Fix settings handler build

internal/server/dbx.go

@@ -0,0 +1,93 @@
+package server
+
+import (
+	"database/sql"
+	"strconv"
+	"strings"
+)
+
+// dbx is the database the server talks to: SQLite, or PostgreSQL. The
+// queries are written once, for SQLite; on PostgreSQL each is rewritten
+// (pgSQL) on its way.
+type dbx struct {
+	*sql.DB
+	pg bool
+}
+
+func (d *dbx) q(query string) string {
+	if d.pg {
+		return pgSQL(query)
+	}
+	return query
+}
+
+func (d *dbx) Exec(query string, args ...any) (sql.Result, error) {
+	return d.DB.Exec(d.q(query), args...)
+}
+func (d *dbx) Query(query string, args ...any) (*sql.Rows, error) {
+	return d.DB.Query(d.q(query), args...)
+}
+func (d *dbx) QueryRow(query string, args ...any) *sql.Row {
+	return d.DB.QueryRow(d.q(query), args...)
+}
+func (d *dbx) Begin() (*txx, error) {
+	tx, err := d.DB.Begin()
+	return &txx{Tx: tx, pg: d.pg}, err
+}
+
+// insert runs an INSERT and gives the new row's id (LastInsertId on SQLite,
+// RETURNING id on PostgreSQL, which has no LastInsertId).
+func (d *dbx) insert(query string, args ...any) (int64, error) {
+	if d.pg {
+		var id int64
+		err := d.DB.QueryRow(pgSQL(query)+" RETURNING id", args...).Scan(&id)
+		return id, err
+	}
+	res, err := d.DB.Exec(query, args...)
+	if err != nil {
+		return 0, err
+	}
+	return res.LastInsertId()
+}
+
+type txx struct {
+	*sql.Tx
+	pg bool
+}
+
+func (t *txx) Exec(query string, args ...any) (sql.Result, error) {
+	if t.pg {
+		query = pgSQL(query)
+	}
+	return t.Tx.Exec(query, args...)
+}
+
+// pgSQL rewrites a query for SQLite into PostgreSQL's: $n placeholders,
+// INSERT OR IGNORE as ON CONFLICT DO NOTHING, and in table definitions
+// BIGSERIAL keys, BIGINT numbers (times are Unix seconds), BYTEA blobs and
+// ADD COLUMN IF NOT EXISTS.
+func pgSQL(q string) string {
+	if strings.HasPrefix(q, "INSERT OR IGNORE ") {
+		q = "INSERT " + strings.TrimPrefix(q, "INSERT OR IGNORE ") + " ON CONFLICT DO NOTHING"
+	}
+	if strings.Contains(q, "CREATE TABLE") || strings.Contains(q, "ALTER TABLE") {
+		q = strings.ReplaceAll(q, "INTEGER PRIMARY KEY AUTOINCREMENT", "BIGSERIAL PRIMARY KEY")
+		q = strings.ReplaceAll(q, "INTEGER", "BIGINT")
+		q = strings.ReplaceAll(q, "BLOB", "BYTEA")
+		q = strings.ReplaceAll(q, "ADD COLUMN ", "ADD COLUMN IF NOT EXISTS ")
+	}
+	var b strings.Builder
+	n, quoted := 0, false
+	for _, r := range q {
+		switch {
+		case r == '\'':
+			quoted = !quoted
+		case r == '?' && !quoted:
+			n++
+			b.WriteString("$" + strconv.Itoa(n))
+			continue
+		}
+		b.WriteRune(r)
+	}
+	return b.String()
+}