From 2b7bdb26242c1f8bf768b2a926919e0825652299 Mon Sep 17 00:00:00 2001
From: Brian Gough <briangough@users.noreply.github.com>
Date: Mon, 9 Dec 2024 14:51:05 +0000
Subject: [PATCH] Merge pull request #22391 from overleaf/bg-issue22370

Provide fallback in web for requests to file urls

GitOrigin-RevId: 793e8e138a08e28e097ac6dd0503333cc17375ab
---
 .../src/Features/History/HistoryController.js | 29 +++++++++++++++++++
 services/web/app/src/router.mjs               |  2 ++
 2 files changed, 31 insertions(+)

diff --git a/services/web/app/src/Features/History/HistoryController.js b/services/web/app/src/Features/History/HistoryController.js
index fe7cbe2c1d..19dfb3eb21 100644
--- a/services/web/app/src/Features/History/HistoryController.js
+++ b/services/web/app/src/Features/History/HistoryController.js
@@ -2,6 +2,7 @@ let HistoryController
 const OError = require('@overleaf/o-error')
 const async = require('async')
 const logger = require('@overleaf/logger')
+const metrics = require('@overleaf/metrics')
 const request = require('request')
 const settings = require('@overleaf/settings')
 const SessionManager = require('../Authentication/SessionManager')
@@ -11,6 +12,7 @@ const Errors = require('../Errors/Errors')
 const HistoryManager = require('./HistoryManager')
 const ProjectDetailsHandler = require('../Project/ProjectDetailsHandler')
 const ProjectEntityUpdateHandler = require('../Project/ProjectEntityUpdateHandler')
+const ProjectLocator = require('../Project/ProjectLocator')
 const RestoreManager = require('./RestoreManager')
 const { pipeline } = require('stream')
 const Stream = require('stream')
@@ -68,6 +70,33 @@ module.exports = HistoryController = {
   getBlob: expressify(getBlob),
   headBlob: expressify(headBlob),
 
+  /** Middleware to translate fileId requests to use the blob API.
+   *
+   *  e.g. incoming requests to /project/:project_id/file/:file_id are
+   *  internally redirected to /project/:project_id/blob/:hash if the file
+   *  has a hash.
+   * */
+  fileToBlobRedirectMiddleware(req, res, next) {
+    const projectId = req.params.Project_id
+    const fileId = req.params.File_id
+    ProjectLocator.findElement(
+      { project_id: projectId, element_id: fileId, type: 'file' },
+      (err, file) => {
+        if (err) {
+          return next(err)
+        }
+        if (file?.hash) {
+          req.url = `/project/${projectId}/blob/${file.hash}`
+        }
+        metrics.inc('fileToBlobRedirectMiddleware', 1, {
+          method: req.method,
+          status: Boolean(file?.hash),
+        })
+        next()
+      }
+    )
+  },
+
   proxyToHistoryApi(req, res, next) {
     const userId = SessionManager.getLoggedInUserId(req.session)
     const url = settings.apis.project_history.url + req.url
diff --git a/services/web/app/src/router.mjs b/services/web/app/src/router.mjs
index 6e920d9dc9..2ec36f55ee 100644
--- a/services/web/app/src/router.mjs
+++ b/services/web/app/src/router.mjs
@@ -543,11 +543,13 @@ async function initialize(webRouter, privateApiRouter, publicApiRouter) {
   webRouter.head(
     '/Project/:Project_id/file/:File_id',
     AuthorizationMiddleware.ensureUserCanReadProject,
+    HistoryController.fileToBlobRedirectMiddleware,
     FileStoreController.getFileHead
   )
   webRouter.get(
     '/Project/:Project_id/file/:File_id',
     AuthorizationMiddleware.ensureUserCanReadProject,
+    HistoryController.fileToBlobRedirectMiddleware,
     FileStoreController.getFile
   )
   webRouter.head(