From 08ef01bf1f20fedee45660bea28b14c3aef77067 Mon Sep 17 00:00:00 2001
From: leandrofars <leandrofars@gmail.com>
Date: Tue, 28 Nov 2023 11:59:06 -0300
Subject: [PATCH] feat(controller): list devices with pagination

---
 .../services/controller/internal/api/api.go   |  1 +
 .../controller/internal/api/device.go         | 88 ++++++++++++++++++-
 .../services/controller/internal/db/device.go | 31 ++++---
 3 files changed, 105 insertions(+), 15 deletions(-)

diff --git a/backend/services/controller/internal/api/api.go b/backend/services/controller/internal/api/api.go
index cbb8643..4a247ca 100644
--- a/backend/services/controller/internal/api/api.go
+++ b/backend/services/controller/internal/api/api.go
@@ -52,6 +52,7 @@ func StartApi(a Api) {
 	iot := r.PathPrefix("/api/device").Subrouter()
 	//TODO: create query for devices
 	iot.HandleFunc("", a.retrieveDevices).Methods("GET")
+	iot.HandleFunc("/{id}", a.retrieveDevices).Methods("GET")
 	iot.HandleFunc("/{sn}/get", a.deviceGetMsg).Methods("PUT")
 	iot.HandleFunc("/{sn}/add", a.deviceCreateMsg).Methods("PUT")
 	iot.HandleFunc("/{sn}/del", a.deviceDeleteMsg).Methods("PUT")
diff --git a/backend/services/controller/internal/api/device.go b/backend/services/controller/internal/api/device.go
index 5719d48..af4e798 100644
--- a/backend/services/controller/internal/api/device.go
+++ b/backend/services/controller/internal/api/device.go
@@ -2,8 +2,10 @@ package api
 
 import (
 	"encoding/json"
+	"go.mongodb.org/mongo-driver/bson"
 	"log"
 	"net/http"
+	"strconv"
 
 	"github.com/gorilla/mux"
 	"github.com/leandrofars/oktopus/internal/db"
@@ -31,12 +33,90 @@ func (a *Api) deviceGetSupportedParametersMsg(w http.ResponseWriter, r *http.Req
 }
 
 func (a *Api) retrieveDevices(w http.ResponseWriter, r *http.Request) {
-	devices, err := a.Db.RetrieveDevices()
-	if err != nil {
-		log.Println(err)
-		w.WriteHeader(http.StatusInternalServerError)
+	const PAGE_SIZE_LIMIT = 50
+	const PAGE_SIZE_DEFAULT = 20
+
+	// Get specific device
+	id := mux.Vars(r)["id"]
+	if id != "" {
+		device, err := a.Db.RetrieveDevice(id)
+		if err != nil {
+			log.Println(err)
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		err = json.NewEncoder(w).Encode(device)
+		if err != nil {
+			log.Println(err)
+		}
 		return
 	}
+
+	// Get devices with pagination
+	page_n := r.URL.Query().Get("page_number")
+	page_s := r.URL.Query().Get("page_size")
+	var err error
+
+	var page_number int64
+	if page_n == "" {
+		page_number = 1
+	} else {
+		page_number, err = strconv.ParseInt(page_n, 10, 64)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+			json.NewEncoder(w).Encode("Page number must be an integer")
+			return
+		}
+	}
+
+	var page_size int64
+	if page_s != "" {
+		page_size, err = strconv.ParseInt(page_s, 10, 64)
+
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+			json.NewEncoder(w).Encode("Page size must be an integer")
+			return
+		}
+
+		if page_size > PAGE_SIZE_LIMIT {
+			w.WriteHeader(http.StatusBadRequest)
+			json.NewEncoder(w).Encode("Page size must not exceed " + strconv.Itoa(PAGE_SIZE_LIMIT))
+			return
+		}
+
+	} else {
+		page_size = PAGE_SIZE_DEFAULT
+	}
+
+	total, err := a.Db.RetrieveDevicesCount(bson.M{})
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		json.NewEncoder(w).Encode("Unable to get devices count from database")
+	}
+
+	skip := page_number * (page_size - 1)
+	if total < page_size {
+		skip = 0
+	}
+
+	//TODO: Create filters
+	//TODO: Create sorting
+
+	filter := bson.A{
+		//bson.M{"$match": filter},
+		//bson.M{"$sort": sort},
+		bson.M{"$skip": skip},
+		bson.M{"$limit": page_size},
+	}
+
+	devices, err := a.Db.RetrieveDevices(filter)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		json.NewEncoder(w).Encode("Unable to aggregate database devices info")
+		return
+	}
+
 	err = json.NewEncoder(w).Encode(devices)
 	if err != nil {
 		log.Println(err)
diff --git a/backend/services/controller/internal/db/device.go b/backend/services/controller/internal/db/device.go
index 0e7f9b2..a01dc85 100644
--- a/backend/services/controller/internal/db/device.go
+++ b/backend/services/controller/internal/db/device.go
@@ -42,20 +42,24 @@ func (d *Database) CreateDevice(device Device) error {
 	log.Printf("Device %s already existed, and got replaced for new info", device.SN)
 	return err
 }
+func (d *Database) RetrieveDevices(filter bson.A) ([]Device, error) {
+	cursor, err := d.devices.Aggregate(d.ctx, filter)
 
-func (d *Database) RetrieveDevices() ([]Device, error) {
 	var results []Device
-	//TODO: filter devices by user ownership
-	cursor, err := d.devices.Find(d.ctx, bson.D{}, nil)
-	if err != nil {
-		log.Println(err)
-		return nil, err
+
+	for cursor.Next(d.ctx) {
+		var device Device
+
+		err := cursor.Decode(&device)
+		if err != nil {
+			log.Println("Error to decode device info fields")
+			continue
+		}
+
+		results = append(results, device)
 	}
-	if err = cursor.All(d.ctx, &results); err != nil {
-		log.Println(err)
-		return nil, err
-	}
-	return results, nil
+
+	return results, err
 }
 
 func (d *Database) RetrieveDevice(sn string) (Device, error) {
@@ -68,6 +72,11 @@ func (d *Database) RetrieveDevice(sn string) (Device, error) {
 	return result, err
 }
 
+func (d *Database) RetrieveDevicesCount(filter bson.M) (int64, error) {
+	count, err := d.devices.CountDocuments(d.ctx, filter)
+	return count, err
+}
+
 func (d *Database) DeleteDevice() {
 
 }