From cc8cd4bbc49f94535647d9b17085ff0f26f3676e Mon Sep 17 00:00:00 2001
From: Daniel Ledda <ledda@cip.ifi.lmu.de>
Date: Wed, 4 Nov 2020 18:08:42 +0100
Subject: [PATCH] Working

---
 Database.go       | 27 +++++++++++++++++++++++++++
 Snapshot.go       | 18 +++++++++++-------
 climate-server.go | 23 ++++++++++++++++-------
 3 files changed, 54 insertions(+), 14 deletions(-)

diff --git a/Database.go b/Database.go
index 4e1316e..15c8693 100644
--- a/Database.go
+++ b/Database.go
@@ -24,4 +24,31 @@ func CloseDb() {
 			fmt.Println("error closing database: " + err.Error())
 		}
 	}
+}
+
+func writeSnapshotToDb(snapshotSub *SnapshotSubmission) error {
+	query := fmt.Sprintf("INSERT INTO `snapshots` (`temp`, `humidity`, `co2`, `time`, `id`) VALUES (%v, %v, %v, '%v', NULL);",
+		snapshotSub.Temp,
+		snapshotSub.Humidity,
+		snapshotSub.Co2,
+		snapshotSub.Timestamp)
+	_, err := ClimateDb.Query(query)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func getSnapshotRecordsFromDb(rowCount int) ([]*SnapshotRecord, error) {
+	records := make([]*SnapshotRecord, rowCount)
+	query := fmt.Sprintf("SELECT * FROM `snapshots` ORDER BY `id` DESC LIMIT %v;", rowCount)
+	rows, err := ClimateDb.Query(query)
+	if err != nil {
+		return nil, err
+	}
+	err = rows.Scan(records)
+	if err != nil {
+		return nil, err
+	}
+	return records, nil
 }
\ No newline at end of file
diff --git a/Snapshot.go b/Snapshot.go
index 7911028..c57cb16 100644
--- a/Snapshot.go
+++ b/Snapshot.go
@@ -5,15 +5,11 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"time"
 )
 
 type SnapshotRecord struct {
-	Id int
-	Timestamp time.Time
-	Temp float32
-	Humidity float32
-	Co2 float32
+	Id int `json:"id"`
+	SnapshotSubmission
 }
 
 type SnapshotSubmission struct {
@@ -23,7 +19,7 @@ type SnapshotSubmission struct {
 	Co2 float32 `json:"co2"`
 }
 
-func createSnapshotFromJson(jsonBodyStream io.ReadCloser) (*SnapshotSubmission, error) {
+func createSnapshotSubFromJsonBodyStream(jsonBodyStream io.ReadCloser) (*SnapshotSubmission, error) {
 	var snapshotSub SnapshotSubmission
 	body, err := ioutil.ReadAll(jsonBodyStream)
 	if err != nil {
@@ -38,4 +34,12 @@ func createSnapshotFromJson(jsonBodyStream io.ReadCloser) (*SnapshotSubmission,
 		return nil, fmt.Errorf("couldn't unmarshal json: %w", err)
 	}
 	return &snapshotSub, nil
+}
+
+func createJsonFromSnapshotRecords(records []*SnapshotRecord) ([]byte, error) {
+	jsonResult, err := json.Marshal(records)
+	if err != nil {
+		return nil, err
+	}
+	return jsonResult, nil
 }
\ No newline at end of file
diff --git a/climate-server.go b/climate-server.go
index 4c2a3fa..791e9bc 100644
--- a/climate-server.go
+++ b/climate-server.go
@@ -32,6 +32,7 @@ func teardown() {
 func startServer() {
 	port := "8001"
 	MainRouter.setGet("/", showCharts)
+	MainRouter.setGet("/data", sendData)
 	MainRouter.setPost("/", saveSnapshot)
 	fmt.Printf("Listening on port %s...\n", port)
 	log.Fatal(http.ListenAndServe(":" + port, nil))
@@ -42,17 +43,25 @@ func showCharts(w http.ResponseWriter, r *http.Request) error {
 	return err
 }
 
+func sendData(w http.ResponseWriter, r *http.Request) error {
+	records, err := getSnapshotRecordsFromDb(50)
+	if err != nil {
+		return fmt.Errorf("couldn't read rows from the database: %w", err)
+	}
+	json, err := createJsonFromSnapshotRecords(records)
+	if err != nil {
+		return fmt.Errorf("couldn't create a json from the records: %w", err)
+	}
+	_, err = fmt.Fprintf(w, string(json))
+	return err
+}
+
 func saveSnapshot(w http.ResponseWriter, r *http.Request) error {
-	snapshotSub, err := createSnapshotFromJson(r.Body)
+	snapshotSub, err := createSnapshotSubFromJsonBodyStream(r.Body)
 	if err != nil {
 		return fmt.Errorf("couldn't create snapshot from JSON: %w", err)
 	}
-	query := fmt.Sprintf("INSERT INTO `snapshots` (`temp`, `humidity`, `co2`, `time`, `id`) VALUES (%v, %v, %v, '%v', NULL);",
-		snapshotSub.Temp,
-		snapshotSub.Humidity,
-		snapshotSub.Co2,
-		snapshotSub.Timestamp)
-	_, err = ClimateDb.Query(query)
+	err = writeSnapshotToDb(snapshotSub)
 	if err != nil {
 		return fmt.Errorf("couldn't submit snapshot into the database: %w", err)
 	}