added the database actions, development started in the db-container repo, for more info, see those commits

1 files changed, 883 insertions, 0 deletions

diff --git a/db_actions.go b/db_actions.go
new file mode 100644
index 0000000..561ce56
--- /dev/null
+++ b/db_actions.go
@@ -0,0 +1,883 @@
+// db_actions defines actions on the database
+// Copyright (C) 2019 Emile Hansmaennel
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+package db_actions
+
+import (
+	"database/sql"
+	"encoding/csv"
+	"fmt"
+	"git.darknebu.la/GalaxySimulator/structs"
+	_ "github.com/lib/pq"
+	"io"
+	"io/ioutil"
+	"log"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	DBUSER    = "postgres"
+	DBNAME    = "postgres"
+	DBSSLMODE = "disable"
+)
+
+var (
+	db *sql.DB
+)
+
+// connectToDB returns a pointer to an sql database writing to the database
+func ConnectToDB() *sql.DB {
+	connStr := fmt.Sprintf("user=%s dbname=%s sslmode=%s", DBUSER, DBNAME, DBSSLMODE)
+	db := dbConnect(connStr)
+	return db
+}
+
+// dbConnect connects to a PostgreSQL database
+func dbConnect(connStr string) *sql.DB {
+	// connect to the database
+	db, err := sql.Open("postgres", connStr)
+	if err != nil {
+		log.Fatalf("[ E ] connection: %v", err)
+	}
+
+	return db
+}
+
+// newTree creates a new tree with the given width
+func NewTree(database *sql.DB, width float64) {
+	db = database
+	// get the current max root id
+	query := fmt.Sprintf("SELECT COALESCE(max(root_id), 0) FROM nodes")
+	var currentMaxRootID int64
+	err := db.QueryRow(query).Scan(&currentMaxRootID)
+	if err != nil {
+		log.Fatalf("[ E ] max root id query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	// build the query creating a new node
+	query = fmt.Sprintf("INSERT INTO nodes (box_width, root_id, box_center, depth, isleaf) VALUES (%f, %d, '{0, 0}', 0, TRUE)", width, currentMaxRootID+1)
+
+	// execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] insert new node query: %v\n\t\t\t query: %s\n", err, query)
+	}
+}
+
+// insertStar inserts the given star into the stars table and the nodes table tree
+func InsertStar(database *sql.DB, star structs.Star2D, index int64) {
+	db = database
+	start := time.Now()
+	// insert the star into the stars table
+	starID := insertIntoStars(star)
+
+	// get the root node id
+	query := fmt.Sprintf("SELECT node_id FROM nodes WHERE root_id=%d", index)
+	var id int64
+	err := db.QueryRow(query).Scan(&id)
+	if err != nil {
+		log.Fatalf("[ E ] Get root node id query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	// insert the star into the tree (using it's ID) starting at the root
+	insertIntoTree(starID, id)
+	elapsedTime := time.Since(start)
+	log.Printf("\t\t\t\t\t %s", elapsedTime)
+}
+
+// insertIntoStars inserts the given star into the stars table
+func insertIntoStars(star structs.Star2D) int64 {
+	// unpack the star
+	x := star.C.X
+	y := star.C.Y
+	vx := star.V.X
+	vy := star.V.Y
+	m := star.M
+
+	// build the request query
+	query := fmt.Sprintf("INSERT INTO stars (x, y, vx, vy, m) VALUES (%f, %f, %f, %f, %f) RETURNING star_id", x, y, vx, vy, m)
+
+	// execute the query
+	var starID int64
+	err := db.QueryRow(query).Scan(&starID)
+	if err != nil {
+		log.Fatalf("[ E ] insert query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	return starID
+}
+
+// insert into tree inserts the given star into the tree starting at the node with the given node id
+func insertIntoTree(starID int64, nodeID int64) {
+	//starRaw := getStar(starID)
+	//nodeCenter := getBoxCenter(nodeID)
+	//nodeWidth := getBoxWidth(nodeID)
+	//log.Printf("[   ] \t Inserting star %v into the node (c: %v, w: %v)", starRaw, nodeCenter, nodeWidth)
+
+	// There exist four cases:
+	//                    | Contains a Star | Does not Contain a Star |
+	// ------------------ + --------------- + ----------------------- +
+	// Node is a Leaf     | Impossible      | insert into node        |
+	//                    |                 | subdivide               |
+	// ------------------ + --------------- + ----------------------- +
