#!/usr/bin/env bash
set -euo pipefail

########################################
# Utilities
########################################

fail() {
  echo "Error: $1" >&2
  exit 1
}

ensure_repo() {
  git rev-parse --is-inside-work-tree >/dev/null 2>&1 ||
    fail "Not inside a git repository"
}

repo_root() {
  git rev-parse --show-toplevel
}

detect_base() {
  if git show-ref --verify --quiet refs/heads/main; then
    echo "main"
  elif git show-ref --verify --quiet refs/heads/master; then
    echo "master"
  else
    git branch --show-current
  fi
}

ensure_clean() {
  git diff --quiet || fail "Working tree is dirty"
  git diff --cached --quiet || fail "Index is dirty"
}

########################################
# Core Paths
########################################

ROOT=$(repo_root)
WT_DIR="$ROOT/.worktrees"

########################################
# Commands
########################################

cmd_new() {
  local name="$1"
  local base="${2:-$(detect_base)}"
  local path="$WT_DIR/$name"

  [ -d "$path" ] && fail "Worktree directory already exists"
  git show-ref --verify --quiet "refs/heads/$name" &&
    fail "Branch '$name' already exists"

  mkdir -p "$WT_DIR"

  git worktree add -b "$name" "$path" "$base"

  echo "Created worktree:"
  echo "  branch: $name"
  echo "  path:   $path"
}

cmd_list() {
  git worktree list
}

cmd_path() {
  echo "$WT_DIR/$1"
}

cmd_rm() {
  local name="$1"
  local path="$WT_DIR/$name"

  [ -d "$path" ] || fail "Worktree not found"

  git worktree remove "$path"
  git branch -D "$name" >/dev/null 2>&1 || true

  echo "Removed worktree '$name'"
}

cmd_finish() {
  local name="$1"
  shift
  local keep_worktree=0
  local path="$WT_DIR/$name"
  local base

  while [[ $# -gt 0 ]]; do
    case "$1" in
      --keep-worktree)
        keep_worktree=1
        shift
        ;;
      *)
        fail "Unknown option for finish: $1"
        ;;
    esac
  done

  [ -d "$path" ] || fail "Worktree not found"
  git show-ref --verify --quiet "refs/heads/$name" ||
    fail "Branch '$name' not found"

  base=$(detect_base)

  echo "Base branch: $base"
  echo "Feature branch: $name"

  git checkout "$base" >/dev/null
  ensure_clean

  if ! git merge --squash "$name"; then
    echo
    echo "Resolve conflicts, then run:"
    echo "  git commit"
    echo "  wt rm $name"
    exit 1
  fi

  git commit -m "$name"

  if [ -d "$path" ] && [ "$keep_worktree" -eq 0 ]; then
    if ! git worktree remove "$path"; then
      git worktree remove --force "$path" || fail "Failed to remove worktree '$name'"
    fi
  fi

  if [ "$keep_worktree" -eq 0 ]; then
    git branch -D "$name"
  fi

  if [ "$keep_worktree" -eq 1 ]; then
    echo "Merged (squash) into '$base' and kept worktree '$path'"
  else
    echo "Merged (squash) and removed '$name'"
  fi
}

cmd_prune() {
  git worktree prune
  echo "Pruned stale worktree metadata"
}

########################################
# Entry
########################################

ensure_repo

case "${1:-}" in
new)
  [ $# -lt 2 ] && fail "Usage: wt new <name> [base]"
  cmd_new "$2" "${3:-}"
  ;;
list)
  cmd_list
  ;;
path)
  [ $# -lt 2 ] && fail "Usage: wt path <name>"
  cmd_path "$2"
  ;;
finish)
  [ $# -lt 2 ] && fail "Usage: wt finish <name>"
  cmd_finish "$2" "${@:3}"
  ;;
rm)
  [ $# -lt 2 ] && fail "Usage: wt rm <name>"
  cmd_rm "$2"
  ;;
prune)
  cmd_prune
  ;;
*)
  cat <<EOF
Usage:
  wt new <name> [base]
  wt list
  wt path <name>
  wt finish <name> [--keep-worktree]
  wt rm <name>
  wt prune
EOF
  exit 1
  ;;
esac