git-grob

#!/usr/bin/env zsh
# ------------------------------------------------------------------------------
# git-grob: Interactive git rebase --onto helper
# Can be invoked as: git grob
# ------------------------------------------------------------------------------

# Dependency check
if ! command -v fzf >/dev/null 2>&1; then
  echo "Error: 'fzf' is not installed. Please install it to use git-grob."
  exit 1
fi

local extra_flags=("$@")

# Text formatting
local bold=$(tput bold)
local reset=$(tput sgr0)
local blue=$(tput setaf 4)
local green=$(tput setaf 2)
local yellow=$(tput setaf 3)
local red=$(tput setaf 1)
local cyan=$(tput setaf 6)
local mag=$(tput setaf 5)
local dim=$(tput setaf 8)

if ! git diff-index --quiet HEAD --; then
  echo "${yellow}⚠️  Warning: Uncommitted changes detected. Please stash or commit first.${reset}"
  exit 1
fi

# 1. Select Target Branch
local target_branch=$(git branch --format='%(refname:short)' | \
  fzf --height 60% --border --prompt="onto ➜ " \
      --header="STEP 1: Select TARGET branch" \
      --preview-window=up:40% \
      --bind 'shift-up:preview-up,shift-down:preview-down' \
      --preview 'git log --oneline --graph --color=always -n 15 {}')

[[ -z "$target_branch" ]] && exit 0

# 2. Select Oldest Commit 
local header_text="TARGET: [${bold}${green}${target_branch}${reset}]"$'\n'"STEP 2: Select the OLDEST commit to move (includes selection + all newer)"

# FIX: Cleaned up the sed quoting and the awk escaping for Zsh compatibility
local preview_cmd='
  git show --format="%C(yellow)%h%C(reset) %C(magenta)%an%C(reset) %C(cyan)(%ad)%C(reset)%n%s" --date=format:"%b %d, %Y" --color=always {1} | head -n 2;
  echo "";
  git diff --shortstat {1}^ {1} | awk "{
    gsub(/[0-9]+/, \"\\033[33m&\\033[0m\");
    gsub(/insertion/, \"\\033[32minsertion\\033[0m\");
    gsub(/deletion/, \"\\033[31mdeletion\\033[0m\");
    print
  }";
  echo "";
  git show --stat --format="" --color=always {1} | sed "\$d";
  echo "";
  echo "'"$(tput setaf 8)"'──────────────────────────────────────────────────'"$reset"'";
  git show -s --format="%C(bold)Full SHA:%C(reset) %H%n%C(bold)Author:%C(reset)   %ae%n%C(bold)Commit:%C(reset)   %ad" --date=format:"%b %d, %Y %H:%M:%S" {1}'

local selection=$(git log --oneline --color=always | \
  fzf --ansi --height 60% --border \
      --prompt="move from ➜ " \
      --header="$header_text" \
      --preview-window=up:6:wrap \
      --bind 'shift-up:preview-up,shift-down:preview-down' \
      --preview "$preview_cmd")

[[ -z "$selection" ]] && exit 0

local commit_hash=$(echo "$selection" | awk '{print $1}')
local commit_index=$(git log --oneline | grep -nF "$commit_hash" | cut -d: -f1)
local base_ref="HEAD~$commit_index"

# 3. Confirmation UI
echo "\n${bold}${cyan}REBASE PREVIEW${reset}"
echo "${dim}====================================================${reset}"
printf "  %-18s %s\n" "${bold}Target Branch:${reset}" "${green}${target_branch}${reset}"
printf "  %-18s %s\n" "${bold}Commit Count :${reset}"  "${yellow}${commit_index} commit(s)${reset}"
printf "  %-18s %s\n" "${bold}Starting At  :${reset}"   "${mag}${commit_hash}${reset}"

if [[ ${#extra_flags[@]} -gt 0 ]]; then
  printf "  %-18s %s\n" "${bold}Extra Flags  :${reset}"   "${blue}${extra_flags[*]}${reset}"
fi

echo "${dim}----------------------------------------------------${reset}"
echo "  ${bold}Command:${reset} ${dim}git rebase --onto $target_branch $base_ref ${extra_flags[*]}${reset}"
echo "${dim}====================================================${reset}\n"

echo -n "  Confirm execution? (y/N): "
read -k 1 confirm
echo "\n" 

if [[ "$confirm" =~ ^[Yy]$ ]]; then
  echo "${green}Executing rebase...${reset}"
  git rebase --onto "$target_branch" "$base_ref" "${extra_flags[@]}"
else
  echo "${dim}Aborted.${reset}"
fi