package gormx

import (
	"gorm.io/gorm"
)

type LimitHandler func(db *gorm.DB) *gorm.DB

func Finder[T any](model T, db *gorm.DB, objs ...LimitHandler) (int64, []T, error) {
	for _, obj := range objs {
		db = obj(db)
	}
	var models []T
	err := db.Model(&model).Find(&models).Error
	if err != nil {
		return 0, nil, err
	}
	var sum int64
	err = db.Model(&model).Count(&sum).Error
	return sum, models, err
}

// FinderPage 分页查找
func FinderPage[T any](db *gorm.DB, page, limit int, objs ...LimitHandler) (int64, []T, error) {
	return pageFinder[T](db, pageHandle(page, limit), objs...)
}

func pageFinder[T any](db *gorm.DB, limit LimitHandler, objs ...LimitHandler) (int64, []T, error) {
	// 定义表
	var model T
	db = db.Model(&model)
	for _, obj := range objs {
		db = obj(db)
	}
	// 查找全部数量
	var sum int64
	if err := db.Model(&model).Count(&sum).Error; err != nil {
		return 0, nil, err
	}
	// 分页查找
	db = limit(db)
	var models []T
	if err := db.Find(&models).Error; err != nil {
		return 0, nil, err
	}
	return sum, models, nil
}

func pageHandle(page, limit int) LimitHandler {
	return func(db *gorm.DB) *gorm.DB {
		// 用户输入起始位
		var beginIndex int
		if page < 0 {
			beginIndex = -1
		} else {
			beginIndex = (page - 1) * limit
		}
		return db.Offset(beginIndex).Limit(limit)
	}
}