feat: basic satellite tracking

README.md

@@ -0,0 +1,7 @@
+# SatTrack
+
+Modern satellite tracking solution
+
+## TODO
+
+- [ ] Custom validation messages

database/models/Satellite.go

@@ -4,7 +4,7 @@ import "gorm.io/gorm"
 
 type TLE struct {
 	gorm.Model
-	CatNBR string
+	CatNBR int
 	Name   string
 	Line1  string
 	Line2  string

dto/Error.go

@@ -0,0 +1,6 @@
+package dto
+
+type Error struct {
+	Status  uint
+	Message string
+}

dto/Tracking.go

@@ -0,0 +1,19 @@
+package dto
+
+import (
+	"time"
+
+	"github.com/SharkEzz/sgp4"
+)
+
+type TrackingRequest struct {
+	CatNBR int     `validate:"required"`
+	Lat    float64 `validate:"required,latitude"`
+	Lng    float64 `validate:"required,longitude"`
+	Alt    float64 `validate:"required"`
+}
+
+type TrackingResponse struct {
+	sgp4.Observation
+	GeneratedAt time.Time
+}

handlers/TrackingHandler.go

@@ -0,0 +1,51 @@
+package handlers
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/SharkEzz/sattrack/dto"
+	"github.com/SharkEzz/sattrack/services"
+	"github.com/SharkEzz/sgp4"
+	"github.com/go-playground/validator/v10"
+	"github.com/gofiber/fiber/v2"
+	"gorm.io/gorm"
+)
+
+func HandlePostTracking(c *fiber.Ctx, db *gorm.DB, validator *validator.Validate) error {
+	requestData := &dto.TrackingRequest{}
+	c.BodyParser(requestData)
+	err := validator.Struct(requestData)
+	if err != nil {
+		c.Response().SetStatusCode(http.StatusBadRequest)
+		return c.JSON(dto.Error{
+			Status:  http.StatusBadRequest,
+			Message: err.Error(),
+		})
+	}
+
+	tle, err := services.GetTLEFromDatabase(requestData.CatNBR, db)
+	if err != nil {
+		c.Response().SetStatusCode(http.StatusNotFound)
+		return c.JSON(dto.Error{
+			Status:  http.StatusNotFound,
+			Message: "Satellite not found",
+		})
+	}
+
+	sgp4, err := sgp4.NewSGP4(tle)
+	if err != nil {
+		c.Response().SetStatusCode(http.StatusInternalServerError)
+		return c.JSON(dto.Error{
+			Status:  http.StatusInternalServerError,
+			Message: "Error while initializing SGP4, please try again later",
+		})
+	}
+
+	observation := sgp4.ObservationFromLocation(requestData.Lat, requestData.Lng, requestData.Alt)
+
+	return c.JSON(dto.TrackingResponse{
+		Observation: observation,
+		GeneratedAt: time.Now(),
+	})
+}

main.go

@@ -1,19 +1,35 @@
 package main
 
 import (
+	"flag"
+
 	"github.com/SharkEzz/sattrack/database"
 	"github.com/SharkEzz/sattrack/database/models"
+	"github.com/SharkEzz/sattrack/handlers"
+	"github.com/SharkEzz/sattrack/services"
+	"github.com/go-playground/validator/v10"
 	"github.com/gofiber/fiber/v2"
 )
 
+var (
+	shouldUpdate = flag.Bool("update", false, "Use this flag to update all the TLE")
+)
+
 func main() {
+	flag.Parse()
 	db := database.Init("database/local.db")
 	db.AutoMigrate(&models.TLE{})
 
+	validator := validator.New()
+
+	if *shouldUpdate {
+		services.UpdateDatabase(db)
+	}
+
 	app := fiber.New()
 
-	app.Get("/", func(c *fiber.Ctx) error {
-		return c.SendString("oui")
+	app.Post("/tracking", func(c *fiber.Ctx) error {
+		return handlers.HandlePostTracking(c, db, validator)
 	})
 
 	app.Listen(":8000")

services/TLEService.go

@@ -0,0 +1,76 @@
+package services
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/SharkEzz/sattrack/database/models"
+	"github.com/SharkEzz/sgp4"
+	"gorm.io/gorm"
+)
+
+// CelesTrack active satellites list
+const activeListUrl string = "https://celestrak.com/NORAD/elements/active.txt"
+
+// Fetch all active satellite from CelesTrack and update the satellites table
+func UpdateDatabase(db *gorm.DB) error {
+	fmt.Println("Updating TLE database")
+	fmt.Println("Deleting record from `tles` table")
+	db.Exec("DELETE FROM tles")
+	fmt.Println("Querying new TLE list")
+	res, err := http.Get(activeListUrl)
+	if err != nil {
+		return err
+	}
+
+	content, _ := io.ReadAll(res.Body)
+	contentStr := strings.TrimSpace(string(content))
+	contentArr := strings.Split(string(contentStr), "\n")
+
+	if len(contentArr)%3 != 0 {
+		return errors.New("invalid TLE count")
+	}
+
+	fmt.Println("Inserting new records")
+	start := time.Now()
+	satellites := []models.TLE{}
+	for i := 0; i < len(contentArr); i += 3 {
+		tle, err := sgp4.NewTLE(contentArr[i][:24], contentArr[i+1][:69], contentArr[i+2][:69])
+		if err != nil {
+			// TODO: error handling
+			continue
+		}
+		satellites = append(satellites, models.TLE{
+			Name:   tle.Name(),
+			CatNBR: tle.NoradNumber(),
+			Line1:  tle.Line1(),
+			Line2:  tle.Line2(),
+		})
+	}
+	db.Create(&satellites)
+
+	fmt.Printf("Inserted %v TLE in %s\n", len(contentArr)/3, time.Since(start))
+
+	return nil
+}
+
+// Get a TLE from the database by it's NORAD catalog number
+func GetTLEFromDatabase(catNbr int, db *gorm.DB) (*sgp4.TLE, error) {
+	dbTLE := new(models.TLE)
+	db.Where("cat_nbr = ?", catNbr).First(&dbTLE)
+
+	if dbTLE == nil {
+		return nil, errors.New("satellite not found")
+	}
+
+	tle, err := sgp4.NewTLE(dbTLE.Name, dbTLE.Line1, dbTLE.Line2)
+	if err != nil {
+		return nil, err
+	}
+
+	return tle, nil
+}