Add db structure, fix filePath, start filtering

This commit I made several changes:

- Use structure instead of simple bson.M(interface{}). bson.M has
  some shortcomings: 1) It makes the database in chaos and hard to
  read, but this's not important; 2) Some entrys may has more or
  less content than others, which makes it hard to decode and filt.
  So I design new data structure to encode and decode. Hopes that
  there's no bugs.
- Fix the way to calculate file path. The original method is to add
  all the PATH entries together, that's totally wrong! PATH entry
  has several types, as it shows in "objtype". I can't find it in
  the kernel src code, so what i know is just "PARENT" means the dir
  the file is in, while the filename itself has the path, so we
  whould ignore all "PARENT"s. When the src code is found, we should
  check it again.
- Fix bugs in updating. The update function of mongodb is set to
  required to has a '$' such as 'set'/'push', so when we update a
  whole doc, we should use replace but not update function. And,
  we should never ignore the error infomation it gives us.

Hope that there's no more bugs for this Big Change.

Now its' time to write filter as well as viewer. Best wishes with
NO BUGS!

1 files changed, 122 insertions, 0 deletions

diff --git a/listener/mongo.go b/listener/mongo.go
new file mode 100644
index 0000000..a51350e
--- /dev/null
+++ b/listener/mongo.go
@@ -0,0 +1,122 @@
+package main
+
+import (
+        "context"
+        "fmt"
+        "reflect"
+        "time"
+
+        "go.mongodb.org/mongo-driver/bson"
+        "go.mongodb.org/mongo-driver/mongo"
+        "go.mongodb.org/mongo-driver/mongo/options"
+)
+
+type mongoClient struct {
+        dbName, colName string
+        client          *mongo.Client
+        col             *mongo.Collection
+}
+
+func (mc *mongoClient) init(dbName, colName string) error {
+        var err error
+        if err = mc.Connect(dbName, colName); err != nil {
+                return err
+        }
+        if err = mc.Drop(); err != nil {
+                return err
+        }
+
+        return nil
+}
+
+func (mc *mongoClient) Connect(dbName, colName string) error {
+        var err error
+        mc.client, err = mongo.NewClient(options.Client().ApplyURI("mongodb://localhost:27017"))
+
+        if err != nil {
+                return err
+        }
+
+        ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
+        err = mc.client.Connect(ctx)
+        if err != nil {
+                return err
+        }
+
+        mc.col = mc.client.Database(dbName).Collection(colName)
+        mc.dbName = dbName
+        mc.colName = colName
+        return nil
+}
+
+func (mc *mongoClient) InsertOne(document interface{}) error {
+        _, err := mc.col.InsertOne(context.Background(), document)
+        return err
+}
+
+func (mc *mongoClient) UpdateOne(filter, update interface{}) error {
+        _, err := mc.col.UpdateOne(context.Background(), filter, update)
+        return err
+}
+
+func (mc *mongoClient) UpdateMany(filter, update interface{}) error {
+        _, err := mc.col.UpdateMany(context.Background(), filter, update)
+        return err
+}
+
+func (mc *mongoClient) ReplaceOne(filter, new interface{}) error {
+        _, err := mc.col.ReplaceOne(context.Background(), filter, new)
+        return err
+}
+
+func (mc *mongoClient) Finddoc(filter bson.M, results interface{}) error {
+        sliceValue := reflect.ValueOf(results)
+
+        if sliceValue.Kind() != reflect.Ptr || sliceValue.Elem().Kind() != reflect.Slice {
+                return fmt.Errorf("Error: result argument must be pointer to slice")
+        }
+        cur, err := mc.col.Find(context.TODO(), filter)
+        if err != nil {
+                return err
+        }
+        defer cur.Close(context.TODO())
+
+        elemType := sliceValue.Elem().Type().Elem()
+
+        sliceValue = sliceValue.Elem()
+
+        for cur.Next(context.TODO()) {
+                elem := reflect.New(elemType).Interface()
+                err := cur.Decode(elem)
+                if err != nil {
+                        return err
+                }
+                sliceValue = reflect.Append(sliceValue, reflect.ValueOf(elem).Elem())
+        }
+
+        reflect.ValueOf(results).Elem().Set(sliceValue)
+        return nil
+}
+
+func (mc *mongoClient) FindOneAndDelete(filter bson.M) (bson.M, error) {
+        res := mc.col.FindOneAndDelete(context.Background(), filter)
+        var result bson.M
+        err := res.Decode(&result)
+        return result, err
+}
+
+func (mc *mongoClient) Drop() error {
+        return mc.col.Drop(context.Background())
+}
+
+func (mc *mongoClient) Disconnect() error {
+        err := mc.client.Disconnect(context.Background())
+        if err != nil {
+                return err
+        }
+        mc.col = nil
+        mc.client = nil
+        mc.dbName = ""
+        mc.colName = ""
+        return nil
+}