#!/bin/zsh
# vren - rename files with vim
# usage: vren [dir]

dir="${1:-.}"
cd "$dir" || exit 1

# git init if no .git
has_git=0
if [ -d .git ]; then
  has_git=1
else
  git init -q
  git add -A
  git commit -q -m "before rename"
fi

# list files
old=$(mktemp)
new=$(mktemp)
ls -1 > "$old"
cp "$old" "$new"

# edit
vim "$new"

# check
old_count=$(wc -l < "$old")
new_count=$(wc -l < "$new")
if [ "$old_count" -ne "$new_count" ]; then
  echo "error: line count mismatch ($old_count -> $new_count)"
  rm "$old" "$new"
  exit 1
fi

# diff
changes=0
paste "$old" "$new" | while IFS=$'\t' read -r o n; do
  [ "$o" != "$n" ] && echo "  $o -> $n" && changes=$((changes+1))
done

if ! diff -q "$old" "$new" >/dev/null 2>&1; then
  echo ""
  printf "apply? (y/n): "
  read -q ans
  echo ""
  if [ "$ans" = "y" ]; then
    paste "$old" "$new" | while IFS=$'\t' read -r o n; do
      [ "$o" != "$n" ] && mv -- "$o" "$n"
    done
    echo "done"
    # restore point
    if [ "$has_git" -eq 0 ]; then
      git add -A
      git commit -q -m "after rename"
      echo "restore: git log / git checkout HEAD~1 -- ."
    fi
  else
    echo "cancelled"
  fi
else
  echo "no changes"
fi

rm "$old" "$new"