Finished?!

database.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"database/sql"
+	_ "github.com/Freeaqingme/golang-sql-driver-mysql"
+	"fmt"
+	"time"
+)
+
+var ClimateDb *sql.DB
+
+func InitDb() error {
+	db, err := sql.Open("mysql", "admin:sekna123jk@tcp(127.0.0.1:3306)/climate")
+	if err != nil {
+		return fmt.Errorf("error connecting to database: %w", err)
+	}
+	ClimateDb = db
+	return nil
+}
+
+func CloseDb() {
+	if ClimateDb != nil {
+		err := ClimateDb.Close()
+		if err != nil {
+			fmt.Println("error closing database: " + err.Error())
+		}
+	}
+}
+
+func writeSnapshotToDb(snapshotSub *SnapshotSubmission) (int64, error) {
+	queryStr := "INSERT INTO `snapshots` (`temp`, `humidity`, `co2`, `time`, `id`) VALUES (?, ?, ?, ?, NULL);"
+	query, err := ClimateDb.Prepare(queryStr)
+	if err != nil {
+		return -1, fmt.Errorf("couldn't prepare snapshot query: %w", err)
+	}
+	result, err := query.Exec(
+		snapshotSub.Temp,
+		snapshotSub.Humidity,
+		snapshotSub.Co2,
+		snapshotSub.Timestamp,
+	)
+	if err != nil {
+		return -1, fmt.Errorf("couldn't execute query to write snapshot to db: %w", err)
+	}
+	id, _ := result.LastInsertId()
+	return id, nil
+}
+
+func getLastSnapshotRecordFromDb() (*SnapshotRecord, error) {
+	var snapshotRecord SnapshotRecord
+	query := "SELECT `%s`, `%s`, `%s`, `%s`, `%s` FROM `snapshots` ORDER BY `id` DESC LIMIT 1;"
+	rows, err := ClimateDb.Query(fmt.Sprintf(query, "id", "temp", "humidity", "co2", "time"))
+	if err != nil {
+		return nil, err
+	}
+	rows.Next()
+	err = rows.Scan(
+		&snapshotRecord.Id,
+		&snapshotRecord.Temp,
+		&snapshotRecord.Humidity,
+		&snapshotRecord.Co2,
+		&snapshotRecord.Timestamp,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("couldn't read last snapshot from the database: %w", err)
+	}
+	return &snapshotRecord, nil
+}
+
+func getSnapshotRecordsFromDb(dateSince time.Time) ([]*SnapshotRecord, error) {
+	snapshots := make([]*SnapshotRecord, 0)
+	query := "SELECT `%s`, `%s`, `%s`, `%s`, `%s` FROM `snapshots` WHERE `%s` > %s ORDER BY `id` DESC;"
+	rows, err := ClimateDb.Query(fmt.Sprintf(query, "id", "temp", "humidity", "co2", "time", "time", dateSince.String()))
+	if err != nil {
+		return nil, fmt.Errorf("couldn't execute select query: %w", err)
+	}
+	for rows.Next() {
+		var snapshotRecord SnapshotRecord
+		err = rows.Scan(
+			&snapshotRecord.Id,
+			&snapshotRecord.Temp,
+			&snapshotRecord.Humidity,
+			&snapshotRecord.Co2,
+			&snapshotRecord.Timestamp,
+		)
+		if err != nil {
+			return nil, fmt.Errorf("couldn't read rows from the database: %w", err)
+		}
+		snapshots = append(snapshots, &snapshotRecord)
+	}
+	return snapshots, nil
+}