+	// Node is not a Leaf | insert preexist | insert into the subtree |
+	//                    | insert new      |                         |
+	// ------------------ + --------------- + ----------------------- +
+
+	// get the node with the given nodeID
+	// find out if the node contains a star or not
+	containsStar := containsStar(nodeID)
+
+	// find out if the node is a leaf
+	isLeaf := isLeaf(nodeID)
+
+	// if the node is a leaf and contains a star
+	// subdivide the tree
+	// insert the preexisting star into the correct subtree
+	// insert the new star into the subtree
+	if isLeaf == true && containsStar == true {
+		//log.Printf("Case 1, \t %v \t %v", nodeWidth, nodeCenter)
+		subdivide(nodeID)
+		//tree := printTree(nodeID)
+
+		// Stage 1: Inserting the blocking star
+		blockingStarID := getStarID(nodeID)                               // get the id of the star blocking the node
+		blockingStar := getStar(blockingStarID)                           // get the actual star
+		blockingStarQuadrant := quadrant(blockingStar, nodeID)            // find out in which quadrant it belongs
+		quadrantNodeID := getQuadrantNodeID(nodeID, blockingStarQuadrant) // get the nodeID of that quadrant
+		insertIntoTree(blockingStarID, quadrantNodeID)                    // insert the star into that node
+		removeStarFromNode(nodeID)                                        // remove the blocking star from the node it was blocking
+
+		// Stage 1: Inserting the actual star
+		star := getStar(starID)                                  // get the actual star
+		starQuadrant := quadrant(star, nodeID)                   // find out in which quadrant it belongs
+		quadrantNodeID = getQuadrantNodeID(nodeID, starQuadrant) // get the nodeID of that quadrant
+		insertIntoTree(starID, nodeID)
+	}
+
+	// if the node is a leaf and does not contain a star
+	// insert the star into the node and subdivide it
+	if isLeaf == true && containsStar == false {
+		//log.Printf("Case 2, \t %v \t %v", nodeWidth, nodeCenter)
+		directInsert(starID, nodeID)
+	}
+
+	// if the node is not a leaf and contains a star
+	// insert the preexisting star into the correct subtree
+	// insert the new star into the subtree
+	if isLeaf == false && containsStar == true {
+		//log.Printf("Case 3, \t %v \t %v", nodeWidth, nodeCenter)
+		// Stage 1: Inserting the blocking star
+		blockingStarID := getStarID(nodeID)                               // get the id of the star blocking the node
+		blockingStar := getStar(blockingStarID)                           // get the actual star
+		blockingStarQuadrant := quadrant(blockingStar, nodeID)            // find out in which quadrant it belongs
+		quadrantNodeID := getQuadrantNodeID(nodeID, blockingStarQuadrant) // get the nodeID of that quadrant
+		insertIntoTree(blockingStarID, quadrantNodeID)                    // insert the star into that node
+		removeStarFromNode(nodeID)                                        // remove the blocking star from the node it was blocking
+
+		// Stage 1: Inserting the actual star
+		star := getStar(blockingStarID)                          // get the actual star
+		starQuadrant := quadrant(star, nodeID)                   // find out in which quadrant it belongs
+		quadrantNodeID = getQuadrantNodeID(nodeID, starQuadrant) // get the nodeID of that quadrant
+		insertIntoTree(starID, nodeID)
+	}
+
+	// if the node is not a leaf and does not contain a star
+	// insert the new star into the according subtree
+	if isLeaf == false && containsStar == false {
+		//log.Printf("Case 4, \t %v \t %v", nodeWidth, nodeCenter)
+		star := getStar(starID)                                   // get the actual star
+		starQuadrant := quadrant(star, nodeID)                    // find out in which quadrant it belongs
+		quadrantNodeID := getQuadrantNodeID(nodeID, starQuadrant) // get the if of that quadrant
+		insertIntoTree(starID, quadrantNodeID)                    // insert the star into that quadrant
+	}
+}
+
+// containsStar returns true if the node with the given id contains a star and returns false if not.
