Add submission page for uploads

* Closes: #13

lib/database/submissions.go

@@ -0,0 +1,48 @@
+package database
+
+type Submission struct {
+	ID           int
+	SubmissionID string
+	Filename     string
+	Status       string
+	BookID       string
+	Book         *Book
+}
+
+func (db *pgDB) AddSubmission(submission Submission) (id int, err error) {
+	err = db.sql.Insert(&submission)
+	return submission.ID, err
+}
+
+func (db *pgDB) UpdateSubmission(id int, status string, book *Book) error {
+	_, err := db.sql.Model(&Submission{}).
+		Set("status = ?", status).
+		Set("book_id = ?", extractID(book)).
+		Where("id = ?", id).
+		Update()
+	return err
+}
+
+func (db *pgDB) UpdateSubmissionByBook(bookID string, status string, book *Book) error {
+	_, err := db.sql.Model(&Submission{}).
+		Set("status = ?", status).
+		Set("book_id = ?", extractID(book)).
+		Where("book_id = ?", bookID).
+		Update()
+	return err
+}
+
+func (db *pgDB) GetSubmission(submissionID string) (submission []Submission, err error) {
+	err = db.sql.Model(&submission).
+		Column("Book").
+		Where("submission_id = ?", submissionID).
+		Select()
+	return
+}
+
+func extractID(book *Book) interface{} {
+	if book == nil {
+		return nil
+	}
+	return book.ID
+}