#!/usr/bin/env bash
# deploy.sh — stow-equivalent deployment of the dotfiles/ packages in this repo.
#
# Model: the repo checkout IS the deployment. Packages are home-relative trees
# under dotfiles/<pkg>/; deploying replaces live files with symlinks into the
# repo so `git pull` + `deploy.sh` is the whole propagation story.
#
# Modes:
#   deploy.sh              sync (default): adopt identicals, link new, quarantine-and-replace divergents
#   deploy.sh --check      dry-run report only; writes nothing
#   deploy.sh --adopt      like sync but divergents are reported and SKIPPED, not quarantined
#
# Host divergence: a package named zz-$(hostname) is stowed LAST with override
# semantics (its files replace symlinks from base packages).
#
# Special cases:
#   - dconf package: dump.txt is loaded via `dconf load /` instead of symlinked.
#   - systemd-user: after linking, daemon-reload + enable --now units whose
#     ExecStart binary resolves on THIS machine (silent no-op elsewhere).
set -euo pipefail

REPO="$(git -C "$(dirname "$(realpath "$0")")" rev-parse --show-toplevel 2>/dev/null || true)"
REPO="${DEPLOY_REPO:-$REPO}"
PKGS_DIR="$REPO/dotfiles"
HOST="${DEPLOY_HOST:-$(hostname)}"
QUAR="$REPO/.quarantine"

MODE="sync"
case "${1:-}" in
  --check) MODE="check" ;;
  --adopt) MODE="adopt" ;;
  ""|sync) MODE="sync" ;;
  *) echo "usage: deploy.sh [--check|--adopt|sync]" >&2; exit 2 ;;
esac

[ -d "$PKGS_DIR" ] || { echo "deploy.sh: no dotfiles/ under $REPO" >&2; exit 1; }

# packages = all dirs in dotfiles/, override package last
mapfile -t PKGS < <(find "$PKGS_DIR" -maxdepth 1 -mindepth 1 -type d ! -name "zz-*" | sort)
OVR="$PKGS_DIR/zz-$HOST"
[ -d "$OVR" ] && PKGS+=("$OVR")

actions=0; quarantined=0; skipped=0

deploy_file() { # $1 = repo file path, $2 = home-relative target path
  local src="$1" tgt="$HOME/$2"
  # Generated theme output is never deployment state: noctalia rewrites these files in
  # place, so a tracked copy is a stale snapshot and syncing one reverts a live palette to
  # the colours of the day it was committed. Classes are those the census measures by
  # mtime — see omp-docs/inventory/home-config-census.md, "Generated palette expansion".
  case "$2" in
    */themes/noctalia*|*/colors/noctalia*|*/noctalia.*|*/noctalia-*|*/Noctalia*)
      echo "SKIP   $2 (generated theme output)"; skipped=$((skipped+1)); return 0 ;;
  esac
  if [ -L "$tgt" ]; then
    if [ "$(realpath "$tgt")" = "$(realpath "$src")" ]; then return 0; fi # already deployed
    case "$MODE" in
      check) echo "RELINK $2 (managed symlink changing owners)" ;;
      adopt) echo "SKIP   $2 (foreign symlink, --adopt does not overwrite)" ; skipped=$((skipped+1)) ;;
      sync)
        if [[ "$(realpath "$tgt")" == "$REPO/"* ]]; then
          # managed file changing owners between packages: silent relink, nothing to quarantine
          ln -sfn "$(realpath "$src")" "$tgt"; actions=$((actions+1))
        else
          ts="$(date +%Y%m%d-%H%M%S)-$$"
          dest="$QUAR/$HOST/$ts/$2"
          mkdir -p "$(dirname "$dest")"
          mv -- "$tgt" "$dest"
          ln -sfn "$(realpath "$src")" "$tgt"
          actions=$((actions+1)); quarantined=$((quarantined+1))
          echo "QUAR   $2 -> .quarantine/$HOST/$ts/$2"
        fi
        ;;
    esac
    return 0
  fi
  if [ -e "$tgt" ]; then
    if cmp -s "$src" "$tgt"; then
      if [ "$MODE" = "check" ]; then echo "ADOPT  $2 (identical, will symlink)"; return 0; fi
      ln -sfn "$(realpath "$src")" "$tgt"; actions=$((actions+1)); return 0
    fi
    case "$MODE" in
      check) echo "DRIFT  $2 (differs from repo; sync would quarantine)" ;;
      adopt) echo "SKIP   $2 (divergent, --adopt does not overwrite)" ; skipped=$((skipped+1)) ;;
      sync)
        ts="$(date +%Y%m%d-%H%M%S)-$$"
        dest="$QUAR/$HOST/$ts/$2"
        mkdir -p "$(dirname "$dest")"
        mv -- "$tgt" "$dest"
        ln -sfn "$(realpath "$src")" "$tgt"
        actions=$((actions+1)); quarantined=$((quarantined+1))
        echo "QUAR   $2 -> .quarantine/$HOST/$ts/$2"
        ;;
    esac
    return 0
  fi
  if [ "$MODE" = "check" ]; then echo "LINK   $2 (missing, will symlink)"; return 0; fi
  mkdir -p "$(dirname "$tgt")"
  ln -sfn "$(realpath "$src")" "$tgt"; actions=$((actions+1))
}

