//go:build go1.10
// +build go1.10

package mssql_test

import (
	"database/sql"
	"log"
	"strings"
	"unicode/utf8"

	mssql "github.com/microsoft/go-mssqldb"
)

const (
	createTestTable = `CREATE TABLE test_table(
		id int IDENTITY(1,1) NOT NULL,
		test_nvarchar nvarchar(50) NULL,
		test_varchar varchar(50) NULL,
		test_float float NULL,
		test_datetime2_3 datetime2(3) NULL,
		test_bitn bit NULL,
		test_bigint bigint NOT NULL,
		test_geom geometry NULL,
	CONSTRAINT PK_table_test_id PRIMARY KEY CLUSTERED
	(
		id ASC
	) ON [PRIMARY]);`
	dropTestTable = "IF OBJECT_ID('test_table', 'U') IS NOT NULL DROP TABLE test_table;"
)

// This example shows how to perform bulk imports
func ExampleCopyIn() {

	connString := makeConnURL().String()

	db, err := sql.Open("sqlserver", connString)
	if err != nil {
		log.Fatal("Open connection failed:", err.Error())
	}
	defer db.Close()

	txn, err := db.Begin()
	if err != nil {
		log.Fatal(err)
	}

	// Create table
	_, err = db.Exec(createTestTable)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Exec(dropTestTable)

	// mssqldb.CopyIn creates string to be consumed by Prepare
	stmt, err := txn.Prepare(mssql.CopyIn("test_table", mssql.BulkOptions{}, "test_varchar", "test_nvarchar", "test_float", "test_bigint"))
	if err != nil {
		log.Fatal(err.Error())
	}

	for i := 0; i < 10; i++ {
		_, err = stmt.Exec(generateString(0, 30), generateStringUnicode(0, 30), i, i)
		if err != nil {
			log.Fatal(err.Error())
		}
	}

	result, err := stmt.Exec()
	if err != nil {
		log.Fatal(err)
	}

	err = stmt.Close()
	if err != nil {
		log.Fatal(err)
	}

	err = txn.Commit()
	if err != nil {
		log.Fatal(err)
	}
	rowCount, _ := result.RowsAffected()
	log.Printf("%d row copied\n", rowCount)
	log.Printf("bye\n")
}

func generateString(x int, n int) string {
	letters := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
	b := make([]byte, n)
	for i := range b {
		b[i] = letters[(x+i)%len(letters)]
	}
	return string(b)
}
func generateStringUnicode(x int, n int) string {
	letters := []byte("ab©💾é?ghïjklmnopqЯ☀tuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
	b := &strings.Builder{}
	for i := 0; i < n; i++ {
		r, sz := utf8.DecodeRune(letters[x%len(letters):])
		x += sz
		b.WriteRune(r)
	}
	return b.String()
}