#!/usr/bin/env sh
# VCN #49 The Swarm - check a machine can run parallel coding agents in git worktrees.
# DOCTOR ONLY. This script changes NOTHING: it creates no worktree, no branch, no
# file, and touches no global config. It reads your git version and repo state and
# tells you whether tonight's lab will work here.
#
# Run:    curl -fsSL https://vcn-49-the-swarm.vercel.app/wire.sh | sh
# From inside the repo you are bringing:
#         cd your-repo && curl -fsSL https://vcn-49-the-swarm.vercel.app/wire.sh | sh
#
# Options (append after -s --):
#   --probe     ALSO do a real worktree add/list/remove round-trip in a temp dir,
#               then clean it up. Proves the mechanism end to end. Still creates
#               nothing inside your repo that it does not remove.
#
# There are NO credentials in this file and it prints none. ASCII only.
# Nothing to uninstall: the default run writes nothing.

set -u

PROBE=0
while [ $# -gt 0 ]; do
  case "$1" in
    --probe) PROBE=1 ;;
    -h|--help) sed -n '2,18p' "$0" 2>/dev/null || echo "see https://vcn-49-the-swarm.vercel.app/wire.sh"; exit 0 ;;
    *) echo "unknown option: $1 (ignored)" ;;
  esac
  shift
done

ok()   { printf '  OK    %s\n' "$1"; }
warn() { printf '  WARN  %s\n' "$1"; }
bad()  { printf '  FAIL  %s\n' "$1"; }
have() { command -v "$1" >/dev/null 2>&1; }

FAILED=0

echo ""
echo "VCN #49 The Swarm - machine doctor"
echo "-----------------------------------"

# 1. git present, and new enough for worktrees (shipped in 2.5, Jul 2015).
if have git; then
  GV=$(git --version 2>/dev/null | awk '{print $3}')
  MAJ=$(echo "$GV" | cut -d. -f1)
  MIN=$(echo "$GV" | cut -d. -f2)
  if [ "${MAJ:-0}" -gt 2 ] 2>/dev/null || { [ "${MAJ:-0}" -eq 2 ] && [ "${MIN:-0}" -ge 5 ]; } 2>/dev/null; then
    ok "git $GV (worktrees need 2.5+)"
  else
    bad "git $GV is older than 2.5 - no worktree support"; FAILED=1
  fi
else
  bad "git not found on PATH"; FAILED=1
fi

# 2. Claude Code, the thing that drives each worker.
if have claude; then ok "claude on PATH"; else
  warn "claude not on PATH - you need it to drive the agents. See $0 notes."
fi

# 3. Are we inside a repo? Everything below only applies if we are.
INREPO=0
if have git && git rev-parse --git-dir >/dev/null 2>&1; then
  INREPO=1
  ok "inside a git repo"
else
  warn "not inside a git repo - re-run this from the repo you are bringing tonight"
fi

if [ "$INREPO" -eq 1 ]; then
  # 4. Clean tree. `git worktree add` works with a dirty tree, but tonight you
  #    will be merging three branches back and an unrelated dirty file is the
  #    thing that turns a clean merge into a confusing one.
  if [ -z "$(git status --porcelain 2>/dev/null)" ]; then
    ok "working tree is clean"
  else
    warn "working tree is dirty - commit or stash before the lab"
  fi

  # 5. How many worktrees already exist. One is the normal starting state.
  N=$(git worktree list 2>/dev/null | wc -l | tr -d ' ')
  if [ "${N:-0}" -le 1 ]; then
    ok "worktrees: $N (a clean starting point)"
  else
    warn "worktrees: $N already exist - 'git worktree list' to see them"
  fi

  # 6. THE ONE THAT BITES. A reparse point (symlink/junction) inside a worktree
  #    is followed by `git worktree remove` and by `rm -rf`, which deletes the
  #    TARGET, outside the worktree, and exits 0 saying nothing. See slide 9.
  LINKS=$(find . -maxdepth 2 \( -type l -o -name .venv -o -name node_modules \) 2>/dev/null | head -5)
  if [ -n "$LINKS" ]; then
    warn "found links or heavy dirs near the root:"
    echo "$LINKS" | sed 's/^/          /'
    warn "if you link any of these INTO a worktree, unlink before removing it"
  else
    ok "no obvious reparse points near the repo root"
  fi
fi

# 7. Optional: prove the mechanism for real, in a temp dir, then clean up.
if [ "$PROBE" -eq 1 ] && have git; then
  echo ""
  echo "  probe: real worktree round-trip in a temp dir"
  T=$(mktemp -d 2>/dev/null || echo "./.swarm-probe-$$")
  ( mkdir -p "$T/r" && cd "$T/r" \
      && git init -q . 2>/dev/null \
      && git -c user.name=probe -c user.email=probe@local commit -q --allow-empty -m init 2>/dev/null \
      && git worktree add ../w -b probe/tmp >/dev/null 2>&1 \
      && git worktree list | tail -1 >/dev/null \
      && git worktree remove ../w >/dev/null 2>&1 ) \
    && ok "worktree add / list / remove all work here" \
    || { bad "worktree round-trip failed on this machine"; FAILED=1; }
  rm -rf "$T" 2>/dev/null
fi

echo ""
if [ "$FAILED" -eq 0 ]; then
  echo "  READY. Bring a repo with THREE independent things to do."
  echo "  Independence is the real prerequisite: if two of them edit the"
  echo "  same file, they are one task, and the lab will show you why."
else
  echo "  NOT READY. Fix the FAIL lines above, then re-run."
fi
echo ""
echo "  Deck:  https://vcn-49-the-swarm.vercel.app"
echo "  Prep:  https://vcn-49-the-swarm.vercel.app/setup.txt"
echo "  Agents: https://vcn-49-the-swarm.vercel.app/llms.txt"
echo ""

exit "$FAILED"