package services

import (
	"app/commons/core"
	"fmt"
	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
	"math"
)

// 业务库公共服务

func NewComService() *CommonService {
	return &CommonService{}
}

type CommonService struct {
}

func (s *CommonService) DB() *gorm.DB {
	return core.MainDb()
}

func (s *CommonService) FromContext(ctx *gin.Context) Context {
	return Context{Context: ctx}
}

// 分页器

type Pagination struct {
	Current int64 `json:"current" query:"current" form:"current" ` //当前页
	Size    int64 `json:"size"    query:"size" form:"size"  `      //每页条数
	Total   int64 `json:"total"   query:"total" form:"total" `     //总条数
	Count   int64 `json:"count"   query:"count" form:"count" `     //总页数
	Start   int64 `json:"start"   query:"start" form:"start" `     //起始条数
}

func NewPagination() *Pagination {
	return &Pagination{}
}

func NewPagingWithCurrentSize(current, size int64) *Pagination {
	return &Pagination{Current: current, Start: size}
}

func InitPaging(p, s int64) *Pagination {
	return &Pagination{Current: p, Size: s}
}

func (p *Pagination) Computer() {
	if p.Current < 1 {
		p.Current = 1
	}
	if p.Size < 1 {
		p.Size = 10
	}
	p.Start = p.Size * (p.Current - 1)
	count := math.Ceil(float64(p.Total) / float64(p.Size))
	p.Count = int64(count)
}

// 获取单条记录

func GetOne[T any](db *gorm.DB, args ...interface{}) (*T, error) {
	db = buildEqualDB(db, args...)
	r := new(T)
	if err := db.First(&r).Error; err != nil {
		return r, err
	}
	return r, nil
}

// 获取最后一条记录

func GetLast[T any](db *gorm.DB, args ...interface{}) (*T, error) {
	db = buildEqualDB(db, args...)
	r := new(T)
	if err := db.Last(&r).Error; err != nil {
		return r, err
	}
	return r, nil
}

// 统计条数

func CountRow[T any](db *gorm.DB, args ...interface{}) int64 {
	db = buildEqualDB(db, args...)
	r := new(T)
	var total int64 = 0
	db.Model(&r).Count(&total)
	return total
}

// 列表查询

func Find[T any](db *gorm.DB, args ...interface{}) ([]*T, error) {
	db = buildEqualDB(db, args...)
	res := make([]*T, 0)
	var total int64
	err := db.Model(&res).Count(&total).Error
	if err != nil {
		return res, err
	}
	if total == 0 {
		return res, nil
	}
	if err := db.Find(&res).Error; err != nil {
		return res, err
	}
	return res, nil
}

// 分页查询
// 可带入简单查询条件

func FindWithPageAndQuery[T any](db *gorm.DB, paging *Pagination, args ...interface{}) ([]*T, *Pagination, error) {
	if paging == nil {
		paging = InitPaging(1, 10)
	}
	db = buildEqualDB(db, args...)
	res := make([]*T, 0)
	err := db.Model(&res).Count(&paging.Total).Error
	if err != nil {
		return res, paging, err
	}
	paging.Computer()
	if paging.Total == 0 {
		return res, paging, nil
	}
	err = db.Model(&res).Limit(int(paging.Size)).Offset(int(paging.Start)).Find(&res).Error
	return res, paging, err
}

func FindWithPage[T any](query *gorm.DB, paging *Pagination) ([]*T, error) {
	if paging == nil {
		paging = InitPaging(1, 10)
	}
	results := make([]*T, 0)
	err := query.Model(&results).Count(&paging.Total).Error
	if err != nil {
		return nil, err
	}
	paging.Computer()
	if paging.Total == 0 {
		return results, nil
	}
	err = query.Model(&results).Limit(int(paging.Size)).Offset(int(paging.Start)).Find(&results).Error
	return results, err
}

// 分页获取所有数据 适用于多条数据

const queryPageSize int64 = 200000 // 批量查询数据最大条数

func FindAllWithBatch[T any](db *gorm.DB) ([]*T, error) {
	count := CountRow[T](db)
	// 分页循环读取用户数据
	paging := &Pagination{
		Size:  queryPageSize,
		Total: count,
	}
	list := make([]*T, 0, count)
	paging.Computer()
	if count > 0 {
		for i := 0; i < int(paging.Count); i++ {
			items, err := findWithPage[T](db, &Pagination{
				Size:    queryPageSize,
				Current: int64(i + 1),
				Total:   count,
			})
			if err != nil {
				return nil, err
			}
			list = append(list, items...)
		}
	}
	return list, nil
}

func buildEqualDB(db *gorm.DB, args ...interface{}) *gorm.DB {
	tms := len(args) / 2
	if tms > 0 {
		for i := 0; i < tms; i++ {
			db = db.Where(fmt.Sprintf("%s = ?", args[i*2]), args[i*2+1])
		}
	}
	return db
}

func findWithPage[T any](db *gorm.DB, paging *Pagination) ([]*T, error) {
	paging.Computer()
	res := make([]*T, 0)
	err := db.Model(&res).Limit(int(paging.Size)).Offset(int(paging.Start)).Find(&res).Error
	return res, err
}