// FindOnUpdateCols finds columns have OnUpdateNow flag.
func FindOnUpdateCols(cols []*Col) []*Col {
	var rcols []*Col
	for _, c := range cols {
		if mysql.HasOnUpdateNowFlag(c.Flag) {
			rcols = append(rcols, c)
		}
	}

	return rcols
}

// NewColDesc returns a new ColDesc for a column.
func NewColDesc(col *Col) *ColDesc {
	// TODO: if we have no primary key and a unique index which's columns are all not null
	// we will set these columns' flag as PriKeyFlag
	// see https://dev.mysql.com/doc/refman/5.7/en/show-columns.html
	// create table
	name := col.Name
	nullFlag := "YES"
	if mysql.HasNotNullFlag(col.Flag) {
		nullFlag = "NO"
	}
	keyFlag := ""
	if mysql.HasPriKeyFlag(col.Flag) {
		keyFlag = "PRI"
	} else if mysql.HasUniKeyFlag(col.Flag) {
		keyFlag = "UNI"
	} else if mysql.HasMultipleKeyFlag(col.Flag) {
		keyFlag = "MUL"
	}
	var defaultValue interface{}
	if !mysql.HasNoDefaultValueFlag(col.Flag) {
		defaultValue = col.DefaultValue
	}

	extra := ""
	if mysql.HasAutoIncrementFlag(col.Flag) {
		extra = "auto_increment"
	} else if mysql.HasOnUpdateNowFlag(col.Flag) {
		extra = "on update CURRENT_TIMESTAMP"
	}

	return &ColDesc{
		Field:        name.O,
		Type:         col.GetTypeDesc(),
		Collation:    col.Collate,
		Null:         nullFlag,
		Key:          keyFlag,
		DefaultValue: defaultValue,
		Extra:        extra,
		Privileges:   defaultPrivileges,
		Comment:      "",
	}
}

func (s *ShowPlan) fetchShowCreateTable(ctx context.Context) error {
	tb, err := s.getTable(ctx)
	if err != nil {
		return errors.Trace(err)
	}

	// TODO: let the result more like MySQL.
	var buf bytes.Buffer
	buf.WriteString(fmt.Sprintf("CREATE TABLE `%s` (\n", tb.TableName().O))
	for i, col := range tb.Cols() {
		buf.WriteString(fmt.Sprintf("  `%s` %s", col.Name.O, col.GetTypeDesc()))
		if mysql.HasAutoIncrementFlag(col.Flag) {
			buf.WriteString(" NOT NULL AUTO_INCREMENT")
		} else {
			if mysql.HasNotNullFlag(col.Flag) {
				buf.WriteString(" NOT NULL")
			}
			switch col.DefaultValue {
			case nil:
				buf.WriteString(" DEFAULT NULL")
			case "CURRENT_TIMESTAMP":
				buf.WriteString(" DEFAULT CURRENT_TIMESTAMP")
			default:
				buf.WriteString(fmt.Sprintf(" DEFAULT '%v'", col.DefaultValue))
			}

			if mysql.HasOnUpdateNowFlag(col.Flag) {
				buf.WriteString(" ON UPDATE CURRENT_TIMESTAMP")
			}
		}
		if i != len(tb.Cols())-1 {
			buf.WriteString(",\n")
		}
	}

	if len(tb.Indices()) > 0 {
		buf.WriteString(",\n")
	}

	for i, idx := range tb.Indices() {
		if idx.Primary {
			buf.WriteString("  PRIMARY KEY ")
		} else if idx.Unique {
			buf.WriteString(fmt.Sprintf("  UNIQUE KEY `%s` ", idx.Name.O))
		} else {
			buf.WriteString(fmt.Sprintf("  KEY `%s` ", idx.Name.O))
		}

		cols := make([]string, 0, len(idx.Columns))
		for _, c := range idx.Columns {
			cols = append(cols, c.Name.O)
		}
		buf.WriteString(fmt.Sprintf("(`%s`)", strings.Join(cols, "`,`")))
		if i != len(tb.Indices())-1 {
			buf.WriteString(",\n")
		}
	}

	buf.WriteString("\n")

	buf.WriteString(") ENGINE=InnoDB")
	if s := tb.Meta().Charset; len(s) > 0 {
		buf.WriteString(fmt.Sprintf(" DEFAULT CHARSET=%s", s))
	} else {
		buf.WriteString(" DEFAULT CHARSET=latin1")
	}

	data := []interface{}{
		tb.TableName().O,
		buf.String(),
	}

	s.rows = append(s.rows, &plan.Row{Data: data})

	return nil
}