Database interface & auditing feature (#332)

* added audit manager

* Basic database DOA setup

* Added base config file

* added sqlite support and creation of schema

* added basic tests and config entry

* corrected issues of database is disabled

* fixed path for test

* WIP

* Added tests fixed config checking

* reverted files back to upstream

* reverted go.mod files

* no more test test test

* removed local testing details for psql

* hello

* added comments

* increased ping to 30 seconds

* renamed database table and added additional condition around test

* removed database test details

* goimport ran on all files

* WIP

* first attempt at migration

* fixes for migration system

* Migration system logger interface implemented

* fixes to print functions

* added write pooling pass

* gofmt :D

* formatted imports correctly

* removed old code

* added creation of migration

* gofmt

* :D Hello

* ❌ 🏎️

* maybe one day i will remember to revert go mod files

* checked err return condition correctly

* first changes for PR feedback

* code clean up

* protect Connected with RWmutex & event with mutex

* : D

* we can just pretend like it never happened

* MOved migrations back to source directory and added README

* readme formatting update

* Addd command line override for datadir

* use correct var when creating a migration and confirm folder is created

* Check if database version is newer than latest migration and also you know make migrations work.....

* uses filepath instead of manual path to use correct path seperator

* Add connection message and lower timeout

* Added support for sslmode for psql

* no longer force Close of database instead allow driver to maage

* Added closer func to test output

* sslmode added to example config

engine/database.go

@@ -0,0 +1,144 @@
+package engine
+
+import (
+	"errors"
+	"fmt"
+	"sync/atomic"
+	"time"
+
+	"github.com/thrasher-corp/gocryptotrader/database"
+	db "github.com/thrasher-corp/gocryptotrader/database/drivers/postgres"
+	dbsqlite3 "github.com/thrasher-corp/gocryptotrader/database/drivers/sqlite"
+	mg "github.com/thrasher-corp/gocryptotrader/database/migration"
+	"github.com/thrasher-corp/gocryptotrader/database/repository/audit"
+	auditPSQL "github.com/thrasher-corp/gocryptotrader/database/repository/audit/postgres"
+	auditSQLite "github.com/thrasher-corp/gocryptotrader/database/repository/audit/sqlite"
+	log "github.com/thrasher-corp/gocryptotrader/logger"
+)
+
+var (
+	dbConn *database.Database
+)
+
+type databaseManager struct {
+	running  atomic.Value
+	shutdown chan struct{}
+}
+
+func (a *databaseManager) Started() bool {
+	return a.running.Load() == true
+}
+
+func (a *databaseManager) Start() (err error) {
+	if a.Started() {
+		return errors.New("database manager already started")
+	}
+
+	log.Debugln(log.DatabaseMgr, "database manager starting...")
+
+	a.shutdown = make(chan struct{})
+
+	if Bot.Config.Database.Enabled {
+		if Bot.Config.Database.Driver == "postgres" {
+			dbConn, err = db.Connect()
+			if err != nil {
+				return fmt.Errorf("database failed to connect: %v Some features that utilise a database will be unavailable", err)
+			}
+
+			dbConn.SQL.SetMaxOpenConns(2)
+			dbConn.SQL.SetMaxIdleConns(1)
+			dbConn.SQL.SetConnMaxLifetime(time.Hour)
+
+			audit.Audit = auditPSQL.Audit()
+		} else if Bot.Config.Database.Driver == "sqlite" {
+			dbConn, err = dbsqlite3.Connect()
+
+			if err != nil {
+				return fmt.Errorf("database failed to connect: %v Some features that utilise a database will be unavailable", err)
+			}
+
+			audit.Audit = auditSQLite.Audit()
+		}
+		dbConn.Connected = true
+		log.Debugf(log.DatabaseMgr, "connection established to %v using %v", dbConn.Config.Host, dbConn.Config.Driver)
+
+		mLogger := mg.MLogger{}
+		migrations := mg.Migrator{
+			Log: mLogger,
+		}
+
+		migrations.Conn = dbConn
+
+		err := migrations.LoadMigrations()
+		if err != nil {
+			return err
+		}
+
+		err = migrations.RunMigration()
+		if err != nil {
+			return err
+		}
+
+		go a.run()
+		return nil
+	}
+
+	return errors.New("database support disabled")
+}
+
+func (a *databaseManager) Stop() error {
+	if !a.Started() {
+		return errors.New("database manager already stopped")
+	}
+
+	log.Debugln(log.DatabaseMgr, "database manager shutting down...")
+	err := dbConn.SQL.Close()
+	if err != nil {
+		log.Errorf(log.DatabaseMgr, "Failed to close database: %v", err)
+	}
+	close(a.shutdown)
+	return nil
+}
+
+func (a *databaseManager) run() {
+	log.Debugln(log.DatabaseMgr, "database manager started.")
+	Bot.ServicesWG.Add(1)
+
+	t := time.NewTicker(time.Second * 2)
+	a.running.Store(true)
+
+	defer func() {
+		t.Stop()
+		a.running.Store(false)
+
+		Bot.ServicesWG.Done()
+
+		log.Debugln(log.DatabaseMgr, "database manager shutdown.")
+	}()
+
+	for {
+		select {
+		case <-a.shutdown:
+			return
+		case <-t.C:
+			a.checkConnection()
+		}
+	}
+}
+
+func (a *databaseManager) checkConnection() {
+	dbConn.Mu.Lock()
+	defer dbConn.Mu.Unlock()
+
+	err := dbConn.SQL.Ping()
+	if err != nil {
+		log.Errorf(log.DatabaseMgr, "database connection error: %v", err)
+		dbConn.Connected = false
+		return
+	}
+
+	if !dbConn.Connected {
+		log.Info(log.DatabaseMgr, "database connection reestablished")
+		dbConn.Connected = true
+	}
+}