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postgres.go
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postgres.go
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package repositories
import (
"context"
"fmt"
"strings"
"time"
gametypes "github.com/cbodonnell/flywheel/pkg/game/types"
"github.com/cbodonnell/flywheel/pkg/kinematic"
"github.com/cbodonnell/flywheel/pkg/log"
"github.com/cbodonnell/flywheel/pkg/repositories/models"
"github.com/jackc/pgx/v5"
)
type PostgresRepository struct {
conn *pgx.Conn
}
// NewPostgresRepository creates a new PSQLRepository.
// It panics if it is unable to connect to the database after 2 minutes.
// The caller is responsible for calling Close() on the repository.
func NewPostgresRepository(ctx context.Context, connStr string) (Repository, error) {
const maxRetry = 24
const retryInterval = time.Second * 5
var conn *pgx.Conn
var err error
for attempt := 1; attempt <= maxRetry; attempt++ {
conn, err = connectDb(ctx, connStr)
if err == nil {
break
}
log.Warn("Unable to connect to the database (attempt %d): %v", attempt, err)
select {
case <-ctx.Done():
return nil, fmt.Errorf("context cancelled while connecting to database: %v", ctx.Err())
case <-time.After(retryInterval):
continue
}
}
if err != nil {
return nil, fmt.Errorf("failed to establish database connection after %d attempts: %v", maxRetry, err)
}
return &PostgresRepository{
conn: conn,
}, nil
}
func connectDb(ctx context.Context, connStr string) (*pgx.Conn, error) {
conn, err := pgx.Connect(ctx, connStr)
if err != nil {
return nil, fmt.Errorf("failed to connect to database: %v", err)
}
var username string
var database string
err = conn.QueryRow(ctx, "SELECT current_user, current_database()").Scan(&username, &database)
if err != nil {
return nil, fmt.Errorf("failed to query database: %v", err)
}
log.Info("Connected to %s as %s", database, username)
return conn, nil
}
func (r *PostgresRepository) Close(ctx context.Context) error {
return r.conn.Close(ctx)
}
func (r *PostgresRepository) CreateUser(ctx context.Context, userID string) (*models.User, error) {
q := `INSERT INTO users (id) VALUES ($1) ON CONFLICT DO NOTHING;`
_, err := r.conn.Exec(ctx, q, userID)
if err != nil {
return nil, fmt.Errorf("failed to insert user: %v", err)
}
return &models.User{
ID: userID,
}, nil
}
func (r *PostgresRepository) ListCharacters(ctx context.Context, userID string) ([]*models.Character, error) {
q := `SELECT id, name FROM characters WHERE user_id = $1;`
rows, err := r.conn.Query(ctx, q, userID)
if err != nil {
return nil, fmt.Errorf("failed to query characters: %v", err)
}
defer rows.Close()
characters := []*models.Character{}
for rows.Next() {
character := &models.Character{}
if err := rows.Scan(&character.ID, &character.Name); err != nil {
return nil, fmt.Errorf("failed to scan character: %v", err)
}
characters = append(characters, character)
}
return characters, nil
}
func (r *PostgresRepository) CountCharacters(ctx context.Context, userID string) (int, error) {
q := `SELECT COUNT(*) FROM characters WHERE user_id = $1;`
var count int
if err := r.conn.QueryRow(ctx, q, userID).Scan(&count); err != nil {
return 0, fmt.Errorf("failed to count characters: %v", err)
}
return count, nil
}
func (r *PostgresRepository) GetCharacter(ctx context.Context, userID string, characterID int32) (*models.Character, error) {
q := `SELECT id, name FROM characters WHERE id = $1 AND user_id = $2;`
