package wrapper

import (
	"fmt"
	"strings"
)

const (
	kDesc      = "DESC"
	kAsc       = "ASC"
	maxColumns = 6
)

// OrderBy 排序（降序（大=>小）desc, 升序（小=>大）asc
// example: "orderBy：[{"col:"create_at","desc":true}, {"col":"id","desc":false}]
//
//	"orderBy：[{"col:"create_at,id","desc":true}]
type OrderBy []*Column

func (ob OrderBy) 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 OrderBy) sqlCol(col *Column, convert ColumnConvert) string {
	if len(col.Column) > 0 && col.Desc {
		return fmt.Sprintf("%s %s", convert(col.Column), kDesc)
	}
	return convert(col.Column)
}

func (ob OrderBy) 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
		}
		c := ob.sqlCol(ob[i], convert)
		if len(c) == 0 {
			continue
		}
		if count == 0 && full {
			builder.WriteString(" ORDER BY ")
		}
		if count > 0 {
			builder.WriteByte(',')
		}
		builder.WriteString(c)
		count++
	}
	return builder.String()
}