[feature] Implement `cache-control` and etags for static assets (#711)

* start working on etag stuff

* add + use cache middleware

* generate etags on the fly

* remove unused field

* clean up filepath

* add license headers to cache files

* add attachgroup function to router interface

* move cache into web module

* rename a couple things

* remove attachStaticFS function from router

* rename + tidy up a few things

* mount assets filesystem

* create assetsFileInfoCache

* update comment

* simplify hash

* fix string fmt

* skip last mod chk, prefer strong etags w/long cache

* move base handler to its own file
this matches the modules in the api folder

* generate new etag if file was modified

* wrap strong etag in quotation marks as per spec

* clarify logic in avatar search

* make hashing a little niftier

1 files changed, 0 insertions, 157 deletions

diff --git a/internal/web/base.go b/internal/web/base.go
index 8e7e539f6..27e7d41c1 100644
--- a/internal/web/base.go
+++ b/internal/web/base.go
@@ -19,89 +19,14 @@
 package web
 
 import (
-	"errors"
-	"fmt"
-	"io/ioutil"
 	"net/http"
-	"path/filepath"
-	"strings"
 
 	"github.com/gin-gonic/gin"
 	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
-	"github.com/superseriousbusiness/gotosocial/internal/processing"
-	"github.com/superseriousbusiness/gotosocial/internal/router"
-	"github.com/superseriousbusiness/gotosocial/internal/uris"
 )
 
-const (
-	confirmEmailPath = "/" + uris.ConfirmEmailPath
-	tokenParam       = "token"
-	usernameKey      = "username"
-	statusIDKey      = "status"
-	profilePath      = "/@:" + usernameKey
-	statusPath       = profilePath + "/statuses/:" + statusIDKey
-)
-
-// Module implements the api.ClientModule interface for web pages.
-type Module struct {
-	processor      processing.Processor
-	assetsPath     string
-	adminPath      string
-	defaultAvatars []string
-}
-
-// New returns a new api.ClientModule for web pages.
-func New(processor processing.Processor) (api.ClientModule, error) {
-	assetsBaseDir := config.GetWebAssetBaseDir()
-	if assetsBaseDir == "" {
-		return nil, fmt.Errorf("%s cannot be empty and must be a relative or absolute path", config.WebAssetBaseDirFlag())
-	}
-
-	assetsPath, err := filepath.Abs(assetsBaseDir)
-	if err != nil {
-		return nil, fmt.Errorf("error getting absolute path of %s: %s", assetsBaseDir, err)
-	}
-
-	defaultAvatarsPath := filepath.Join(assetsPath, "default_avatars")
-	defaultAvatarFiles, err := ioutil.ReadDir(defaultAvatarsPath)
-	if err != nil {
-		return nil, fmt.Errorf("error reading default avatars at %s: %s", defaultAvatarsPath, err)
-	}
-
-	defaultAvatars := []string{}
-	for _, f := range defaultAvatarFiles {
-		// ignore directories
-		if f.IsDir() {
-			continue
-		}
-
-		// ignore files bigger than 50kb
-		if f.Size() > 50000 {
-			continue
-		}
-
-		extension := strings.TrimPrefix(strings.ToLower(filepath.Ext(f.Name())), ".")
-
-		// take only files with simple extensions
-		switch extension {
-		case "svg", "jpeg", "jpg", "gif", "png":
-			defaultAvatarPath := fmt.Sprintf("/assets/default_avatars/%s", f.Name())
-			defaultAvatars = append(defaultAvatars, defaultAvatarPath)
-		default:
-			continue
-		}
-	}
-
-	return &Module{
-		processor:      processor,
-		assetsPath:     assetsPath,
-		adminPath:      filepath.Join(assetsPath, "admin"),
-		defaultAvatars: defaultAvatars,
-	}, nil
-}
-
 func (m *Module) baseHandler(c *gin.Context) {
 	host := config.GetHost()
 	instance, err := m.processor.InstanceGet(c.Request.Context(), host)
@@ -114,85 +39,3 @@ func (m *Module) baseHandler(c *gin.Context) {
 		"instance": instance,
 	})
 }
-
-// TODO: abstract the {admin, user}panel handlers in some way
-func (m *Module) AdminPanelHandler(c *gin.Context) {
-	host := config.GetHost()
-	instance, err := m.processor.InstanceGet(c.Request.Context(), host)
-	if err != nil {
-		api.ErrorHandler(c, gtserror.NewErrorInternalError(err), m.processor.InstanceGet)
-		return
-	}
-
-	c.HTML(http.StatusOK, "frontend.tmpl", gin.H{
-		"instance": instance,
-		"stylesheets": []string{
-			"/assets/Fork-Awesome/css/fork-awesome.min.css",
-			"/assets/dist/panels-admin-style.css",
-		},
-		"javascript": []string{
-			"/assets/dist/bundle.js",
-			"/assets/dist/admin-panel.js",
-		},
-	})
-}
-
-func (m *Module) UserPanelHandler(c *gin.Context) {
-	host := config.GetHost()
-	instance, err := m.processor.InstanceGet(c.Request.Context(), host)
-	if err != nil {
-		api.ErrorHandler(c, gtserror.NewErrorInternalError(err), m.processor.InstanceGet)
-		return
-	}
-
-	c.HTML(http.StatusOK, "frontend.tmpl", gin.H{
-		"instance": instance,
-		"stylesheets": []string{
-			"/assets/Fork-Awesome/css/fork-awesome.min.css",
-			"/assets/dist/_colors.css",
-			"/assets/dist/base.css",
-			"/assets/dist/panels-user-style.css",
-		},
-		"javascript": []string{
-			"/assets/dist/bundle.js",
-			"/assets/dist/user-panel.js",
-		},
-	})
-}
-
-// Route satisfies the RESTAPIModule interface
-func (m *Module) Route(s router.Router) error {
-	// serve static files from assets dir at /assets
-	s.AttachStaticFS("/assets", fileSystem{http.Dir(m.assetsPath)})
-
-	s.AttachHandler(http.MethodGet, "/admin", m.AdminPanelHandler)
-	// redirect /admin/ to /admin
-	s.AttachHandler(http.MethodGet, "/admin/", func(c *gin.Context) {
-		c.Redirect(http.StatusMovedPermanently, "/admin")
-	})
-
-	s.AttachHandler(http.MethodGet, "/user", m.UserPanelHandler)
-	// redirect /settings/ to /settings
-	s.AttachHandler(http.MethodGet, "/user/", func(c *gin.Context) {
-		c.Redirect(http.StatusMovedPermanently, "/user")
-	})
-
-	// serve front-page
-	s.AttachHandler(http.MethodGet, "/", m.baseHandler)
-
-	// serve profile pages at /@username
-	s.AttachHandler(http.MethodGet, profilePath, m.profileGETHandler)
-
-	// serve statuses
-	s.AttachHandler(http.MethodGet, statusPath, m.threadGETHandler)
-
-	// serve email confirmation page at /confirm_email?token=whatever
-	s.AttachHandler(http.MethodGet, confirmEmailPath, m.confirmEmailGETHandler)
-
-	// 404 handler
-	s.AttachNoRouteHandler(func(c *gin.Context) {
-		api.ErrorHandler(c, gtserror.NewErrorNotFound(errors.New(http.StatusText(http.StatusNotFound))), m.processor.InstanceGet)
-	})
-
-	return nil
-}