package v1
import (
"fmt"
"net/http"
"strconv"
"github.com/helixml/kodit/domain/repository"
"github.com/helixml/kodit/infrastructure/api/jsonapi"
)
// PaginationParams holds pagination parameters parsed from query strings.
type PaginationParams struct {
page int
pageSize int
}
// DefaultPageSize is the default number of items per page.
const DefaultPageSize = 20
// MaxPageSize is the maximum allowed page size.
const MaxPageSize = 100
// NewPaginationParams creates pagination params with defaults.
func NewPaginationParams() PaginationParams {
return PaginationParams{
page: 1,
pageSize: DefaultPageSize,
}
}
// ParsePagination parses pagination parameters from an HTTP request.
// Default: page=1, page_size=20
// Max page_size: 100
func ParsePagination(r *http.Request) PaginationParams {
params := NewPaginationParams()
// Parse page parameter
if pageStr := r.URL.Query().Get("page"); pageStr != "" {
if page, err := strconv.Atoi(pageStr); err == nil && page >= 1 {
params.page = page
}
}
// Parse page_size parameter
if sizeStr := r.URL.Query().Get("page_size"); sizeStr != "" {
if size, err := strconv.Atoi(sizeStr); err == nil && size >= 1 {
params.pageSize = size
if params.pageSize > MaxPageSize {
params.pageSize = MaxPageSize
}
}
}
return params
}
// Page returns the page number (1-indexed).
func (p PaginationParams) Page() int { return p.page }
// PageSize returns the page size.
func (p PaginationParams) PageSize() int { return p.pageSize }
// Offset returns the offset for database queries.
func (p PaginationParams) Offset() int {
return (p.page - 1) * p.pageSize
}
// Limit returns the limit for database queries.
func (p PaginationParams) Limit() int {
return p.pageSize
}
// WithPage returns a copy with the specified page.
func (p PaginationParams) WithPage(page int) PaginationParams {
if page < 1 {
page = 1
}
p.page = page
return p
}
// WithPageSize returns a copy with the specified page size.
func (p PaginationParams) WithPageSize(size int) PaginationParams {
if size < 1 {
size = DefaultPageSize
}
if size > MaxPageSize {
size = MaxPageSize
}
p.pageSize = size
return p
}
// Options returns repository options for database pagination.
func (p PaginationParams) Options() []repository.Option {
return repository.WithPagination(p.Limit(), p.Offset())
}
// PaginationMeta builds a JSON:API meta object from pagination params and total count.
func PaginationMeta(params PaginationParams, totalCount int64) *jsonapi.Meta {
totalPages := 0
if params.PageSize() > 0 {
totalPages = (int(totalCount) + params.PageSize() - 1) / params.PageSize()
}
return &jsonapi.Meta{
"page": params.Page(),
"page_size": params.PageSize(),
"total_count": totalCount,
"total_pages": totalPages,
}
}
// PaginationLinks builds JSON:API links from the request, params, and total count.
func PaginationLinks(r *http.Request, params PaginationParams, totalCount int64) *jsonapi.Links {
totalPages := 0
if params.PageSize() > 0 {
totalPages = (int(totalCount) + params.PageSize() - 1) / params.PageSize()
}
buildURL := func(page int) string {
q := r.URL.Query()
q.Set("page", strconv.Itoa(page))
q.Set("page_size", strconv.Itoa(params.PageSize()))
return fmt.Sprintf("%s?%s", r.URL.Path, q.Encode())
}
links := jsonapi.Links{
Self: buildURL(params.Page()),
First: buildURL(1),
}
if totalPages > 0 {
links.Last = buildURL(totalPages)
}
if params.Page() > 1 {
links.Prev = buildURL(params.Page() - 1)
}
if params.Page() < totalPages {
links.Next = buildURL(params.Page() + 1)
}
return &links
}
