# Stage 1: Build the application
# Using node:21-alpine for a lightweight, secure build environment.
FROM node:21-alpine AS builder
WORKDIR /app

# Install dependencies first for better Docker layer caching.
# This step only reruns if package.json or package-lock.json changes.
COPY package*.json ./
RUN npm install

# Copy the rest of the source code.
COPY . .

# Build Argument to determine build environment (staging, prod, or production).
# Defaults to "staging".
ARG BUILD_MODE=staging
ENV NODE_ENV=production

# Perform the build based on the BUILD_MODE argument.
# This runs the existing scripts in package.json, which already
# handle copying the correct .env file to .env.production for Vite.
RUN if [ "$BUILD_MODE" = "prod" ] || [ "$BUILD_MODE" = "production" ]; then \
        npm run build:prod; \
    else \
        npm run build:staging; \
    fi

# Stage 2: Final runtime image
FROM node:21-alpine AS deploy-node
WORKDIR /app

# Copy only the built files and necessary scripts from the builder stage.
COPY --from=builder /app/build .
COPY --from=builder /app/package.json .

# Install only production dependencies for a smaller, cleaner image.
RUN npm install --omit=dev

# Copy the resulting .env.production file to .env.
# adapter-node reads from .env at runtime for non-PUBLIC_ variables.
COPY --from=builder /app/.env.production .env

# SvelteKit (via adapter-node) defaults to port 3000.
EXPOSE 3000

# Healthcheck to verify the app is running
HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
  CMD node -e "fetch('http://localhost:3000/health').then(r => r.ok ? process.exit(0) : process.exit(1)).catch(() => process.exit(1))"

CMD ["node", "index.js"]