package storage

import (
	"context"
	"database/sql"
	"fmt"
	"log"
	"time"

	_ "github.com/ClickHouse/clickhouse-go/v2"
)

type ClickHouseConfig struct {
	Host     string
	User     string
	Password string
	Database string
}

func OpenClickHouse(cfg ClickHouseConfig) (*sql.DB, error) {
	dsn := fmt.Sprintf("clickhouse://%s:%s@%s/%s",
		cfg.User, cfg.Password, cfg.Host, cfg.Database)

	db, err := sql.Open("clickhouse", dsn)
	if err != nil {
		return nil, fmt.Errorf("clickhouse open: %w", err)
	}

	db.SetMaxOpenConns(5)
	db.SetMaxIdleConns(2)
	db.SetConnMaxLifetime(10 * time.Minute)

	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	if err := db.PingContext(ctx); err != nil {
		db.Close()
		return nil, fmt.Errorf("clickhouse ping: %w", err)
	}

	log.Printf("ClickHouse connected via database/sql: %s", cfg.Host)
	return db, nil
}

// OpenClickHouseWithRetry attempts to connect to ClickHouse with retries and backoff.
func OpenClickHouseWithRetry(
	cfg ClickHouseConfig,
	maxRetries int,
	initialDelay time.Duration,
) (*sql.DB, error) {
	var lastErr error
	delay := initialDelay

	for i := 0; i < maxRetries; i++ {
		db, err := OpenClickHouse(cfg)
		if err == nil {
			return db, nil
		}
		lastErr = err
		log.Printf(
			"ClickHouse connection attempt %d/%d failed: %v, retrying in %v...",
			i+1,
			maxRetries,
			err,
			delay,
		)
		time.Sleep(delay)
		delay *= 2
	}

	return nil, fmt.Errorf(
		"clickhouse connection failed after %d attempts: %w",
		maxRetries,
		lastErr,
	)
}