#!/usr/bin/env bash
#
# rollback.sh — Roll back to the previously deployed commit.
#
# Usage:
#   rollback.sh              # roll back to .last-deployed-sha
#   rollback.sh <sha>        # roll back to a specific commit
#
# .env is gitignored and is never touched by git operations. It survives
# updates and rollbacks unchanged.
#
# Must be run as root (uses runuser to build as the service user).

set -euo pipefail

INSTALL_DIR="${ZOPU_INSTALL_DIR:-/opt/zopu}"
SERVICE_USER="${ZOPU_SERVICE_USER:-zopu}"

GREEN='\033[0;32m'
RED='\033[0;31m'
NC='\033[0m'

log() { echo -e "${GREEN}[rollback]${NC} $*"; }
err() { echo -e "${RED}[rollback]${NC} $*" >&2; }

run_as_service() {
  runuser -u "$SERVICE_USER" -- "$@"
}

cd "$INSTALL_DIR"

# Determine target
ROLLBACK_SHA="${1:-}"
if [[ -z "$ROLLBACK_SHA" ]]; then
  LAST_SHA_FILE="${INSTALL_DIR}/.last-deployed-sha"
  if [[ ! -f "$LAST_SHA_FILE" ]]; then
    err "No previous deployment recorded in ${LAST_SHA_FILE}."
    err "Pass a commit SHA explicitly: rollback.sh <sha>"
    exit 1
  fi
  ROLLBACK_SHA=$(cat "$LAST_SHA_FILE")
fi

# Validate commit exists
if ! git rev-parse --verify "${ROLLBACK_SHA}^{commit}" &>/dev/null; then
  err "Commit ${ROLLBACK_SHA} does not exist in the local repository."
  exit 1
fi

CURRENT_SHA=$(git rev-parse HEAD)
log "Current: ${CURRENT_SHA:0:12}"
log "Rolling back to: ${ROLLBACK_SHA:0:12}"

# Save current state before rolling back (enables re-rollback)
echo "$CURRENT_SHA" > "${INSTALL_DIR}/.pre-rollback-sha"

# Checkout target
git checkout "$ROLLBACK_SHA"

# Restore ownership of the checkout to the service user after git operations
log "Setting ownership of checkout to $SERVICE_USER..."
chown -R "$SERVICE_USER":"$SERVICE_USER" "$INSTALL_DIR"

# Confirm .env is intact and has correct permissions
if [[ -f "${INSTALL_DIR}/.env" ]]; then
  log ".env preserved."
  chmod 600 "${INSTALL_DIR}/.env"
else
  err ".env is missing! Restore it from backup before starting services."
fi

log "Running bun install..."
run_as_service bun install

log "Building daemon..."
run_as_service bun run build:daemon

log "Building agent service..."
run_as_service bun run build:agents

log "Restarting services..."
systemctl restart zopu-daemon
sleep 3
systemctl restart zopu-agent
sleep 5

# Health check
HEALTH_SCRIPT="${INSTALL_DIR}/deploy/zopu-runtime/scripts/health-check.sh"
if [[ -x "$HEALTH_SCRIPT" ]]; then
  log "Running health check..."
  if "$HEALTH_SCRIPT"; then
    log "Rollback complete and healthy."
  else
    err "Health check failed after rollback!"
    err "  journalctl -u zopu-daemon -n 50"
    err "  journalctl -u zopu-agent -n 50"
    exit 1
  fi
fi