# =============================================================================
# Dockerfile.nextjs — multi-stage build for the Next.js frontend
# =============================================================================
#
# Production-ready Docker image for Next.js with:
#   - Multi-stage build for minimal image size
#   - Standalone server output for containerized deployment
#   - Non-root user for security
#   - Health check support
#
# Build args (set via --build-arg or docker-compose args):
#   - NEXT_PUBLIC_API_URL: Public URL for the frontend (inlined at build time)
#   - NODE_ENV: Environment (defaults to production)
#
# Required: next.config.ts must have `output: "standalone"` enabled.
# =============================================================================

# ── Stage 1: Dependencies ────────────────────────────────────────────────────
FROM node:20-alpine AS deps
WORKDIR /app

# Copy package files
COPY package.json package-lock.json* ./

# Install dependencies
RUN if [ -f package-lock.json ]; then \
      npm ci --no-audit --no-fund; \
    else \
      npm install --no-audit --no-fund; \
    fi

# ── Stage 2: Build ───────────────────────────────────────────────────────────
FROM node:20-alpine AS builder
WORKDIR /app

# Copy node_modules from deps stage
COPY --from=deps /app/node_modules ./node_modules

# Copy source files
COPY . .

# Set build arguments (inlined into client bundle)
ARG NEXT_PUBLIC_API_URL=http://localhost:3000
ENV NEXT_PUBLIC_API_URL=${NEXT_PUBLIC_API_URL}
ARG NODE_ENV=production
ENV NODE_ENV=${NODE_ENV}

# Build the Next.js application
RUN npm run build

# ── Stage 3: Runtime ─────────────────────────────────────────────────────────
FROM node:20-alpine AS runner
WORKDIR /app

# Set production environment
ENV NODE_ENV=production
ENV PORT=3000

# Create non-root user for security
RUN addgroup --system --gid 1001 nodejs \
 && adduser --system --uid 1001 nextjs

# Copy standalone server and static assets from builder
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
COPY --from=builder --chown=nextjs:nodejs /app/public ./public

# Expose the port
EXPOSE 3000

# Switch to non-root user
USER nextjs

# Health check
HEALTHCHECK --interval=10s --timeout=5s --start-period=30s --retries=6 \
  CMD wget -qO- http://localhost:3000/ || exit 1

# Start the standalone server
CMD ["node", "server.js"]