+func containsStar(id int64) bool {
+	var starID int64
+
+	query := fmt.Sprintf("SELECT star_id FROM nodes WHERE node_id=%d", id)
+	err := db.QueryRow(query).Scan(&starID)
+	if err != nil {
+		log.Fatalf("[ E ] containsStar query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	if starID != 0 {
+		return true
+	}
+
+	return false
+}
+
+// isLeaf returns true if the node with the given id is a leaf
+func isLeaf(nodeID int64) bool {
+	var isLeaf bool
+
+	query := fmt.Sprintf("SELECT COALESCE(isleaf, FALSE) FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&isLeaf)
+	if err != nil {
+		log.Fatalf("[ E ] isLeaf query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	if isLeaf == true {
+		return true
+	}
+
+	return false
+}
+
+// directInsert inserts the star with the given ID into the given node inside of the given database
+func directInsert(starID int64, nodeID int64) {
+	// build the query
+	query := fmt.Sprintf("UPDATE nodes SET star_id=%d WHERE node_id=%d", starID, nodeID)
+
+	// Execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] directInsert query: %v\n\t\t\t query: %s\n", err, query)
+	}
+}
+
+// subdivide subdivides the given node creating four child nodes
+func subdivide(nodeID int64) {
+	boxWidth := getBoxWidth(nodeID)
+	boxCenter := getBoxCenter(nodeID)
+	originalDepth := getNodeDepth(nodeID)
+
+	// calculate the new positions
+	newPosX := boxCenter[0] + (boxWidth / 2)
+	newPosY := boxCenter[1] + (boxWidth / 2)
+	newNegX := boxCenter[0] - (boxWidth / 2)
+	newNegY := boxCenter[1] - (boxWidth / 2)
+	newWidth := boxWidth / 2
+
+	// create new news with those positions
+	newNodeIDA := newNode(newPosX, newPosY, newWidth, originalDepth+1)
+	newNodeIDB := newNode(newPosX, newNegY, newWidth, originalDepth+1)
+	newNodeIDC := newNode(newNegX, newPosY, newWidth, originalDepth+1)
+	newNodeIDD := newNode(newNegX, newNegY, newWidth, originalDepth+1)
+
+	// Update the subtrees of the parent node
+
+	// build the query
+	query := fmt.Sprintf("UPDATE nodes SET subnode='{%d, %d, %d, %d}', isleaf=FALSE WHERE node_id=%d", newNodeIDA, newNodeIDB, newNodeIDC, newNodeIDD, nodeID)
+
+	// Execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] subdivide query: %v\n\t\t\t query: %s\n", err, query)
+	}
+}
+
+// getBoxWidth gets the width of the box from the node width the given id
+func getBoxWidth(nodeID int64) float64 {
+	var boxWidth float64
+
+	query := fmt.Sprintf("SELECT box_width FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&boxWidth)
+	if err != nil {
+		log.Fatalf("[ E ] getBoxWidth query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	return boxWidth
+}
+
+// getBoxWidth gets the center of the box from the node width the given id
+func getBoxCenter(nodeID int64) []float64 {
+	var boxCenterX, boxCenterY []uint8
+
+	query := fmt.Sprintf("SELECT box_center[1], box_center[2] FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&boxCenterX, &boxCenterY)
+	if err != nil {
+		log.Fatalf("[ E ] getBoxCenter query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	x, parseErr := strconv.ParseFloat(string(boxCenterX), 64)
+	y, parseErr := strconv.ParseFloat(string(boxCenterX), 64)
+
+	if parseErr != nil {
+		log.Fatalf("[ E ] parse boxCenter: %v\n\t\t\t query: %s\n", err, query)
+		log.Fatalf("[ E ] parse boxCenter: (%f, %f)\n", x, y)
+	}
+
+	boxCenterFloat := []float64{x, y}
+
+	return boxCenterFloat
+}
+
+// newNode Inserts a new node into the database with the given parameters
+func newNode(x float64, y float64, width float64, depth int64) int64 {
+	// build the query creating a new node
+	query := fmt.Sprintf("INSERT INTO nodes (box_center, box_width, depth, isleaf) VALUES ('{%f, %f}', %f, %d, TRUE) RETURNING node_id", x, y, width, depth)
+
+	var nodeID int64
+
+	// execute the query
+	err := db.QueryRow(query).Scan(&nodeID)
+	if err != nil {
+		log.Fatalf("[ E ] newNode query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	return nodeID
+}
+
