package model

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"gin_test/config"

	_ "modernc.org/sqlite"
)

func OpenDB(cfg config.DBConfig) (*sql.DB, error) {
	if cfg.Driver == "" {
		return nil, errors.New("db.driver is empty")
	}
	if cfg.DSN == "" {
		return nil, errors.New("db.dsn is empty")
	}

	// 本 demo 只实现 sqlite；其他 driver 后续可以扩展。
	switch cfg.Driver {
	case "sqlite":
		// modernc sqlite driver name 是 "sqlite"
		db, err := sql.Open("sqlite", cfg.DSN)
		if err != nil {
			return nil, err
		}

		db.SetMaxOpenConns(cfg.MaxOpenConns)
		db.SetMaxIdleConns(cfg.MaxIdleConns)
		db.SetConnMaxLifetime(time.Duration(cfg.ConnMaxLifetimeSeconds) * time.Second)

		ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
		defer cancel()
		if err := db.PingContext(ctx); err != nil {
			_ = db.Close()
			return nil, err
		}

		return db, nil
	default:
		return nil, fmt.Errorf("unsupported db.driver: %s", cfg.Driver)
	}
}

func Migrate(ctx context.Context, db *sql.DB) error {
	schemaPath := filepath.Join("model", "schema.sql")
	raw, err := os.ReadFile(schemaPath)
	if err != nil {
		return err
	}

	// sqlite 驱动会把这类多语句脚本当作一段执行（示例中只有 CREATE TABLE）。
	_, err = db.ExecContext(ctx, string(raw))
	return err
}