    $redis.zunionstore "tmp.zu", [x, y], :weights=>[1,-1], :aggregate=>:sum
    $redis.zremrangebyscore("tmp.zu", "0", "+inf")
    $redis.zinterstore "o", ["tmp.zu", y], :weights=>[1,1], :aggregate=>:max
    x = $redis.zrange "o", 0, -1, :with_scores => true
    return Hash[*x.flatten]
end

# do a zdiffstore ignoring scores that differ
# ie [23:12345] will be removed by [23:12350]
def zdiffstore_justkeys(x, y)
    $redis.zunionstore "tmp.zu", [x, y], :weights=>['-inf',1], :aggregate=>:sum
    $redis.zremrangebyscore("tmp.zu", "-inf", "0")
    $redis.zinterstore "o", ["tmp.zu", y], :weights=>[1,1], :aggregate=>:max
    x = $redis.zrange "o", 0, -1, :with_scores => true
    return Hash[*x.flatten]
end

a = zdiffstore("user:rjp:read", "all:messages")
p a.size