+// getStarID returns the id of the star inside of the node with the given ID
+func getStarID(nodeID int64) int64 {
+	// get the star id from the node
+	var starID int64
+	query := fmt.Sprintf("SELECT star_id FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&starID)
+	if err != nil {
+		log.Fatalf("[ E ] getStarID id query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	return starID
+}
+
+// deleteAll Stars deletes all the rows in the stars table
+func DeleteAllStars(database *sql.DB) {
+	db = database
+	// build the query creating a new node
+	query := "DELETE FROM stars WHERE TRUE"
+
+	// execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] deleteAllStars query: %v\n\t\t\t query: %s\n", err, query)
+	}
+}
+
+// deleteAll Stars deletes all the rows in the nodes table
+func DeleteAllNodes(database *sql.DB) {
+	db = database
+	// build the query creating a new node
+	query := "DELETE FROM nodes WHERE TRUE"
+
+	// execute the query
+	_, err := db.Query(query)
+	if err != nil {
+		log.Fatalf("[ E ] deleteAllStars query: %v\n\t\t\t query: %s\n", err, query)
+	}
+}
+
+// getNodeDepth returns the depth of the given node in the tree
+func getNodeDepth(nodeID int64) int64 {
+	// build the query
+	query := fmt.Sprintf("SELECT depth FROM nodes WHERE node_id=%d", nodeID)
+
+	var depth int64
+
+	// Execute the query
+	err := db.QueryRow(query).Scan(&depth)
+	if err != nil {
+		log.Fatalf("[ E ] getNodeDepth query: %v \n\t\t\t query: %s\n", err, query)
+	}
+
+	return depth
+}
+
+// quadrant returns the quadrant into which the given star belongs
+func quadrant(star structs.Star2D, nodeID int64) int64 {
+	// get the center of the node the star is in
+	center := getBoxCenter(nodeID)
+	centerX := center[0]
+	centerY := center[1]
+
+	if star.C.X > centerX {
+		if star.C.Y > centerY {
+			// North East condition
+			return 1
+		}
+		// South East condition
+		return 3
+	}
+
+	if star.C.Y > centerY {
+		// North West condition
+		return 0
+	}
+	// South West condition
+	return 2
+}
+
+// getQuadrantNodeID returns the id of the requested child-node
+// Example: if a parent has four children and quadrant 0 is requested, the function returns the north east child id
+func getQuadrantNodeID(parentNodeID int64, quadrant int64) int64 {
+	var a, b, c, d []uint8
+
+	// get the star from the stars table
+	query := fmt.Sprintf("SELECT subnode[1], subnode[2], subnode[3], subnode[4] FROM nodes WHERE node_id=%d", parentNodeID)
+	err := db.QueryRow(query).Scan(&a, &b, &c, &d)
+	if err != nil {
+		log.Fatalf("[ E ] getQuadrantNodeID star query: %v \n\t\t\tquery: %s\n", err, query)
+	}
+
+	returnA, _ := strconv.ParseInt(string(a), 10, 64)
+	returnB, _ := strconv.ParseInt(string(b), 10, 64)
+	returnC, _ := strconv.ParseInt(string(c), 10, 64)
+	returnD, _ := strconv.ParseInt(string(d), 10, 64)
+
+	switch quadrant {
+	case 0:
+		return returnA
+	case 1:
+		return returnB
+	case 2:
+		return returnC
+	case 3:
+		return returnD
+	}
+
+	return -1
+}
+
+// getStar returns the star with the given ID from the stars table
+func getStar(starID int64) structs.Star2D {
+	var x, y, vx, vy, m float64
+
+	// get the star from the stars table
+	query := fmt.Sprintf("SELECT x, y, vx, vy, m FROM stars WHERE star_id=%d", starID)
+	err := db.QueryRow(query).Scan(&x, &y, &vx, &vy, &m)
+	if err != nil {
+		log.Fatalf("[ E ] getStar query: %v \n\t\t\tquery: %s\n", err, query)
+	}
+
+	star := structs.Star2D{
+		C: structs.Vec2{
+			X: x,
+			Y: y,
+		},
+		V: structs.Vec2{
+			X: vx,
+			Y: vy,
+		},
+		M: m,
+	}
+
+	return star
+}
+
+// getStarMass returns the mass if the star with the given ID
+func getStarMass(starID int64) float64 {
+	var mass float64
+
+	// get the star from the stars table
+	query := fmt.Sprintf("SELECT m FROM stars WHERE star_id=%d", starID)
+	err := db.QueryRow(query).Scan(&mass)
+	if err != nil {
+		log.Fatalf("[ E ] getStarMass query: %v \n\t\t\tquery: %s\n", err, query)
+	}
+
+	return mass
+}
