#!/usr/bin/env bash
# dotsync — sync dotfiles with the least churn.
#
# Deployed configs are symlinks into this repo, so `git pull` makes edits LIVE instantly
# with no re-stow — meaning no symlink churn and no app reloads (kitty etc. keep their
# runtime state). Re-stowing (install.sh) is only needed when files are ADDED / REMOVED,
# to create or prune symlinks. dotsync does the minimum: pull, and re-link ONLY if the
# pull added/removed/renamed files.
#
#   dotsync            pull, then relink only if the file set changed
#   dotsync -n         preview incoming changes (fetch only; no pull, no relink)
set -uo pipefail
DOTS="$(cd "$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")/.." && pwd)"
cd "$DOTS" || exit 1

if [ "${1:-}" = "-n" ] || [ "${1:-}" = "--dry-run" ]; then
  git fetch -q 2>/dev/null || { echo "fetch failed (offline?)"; exit 1; }
  up="$(git rev-parse --abbrev-ref '@{u}' 2>/dev/null)" || { echo "no upstream set"; exit 1; }
  # rev-list, not diff: a plain diff also fires when the LOCAL side is ahead, mislabelling
  # your own unpushed commits as incoming. Count commits that exist only on the upstream.
  n="$(git rev-list --count "HEAD..$up")"
  if [ "$n" -eq 0 ]; then echo "already up to date with $up."; else
    echo "incoming from $up ($n commit(s)):"; git --no-pager diff --stat "HEAD...$up"
  fi
  exit 0
fi

before="$(git rev-parse HEAD)"
if ! git pull --ff-only; then
  echo "pull not fast-forward (local commits or conflicts) — commit/stash, then retry." >&2
  exit 1
fi
after="$(git rev-parse HEAD)"

if [ "$before" = "$after" ]; then
  echo "already up to date — nothing to sync."
  exit 0
fi

# Services that read config ONCE at startup don't pick up pulled edits — nudge loudly.
# (Symlinked edits are live for everything else; these are the exceptions that bit us.)
if git diff --name-only "$before" "$after" | grep -q '\.config/llamacpp/' \
   && systemctl cat llama.service &>/dev/null; then
  echo ""
  echo "⚠⚠  llamacpp presets changed — the router reads them only at startup. Apply with:"
  echo "      sudo systemctl restart llama.service"
  echo ""
fi

# A unit file is read from /etc, not through the stow symlink — needs daemon-reload as well.
if git diff --name-only "$before" "$after" | grep -q '\.config/whisper/' \
   && systemctl cat whisper.service &>/dev/null; then
  echo ""
  echo "⚠⚠  whisper unit changed — apply with:"
  echo "      sudo systemctl daemon-reload && sudo systemctl restart whisper.service"
  echo ""
fi

# Modified files (M) are already live through the symlinks. Only Added/Deleted/Renamed
# need (un)linking, which is the only case that justifies the churny re-stow.
if git diff --name-status "$before" "$after" | grep -qE '^(A|D|R)'; then
  echo "files added/removed/renamed — re-linking via install.sh (this may reload some apps)…"
  exec "$DOTS/install.sh"
else
  echo "edits only — already live through the symlinks; no re-stow, no reload needed."
fi