1 files changed, 69 insertions, 0 deletions
diff --git a/internal/store/design.go b/internal/store/design.go
new file mode 100644
index 0000000..4556d96
--- /dev/null
+++ b/internal/store/design.go
@@ -0,0 +1,69 @@
+package store
+
+import (
+	"context"
+	"encoding/json"
+)
+
+// SaveDesign stores the design form in one go: the theme, the modules of every
+// area and the menu, so a half-applied save is impossible. mods and menu are
+// the complete new state in display order: rows with an ID are updated, rows
+// without one inserted, and anything else is deleted.
+func (bs *BlogStore) SaveDesign(ctx context.Context, theme json.RawMessage, mods []Module, menu []MenuItem) error {
+	tx, err := bs.db.Begin(ctx)
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback(ctx)
+	if _, err := tx.Exec(ctx, `UPDATE settings SET theme=$1, updated_at=now()`, theme); err != nil {
+		return err
+	}
+
+	keep := []int64{}
+	for _, m := range mods {
+		if m.ID != 0 {
+			keep = append(keep, m.ID)
+		}
+	}
+	if _, err := tx.Exec(ctx, `DELETE FROM modules WHERE id <> ALL($1)`, keep); err != nil {
+		return err
+	}
+	order := map[string]int{} // sort_order restarts in every area
+	for _, m := range mods {
+		pos := order[m.Area]
+		order[m.Area]++
+		if m.ID != 0 { // area and kind never change
+			_, err = tx.Exec(ctx, `UPDATE modules SET title=$2, body=$3, count=$4, sort_order=$5, updated_at=now() WHERE id=$1`, m.ID, m.Title, m.Body, m.Count, pos)
+		} else {
+			_, err = tx.Exec(ctx, `INSERT INTO modules (area, kind, title, body, count, sort_order) VALUES ($1,$2,$3,$4,$5,$6)`, m.Area, m.Kind, m.Title, m.Body, m.Count, pos)
+		}
+		if err != nil {
+			return wrap(err)
+		}
+	}
+
+	keep = keep[:0]
+	for _, it := range menu {
+		if it.ID != 0 {
+			keep = append(keep, it.ID)
+		}
+	}
+	if _, err := tx.Exec(ctx, `DELETE FROM menu_items WHERE id <> ALL($1)`, keep); err != nil {
+		return err
+	}
+	for i, it := range menu {
+		switch {
+		case it.ID != 0:
+			_, err = tx.Exec(ctx, `UPDATE menu_items SET label=$2, url=$3, sort_order=$4 WHERE id=$1`, it.ID, it.Label, it.URL, i)
+		case it.PageID != nil: // a page deleted meanwhile simply adds nothing
+			_, err = tx.Exec(ctx, `INSERT INTO menu_items (page_id, sort_order) SELECT id, $2 FROM pages WHERE id=$1
+				ON CONFLICT (page_id) WHERE page_id IS NOT NULL DO UPDATE SET sort_order=excluded.sort_order`, *it.PageID, i)
+		default:
+			_, err = tx.Exec(ctx, `INSERT INTO menu_items (label, url, sort_order) VALUES ($1,$2,$3)`, it.Label, it.URL, i)
+		}
+		if err != nil {
+			return wrap(err)
+		}
+	}
+	return tx.Commit(ctx)
+}