#!/usr/bin/env bash
#
# Pull the latest commit, rebuild the image and restart the stack.
# Rolls back to the previous commit if the new container never turns healthy.
#
# Usage:  ./scripts/update.sh [--force] [--branch <name>]
#   --force    rebuild and restart even when there is no new commit
#   --branch   branch to deploy (default: the currently checked out branch)

set -Eeuo pipefail

REPO_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
cd "$REPO_DIR"

FORCE=0
BRANCH=""
HEALTH_TIMEOUT="${HEALTH_TIMEOUT:-120}"

while [ $# -gt 0 ]; do
  case "$1" in
    --force) FORCE=1; shift ;;
    --branch) BRANCH="${2:?--branch needs a value}"; shift 2 ;;
    *) echo "unknown argument: $1" >&2; exit 2 ;;
  esac
done

log() { printf '\033[1;34m==>\033[0m %s\n' "$*"; }
err() { printf '\033[1;31m!!\033[0m %s\n' "$*" >&2; }

compose() { docker compose "$@"; }

# --- preconditions -----------------------------------------------------------

command -v git >/dev/null || { err "git not found"; exit 1; }
docker compose version >/dev/null 2>&1 || { err "docker compose not available"; exit 1; }

[ -f .env ] || { err ".env missing — copy .env.example to .env and fill it in"; exit 1; }

if [ -n "$(git status --porcelain)" ]; then
  err "working tree has uncommitted changes — refusing to update"
  git status --short >&2
  exit 1
fi

[ -n "$BRANCH" ] || BRANCH="$(git rev-parse --abbrev-ref HEAD)"
PREV_COMMIT="$(git rev-parse HEAD)"

# --- fetch -------------------------------------------------------------------

log "Fetching origin/$BRANCH"
git fetch --quiet origin "$BRANCH"

TARGET_COMMIT="$(git rev-parse "origin/$BRANCH")"

if [ "$PREV_COMMIT" = "$TARGET_COMMIT" ] && [ "$FORCE" -eq 0 ]; then
  log "Already at $(git rev-parse --short HEAD) — nothing to do (use --force to rebuild anyway)"
  exit 0
fi

log "Updating $(git rev-parse --short "$PREV_COMMIT") -> $(git rev-parse --short "$TARGET_COMMIT")"
git checkout --quiet "$BRANCH"
git merge --ff-only --quiet "origin/$BRANCH"

# --- health helper -----------------------------------------------------------

container_id() { compose ps -q app; }

wait_for_health() {
  local deadline=$((SECONDS + HEALTH_TIMEOUT))
  local cid status
  while [ "$SECONDS" -lt "$deadline" ]; do
    cid="$(container_id)"
    if [ -n "$cid" ]; then
      status="$(docker inspect -f '{{if .State.Health}}{{.State.Health.Status}}{{else}}no-healthcheck{{end}}' "$cid" 2>/dev/null || echo missing)"
      case "$status" in
        healthy|no-healthcheck) return 0 ;;
        unhealthy) return 1 ;;
      esac
    fi
    sleep 3
  done
  return 1
}

rollback() {
  err "Deployment failed — rolling back to $(git rev-parse --short "$PREV_COMMIT")"
  compose logs --tail 50 app >&2 || true
  git reset --hard --quiet "$PREV_COMMIT"
  compose build app
  compose up -d app
  if wait_for_health; then
    err "Rolled back successfully. The stack runs the previous commit again."
  else
    err "ROLLBACK ALSO UNHEALTHY — manual intervention required."
  fi
  exit 1
}

# --- build & restart ---------------------------------------------------------

log "Building image"
compose build app || rollback

log "Restarting stack"
compose up -d app || rollback

log "Waiting for healthcheck (timeout ${HEALTH_TIMEOUT}s)"
wait_for_health || rollback

# --- cleanup -----------------------------------------------------------------

log "Pruning dangling images"
docker image prune -f >/dev/null

log "Deployed $(git rev-parse --short HEAD) — stack is healthy"