// 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 api

import (
	"github.com/gin-gonic/gin"
	"github.com/superseriousbusiness/gotosocial/internal/api/fileserver"
	"github.com/superseriousbusiness/gotosocial/internal/config"
	"github.com/superseriousbusiness/gotosocial/internal/middleware"
	"github.com/superseriousbusiness/gotosocial/internal/processing"
	"github.com/superseriousbusiness/gotosocial/internal/router"
)

type Fileserver struct {
	fileserver *fileserver.Module
}

func (f *Fileserver) Route(r *router.Router, m ...gin.HandlerFunc) {
	fileserverGroup := r.AttachGroup("fileserver")

	// Attach middlewares appropriate for this group.
	fileserverGroup.Use(m...)
	// If we're using local storage or proxying s3, we can set a
	// long max-age + immutable on all file requests to reflect
	// that we never host different files at the same URL (since
	// ULIDs are generated per piece of media), so we can
	// easily prevent clients having to fetch files repeatedly.
	//
	// If we *are* using non-proxying s3, however, the max age
	// must be set dynamically within the request handler,
	// based on how long the signed URL has left to live before
	// it expires. This ensures that clients won't cache expired
	// links. This is done within fileserver/servefile.go, so we
	// should not set the middleware here in that case.
	//
	// See:
	//
	// - https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching#avoiding_revalidation
	// - https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#immutable
	if config.GetStorageBackend() == "local" || config.GetStorageS3Proxy() {
		fileserverGroup.Use(middleware.CacheControl(middleware.CacheControlConfig{
			Directives: []string{"private", "max-age=604800", "immutable"},
			Vary:       []string{"Range"}, // Cache partial ranges separately.
		}))
	}

	f.fileserver.Route(fileserverGroup.Handle)
}

func NewFileserver(p *processing.Processor) *Fileserver {
	return &Fileserver{
		fileserver: fileserver.New(p),
	}
}