for pkg in "${PKGS[@]}"; do
  pkgname="$(basename "$pkg")"
  # dconf package: load dump instead of symlinking
  if [ "$pkgname" = "dconf" ] && [ -f "$pkg/dump.txt" ]; then
    if [ "$MODE" != "check" ]; then
      if command -v dconf >/dev/null; then dconf load / < "$pkg/dump.txt" && echo "LOAD   $pkgname/dump.txt -> dconf"; fi
    else
      echo "LOAD   $pkgname/dump.txt (dconf load / would run on sync)"
    fi
    continue
  fi
  while IFS= read -r -d '' f; do
    rel="${f#"$pkg"/}"
    # override packages nest base-package dirs internally: strip that segment for targets
    if [ "${pkgname#zz-}" != "$pkgname" ]; then case "$rel" in */*) [ -d "$PKGS_DIR/${rel%%/*}" ] && rel="${rel#*/}";; esac; fi
    deploy_file "$f" "$rel"
  done < <(find "$pkg" \( -type f -o -type l \) ! -name 'dump.txt' ! -path '*/.AGENTTRASH/*' -print0)
done

if [ "$MODE" != "check" ] && [ -d "$PKGS_DIR/systemd-user/.config/systemd/user" ]; then
  systemctl --user daemon-reload || true
  UNITS_DIR="$PKGS_DIR/systemd-user/.config/systemd/user"
  # Services AND timers. A timer is the schedule that makes a oneshot service run at all, and it
  # carries no ExecStart of its own — the binary that decides whether the unit belongs on this
  # box lives in the service it activates. Walking *.service only deployed live-sync.service on
  # every rebuild and never armed live-sync.timer: the heartbeat was present and never ticked.
  for unit in "$UNITS_DIR"/*.service "$UNITS_DIR"/*.timer; do
    [ -e "$unit" ] || continue
    name="$(basename "$unit")"
    probe="$unit"
    if [ "${name##*.}" = timer ]; then
      act="$(sed -n 's/^Unit=\(.*\)$/\1/p' "$unit" | head -1)"
      probe="$UNITS_DIR/${act:-"${name%.timer}.service"}"
    fi
    bin="$(sed -n 's/^ExecStart=\([^ ]*\).*/\1/p' "$probe" 2>/dev/null | head -1)"
    # systemd expands specifiers inside ExecStart; this shell does not. Matching the literal
    # `%h/…` makes a unit of THIS box look foreign and skips it in silence — which is exactly
    # how live-sync.service, the repo's own heartbeat, has been reported "absent on this
    # host" on every machine that deployed it. Expand what a user unit can carry; leave any
    # other specifier unmatched rather than guess at it. Refs #44.
    bin="${bin//%h/$HOME}"
    bin="${bin//%u/$(id -un)}"
    bin="${bin//%U/$(id -u)}"
    if [ -n "$bin" ] && command -v "$bin" >/dev/null 2>&1; then
      # Read the state, not the exit status: `is-enabled` exits 1 for a `linked` unit exactly
      # as for a `disabled` one. Starting something already installed is how a deploy locks a
      # live session — swayidle-lock sits enabled/inactive on blankpad and `--now` arms it
      # mid-conversation. Only a unit nothing has installed yet gets started. Refs #44.
      state="$(systemctl --user is-enabled "$name" 2>/dev/null || true)"
      if ! grep -q '^\[Install\]' "$unit"; then
        # systemd refuses to enable these: no [Install] section means nothing can want the unit
        # at login, and live-sync.service has none on purpose — its timer pulls it in. The old
        # branch swallowed that failure and printed ENABLE anyway, so the one line a rebuild is
        # checked by was false on every box. The section is readable right here, so do not make
        # the call at all. Refs #60.
        echo "INERT  $name (state=${state:-none}; no [Install] section — another unit arms it, enable cannot)"
      elif [ -z "$state" ] || [ "$state" = disabled ]; then
        if systemctl --user enable --now "$name"; then
          echo "ENABLE $name (ExecStart resolves here; nothing running it yet)"
        else
          echo "INERT  $name (enable --now failed — systemd's message above says why)"
        fi
      elif systemctl --user enable "$name"; then
        echo "ENABLE $name (already $state; not started — a live session decides what runs)"
      else
        echo "INERT  $name (already $state; enable failed — systemd's message above says why)"
      fi
    else
      echo "SKIP   $name (ExecStart '$bin' absent on this host)"
    fi
  done
fi

# keep the secret gate armed on every machine that deploys
git -C "$REPO" config core.hooksPath .githooks

echo "deploy.sh [$MODE] host=$HOST repo=$REPO — actions=$actions quarantined=$quarantined skipped=$skipped"