package service

/*
 @Author : lanyulei
*/

import (
	"fmt"
	"math"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

type Param struct {
	C       *gin.Context
	DB      *gorm.DB
	ShowSQL bool
}

type Paginator struct {
	TotalCount int         `json:"total_count"`
	TotalPage  int         `json:"total_page"`
	Data       interface{} `json:"data"`
	PerPage    int         `json:"per_page"`
	Page       int         `json:"page"`
}

type ListRequest struct {
	Page    int `json:"page" form:"page"`
	PerPage int `json:"per_page" form:"per_page"`
	Sort    int `json:"sort" form:"sort"`
}

// Paging 分页
func Paging(p *Param, result interface{}, args ...interface{}) (*Paginator, error) {
	var (
		param     ListRequest
		paginator Paginator
		count     int
		offset    int
		tableName string
	)

	if err := p.C.Bind(&param); err != nil {
		return nil, err
	}

	db := p.DB

	if p.ShowSQL {
		db = db.Debug()
	}

	if param.Page < 1 {
		param.Page = 1
	}

	if param.PerPage == 0 {
		param.PerPage = 10
	}

	if param.Sort == 0 || param.Sort == -1 {
		db = db.Order("id desc")
	}

	if len(args) > 1 {
		tableName = fmt.Sprintf("`%s`.", args[1].(string))
	}

	if len(args) > 0 {
		for paramType, paramsValue := range args[0].(map[string]map[string]interface{}) {
			if paramType == "like" {
				for key, value := range paramsValue {
					db = db.Where(fmt.Sprintf("%v%v like ?", tableName, key), fmt.Sprintf("%%%v%%", value))
				}
			} else if paramType == "equal" {
				for key, value := range paramsValue {
					db = db.Where(fmt.Sprintf("%v%v = ?", tableName, key), value)
				}
			}
		}
	}

	done := make(chan bool, 1)

	countRecords(db, result, done, &count)

	if param.Page == 1 {
		offset = 0
	} else {
		offset = (param.Page - 1) * param.PerPage
	}
	err := db.Limit(param.PerPage).Offset(offset).Scan(result).Error
	if err != nil {
		return nil, err
	}
	<-done

	paginator.TotalCount = count
	paginator.Data = result
	paginator.Page = param.Page
	paginator.PerPage = param.PerPage
	paginator.TotalPage = int(math.Ceil(float64(count) / float64(param.PerPage)))

	return &paginator, nil
}

func countRecords(db *gorm.DB, anyType interface{}, done chan bool, count *int) {
	var num int64
	db.Model(anyType).Count(&num)
	*count = int(num)
	done <- true
}