Backup database if a migration is needed (#415)

* Confirm before migrating database

Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

pkg/api/migrate.go

@@ -0,0 +1,66 @@
+package api
+
+import (
+	"fmt"
+	"html/template"
+	"net/http"
+
+	"github.com/stashapp/stash/pkg/database"
+)
+
+type migrateData struct {
+	ExistingVersion uint
+	MigrateVersion  uint
+	BackupPath      string
+}
+
+func getMigrateData() migrateData {
+	return migrateData{
+		ExistingVersion: database.Version(),
+		MigrateVersion:  database.AppSchemaVersion(),
+		BackupPath:      database.DatabaseBackupPath(),
+	}
+}
+
+func getMigrateHandler(w http.ResponseWriter, r *http.Request) {
+	if !database.NeedsMigration() {
+		http.Redirect(w, r, "/", 301)
+		return
+	}
+
+	data, _ := setupUIBox.Find("migrate.html")
+	templ, err := template.New("Migrate").Parse(string(data))
+	if err != nil {
+		http.Error(w, fmt.Sprintf("error: %s", err), 500)
+		return
+	}
+
+	err = templ.Execute(w, getMigrateData())
+	if err != nil {
+		http.Error(w, fmt.Sprintf("error: %s", err), 500)
+	}
+}
+
+func doMigrateHandler(w http.ResponseWriter, r *http.Request) {
+	err := r.ParseForm()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("error: %s", err), 500)
+	}
+
+	backupPath := r.Form.Get("backuppath")
+
+	// perform database backup
+	if backupPath != "" {
+		if err = database.Backup(backupPath); err != nil {
+			http.Error(w, fmt.Sprintf("error backing up database: %s", err), 500)
+			return
+		}
+	}
+
+	err = database.RunMigrations()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("error performing migration: %s", err), 500)
+		return
+	}
+	http.Redirect(w, r, "/", 301)
+}