#!/bin/sh

###
# help
###

if [ "$1" = "--help" ] || [ "$1" = "-h" ] ; then
  echo 'edname: rename files using $EDITOR.'
  echo
  echo 'usage:'
  echo
  echo ' edname <dir or files>'
  echo '  to rename'
  echo
  echo ' edname --undo'
  echo '  to undo the last rename (as well as possible)'
  echo
  exit 1
fi

###
# functions
###

execute_rename() {
  command="$1"

  lines="$(cat .original.edname | wc -l)"
  IFS=$'\n' read -rd '' -a src_lines < .original.edname
  IFS=$'\n' read -rd '' -a dest_lines < .rename.edname

  for line in $(seq 1 "$lines") ; do
    src="${src_lines[$line]}"
    dest="${dest_lines[$line]}"
    if [ "$src" != "$dest" ] ; then
      eval "$command"
    fi
  done
}

###
# main
###

if [ "$1" = "--undo" ] ; then
  echo "undoing rename"
  execute_rename "echo \"\\\"\$dest\\\" -> \\\"\$src\\\"\""
  execute_rename 'mv "$dest" "$src"'
  echo "done"
  exit
fi

echo "-- DO NOT delete lines. This will cause files to be renamed erratically. --" > .original.edname
ls "$@" >> .original.edname
cp .{original,rename}.edname

echo opening editor.

$EDITOR .rename.edname || exit $?

echo

echo "*** about to do the following rename:"
echo
execute_rename "echo \"\\\"\$src\\\" -> \\\"\$dest\\\"\""
echo
echo "***"

echo
echo "note: possible collisions will be ignored and Not renamed."
echo -n "confirm rename? (enter/^C) "

read

execute_rename 'mv --no-clobber "$src" "$dest"'

echo
echo "you may undo this rename using 'edname --undo'. thank you."