package business

import (
	"fmt"
	"strings"

	"gorm.io/gorm"
)

func migrateBindingStatusIndex(db *gorm.DB) error {
	const name = "idx_sys_user_bind_platform_status"
	if !db.Migrator().HasTable(&bindingPO{}) {
		return nil
	}
	if db.Migrator().HasIndex(&bindingPO{}, name) {
		return nil
	}
	return db.Migrator().CreateIndex(&bindingPO{}, name)
}

// Preserve IDs and the high-water mark: lowering AUTO_INCREMENT could reuse
// a deleted ID that still appears in historical records or external systems.
func migratePromoteIDCapacity(db *gorm.DB) error {
	if db.Dialector.Name() != "mysql" || !db.Migrator().HasTable("tab_promote") {
		return nil
	}
	var column struct {
		DataType, ColumnType, IsNullable, Extra, ColumnComment string
	}
	if err := db.Raw("SELECT data_type,column_type,is_nullable,extra,column_comment FROM information_schema.columns WHERE table_schema=DATABASE() AND table_name='tab_promote' AND column_name='id'").Scan(&column).Error; err != nil {
		return err
	}
	if column.DataType == "bigint" {
		return nil
	}
	if column.DataType != "int" || column.IsNullable != "NO" || column.Extra != "auto_increment" {
		return fmt.Errorf("unexpected tab_promote.id definition; capacity migration stopped")
	}
	var next uint64
	if err := db.Raw("SELECT auto_increment FROM information_schema.tables WHERE table_schema=DATABASE() AND table_name='tab_promote'").Scan(&next).Error; err != nil {
		return err
	}
	typeName := "BIGINT"
	if strings.Contains(column.ColumnType, "unsigned") {
		typeName += " UNSIGNED"
	}
	// MySQL 5.7 rebuilds the table when widening an integer. Execute before
	// starting writers and retain the original next ID and column comment.
	return db.Connection(func(conn *gorm.DB) error {
		var mode string
		if err := conn.Raw("SELECT @@session.sql_mode").Scan(&mode).Error; err != nil {
			return err
		}
		comment := column.ColumnComment
		if !strings.Contains(mode, "NO_BACKSLASH_ESCAPES") {
			comment = strings.ReplaceAll(comment, `\`, `\\`)
		}
		comment = "'" + strings.ReplaceAll(comment, "'", "''") + "'"
		// MySQL does not permit a prepared-statement placeholder in COMMENT.
		return conn.Session(&gorm.Session{NewDB: true}).Exec(fmt.Sprintf("ALTER TABLE tab_promote MODIFY COLUMN id %s NOT NULL AUTO_INCREMENT COMMENT %s, AUTO_INCREMENT=%d", typeName, comment, next)).Error
	})
}