add db package

db package allows for writing games to postgres db

db/db.go

@@ -0,0 +1,97 @@
+package db
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/BattlesnakeOfficial/rules/board"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// the db package provides a simple interface to interact with a PostgreSQL database, it is extremely simple and only writing, reading and deleting game info
+
+// @ author Bhavnoor Singh  Saroya
+
+// Database wraps pgxpool
+type Database struct {
+	Pool *pgxpool.Pool
+}
+
+// Connect initializes the pool and creates the table if needed
+func Connect(dsn string) (*Database, error) {
+	ctx := context.Background()
+
+	pool, err := pgxpool.New(ctx, dsn)
+	if err != nil {
+		return nil, fmt.Errorf("db connect: %w", err)
+	}
+
+	// Ensure table exists
+	_, err = pool.Exec(ctx, `
+		CREATE TABLE IF NOT EXISTS items (
+			id UUID PRIMARY KEY,
+			info JSONB NOT NULL,
+			frames JSONB[]
+		)
+	`)
+	if err != nil {
+		return nil, fmt.Errorf("create table: %w", err)
+	}
+
+	return &Database{Pool: pool}, nil
+}
+
+func (db *Database) GetInfo(ctx context.Context, id string) (*board.Game, error) {
+	var gameData []byte
+	var it board.Game
+	err := db.Pool.QueryRow(ctx,
+		"SELECT info FROM items WHERE id=$1", id).
+		Scan(&gameData)
+	if err != nil {
+		return nil, err
+	}
+	// 2. Unmarshal the byte slice into the struct.
+	err = json.Unmarshal(gameData, &it)
+	if err != nil {
+		return nil, err
+	}
+	return &it, nil
+}
+
+func (db *Database) WriteInfo(ctx context.Context, info board.Game, frames []board.GameEvent) error {
+	var err error
+	var uuid string = info.ID
+	// 1. Marshal the struct into a byte slice.
+	gameData, err := json.Marshal(info)
+	if err != nil {
+		return fmt.Errorf("marshal game info: %w", err)
+	}
+
+	// convert []board.GameEvent to []json.RawMessage
+	var framesData []json.RawMessage
+	for _, f := range frames {
+		b, err := json.Marshal(f)
+		if err != nil {
+			return fmt.Errorf("marshal frame: %w", err)
+		}
+		framesData = append(framesData, b)
+	}
+
+	// use pgtype to wrap into postgres []JSONB
+	_, errr := db.Pool.Exec(ctx,
+		"INSERT INTO items (id, info, frames) VALUES ($1, $2, $3)",
+		uuid, gameData, framesData)
+	if errr != nil {
+		print("error writing to db, bad stuff happened: ")
+		// panic(fmt.Sprintf("Error inserting item: %v", err))
+		return fmt.Errorf("insert item: %w", errr)
+	}
+	return nil
+}
+
+func (db *Database) Delete(ctx context.Context, id int) error {
+	_, err := db.Pool.Exec(ctx,
+		"DELETE FROM items WHERE id=$1", id)
+	return err
+}