Batch file to rename physical files from CSV entries

This batch file will read a CSV file with “id” in “A” column, user name in “B” column and file name in “C” column. The problem statement is to read user name in column B in the CSV file and rename the file specified in column C with the user name.
Some tips:
a. The following line reads the CSV file in a loop with delimiter as comma:
FOR /F “skip=1 tokens=2-4 delims=,” %%a IN (%1) do ^

b. %%~xi automatically picks up the file extension from a file name.

c. ext is used as a variable here.
setlocal ENABLEDELAYEDEXPANSION enables proper usage of this variable.

d. %%a, %%b, %%c specifies columns A, B, C in the CSV file.

e. Following line extracts the file name extension and echoes it:
for %%i in (%%c) do echo %%~xi

f. The following line copies file name in C column with name in B column with extension variable “ext”
echo copying %%c “%%b!ext!”
Hence original file extensions are preserved while copying/ renaming.

g. The renamed files are copied to folder called “renamed” in the parent folder.

h. usage is rename_files.bat (csv-file)

i. Place the CSV file, bat file and photos in same parent folder

j. The if/else part appears because when an extra column appears in a column b data is pushed to c
column (four digit number in column A causes an extra column to appear in id column)

k. %1 represents the run time argument passed to the batch file.

@echo off
if not exist (%1) (
 echo Input file missing.  Usage: rename_jpg.bat (csv-file)
FOR /F "skip=1 tokens=2-4 delims=," %%a IN (%1) do ^
if [%%c]==[] (
for %%i in (%%b) do echo %%~xi
for %%i in (%%b) do (
 set "ext=%%~xi"
 echo copying %%b "%%a!ext!"
 copy %%b "%%a!ext!"
 move "%%a!ext!" renamed
) else (
for %%i in (%%c) do echo %%~xi
for %%i in (%%c) do (
 set "ext=%%~xi"
 echo copying %%c "%%b!ext!"
 copy %%c "%%b!ext!"
 move "%%b!ext!" renamed

example of CSV entries:

Id	User Name	File Name	
1	1408946308922	a2298d70-91a2-4254-a3bf-f721ee2d.jpg	
2	1408946892590	5bc14e6f-5922-4864-b5c6-ceb69ad0.jpg	
3	1408947330112	06545cfb-703a-4d57-aaa8-419b0295.jpg	
4	1408946289199	46f98f8d-b11a-4617-b05a-80c0ff53.jpg