FROM node:18-alpine

WORKDIR /app

# Copy package files
COPY backend/package*.json ./

# Install dependencies with npm ci for reproducibility
RUN npm ci --only=production || npm install --production

# Verify critical dependencies are installed
RUN test -d node_modules/express || (echo "ERROR: express not installed" && exit 1)

# Copy application code
COPY backend/src ./src
COPY frontend ./frontend

EXPOSE 4001

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