+
+// getNodeTotalMass returns the total mass of the node with the given ID and its children
+func getNodeTotalMass(nodeID int64) float64 {
+	var mass float64
+
+	// get the star from the stars table
+	query := fmt.Sprintf("SELECT total_mass FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&mass)
+	if err != nil {
+		log.Fatalf("[ E ] getStarMass query: %v \n\t\t\tquery: %s\n", err, query)
+	}
+
+	return mass
+}
+
+// removeStarFromNode removes the star from the node with the given ID
+func removeStarFromNode(nodeID int64) {
+	// build the query
+	query := fmt.Sprintf("UPDATE nodes SET star_id=0 WHERE node_id=%d", nodeID)
+
+	// Execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] removeStarFromNode query: %v\n\t\t\t query: %s\n", err, query)
+	}
+}
+
+// getListOfStarsGo returns the list of stars in go struct format
+func GetListOfStarsGo(database *sql.DB) []structs.Star2D {
+	db = database
+	// build the query
+	query := fmt.Sprintf("SELECT * FROM stars")
+
+	// Execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] removeStarFromNode query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	var starList []structs.Star2D
+
+	// iterate over the returned rows
+	for rows.Next() {
+
+		var starID int64
+		var x, y, vx, vy, m float64
+		scanErr := rows.Scan(&starID, &x, &y, &vx, &vy, &m)
+		if scanErr != nil {
+			log.Fatalf("[ E ] scan error: %v", scanErr)
+		}
+
+		star := structs.Star2D{
+			C: structs.Vec2{
+				X: x,
+				Y: y,
+			},
+			V: structs.Vec2{
+				X: vx,
+				Y: vy,
+			},
+			M: m,
+		}
+
+		starList = append(starList, star)
+	}
+
+	return starList
+}
+
+// getListOfStarsCsv returns an array of strings containing the coordinates of all the stars in the stars table
+func GetListOfStarsCsv(database *sql.DB) []string {
+	db = database
+	// build the query
+	query := fmt.Sprintf("SELECT * FROM stars")
+
+	// Execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] removeStarFromNode query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	var starList []string
+
+	// iterate over the returned rows
+	for rows.Next() {
+
+		var starID int64
+		var x, y, vx, vy, m float64
+		scanErr := rows.Scan(&starID, &x, &y, &vx, &vy, &m)
+		if scanErr != nil {
+			log.Fatalf("[ E ] scan error: %v", scanErr)
+		}
+
+		row := fmt.Sprintf("%d, %f, %f, %f, %f, %f", starID, x, y, vx, vy, m)
+		starList = append(starList, row)
+	}
+
+	return starList
+}
+
+// insertList inserts all the stars in the given .csv into the stars and nodes table
+func InsertList(database *sql.DB, filename string) {
+	db = database
+	// open the file
+	content, readErr := ioutil.ReadFile(filename)
+	if readErr != nil {
+		panic(readErr)
+	}
+
+	in := string(content)
+	reader := csv.NewReader(strings.NewReader(in))
+
+	// insert all the stars into the db
+	for {
+		record, err := reader.Read()
+		if err == io.EOF {
+			log.Println("EOF")
+			break
+		}
+		if err != nil {
+			log.Println("insertListErr")
+			panic(err)
+		}
+
+		x, _ := strconv.ParseFloat(record[0], 64)
+		y, _ := strconv.ParseFloat(record[1], 64)
+
+		star := structs.Star2D{
+			C: structs.Vec2{
+				X: x / 100000,
+				Y: y / 100000,
+			},
+			V: structs.Vec2{
+				X: 0,
+				Y: 0,
+			},
+			M: 1000,
+		}
+
+		fmt.Printf("Inserting (%f, %f)\n", star.C.X, star.C.Y)
+		InsertStar(db, star, 1)
+	}
+}
+
+// getRootNodeID gets a tree index and returns the nodeID of its root node
+func getRootNodeID(index int64) int64 {
+	var nodeID int64
+
+	query := fmt.Sprintf("SELECT node_id FROM nodes WHERE root_id=%d", index)
+	err := db.QueryRow(query).Scan(&nodeID)
+	if err != nil {
+		log.Fatalf("[ E ] getRootNodeID query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	return nodeID
+}
+
+// updateTotalMass gets a tree index and returns the nodeID of the trees root node
+func UpdateTotalMass(database *sql.DB, index int64) {
+	db = database
+	rootNodeID := getRootNodeID(index)
+	log.Printf("RootID: %d", rootNodeID)
