go-omni/database/database.go

// Package database provides the database/sql lifecycle used by GoOmni projects.
// It deliberately does not import a database driver; each application chooses one.
package database

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"
)

type Config struct {
	Driver          string        `json:"driver"`
	DSN             string        `json:"-"`
	MaxOpenConns    int           `json:"maxOpenConns"`
	MaxIdleConns    int           `json:"maxIdleConns"`
	ConnMaxLifetime time.Duration `json:"connMaxLifetime"`
	ConnMaxIdleTime time.Duration `json:"connMaxIdleTime"`
	PingTimeout     time.Duration `json:"pingTimeout"`
}

func DefaultConfig() Config { return DefaultPoolConfig().config() }

// PoolConfig returns driver-independent connection pool settings.
func (c Config) PoolConfig() PoolConfig {
	return PoolConfig{
		MaxOpenConns: c.MaxOpenConns, MaxIdleConns: c.MaxIdleConns,
		ConnMaxLifetime: c.ConnMaxLifetime, ConnMaxIdleTime: c.ConnMaxIdleTime,
		PingTimeout: c.PingTimeout,
	}
}

// ConfigFromEnv reads GO_OMNI_DB_* style settings. DSN is required.
func ConfigFromEnv(prefix string) (Config, error) {
	return ApplyEnv(DefaultConfig(), prefix)
}

// ApplyEnv overlays nonempty environment settings on file/default configuration.
// DSN is environment-only when Config is decoded from JSON or YAML.
func ApplyEnv(cfg Config, prefix string) (Config, error) {
	prefix = strings.TrimSpace(prefix)
	if prefix == "" {
		prefix = "GO_OMNI_DB_"
	}
	if value := strings.TrimSpace(os.Getenv(prefix + "DRIVER")); value != "" {
		cfg.Driver = value
	}
	if cfg.Driver == "" {
		cfg.Driver = "mysql"
	}
	if value := strings.TrimSpace(os.Getenv(prefix + "DSN")); value != "" {
		cfg.DSN = value
	}
	if cfg.DSN == "" {
		return Config{}, fmt.Errorf("%sDSN is required", prefix)
	}
	var err error
	if cfg.MaxOpenConns, err = envInt(prefix+"MAX_OPEN_CONNS", cfg.MaxOpenConns); err != nil {
		return Config{}, err
	}
	if cfg.MaxIdleConns, err = envInt(prefix+"MAX_IDLE_CONNS", cfg.MaxIdleConns); err != nil {
		return Config{}, err
	}
	if cfg.ConnMaxLifetime, err = envDuration(prefix+"CONN_MAX_LIFETIME", cfg.ConnMaxLifetime); err != nil {
		return Config{}, err
	}
	if cfg.ConnMaxIdleTime, err = envDuration(prefix+"CONN_MAX_IDLE_TIME", cfg.ConnMaxIdleTime); err != nil {
		return Config{}, err
	}
	if cfg.PingTimeout, err = envDuration(prefix+"PING_TIMEOUT", cfg.PingTimeout); err != nil {
		return Config{}, err
	}
	return cfg, cfg.Validate()
}

func (c Config) Validate() error {
	if strings.TrimSpace(c.Driver) == "" {
		return errors.New("database driver is required")
	}
	if strings.TrimSpace(c.DSN) == "" {
		return errors.New("database DSN is required")
	}
	return c.PoolConfig().Validate()
}

// DB owns a connection pool and exposes the embedded database/sql methods.
type DB struct {
	*sql.DB
	config Config
}

func Open(ctx context.Context, cfg Config) (*DB, error) {
	if ctx == nil {
		ctx = context.Background()
	}
	if err := cfg.Validate(); err != nil {
		return nil, err
	}
	db, err := sql.Open(cfg.Driver, cfg.DSN)
	if err != nil {
		return nil, fmt.Errorf("open database: %w", err)
	}
	return initializePool(ctx, db, cfg)
}

// initializePool is the shared ownership boundary for both creation paths.
// All configuration is validated before creating the sql.DB.
func initializePool(ctx context.Context, db *sql.DB, cfg Config) (*DB, error) {
	db.SetMaxOpenConns(cfg.MaxOpenConns)
	db.SetMaxIdleConns(cfg.MaxIdleConns) // Zero explicitly disables idle connections.
	db.SetConnMaxLifetime(cfg.ConnMaxLifetime)
	db.SetConnMaxIdleTime(cfg.ConnMaxIdleTime)
	checkCtx, cancel := context.WithTimeout(ctx, cfg.PingTimeout)
	defer cancel()
	if err := db.PingContext(checkCtx); err != nil {
		pingErr := fmt.Errorf("ping database: %w", err)
		if closeErr := db.Close(); closeErr != nil {
			return nil, errors.Join(pingErr, fmt.Errorf("close database after failed ping: %w", closeErr))
		}
		return nil, pingErr
	}
	return &DB{DB: db, config: cfg}, nil
}

// Config returns the original DSN configuration. Pools opened with a Connector
// have empty Driver/DSN fields; their connector cannot be reconstructed from Config.
func (db *DB) Config() Config { return db.config }

func (db *DB) Health(ctx context.Context) error {
	if db == nil || db.DB == nil {
		return errors.New("database is not initialized")
	}
	if ctx == nil {
		ctx = context.Background()
	}
	checkCtx, cancel := context.WithTimeout(ctx, db.config.PingTimeout)
	defer cancel()
	return db.PingContext(checkCtx)
}

// InTx commits only when work returns nil. Any work error or panic rolls back.
func (db *DB) InTx(ctx context.Context, options *sql.TxOptions, work func(*sql.Tx) error) (err error) {
	if db == nil || db.DB == nil {
		return errors.New("database is not initialized")
	}
	tx, err := db.BeginTx(ctx, options)
	if err != nil {
		return fmt.Errorf("begin transaction: %w", err)
	}
	defer func() {
		rollbackErr := tx.Rollback()
		if rollbackErr != nil && !errors.Is(rollbackErr, sql.ErrTxDone) {
			err = errors.Join(err, fmt.Errorf("rollback transaction: %w", rollbackErr))
		}
	}()
	if err = work(tx); err != nil {
		return err
	}
	if err = tx.Commit(); err != nil {
		return fmt.Errorf("commit transaction: %w", err)
	}
	return nil
}

func envInt(key string, fallback int) (int, error) {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback, nil
	}
	parsed, err := strconv.Atoi(value)
	if err != nil {
		return 0, fmt.Errorf("%s must be an integer: %w", key, err)
	}
	return parsed, nil
}

func envDuration(key string, fallback time.Duration) (time.Duration, error) {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback, nil
	}
	parsed, err := time.ParseDuration(value)
	if err != nil {
		return 0, fmt.Errorf("%s must be a duration: %w", key, err)
	}
	return parsed, nil
}