package services

import (
	"context"
	"fmt"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
	"jd-book-uploader/config"
)

// DB holds the database connection pool
var DB *pgxpool.Pool

// NewDBPool creates a new database connection pool
func NewDBPool(cfg *config.Config) (*pgxpool.Pool, error) {
	// Build connection string
	connString := fmt.Sprintf(
		"host=%s port=%s user=%s password=%s dbname=%s sslmode=disable",
		cfg.DBHost,
		cfg.DBPort,
		cfg.DBUser,
		cfg.DBPassword,
		cfg.DBName,
	)

	// Parse connection string
	poolConfig, err := pgxpool.ParseConfig(connString)
	if err != nil {
		return nil, fmt.Errorf("failed to parse connection string: %w", err)
	}

	// Configure connection pool
	poolConfig.MaxConns = 10
	poolConfig.MinConns = 2
	poolConfig.MaxConnLifetime = time.Hour
	poolConfig.MaxConnIdleTime = time.Minute * 30
	poolConfig.HealthCheckPeriod = time.Minute

	// Set connection timeout
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	// Create connection pool
	pool, err := pgxpool.NewWithConfig(ctx, poolConfig)
	if err != nil {
		return nil, fmt.Errorf("failed to create connection pool: %w", err)
	}

	// Test connection
	if err := pool.Ping(ctx); err != nil {
		pool.Close()
		return nil, fmt.Errorf("failed to ping database: %w", err)
	}

	DB = pool
	return pool, nil
}

// CloseDB closes the database connection pool
func CloseDB() error {
	if DB != nil {
		DB.Close()
	}
	return nil
}

// RetryConnection attempts to reconnect to the database with retries
func RetryConnection(cfg *config.Config, maxRetries int, retryDelay time.Duration) (*pgxpool.Pool, error) {
	var pool *pgxpool.Pool
	var err error

	for i := 0; i < maxRetries; i++ {
		pool, err = NewDBPool(cfg)
		if err == nil {
			return pool, nil
		}

		if i < maxRetries-1 {
			time.Sleep(retryDelay)
		}
	}

	return nil, fmt.Errorf("failed to connect after %d attempts: %w", maxRetries, err)
}