add a debug output mode

This can be enabled in the config, but needs to be added in other
places.

main.go

@@ -23,6 +23,7 @@ type (
 			Type       string `toml:"type"`
 			Connection string `toml:"conn"`
 		} `toml:"db"`
+		Debug bool `toml:"debug_mode"`
 	}
 )
 
@@ -59,7 +60,7 @@ func main() {
 		return
 	}
 
-	s, err := NewServer(db)
+	s, err := NewServer(db, cfg.Debug)
 	if err != nil {
 		log.Fatalf("could not create server instance: %s", err)
 		return

server.go

@@ -21,6 +21,7 @@ type (
 	Server struct {
 		db     *sql.DB
 		routes map[string]Handler
+		debug  bool
 	}
 
 	// Handler is a function receiving a Context to process a request.
@@ -31,9 +32,10 @@ type (
 	// It contains a prepared transaction for usage and important details like
 	// the user account.
 	Context struct {
-		id  string
-		req *http.Request
-		w   http.ResponseWriter
+		id    string
+		req   *http.Request
+		w     http.ResponseWriter
+		debug bool // print debug output to the console
 
 		username string
 		tx       *sql.Tx
@@ -59,13 +61,14 @@ type (
 )
 
 // NewServer creates a new server handler.
-func NewServer(db *sql.DB) (*Server, error) {
+func NewServer(db *sql.DB, debug bool) (*Server, error) {
 	if db == nil {
 		return nil, fmt.Errorf("database connection is not set")
 	}
 	return &Server{
 		db:     db,
 		routes: map[string]Handler{},
+		debug:  debug,
 	}, nil
 }
 
@@ -96,6 +99,7 @@ func (s *Server) Handle(w http.ResponseWriter, r *http.Request) {
 		id:       id,
 		req:      r,
 		w:        w,
+		debug:    s.debug,
 		username: "unknown",
 	}
 
@@ -172,6 +176,13 @@ func (c *Context) Logf(level, msg string, args ...interface{}) {
 	log.Printf("%s - %s - %s", c.id, level, fmt.Sprintf(msg, args...))
 }
 
+// Debugf logs output only when the server is set into debug mode.
+func (c *Context) Debugf(level, msg string, args ...interface{}) {
+	if c.debug {
+		log.Printf("%s - %s - %s", c.id, level, fmt.Sprintf(msg, args...))
+	}
+}
+
 // Generate a useable request ID, so that it can be found in the logs.
 func newIdent() (string, error) {
 	b := make([]byte, 16)