wip: first NewPGState

pkg/state/state_postgres.go

@@ -0,0 +1,60 @@
+package state
+
+import (
+	"context"
+	"log/slog"
+	"os"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// ----- PGState holds the shared connection pool
+type PGState struct {
+	pool *pgxpool.Pool
+}
+
+// ----- Create a new PGState, reading connection info from env vars
+func NewPGState() *PGState {
+	ctx := context.Background()
+
+	// Get connection URL from environment (standard: PGHOST, PGPORT, etc.)
+	dbURL := os.Getenv("DATABASE_URL") // canonical way: use DATABASE_URL
+	if dbURL == "" {
+		slog.Error("DATABASE_URL environment variable must be set")
+		os.Exit(1)
+	}
+
+	// Create a pool config
+	config, err := pgxpool.ParseConfig(dbURL)
+	if err != nil {
+		slog.Error("Failed to parse DATABASE_URL", "error", err)
+		os.Exit(1)
+	}
+
+	// Optionally set pool tuning here
+	config.MaxConns = 10
+
+	pool, err := pgxpool.NewWithConfig(ctx, config)
+	if err != nil {
+		slog.Error("Failed to create pgx pool", "error", err)
+		os.Exit(1)
+	}
+
+	slog.Info("Connected to Postgres", "max_conns", config.MaxConns)
+	return &PGState{pool: pool}
+}
+
+// ----- Sequence-based NextID (implements ServerState)
+func (s *PGState) NextID() int {
+	ctx := context.Background()
+
+	var id int
+	err := s.pool.QueryRow(ctx, `SELECT nextval('session_id_seq')`).Scan(&id)
+	if err != nil {
+		slog.Error("NextID query failed", "error", err)
+		panic("NextID(): " + err.Error()) // interface doesn't allow returning error
+	}
+
+	slog.Debug("NextID generated", "id", id)
+	return id
+}