Refactoring validation to belong to model

internal/models/note_errors.go

@@ -0,0 +1,42 @@
+package models
+
+import (
+	"fmt"
+	"strings"
+)
+
+type ErrEmptyNoteContent struct{}
+type ErrEmptyNoteTitle struct{}
+type ErrNoteIncomplete struct {
+	why []error
+}
+type ErrNoteTitleOverflow struct {
+	length int
+}
+
+func (e *ErrEmptyNoteContent) Error() string {
+	return "content cannot be empty"
+}
+
+func (e *ErrEmptyNoteTitle) Error() string {
+	return "title cannot be empty"
+}
+
+func (e *ErrNoteIncomplete) Error() string {
+	if len(e.why) == 0 {
+		panic("ok so if we use this we need to know why it is incomplete")
+	}
+	s := make([]string, len(e.why))
+	for i, err := range e.why {
+		s[i] = err.Error()
+	}
+	return "note incomplete: " + strings.Join(s, " & ")
+}
+
+func (e *ErrNoteIncomplete) Unwrap() []error {
+	return e.why
+}
+
+func (e *ErrNoteTitleOverflow) Error() string {
+	return fmt.Sprintf("title max length %d, %d provided", NoteTitleMaxLength, e.length)
+}