// 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 web

import (
	"context"
	"net/http"
	"net/url"
	"path/filepath"

	"codeberg.org/gruf/go-cache/v3"
	"github.com/gin-gonic/gin"
	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
	"github.com/superseriousbusiness/gotosocial/internal/config"
	"github.com/superseriousbusiness/gotosocial/internal/db"
	"github.com/superseriousbusiness/gotosocial/internal/log"
	"github.com/superseriousbusiness/gotosocial/internal/middleware"
	"github.com/superseriousbusiness/gotosocial/internal/processing"
	"github.com/superseriousbusiness/gotosocial/internal/router"
	"github.com/superseriousbusiness/gotosocial/internal/uris"
)

const (
	confirmEmailPath   = "/" + uris.ConfirmEmailPath
	profileGroupPath   = "/@:" + usernameKey
	statusPath         = "/statuses/:" + apiutil.WebStatusIDKey // leave out the '/@:username' prefix as this will be served within the profile group
	tagsPath           = "/tags/:" + apiutil.TagNameKey
	customCSSPath      = profileGroupPath + "/custom.css"
	rssFeedPath        = profileGroupPath + "/feed.rss"
	assetsPathPrefix   = "/assets"
	distPathPrefix     = assetsPathPrefix + "/dist"
	settingsPathPrefix = "/settings"
	settingsPanelGlob  = settingsPathPrefix + "/*panel"
	userPanelPath      = settingsPathPrefix + "/user"
	adminPanelPath     = settingsPathPrefix + "/admin"

	tokenParam  = "token"
	usernameKey = "username"

	cacheControlHeader    = "Cache-Control"     // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
	cacheControlNoCache   = "no-cache"          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#response_directives
	ifModifiedSinceHeader = "If-Modified-Since" // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Modified-Since
	ifNoneMatchHeader     = "If-None-Match"     // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-None-Match
	eTagHeader            = "ETag"              // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag
	lastModifiedHeader    = "Last-Modified"     // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Last-Modified
)

type Module struct {
	processor    *processing.Processor
	eTagCache    cache.Cache[string, eTagCacheEntry]
	isURIBlocked func(context.Context, *url.URL) (bool, error)
}

func New(db db.DB, processor *processing.Processor) *Module {
	return &Module{
		processor:    processor,
		eTagCache:    newETagCache(),
		isURIBlocked: db.IsURIBlocked,
	}
}

func (m *Module) Route(r router.Router, mi ...gin.HandlerFunc) {
	// Group all static files from assets dir at /assets,
	// so that they can use the same cache control middleware.
	webAssetsAbsFilePath, err := filepath.Abs(config.GetWebAssetBaseDir())
	if err != nil {
		log.Panicf(nil, "error getting absolute path of assets dir: %s", err)
	}
	fs := fileSystem{http.Dir(webAssetsAbsFilePath)}
	assetsGroup := r.AttachGroup(assetsPathPrefix)
	assetsGroup.Use(m.assetsCacheControlMiddleware(fs))
	assetsGroup.Use(mi...)
	assetsGroup.StaticFS("/", fs)

	// handlers that serve profiles and statuses should use the SignatureCheck
	// middleware, so that requests with content-type application/activity+json
	// can still be served
	profileGroup := r.AttachGroup(profileGroupPath)
	profileGroup.Use(mi...)
	profileGroup.Use(middleware.SignatureCheck(m.isURIBlocked), middleware.CacheControl(middleware.CacheControlConfig{
		Directives: []string{"no-store"},
	}))
	profileGroup.Handle(http.MethodGet, "", m.profileGETHandler) // use empty path here since it's the base of the group
	profileGroup.Handle(http.MethodGet, statusPath, m.threadGETHandler)

	// Attach individual web handlers which require no specific middlewares
	r.AttachHandler(http.MethodGet, "/", m.baseHandler) // front-page
	r.AttachHandler(http.MethodGet, settingsPathPrefix, m.SettingsPanelHandler)
	r.AttachHandler(http.MethodGet, settingsPanelGlob, m.SettingsPanelHandler)
	r.AttachHandler(http.MethodGet, customCSSPath, m.customCSSGETHandler)
	r.AttachHandler(http.MethodGet, rssFeedPath, m.rssFeedGETHandler)
	r.AttachHandler(http.MethodGet, confirmEmailPath, m.confirmEmailGETHandler)
	r.AttachHandler(http.MethodGet, robotsPath, m.robotsGETHandler)
	r.AttachHandler(http.MethodGet, aboutPath, m.aboutGETHandler)
	r.AttachHandler(http.MethodGet, domainBlockListPath, m.domainBlockListGETHandler)
	r.AttachHandler(http.MethodGet, tagsPath, m.tagGETHandler)

	// Attach redirects from old endpoints to current ones for backwards compatibility
	r.AttachHandler(http.MethodGet, "/auth/edit", func(c *gin.Context) { c.Redirect(http.StatusMovedPermanently, userPanelPath) })
	r.AttachHandler(http.MethodGet, "/user", func(c *gin.Context) { c.Redirect(http.StatusMovedPermanently, userPanelPath) })
	r.AttachHandler(http.MethodGet, "/admin", func(c *gin.Context) { c.Redirect(http.StatusMovedPermanently, adminPanelPath) })
}