GoToSocial/internal/util/paging.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package util
import (
"fmt"
"net/url"
"strings"
apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
"github.com/superseriousbusiness/gotosocial/internal/config"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
)
// PageableResponseParams models the parameters to pass to PackagePageableResponse.
//
// The given items will be provided in the paged response.
//
// The other values are all used to create the Link header so that callers know
// which endpoint to query next and previously in order to do paging.
type PageableResponseParams struct {
Items []interface{} // Sorted slice of items (statuses, notifications, etc)
Path string // path to use for next/prev queries in the link header
NextMaxIDKey string // key to use for the next max id query param in the link header, defaults to 'max_id'
NextMaxIDValue string // value to use for next max id
PrevMinIDKey string // key to use for the prev min id query param in the link header, defaults to 'min_id'
PrevMinIDValue string // value to use for prev min id
Limit int // limit number of entries to return
ExtraQueryParams []string // any extra query parameters to provide in the link header, should be in the format 'example=value'
}
// PackagePageableResponse is a convenience function for returning
// a bunch of pageable items (notifications, statuses, etc), as well
// as a Link header to inform callers of where to find next/prev items.
func PackagePageableResponse(params PageableResponseParams) (*apimodel.PageableResponse, gtserror.WithCode) {
if len(params.Items) == 0 {
// No items to page through.
return EmptyPageableResponse(), nil
}
// Set default paging values, if
// they weren't set by the caller.
if params.NextMaxIDKey == "" {
params.NextMaxIDKey = "max_id"
}
if params.PrevMinIDKey == "" {
params.PrevMinIDKey = "min_id"
}
var (
protocol = config.GetProtocol()
host = config.GetHost()
nextLink string
prevLink string
linkHeaderParts = make([]string, 0, 2)
)
// Parse next link.
if params.NextMaxIDValue != "" {
nextRaw := params.NextMaxIDKey + "=" + params.NextMaxIDValue
if params.Limit != 0 {
nextRaw = fmt.Sprintf("limit=%d&", params.Limit) + nextRaw
}
for _, p := range params.ExtraQueryParams {
nextRaw += "&" + p
}
nextLink = func() string {
u := &url.URL{
Scheme: protocol,
Host: host,
Path: params.Path,
RawQuery: nextRaw,
}
return u.String()
}()
linkHeaderParts = append(linkHeaderParts, `<`+nextLink+`>; rel="next"`)
}
// Parse prev link.
if params.PrevMinIDValue != "" {
prevRaw := params.PrevMinIDKey + "=" + params.PrevMinIDValue
if params.Limit != 0 {
prevRaw = fmt.Sprintf("limit=%d&", params.Limit) + prevRaw
}
for _, p := range params.ExtraQueryParams {
prevRaw = prevRaw + "&" + p
}
prevLink = func() string {
u := &url.URL{
Scheme: protocol,
Host: host,
Path: params.Path,
RawQuery: prevRaw,
}
return u.String()
}()
linkHeaderParts = append(linkHeaderParts, `<`+prevLink+`>; rel="prev"`)
}
return &apimodel.PageableResponse{
Items: params.Items,
LinkHeader: strings.Join(linkHeaderParts, ", "),
NextLink: nextLink,
PrevLink: prevLink,
}, nil
}
// EmptyPageableResponse just returns an empty
// PageableResponse with no link header or items.
func EmptyPageableResponse() *apimodel.PageableResponse {
return &apimodel.PageableResponse{
Items: []interface{}{},
}
}