package dbx

import (
	"time"

	"github.com/jackc/pgx/v5"
)

// Config is the top-level configuration for a Cluster.
type Config struct {
	Master             NodeConfig
	Replicas           []NodeConfig
	Retry              RetryConfig
	Logger             Logger
	Metrics            *MetricsHook
	HealthCheck        HealthCheckConfig
	SlowQueryThreshold time.Duration
}

// NodeConfig describes a single database node.
type NodeConfig struct {
	Name   string // human-readable name for logs/metrics, e.g. "master", "replica-1"
	DSN    string
	Pool   PoolConfig
	Tracer pgx.QueryTracer
}

// PoolConfig controls pgxpool.Pool parameters.
type PoolConfig struct {
	MaxConns          int32
	MinConns          int32
	MaxConnLifetime   time.Duration
	MaxConnIdleTime   time.Duration
	HealthCheckPeriod time.Duration
}

// RetryConfig controls retry behaviour.
type RetryConfig struct {
	MaxAttempts     int                // default: 3
	BaseDelay       time.Duration      // default: 50ms
	MaxDelay        time.Duration      // default: 1s
	RetryableErrors func(error) bool   // optional custom classifier
}

// HealthCheckConfig controls the background health checker.
type HealthCheckConfig struct {
	Interval time.Duration // default: 5s
	Timeout  time.Duration // default: 2s
}

// defaults fills zero-valued fields with sensible defaults.
func (c *Config) defaults() {
	if c.Logger == nil {
		c.Logger = nopLogger{}
	}
	if c.Retry.MaxAttempts <= 0 {
		c.Retry.MaxAttempts = 3
	}
	if c.Retry.BaseDelay <= 0 {
		c.Retry.BaseDelay = 50 * time.Millisecond
	}
	if c.Retry.MaxDelay <= 0 {
		c.Retry.MaxDelay = time.Second
	}
	if c.HealthCheck.Interval <= 0 {
		c.HealthCheck.Interval = 5 * time.Second
	}
	if c.HealthCheck.Timeout <= 0 {
		c.HealthCheck.Timeout = 2 * time.Second
	}
	if c.Master.Name == "" {
		c.Master.Name = "master"
	}
	for i := range c.Replicas {
		if c.Replicas[i].Name == "" {
			c.Replicas[i].Name = "replica-" + itoa(i+1)
		}
	}
}

// itoa is a minimal int-to-string without importing strconv.
func itoa(n int) string {
	if n == 0 {
		return "0"
	}
	buf := [20]byte{}
	i := len(buf)
	for n > 0 {
		i--
		buf[i] = byte('0' + n%10)
		n /= 10
	}
	return string(buf[i:])
}