package rest_gorm

import (
	"fmt"

	"git.ali33.ru/fcg-xvii/rest"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

type List struct {
	Conditions rest.ConditionList `json:"Conditions" swagger:"items=$ref:rest.Condition"`
	Orders     []*rest.Order      `json:"Orders" swagger:"items=$ref:rest.Order"`
	Offset     int                `json:"Offset"`
	Limit      int                `json:"Limit"`
}

func (s *List) Prepare() {
	if s.Limit <= 0 || s.Limit > 20 {
		s.Limit = 20
	}
}

func (s *List) Result(pg *gorm.DB, fields rest.FieldNamesList, res any) (count int64, err rest.IErrorArgs) {
	s.Prepare()
	for i, cond := range s.Conditions {
		if !cond.Logic.IsValid() {
			err = rest.ErrorFiled(cond.Field, "Unexpected logic")
			return
		}
		if !cond.Operator.IsValid() {
			err = rest.ErrorFiled(cond.Field, "Unexpected operator")
			return
		}
		if !fields.Exists(cond.Field) {
			err = rest.ErrorFiled(cond.Field, "Unexpected field")
			return
		}
		if cond.Value == nil {
			q := fmt.Sprintf("%s %s ?", CamelToSnake(cond.Field), cond.Operator)
			if i == 0 || cond.Logic == rest.LogicAND {
				pg = pg.Where(q, cond.Value)
			} else {
				pg = pg.Or(q, cond.Value)
			}
		} else {
			if cond.Operator != "" && cond.Operator != rest.OperatorNot {
				err = rest.ErrorFiled(cond.Field, "Expected empty operator or not")
			}
			q := fmt.Sprintf("%s is %s null", CamelToSnake(cond.Field), cond.Operator)
			if i == 0 || cond.Logic == rest.LogicAND {
				pg = pg.Where(q, cond.Value)
			} else {
				pg = pg.Or(q, cond.Value)
			}
		}
	}

	// count
	if dbRes := pg.Count(&count); dbRes.Error != nil {
		err = rest.ErrorFiled("ErrDB", dbRes.Error.Error())
		return
	}

	// offset limit
	pg = pg.Offset(s.Offset).Limit(s.Limit)

	// orders
	for _, order := range s.Orders {
		pg = pg.Order(
			clause.OrderByColumn{
				Column: clause.Column{
					Name: CamelToSnake(order.Name),
				},
				Desc: !order.IsAsc,
			},
		)
	}

	if pg = pg.Find(res); pg.Error != nil {
		err = rest.ErrorFiled("ErrDB", pg.Error.Error())
		return
	}
	return
}