From 2c27d2626e7bf1f41d64ff12cfcc1003551814e5 Mon Sep 17 00:00:00 2001
From: Harshil Sharma <18575143+harshilsharma63@users.noreply.github.com>
Date: Thu, 6 Oct 2022 01:46:03 +0530
Subject: [PATCH] Fix bug where workspace era uploaded files won't load on team
 era codebase (#3907)

* WIP

* Added comment for explaination

* Lint fix

* move file if found in channel directory

* lint fixes

Co-authored-by: Scott Bishel <scott.bishel@mattermost.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
---
 server/api/files.go | 21 ++++++++++++++++++++-
 server/app/files.go | 18 ++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/server/api/files.go b/server/api/files.go
index e6d2a57af..825ff22f1 100644
--- a/server/api/files.go
+++ b/server/api/files.go
@@ -2,12 +2,15 @@ package api
 
 import (
 	"encoding/json"
+	"errors"
 	"io"
 	"net/http"
 	"path/filepath"
 	"strings"
 	"time"
 
+	"github.com/mattermost/focalboard/server/app"
+
 	"github.com/gorilla/mux"
 	"github.com/mattermost/focalboard/server/model"
 	"github.com/mattermost/focalboard/server/services/audit"
@@ -144,10 +147,26 @@ func (a *API) handleServeFile(w http.ResponseWriter, r *http.Request) {
 	}
 
 	fileReader, err := a.app.GetFileReader(board.TeamID, boardID, filename)
-	if err != nil {
+	if err != nil && !errors.Is(err, app.ErrFileNotFound) {
 		a.errorResponse(w, r, err)
 		return
 	}
+
+	if errors.Is(err, app.ErrFileNotFound) && board.ChannelID != "" {
+		// prior to moving from workspaces to teams, the filepath was constructed from
+		// workspaceID, which is the channel ID in plugin mode.
+		// If a file is not found from team ID as we tried above, try looking for it via
+		// channel ID.
+		fileReader, err = a.app.GetFileReader(board.ChannelID, boardID, filename)
+		if err != nil {
+			a.errorResponse(w, r, err)
+			return
+		}
+		// move file to team location
+		// nothing to do if there is an error
+		_ = a.app.MoveFile(board.ChannelID, board.TeamID, boardID, filename)
+	}
+
 	defer fileReader.Close()
 	http.ServeContent(w, r, filename, time.Now(), fileReader)
 	auditRec.Success()
diff --git a/server/app/files.go b/server/app/files.go
index 5820937e0..081b78e14 100644
--- a/server/app/files.go
+++ b/server/app/files.go
@@ -17,6 +17,7 @@ import (
 const emptyString = "empty"
 
 var errEmptyFilename = errors.New("IsFileArchived: empty filename not allowed")
+var ErrFileNotFound = errors.New("file not found")
 
 func (a *App) SaveFile(reader io.Reader, teamID, rootID, filename string) (string, error) {
 	// NOTE: File extension includes the dot
@@ -111,6 +112,8 @@ func (a *App) GetFileReader(teamID, rootID, filename string) (filestore.ReadClos
 				)
 			}
 		}
+	} else if !exists {
+		return nil, ErrFileNotFound
 	}
 
 	reader, err := a.filesBackend.Reader(filePath)
@@ -120,3 +123,18 @@ func (a *App) GetFileReader(teamID, rootID, filename string) (filestore.ReadClos
 
 	return reader, nil
 }
+
+func (a *App) MoveFile(channelID, teamID, boardID, filename string) error {
+	oldPath := filepath.Join(channelID, boardID, filename)
+	newPath := filepath.Join(teamID, boardID, filename)
+	err := a.filesBackend.MoveFile(oldPath, newPath)
+	if err != nil {
+		a.logger.Error("ERROR moving file",
+			mlog.String("old", oldPath),
+			mlog.String("new", newPath),
+			mlog.Err(err),
+		)
+		return err
+	}
+	return nil
+}