Init

backend/internal/db/db.go

@@ -0,0 +1,82 @@
+package db
+
+import (
+	"context"
+	"fmt"
+	"io/fs"
+	"sort"
+	"strings"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func Connect(ctx context.Context, databaseURL string) (*pgxpool.Pool, error) {
+	pool, err := pgxpool.New(ctx, databaseURL)
+	if err != nil {
+		return nil, fmt.Errorf("connecting to database: %w", err)
+	}
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("pinging database: %w", err)
+	}
+	return pool, nil
+}
+
+func RunMigrations(ctx context.Context, pool *pgxpool.Pool, migrationsFS fs.FS) error {
+	entries, err := fs.ReadDir(migrationsFS, ".")
+	if err != nil {
+		return fmt.Errorf("reading migrations directory: %w", err)
+	}
+
+	sort.Slice(entries, func(i, j int) bool {
+		return entries[i].Name() < entries[j].Name()
+	})
+
+	for _, entry := range entries {
+		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".sql") {
+			continue
+		}
+
+		var version int
+		fmt.Sscanf(entry.Name(), "%d", &version)
+
+		var exists bool
+		err := pool.QueryRow(ctx,
+			"SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version = $1)", version,
+		).Scan(&exists)
+		if err != nil {
+			exists = false
+		}
+		if exists {
+			continue
+		}
+
+		content, err := fs.ReadFile(migrationsFS, entry.Name())
+		if err != nil {
+			return fmt.Errorf("reading migration %s: %w", entry.Name(), err)
+		}
+
+		tx, err := pool.Begin(ctx)
+		if err != nil {
+			return fmt.Errorf("beginning transaction for %s: %w", entry.Name(), err)
+		}
+
+		if _, err := tx.Exec(ctx, string(content)); err != nil {
+			tx.Rollback(ctx)
+			return fmt.Errorf("executing migration %s: %w", entry.Name(), err)
+		}
+
+		if _, err := tx.Exec(ctx,
+			"INSERT INTO schema_migrations (version) VALUES ($1)", version,
+		); err != nil {
+			tx.Rollback(ctx)
+			return fmt.Errorf("recording migration %s: %w", entry.Name(), err)
+		}
+
+		if err := tx.Commit(ctx); err != nil {
+			return fmt.Errorf("committing migration %s: %w", entry.Name(), err)
+		}
+	}
+
+	return nil
+}