# =============================================================================
# Dockerfile.nextjs — multi-stage build for the Next.js frontend
# =============================================================================
# Used by docker-compose.yml's `nextjs` service.
#
# Why this looks the way it does:
#   - `NEXT_PUBLIC_API_URL` must be present at BUILD time (Next.js inlines
#     it into the client JS). We pass it through as an ARGs so the build
#     context is reproducible (`docker build --build-arg` or via deploy.sh's
#     `docker compose --env-file` flow).
#   - We copy the host's pre-built `.next/` (produced by `npm run build` in
#     deploy.sh) rather than running `next build` inside the image. This
#     keeps the image lean and avoids double-building.
# =============================================================================

# ---- builder: produce node_modules with dev deps for the build step --------
FROM node:20-alpine AS deps
WORKDIR /app
COPY package.json package-lock.json* ./
RUN if [ -f package-lock.json ]; then npm ci; else npm install; fi

# ---- builder: produce the standalone .next/ output ------------------------
FROM node:20-alpine AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .

# These ARGs are wired through docker-compose's `args:` block (or the CLI).
# deploy.sh exports them in the build environment.
ARG NEXT_PUBLIC_API_URL
ENV NEXT_PUBLIC_API_URL=${NEXT_PUBLIC_API_URL}
ARG NEXTJS_HOST_PORT
ENV NEXTJS_HOST_PORT=${NEXTJS_HOST_PORT}

RUN npm run build

# ---- runner: minimal image, standalone server -----------------------------
FROM node:20-alpine AS runner
WORKDIR /app
ENV NODE_ENV=production
ENV PORT=3000

# Run as non-root.
RUN addgroup --system --gid 1001 nodejs \
 && adduser  --system --uid 1001 nextjs

# Copy only what the standalone server needs.
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

USER nextjs
EXPOSE 3000

# Adjust this CMD to match the actual server file your build emits.
# For `output: "standalone"` in next.config.js the file is server.js.
CMD ["node", "server.js"]
