#!/usr/bin/env bash
# Expria auto-deploy script (VPS Paris).
#
# Runs as the non-root `deploy` user, invoked by deploy/webhook-listener.mjs on
# a verified push to origin/main. Fast-forwards the checkout, installs, builds,
# and restarts expria-backend.service via ONE restricted sudo rule:
#   deploy ALL=(root) NOPASSWD: /usr/bin/systemctl restart expria-backend.service
#
# On a build or health-check failure it auto-rolls back to the previous commit.
# All output goes to stdout -> journald (journalctl -u expria-deploy).
set -euo pipefail

REPO_DIR="/opt/expria/expria-backend"
BRANCH="main"
SERVICE="expria-backend.service"
HEALTH_URL="${HEALTH_URL:-http://127.0.0.1:4000/}"
LOCK_FILE="/tmp/expria-deploy.lock"

log() { echo "$(date --iso-8601=seconds) [deploy] $*"; }

# Serialize concurrent deploys: a second webhook waits here, or bails out.
exec 9>"$LOCK_FILE"
if ! flock -n 9; then
  log "another deploy is already in progress — aborting this run"
  exit 0
fi

cd "$REPO_DIR"

PREV="$(git rev-parse HEAD)"
log "start (current=${PREV:0:8})"

restart_backend() {
  sudo /usr/bin/systemctl restart "$SERVICE"
}

# Poll the liveness endpoint (GET / always returns 200 when the process is up).
health_check() {
  for _ in $(seq 1 10); do
    if curl -fsS --max-time 3 "$HEALTH_URL" >/dev/null 2>&1; then
      return 0
    fi
    sleep 2
  done
  return 1
}

rollback() {
  log "ROLLBACK to ${PREV:0:8}"
  if git reset --hard "$PREV" && npm ci && npm run build; then
    if restart_backend && health_check; then
      log "ROLLBACK ok — service healthy on ${PREV:0:8}"
      return 0
    fi
  fi
  log "ROLLBACK FAILED — manual intervention required (was on ${PREV:0:8})"
  return 1
}

# 1. Fetch + fast-forward only (refuses a diverged history, no destructive pull).
git fetch --prune origin "$BRANCH"
if ! git merge --ff-only "origin/$BRANCH"; then
  log "fast-forward failed (diverged history) — aborting, no changes applied"
  exit 1
fi
NEW="$(git rev-parse HEAD)"
log "pulled ${PREV:0:8} -> ${NEW:0:8}"

if [ "$PREV" = "$NEW" ]; then
  log "already up to date — nothing to deploy"
  exit 0
fi

# 2. Install + build (rollback on failure).
if ! npm ci; then
  log "npm ci FAILED"
  rollback
  exit 1
fi
if ! npm run build; then
  log "npm run build FAILED"
  rollback
  exit 1
fi

# 3. Restart + health check (rollback on failure).
if ! restart_backend; then
  log "systemctl restart FAILED"
  rollback
  exit 1
fi
if health_check; then
  log "SUCCESS — deployed ${NEW:0:8}"
else
  log "health check FAILED after restart"
  rollback
  exit 1
fi