otter-space-sdk/pkg/database/scopes.go

package database

import (
	"math"

	"git.anthrove.art/Anthrove/otter-space-sdk/v4/pkg/models"
	"gorm.io/gorm"
)

type Pagination struct {
	Limit      int    `json:"limit,omitempty;query:limit"`
	Page       int    `json:"page,omitempty;query:page"`
	Sort       string `json:"sort,omitempty;query:sort"`
	TotalRows  int64  `json:"total_rows"`
	TotalPages int    `json:"total_pages"`
}

// Paginate applies pagination to a GORM query.
// It takes two parameters:
//
// - page: the current page number (1-based index). If the page is less than or equal to 0, it defaults to 1.
//
// - pageSize: the number of records per page. If the pageSize is greater than the MaxPageSizeLimit defined in models, it defaults to MaxPageSizeLimit. If the pageSize is less than or equal to 0, it defaults to DefaultPageSize defined in models.
//
// The function calculates the offset based on the page and pageSize, and applies the offset and limit to the GORM DB instance.
func Paginate(page int, pageSize int) func(db *gorm.DB) *gorm.DB {
	return func(db *gorm.DB) *gorm.DB {

		if page <= 0 {
			page = 1
		}

		switch {
		case pageSize > models.MaxPageSizeLimit:
			pageSize = models.MaxPageSizeLimit
		case pageSize <= 0:
			pageSize = models.DefaultPageSize
		}

		offset := (page - 1) * pageSize
		return db.Offset(offset).Limit(pageSize)
	}
}

// AdvancedPagination applies pagination, sorting, and counting to a GORM query.
// Parameters:
//
// - value: The model or table to query.
//
// - pagination: A pointer to a Pagination struct containing page, limit, sort, total rows, and total pages information.
//
// - db: A pointer to the GORM database instance.
//
// The function calculates the offset based on the Page and Limit of the Pagination struct, and applies the offset and limit to the GORM DB instance.
func AdvancedPagination(value any, pagination *Pagination, db *gorm.DB) func(db *gorm.DB) *gorm.DB {
	var totalRows int64

	if pagination.Page <= 0 {
		pagination.Page = 1
	}

	switch {
	case pagination.Limit > models.MaxPageSizeLimit:
		pagination.Limit = models.MaxPageSizeLimit
	case pagination.Limit <= 0:
		pagination.Limit = models.DefaultPageSize
	}

	db.Model(value).Count(&totalRows)

	pagination.TotalRows = totalRows
	totalPages := int(math.Ceil(float64(totalRows) / float64(pagination.Limit)))
	pagination.TotalPages = totalPages

	offset := (pagination.Page - 1) * pagination.Limit

	return func(db *gorm.DB) *gorm.DB {
		return db.Offset(offset).Limit(pagination.Limit)
	}
}

// OrderBy applies an order operation to a GORM query.
// Parameters:
//
// - sort: a SQL order query like "id desc".
func OrderBy(sort string) func(db *gorm.DB) *gorm.DB {
	return func(db *gorm.DB) *gorm.DB {
		return db.Order(sort)
	}

}