FROM node:20-alpine

WORKDIR /app

# Install deps first for better caching
COPY package.json package-lock.json* ./
RUN if [ -f package-lock.json ]; then npm ci --omit=dev; else npm install --omit=dev; fi

# Copy application code
COPY server.js ./
COPY public ./public

# Persisted data lives here; mount a volume in compose
RUN mkdir -p /app/data
ENV DATA_DIR=/app/data
ENV NODE_ENV=production
ENV PORT=3000

EXPOSE 3000

HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
  CMD wget -qO- http://127.0.0.1:3000/healthz >/dev/null 2>&1 || exit 1

CMD ["node", "server.js"]