+	updateTotalMassNode(rootNodeID)
+}
+
+// updateTotalMassNode updates the total mass of the given node
+func updateTotalMassNode(nodeID int64) float64 {
+	var totalmass float64
+
+	// get the subnode ids
+	var subnode [4]int64
+
+	query := fmt.Sprintf("SELECT subnode[1], subnode[2], subnode[3], subnode[4] FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&subnode[0], &subnode[1], &subnode[2], &subnode[3])
+	if err != nil {
+		log.Fatalf("[ E ] updateTotalMassNode query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	// iterate over all subnodes updating their total masses
+	for _, subnodeID := range subnode {
+		fmt.Println("----------------------------")
+		fmt.Printf("SubdnodeID: %d\n", subnodeID)
+		if subnodeID != 0 {
+			totalmass += updateTotalMassNode(subnodeID)
+		} else {
+			// get the starID for getting the star mass
+			starID := getStarID(nodeID)
+			fmt.Printf("StarID: %d\n", starID)
+			if starID != 0 {
+				mass := getStarMass(starID)
+				log.Printf("starID=%d \t mass: %f", starID, mass)
+				totalmass += mass
+			}
+
+			// break, this stops a star from being counted multiple (4) times
+			break
+		}
+		fmt.Println("----------------------------")
+	}
+
+	query = fmt.Sprintf("UPDATE nodes SET total_mass=%f WHERE node_id=%d", totalmass, nodeID)
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] insert total_mass query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	fmt.Printf("nodeID: %d \t totalMass: %f\n", nodeID, totalmass)
+
+	return totalmass
+}
+
+// updateCenterOfMass recursively updates the center of mass of all the nodes starting at the node with the given
+// root index
+func UpdateCenterOfMass(database *sql.DB, index int64) {
+	db = database
+	rootNodeID := getRootNodeID(index)
+	log.Printf("RootID: %d", rootNodeID)
+	updateCenterOfMassNode(rootNodeID)
+}
+
+// updateCenterOfMassNode updates the center of mass of the node with the given nodeID recursively
+// center of mass := ((x_1 * m) + (x_2 * m) + ... + (x_n * m)) / m
+func updateCenterOfMassNode(nodeID int64) structs.Vec2 {
+	fmt.Println("++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++")
+
+	var centerOfMass structs.Vec2
+
+	// get the subnode ids
+	var subnode [4]int64
+	var starID int64
+
+	query := fmt.Sprintf("SELECT subnode[1], subnode[2], subnode[3], subnode[4], star_id FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&subnode[0], &subnode[1], &subnode[2], &subnode[3], &starID)
+	if err != nil {
+		log.Fatalf("[ E ] updateCenterOfMassNode query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	// if the nodes does not contain a star but has children, update the center of mass
+	if subnode != ([4]int64{0, 0, 0, 0}) {
+		log.Println("[   ] recursing deeper")
+
+		// define variables storing the values of the subnodes
+		var totalMass float64
+		var centerOfMassX float64
+		var centerOfMassY float64
+
+		// iterate over all the subnodes and calculate the center of mass of each node
+		for _, subnodeID := range subnode {
+			subnodeCenterOfMass := updateCenterOfMassNode(subnodeID)
+
+			if subnodeCenterOfMass.X != 0 && subnodeCenterOfMass.Y != 0 {
+				fmt.Printf("SubnodeCenterOfMass: (%f, %f)\n", subnodeCenterOfMass.X, subnodeCenterOfMass.Y)
+				subnodeMass := getNodeTotalMass(subnodeID)
+				totalMass += subnodeMass
+
+				centerOfMassX += subnodeCenterOfMass.X * subnodeMass
+				centerOfMassY += subnodeCenterOfMass.Y * subnodeMass
+			}
+		}
+
+		// calculate the overall center of mass of the subtree
+		centerOfMass = structs.Vec2{
+			X: centerOfMassX / totalMass,
+			Y: centerOfMassY / totalMass,
+		}
+
+		// else, use the star as the center of mass (this can be done, because of the rule defining that there
+		// can only be one star in a cell)
+	} else {
+		log.Println("[   ] using the star in the node as the center of mass")
+		log.Printf("[   ] NodeID: %v", nodeID)
+		starID := getStarID(nodeID)
+
+		if starID == 0 {
+			log.Println("[   ] StarID == 0...")
