func BuildUpdateDelteOplog()

in oplog/oplog.go [315:385]
61 lines of code
18 McCabe index (conditional complexity)

func BuildUpdateDelteOplog(prefixField string, obj bson.D) (interface{}, error) {
	var result bson.D

	for _, ele := range obj {
		if ele.Key == "d" {
			result = append(result, primitive.E{
				Key:   "$unset",
				Value: combinePrefixField(prefixField, ele.Value)})

		} else if ele.Key == "i" || ele.Key == "u" {
			result = append(result, primitive.E{
				Key:   "$set",
				Value: combinePrefixField(prefixField, ele.Value)})

		} else if len(ele.Key) > 1 && ele.Key[0] == 's' {
			// s means subgroup field(array or nest)
			tmpPrefixField := ""
			if len(prefixField) == 0 {
				tmpPrefixField = ele.Key[1:]
			} else {
				tmpPrefixField = prefixField + "." + ele.Key[1:]
			}

			nestObj, err := BuildUpdateDelteOplog(tmpPrefixField, ele.Value.(bson.D))
			if err != nil {
				return obj, fmt.Errorf("parse ele[%v] failed, updateObj:[%v]", ele, obj)
			}
			if _, ok := nestObj.(mongo.Pipeline); ok {
				return nestObj, nil
			} else if _, ok := nestObj.(bson.D); ok {
				for _, nestObjEle := range nestObj.(bson.D) {
					result = append(result, nestObjEle)
				}
			} else {
				return obj, fmt.Errorf("unknown nest type ele[%v] updateObj:[%v] nestObj[%v]", ele, obj, nestObj)
			}

		} else if len(ele.Key) > 1 && ele.Key[0] == 'u' {
			result = append(result, primitive.E{
				Key: "$set",
				Value: bson.D{
					primitive.E{
						Key:   prefixField + "." + ele.Key[1:],
						Value: ele.Value,
					},
				},
			})

		} else if ele.Key == "l" {
			if len(result) != 0 {
				return obj, fmt.Errorf("len should be 0, Key[%v] updateObj:[%v], result:[%v]",
					ele, obj, result)
			}

			return mongo.Pipeline{
				{{"$set", bson.D{
					{prefixField, bson.D{
						{"$slice", []interface{}{"$" + prefixField, ele.Value}},
					}},
				}}},
			}, nil

		} else if ele.Key == "a" && ele.Value == true {
			continue
		} else {
			return obj, fmt.Errorf("unknow Key[%v] updateObj:[%v]", ele, obj)
		}
	}

	return result, nil
}