如何使用Redis和Lua开发简单的评分系统功能

-- 参数说明：
-- entityId: 实体的唯一标识
-- userId: 用户的唯一标识
-- voteType: 投票类型，1表示赞成，-1表示反对

function vote(entityId, userId, voteType)
    -- 检查用户是否已经投过票，如果是则取消之前的投票
    local prevVoteType = redis.call("HGET", "vote:" .. entityId, userId)
    if prevVoteType == "1" then
        redis.call("HINCRBY", "score:" .. entityId, "upvotes", -1)
    elseif prevVoteType == "-1" then
        redis.call("HINCRBY", "score:" .. entityId, "downvotes", -1)
    end

    -- 更新用户的投票记录
    redis.call("HSET", "vote:" .. entityId, userId, voteType)

    -- 更新实体的分数
    if voteType == "1" then
        redis.call("HINCRBY", "score:" .. entityId, "upvotes", 1)
    elseif voteType == "-1" then
        redis.call("HINCRBY", "score:" .. entityId, "downvotes", 1)
    end
end

-- 参数说明：
-- entityId: 实体的唯一标识

function calculateScore(entityId)
    local upvotes = redis.call("HGET", "score:" .. entityId, "upvotes") or 0
    local downvotes = redis.call("HGET", "score:" .. entityId, "downvotes") or 0

    -- 分数计算规则可以根据实际需求进行调整
    local score = tonumber(upvotes) - tonumber(downvotes)

    -- 更新实体的分数
    redis.call("HSET", "score:" .. entityId, "score", score)

    return score
end

-- 参数说明：
-- entityIds: 实体的唯一标识列表

function sortEntities(entityIds)
    local scores = {}
    for i, entityId in ipairs(entityIds) do
        local score = redis.call("HGET", "score:" .. entityId, "score") or 0
        scores[i] = {entityId, tonumber(score)}
    end

    -- 根据分数进行排序
    table.sort(scores, function(a, b) return a[2] > b[2] end)

    -- 返回按照分数排序后的实体列表
    local sortedEntities = {}
    for i, entity in ipairs(scores) do
        sortedEntities[i] = entity[1]
    end

    return sortedEntities
end