package postgres

import (
	"fmt"
	"net/url"
)

// Config holds PostgreSQL connection settings. Required fields must be supplied
// by the caller; optional fields have production-safe defaults via [DefaultConfig].
type Config struct {
	Host              string `env:"EINHERJAR_PG_HOST,required"`
	Port              int    `env:"EINHERJAR_PG_PORT"                envDefault:"5432"`
	User              string `env:"EINHERJAR_PG_USER,required"`
	Password          string `env:"EINHERJAR_PG_PASSWORD,required"`
	Name              string `env:"EINHERJAR_PG_NAME,required"`
	SSLMode           string `env:"EINHERJAR_PG_SSL_MODE"            envDefault:"disable"`
	Timezone          string `env:"EINHERJAR_PG_TIMEZONE"            envDefault:"UTC"`
	MaxConns          int    `env:"EINHERJAR_PG_MAX_CONNS"           envDefault:"5"`
	MinConns          int    `env:"EINHERJAR_PG_MIN_CONNS"           envDefault:"2"`
	MaxConnLifetime   string `env:"EINHERJAR_PG_MAX_CONN_LIFETIME"   envDefault:"1h"`
	MaxConnIdleTime   string `env:"EINHERJAR_PG_MAX_CONN_IDLE_TIME"  envDefault:"30m"`
	HealthCheckPeriod string `env:"EINHERJAR_PG_HEALTH_CHECK_PERIOD" envDefault:"1m"`
}

// DefaultConfig returns a Config with all optional fields set to production-safe
// defaults. Callers must supply Host, Port, User, Password, and Name.
func DefaultConfig() Config {
	return Config{
		Port:              5432,
		SSLMode:           "disable",
		Timezone:          "UTC",
		MaxConns:          5,
		MinConns:          2,
		MaxConnLifetime:   "1h",
		MaxConnIdleTime:   "30m",
		HealthCheckPeriod: "1m",
	}
}

// DSN constructs a PostgreSQL connection string from the configuration.
func (c Config) DSN() string {
	u := &url.URL{
		Scheme: "postgres",
		User:   url.UserPassword(c.User, c.Password),
		Host:   fmt.Sprintf("%s:%d", c.Host, c.Port),
		Path:   "/" + c.Name,
	}
	q := u.Query()
	q.Set("sslmode", c.SSLMode)
	q.Set("timezone", c.Timezone)
	u.RawQuery = q.Encode()
	return u.String()
}