#
# FRONTEND DOCKERFILE
#
# This Dockerfile builds the container for the Next.js frontend application.
# It uses a multi-stage build process to create lean, optimized images for
# production while providing a flexible environment for development.
#
# Stages:
# - `base`:    Installs Node.js and sets up a non-root user.
# - `deps`:    Installs npm dependencies.
# - `builder`: Builds the Next.js application for production.
# - `runner`:  A minimal production-ready image that serves the built app.
# - `dev`:     A development-ready image with hot-reloading enabled.
#
# For more details, see: ./docs/architecture.md
#

# ------------------------------------------------------------------------------
#   1. Base Stage
#      - Installs Node.js and sets up a non-root user for security.
# ------------------------------------------------------------------------------
FROM node:20-slim AS base

# Set environment variables for non-interactive installation.
ENV NPM_CONFIG_LOGLEVEL=warn

# Create a non-root user and group for running the application.
# This is a critical security measure to avoid running as root.
RUN addgroup --system --gid 1001 nextjs
RUN adduser --system --uid 1001 nextjs

# ------------------------------------------------------------------------------
#   2. Dependencies Stage
#      - Installs npm dependencies. This layer is cached to speed up builds
#        when only source code changes.
# ------------------------------------------------------------------------------
FROM base AS deps

WORKDIR /app

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

# Install dependencies.
RUN npm ci

# ------------------------------------------------------------------------------
#   3. Builder Stage
#      - Builds the Next.js application for production.
# ------------------------------------------------------------------------------
FROM base AS builder

WORKDIR /app

# Copy dependencies from the `deps` stage.
COPY --from=deps /app/node_modules ./node_modules
# Copy the application source code.
COPY . .

# Build the Next.js application. This creates an optimized production build
# in the .next/ directory.
RUN npm run build

# ------------------------------------------------------------------------------
#   4. Runner Stage (Production)
#      - Creates a minimal, secure image for serving the production application.
# ------------------------------------------------------------------------------
FROM base AS runner

WORKDIR /app

# Set the environment to "production". This tells Next.js to use the
# optimized build and enables other production-specific behaviors.
ENV NODE_ENV=production

# Switch to the non-root user.
USER nextjs

# Copy the built application from the `builder` stage.
# We copy only the necessary files to keep the image small.
COPY --from=builder --chown=nextjs:nextjs /app/public ./public
COPY --from=builder --chown=nextjs:nextjs /app/.next ./.next
COPY --from=builder --chown=nextjs:nextjs /app/node_modules ./node_modules
COPY --from=builder --chown=nextjs:nextjs /app/package.json ./package.json

# Expose the port the Next.js server will run on.
EXPOSE 3000

# The command to start the Next.js server in production mode.
CMD ["npm", "start"]

# ------------------------------------------------------------------------------
#   5. Dev Stage (Development)
#      - Creates an image for local development with hot-reloading.
# ------------------------------------------------------------------------------
FROM base AS dev

WORKDIR /app

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

# Expose the development port.
EXPOSE 3000

# The command to start the Next.js development server.
# This will be overridden by the docker-compose file for bind mounting.
CMD ["npm", "run", "dev"]