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

REPO_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
QUICK=no
DO_COMMIT=no
INSTALL_HOOK=no
DRY_RUN=no

usage() {
  cat <<EOF
Sync live system state back into the dotfiles repo.

Usage: $0 [options]

  -q, --quick        non-interactive, minimal output (used by postsync hook)
  -c, --commit       git add -A && git commit after syncing
  -h, --hook-install write /etc/portage/postsync.d hook (auto after each emerge)
  -n, --dry-run      show what would change without copying
  --help             show this help
EOF
}

while [[ $# -gt 0 ]]; do
  case "$1" in
  -q | --quick) QUICK=yes ;;
  -c | --commit) DO_COMMIT=yes ;;
  -h | --hook-install) INSTALL_HOOK=yes ;;
  -n | --dry-run) DRY_RUN=yes ;;
  --help)
    usage
    exit 0
    ;;
  *)
    echo "unknown option: $1" >&2
    usage >&2
    exit 2
    ;;
  esac
  shift
done

log() { printf '\033[1;32m[sync]\033[0m %s\n' "$*"; }
warn() { printf '\033[1;33m[warn]\033[0m %s\n' "$*"; }

root_cp() {
  if [[ "$DRY_RUN" == "yes" ]]; then
    log "  would copy $1 -> $2"
    return 0
  fi
  if [[ $EUID -eq 0 ]]; then
    cp "$1" "$2"
  elif cp "$1" "$2" 2>/dev/null; then
    : # readable as current user — done
  elif command -v sudo >/dev/null 2>&1; then
    sudo cp "$1" "$2"
  else
    warn "need root to copy $1"
    return 1
  fi
}

rsync_portage() {
  # -L: dereference symlinks so /etc/portage symlinks back into the repo
  #     are copied as content, never re-created as self-referencing symlinks.
  # Broken symlinks are excluded (rsync -L aborts on dangling referents).
  local exfile
  exfile="$(mktemp)"
  printf '.gitkeep\nmake.profile\n' >"$exfile"
  find /etc/portage -type l ! -exec test -e {} \; -printf '%P\n' >>"$exfile"

  local -a opts=(-aL --delete "--exclude-from=$exfile")
  [[ "$DRY_RUN" == "yes" ]] && opts+=(-n)
  log "portage /etc/portage -> repo/portage/etc/portage"
  rsync "${opts[@]}" /etc/portage/ "$REPO_DIR/portage/etc/portage/"
  rm -f "$exfile"
}

sync_portage() {
  rsync_portage

  if [[ -e /etc/portage/make.profile ]]; then
    log "profile: $(readlink /etc/portage/make.profile)"
    if [[ "$DRY_RUN" != "yes" ]]; then
      printf '%s\n' "$(readlink /etc/portage/make.profile)" >"$REPO_DIR/portage/PROFILE"
    else
      log "  would write: portage/PROFILE"
    fi
  fi

  log "world /var/lib/portage/world -> repo"
  if [[ -L /var/lib/portage/world ]] &&
    [[ "$(readlink -f /var/lib/portage/world)" == "$REPO_DIR/portage/var/lib/portage/world" ]]; then
    log "  already a symlink into the repo — no copy needed"
  else
    root_cp /var/lib/portage/world "$REPO_DIR/portage/var/lib/portage/world"
  fi

  if [[ -s /var/lib/portage/world_sets ]]; then
    log "world_sets /var/lib/portage/world_sets -> repo"
    root_cp /var/lib/portage/world_sets "$REPO_DIR/portage/var/lib/portage/world_sets"
  fi
}

sync_system() {
  log "fstab /etc/fstab -> repo/fstab/etc/fstab"
  root_cp /etc/fstab "$REPO_DIR/fstab/etc/fstab"

  if [[ -f /etc/greetd/config.toml ]]; then
    log "greetd /etc/greetd/config.toml -> repo/config.toml"
    root_cp /etc/greetd/config.toml "$REPO_DIR/config.toml"
  fi
}

install_hook() {
  local hook=/etc/portage/postsync.d/update-dotfiles
  if [[ "$DRY_RUN" == "yes" ]]; then
    log "  would write: $hook"
    return 0
  fi
  log "writing $hook"
  if [[ $EUID -eq 0 ]]; then
    mkdir -p /etc/portage/postsync.d
    cat >"$hook" <<EOF
#!/usr/bin/env bash
# generated by update.sh --hook-install — keeps dotfiles fresh after each emerge
exec "$REPO_DIR/update.sh" --quick
EOF
    chmod +x "$hook"
  elif command -v sudo >/dev/null 2>&1; then
    sudo tee "$hook" >/dev/null <<EOF
#!/usr/bin/env bash
# generated by update.sh --hook-install — keeps dotfiles fresh after each emerge
exec "$REPO_DIR/update.sh" --quick
EOF
    sudo chmod +x "$hook"
  else
    warn "need root to write $hook"
  fi
}

commit() {
  cd "$REPO_DIR"
  if [[ -n "$(git status --porcelain)" ]]; then
    git add -A
    git commit -q -m "sync system state: $(date '+%Y-%m-%d %H:%M')"
    log "committed."
  else
    log "nothing to commit."
  fi
}

main() {
  if [[ "$DRY_RUN" == "yes" ]]; then
    log "dry-run mode — showing changes, nothing written"
  fi
  sync_portage
  sync_system
  [[ "$INSTALL_HOOK" == "yes" ]] && install_hook

  if [[ "$DO_COMMIT" == "yes" ]]; then
    commit
  elif [[ "$DRY_RUN" != "yes" && "$QUICK" != "yes" ]]; then
    cd "$REPO_DIR"
    if [[ -n "$(git status --porcelain)" ]]; then
      warn "dotfiles changed — review and commit (or rerun with --commit)."
      git status --short
    else
      log "repo is up to date."
    fi
  fi
}

main "$@"