+			centerOfMass = structs.Vec2{
+				X: 0,
+				Y: 0,
+			}
+		} else {
+			log.Printf("[   ] NodeID: %v", starID)
+			star := getStar(starID)
+			centerOfMassX := star.C.X
+			centerOfMassY := star.C.Y
+			centerOfMass = structs.Vec2{
+				X: centerOfMassX,
+				Y: centerOfMassY,
+			}
+		}
+	}
+
+	// build the query
+	query = fmt.Sprintf("UPDATE nodes SET center_of_mass='{%f, %f}' WHERE node_id=%d", centerOfMass.X, centerOfMass.Y, nodeID)
+
+	// Execute the query
+	rows, err := db.Query(query)
+	defer rows.Close()
+	if err != nil {
+		log.Fatalf("[ E ] update center of mass query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	fmt.Printf("[   ] CenterOfMass: (%f, %f)\n", centerOfMass.X, centerOfMass.Y)
+
+	return centerOfMass
+}
+
+// genForestTree generates a forest representation of the tree with the given index
+func GenForestTree(database *sql.DB, index int64) string {
+	db = database
+	rootNodeID := getRootNodeID(index)
+	return genForestTreeNode(rootNodeID)
+}
+
+// genForestTreeNodes returns a sub-representation of a given node in forest format
+func genForestTreeNode(nodeID int64) string {
+	var returnString string
+
+	// get the subnode ids
+	var subnode [4]int64
+
+	query := fmt.Sprintf("SELECT subnode[1], subnode[2], subnode[3], subnode[4] FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&subnode[0], &subnode[1], &subnode[2], &subnode[3])
+	if err != nil {
+		log.Fatalf("[ E ] updateTotalMassNode query: %v\n\t\t\t query: %s\n", err, query)
+	}
+
+	returnString += "["
+
+	// iterate over all subnodes updating their total masses
+	for _, subnodeID := range subnode {
+		if subnodeID != 0 {
+			centerOfMass := getCenterOfMass(nodeID)
+			mass := getNodeTotalMass(nodeID)
+			returnString += fmt.Sprintf("%.0f %.0f %.0f", centerOfMass.X, centerOfMass.Y, mass)
+			returnString += genForestTreeNode(subnodeID)
+		} else {
+			if getStarID(nodeID) != 0 {
+				coords := getStarCoordinates(nodeID)
+				starID := getStarID(nodeID)
+				mass := getStarMass(starID)
+				returnString += fmt.Sprintf("[%.0f %.0f %.0f]", coords.X, coords.Y, mass)
+			} else {
+				returnString += fmt.Sprintf("[0 0]")
+			}
+			// break, this stops a star from being counted multiple (4) times
+			break
+		}
+	}
+
+	returnString += "]"
+
+	return returnString
+}
+
+// getCenterOfMass returns the center of mass of the given nodeID
+func getCenterOfMass(nodeID int64) structs.Vec2 {
+
+	var CenterOfMass [2]float64
+
+	// get the star from the stars table
+	query := fmt.Sprintf("SELECT center_of_mass[1], center_of_mass[2] FROM nodes WHERE node_id=%d", nodeID)
+	err := db.QueryRow(query).Scan(&CenterOfMass[0], &CenterOfMass[1])
+	if err != nil {
+		log.Fatalf("[ E ] getCenterOfMass query: %v \n\t\t\tquery: %s\n", err, query)
+	}
+
+	return structs.Vec2{X: CenterOfMass[0], Y: CenterOfMass[1]}
+}
+
+// getStarCoordinates gets the star coordinates of a star using a given nodeID. It returns a vector describing the
+// coordinates
+func getStarCoordinates(nodeID int64) structs.Vec2 {
+	var Coordinates [2]float64
+
+	starID := getStarID(nodeID)
+
+	// get the star from the stars table
+	query := fmt.Sprintf("SELECT x, y FROM stars WHERE star_id=%d", starID)
+	err := db.QueryRow(query).Scan(&Coordinates[0], &Coordinates[1])
+	if err != nil {
+		log.Fatalf("[ E ] getStarCoordinates query: %v \n\t\t\tquery: %s\n", err, query)
+	}
+
+	fmt.Printf("%v\n", Coordinates)
+
+	return structs.Vec2{X: Coordinates[0], Y: Coordinates[1]}
+}