package wrapper

import "strings"

type GroupBy []*Column

func (ob GroupBy) Check(filters []FField) {
	length := len(ob)
	if length > maxColumns { //防止多
		length = maxColumns
	}
	cols := ob[:length]
	for i := range cols {
		cols[i].Check(filters)
	}
}

func (ob GroupBy) Sql(full bool, convert ColumnConvert) string {
	if convert == nil {
		convert = defColumnConvert
	}
	count := 0
	builder := strings.Builder{}
	for i := range ob {
		if count >= maxColumns {
			//后面不要接入
			break
		}
		if len(ob[i].Column) == 0 {
			continue
		}
		if count == 0 && full {
			builder.WriteString(" GROUP BY ")
		}
		if count > 0 {
			builder.WriteByte(',')
		}
		builder.WriteString(convert(ob[i].Column))
		count++
	}
	return builder.String()
}