# Multi-stage Dockerfile for Next.js Blog Application
# Optimized for Static Site Generation with standalone output
# Final image size: ~150MB

# ============================================
# Stage 1: Dependencies Installation
# ============================================
FROM node:22-alpine AS deps

# Install libc6-compat for better compatibility
RUN apk add --no-cache libc6-compat

WORKDIR /app

# Copy package files for dependency installation
# These files are copied first to leverage Docker layer caching
# If package.json hasn't changed, this layer will be reused
COPY package.json package-lock.json* ./

# Install dependencies using npm ci for reproducible builds
# --only=production flag is not used here because we need dev dependencies for build
RUN npm ci

# ============================================
# Stage 2: Build Next.js Application
# ============================================
FROM node:22-alpine AS builder

WORKDIR /app

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

# Copy .env file for build-time variables
# This file is created by CI/CD workflow from Gitea secrets
# NEXT_PUBLIC_* variables are embedded in client-side bundle during build
COPY .env* ./

# Copy all application source code
# This includes:
# - app/ directory (Next.js 16 App Router)
# - components/ directory
# - lib/ directory (markdown utilities)
# - content/blog/ directory (markdown blog posts)
# - public/ directory (static assets)
# - next.config.js, tsconfig.json, tailwind.config.js, etc.
COPY . .

# Set environment variables for build
ENV NEXT_TELEMETRY_DISABLED=1
ENV NODE_ENV=production

# Build the Next.js application
# This will:
# 1. Process all markdown files from content/blog/
# 2. Generate static pages for all blog posts (SSG)
# 3. Create standalone output in .next/standalone/
# 4. Optimize images and assets
# 5. Bundle and minify JavaScript
RUN npm run build

# ============================================
# Stage 3: Production Runtime
# ============================================
FROM node:22-alpine AS runner

# Install curl for health checks
RUN apk add --no-cache curl

WORKDIR /app

# Set production environment
ENV NODE_ENV=production
ENV NEXT_TELEMETRY_DISABLED=1

# Create a non-root user for security
# The application will run as this user instead of root
RUN addgroup --system --gid 1001 nodejs && \
    adduser --system --uid 1001 nextjs

# Copy only the necessary files from builder stage
# Next.js standalone output includes all dependencies needed to run
COPY --from=builder /app/public ./public

# Copy standalone output (includes minimal node_modules and server files)
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./

# Copy static files (CSS, JS bundles, optimized images)
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static

# Create directories for logs (optional, if your app writes logs)
RUN mkdir -p /app/logs && chown nextjs:nodejs /app/logs

# Switch to non-root user
USER nextjs

# Expose the application port
# Note: This matches the port in package.json "dev" script (-p 3030)
EXPOSE 3030

# Set the port environment variable
ENV PORT=3030
ENV HOSTNAME="0.0.0.0"

# Health check to verify the application is running
# Docker will periodically check this endpoint
# If it fails, the container is marked as unhealthy
HEALTHCHECK --interval=30s --timeout=10s --start-period=40s --retries=3 \
  CMD curl -f http://localhost:3030/ || exit 1

# Start the Next.js server
# The standalone output includes a minimal server.js file
CMD ["node", "server.js"]