character := &models.Character{}
if err := r.conn.QueryRow(ctx, q, characterID, userID).Scan(&character.ID, &character.Name); err != nil {
if err == pgx.ErrNoRows {
return nil, &ErrNotFound{}
}
return nil, fmt.Errorf("failed to scan character: %v", err)
}
return character, nil
}
func (r *PostgresRepository) CreateCharacter(ctx context.Context, userID string, name string) (*models.Character, error) {
q := `INSERT INTO characters (user_id, name) VALUES ($1, $2) RETURNING id;`
var characterID int32
if err := r.conn.QueryRow(ctx, q, userID, name).Scan(&characterID); err != nil {
if strings.Contains(err.Error(), "duplicate key value violates unique constraint \"characters_name_unique\"") {
return nil, &ErrNameExists{}
}
return nil, fmt.Errorf("failed to insert character: %v", err)
}
return &models.Character{
ID: characterID,
UserID: userID,
Name: name,
}, nil
}
func (r *PostgresRepository) DeleteCharacter(ctx context.Context, userID string, characterID int32) error {
q := `DELETE FROM characters WHERE id = $1 AND user_id = $2;`
res, err := r.conn.Exec(ctx, q, characterID, userID)
if err != nil {
return fmt.Errorf("failed to delete character: %v", err)
}
if res.RowsAffected() == 0 {
return &ErrNotFound{}
}
return nil
}
func (r *PostgresRepository) NameExists(ctx context.Context, name string) (bool, error) {
q := `SELECT EXISTS(SELECT 1 FROM characters WHERE LOWER(name) = LOWER($1));`
var exists bool
if err := r.conn.QueryRow(ctx, q, name).Scan(&exists); err != nil {
return false, fmt.Errorf("failed to query name: %v", err)
}
return exists, nil
}
func (r *PostgresRepository) SaveGameState(ctx context.Context, gameState *gametypes.GameState) error {
tx, err := r.conn.Begin(ctx)
if err != nil {
return fmt.Errorf("failed to begin transaction: %v", err)
}
for _, playerState := range gameState.Players {
q := `
INSERT INTO players (character_id, timestamp, x, y, hitpoints) VALUES ($1, $2, $3, $4, $5)
ON CONFLICT (character_id) DO UPDATE SET timestamp = $2, x = $3, y = $4, hitpoints = $5;
`
_, err = tx.Exec(ctx, q, playerState.CharacterID, gameState.Timestamp, playerState.Position.X, playerState.Position.Y, playerState.Hitpoints)
if err != nil {
return fmt.Errorf("failed to insert player: %v", err)
}
}
if err := tx.Commit(ctx); err != nil {
return fmt.Errorf("failed to commit transaction: %v", err)
}
return nil
}
func (r *PostgresRepository) SavePlayerState(ctx context.Context, timestamp int64, characterID int32, playerState *gametypes.PlayerState) error {
q := `
INSERT INTO players (character_id, timestamp, x, y, hitpoints) VALUES ($1, $2, $3, $4, $5)
ON CONFLICT (character_id) DO UPDATE SET timestamp = $2, x = $3, y = $4, hitpoints = $5;
`
_, err := r.conn.Exec(ctx, q, characterID, timestamp, playerState.Position.X, playerState.Position.Y, playerState.Hitpoints)
if err != nil {
return fmt.Errorf("failed to insert player: %v", err)
}
return nil
}
func (r *PostgresRepository) LoadPlayerState(ctx context.Context, characterID int32) (*gametypes.PlayerState, error) {
q := `
SELECT x, y, hitpoints FROM players WHERE character_id = $1;
`
var x float64
var y float64
var hitpoints int16
if err := r.conn.QueryRow(ctx, q, characterID).Scan(&x, &y, &hitpoints); err != nil {
if err == pgx.ErrNoRows {
return nil, &ErrNotFound{}
}
return nil, fmt.Errorf("failed to scan player: %v", err)
}
return &gametypes.PlayerState{
CharacterID: characterID,
Position: kinematic.Vector{
X: x,
Y: y,
},
Hitpoints: hitpoints,
}, nil
}