# --- Builder Stage --- 
ARG GO_VERSION=1.23
FROM golang:${GO_VERSION}-alpine AS builder

# Set necessary environment variables
ENV CGO_ENABLED=0
ENV GOOS=linux
ENV GOARCH=amd64

# Set the working directory inside the container
WORKDIR /app

# Install build dependencies (e.g., git, tools for private repos if needed)
# RUN apk add --no-cache git

# Copy go module files
COPY go.mod go.sum ./

# Download Go modules
# Using 'go mod download' allows Docker to cache these layers
RUN go mod download

# Copy the entire source code
# Consider using .dockerignore to exclude unnecessary files/dirs (like .git, tmp, build, vendor if not needed)
COPY . .

# Build the Go application
# Use -ldflags "-w -s" to strip debug information and reduce binary size for production
# Replace './cmd/server/main.go' with your actual main package path if different
RUN go build -ldflags="-w -s" -o /app/server ./cmd/server/main.go

# --- Final Stage --- 
# Use a minimal base image like alpine or distroless
# alpine is small and includes a shell, useful for debugging
FROM alpine:latest AS final
# OR use distroless for a more secure, minimal image (no shell, only the app and its dependencies)
# FROM gcr.io/distroless/static-debian11 AS final 

# Install necessary certificates (needed for HTTPS connections)
# For Alpine:
RUN apk add --no-cache ca-certificates
# For Debian-based (like distroless): Usually included, but verify

# Create a non-root user and group
RUN addgroup -S appgroup && adduser -S appuser -G appgroup

# Set the working directory
WORKDIR /app

# Copy the built binary from the builder stage
COPY --from=builder /app/server /app/server

# Copy configuration files, migrations, or other necessary assets
# Adjust paths as needed based on your application structure
COPY configs/ /app/configs/
COPY migrations/ /app/migrations/ 
# Add other COPY lines for templates, static assets etc. if needed

# Ensure the non-root user owns the application files
RUN chown -R appuser:appgroup /app

# Switch to the non-root user
USER appuser

# Expose the port the application listens on (replace 8080 if different)
EXPOSE 8080

# Define the entry point for the container
# CMD ["/app/server", "--config=/app/configs/config.yaml"] # Example with config flag
ENTRYPOINT ["/app/server"]