package migrator

type MigrationCondition interface {
	SQL(dialect Dialect) (string, []interface{})
	IsFulfilled(results []map[string][]byte) bool
}

type ExistsMigrationCondition struct{}

func (c *ExistsMigrationCondition) IsFulfilled(results []map[string][]byte) bool {
	return len(results) >= 1
}

type NotExistsMigrationCondition struct{}

func (c *NotExistsMigrationCondition) IsFulfilled(results []map[string][]byte) bool {
	return len(results) == 0
}

type IfIndexExistsCondition struct {
	ExistsMigrationCondition
	TableName string
	IndexName string
}

func (c *IfIndexExistsCondition) SQL(dialect Dialect) (string, []interface{}) {
	return dialect.IndexCheckSQL(c.TableName, c.IndexName)
}

type IfIndexNotExistsCondition struct {
	NotExistsMigrationCondition
	TableName string
	IndexName string
}

func (c *IfIndexNotExistsCondition) SQL(dialect Dialect) (string, []interface{}) {
	return dialect.IndexCheckSQL(c.TableName, c.IndexName)
}

type IfColumnNotExistsCondition struct {
	NotExistsMigrationCondition
	TableName  string
	ColumnName string
}

func (c *IfColumnNotExistsCondition) SQL(dialect Dialect) (string, []interface{}) {
	return dialect.ColumnCheckSQL(c.TableName, c.ColumnName)
}

type IfColumnExistsCondition struct {
	ExistsMigrationCondition
	TableName  string
	ColumnName string
}

func (c *IfColumnExistsCondition) SQL(dialect Dialect) (string, []interface{}) {
	return dialect.ColumnCheckSQL(c.TableName, c.ColumnName)
}

type IfPrimaryKeyNotExistsCondition struct {
	NotExistsMigrationCondition
	TableName  string
	ColumnName string
}

func (c *IfPrimaryKeyNotExistsCondition) SQL(dialect Dialect) (string, []interface{}) {
	// only use it with mysql
	if dialect.DriverName() == "mysql" {
		return "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME=? AND COLUMN_KEY='PRI'", []interface{}{c.TableName}
	}

	return "", nil
}