#!/bin/bash

set -e

# Configuration
REGISTRY="${REGISTRY:-gitea.ahkhan.me}"
REGISTRY_PATH="${REGISTRY_PATH:-docker}"
REPO_PREFIX="${REPO_PREFIX:-ubuntu}"
PLATFORMS="${PLATFORMS:-linux/amd64,linux/arm64}"
DATE_TAG=$(date +%Y-%m-%d)

# Ubuntu versions to build (in order, latest first)
UBUNTU_VERSIONS=("24.04" "22.04" "20.04")
LATEST_VERSION="24.04"

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

log() {
    echo -e "${BLUE}[$(date '+%H:%M:%S')]${NC} $1"
}

success() {
    echo -e "${GREEN}[$(date '+%H:%M:%S')]${NC} $1"
}

warn() {
    echo -e "${YELLOW}[$(date '+%H:%M:%S')]${NC} $1"
}

error() {
    echo -e "${RED}[$(date '+%H:%M:%S')]${NC} $1"
}

# Function to build single Ubuntu version
build_ubuntu_version() {
    local version=$1
    local repo_name="${REPO_PREFIX}-${version}"
    
    log "Building Ubuntu ${version}..."
    
    # Build tags for this version
    local tags=(
        "${REGISTRY}/${REGISTRY_PATH}/${repo_name}:latest"
        "${REGISTRY}/${REGISTRY_PATH}/${repo_name}:${DATE_TAG}"
    )
    
    # Add ubuntu:latest tag only for the latest version
    if [[ "$version" == "$LATEST_VERSION" ]]; then
        tags+=("${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}:latest")
    fi
    
    # Build tag arguments
    local tag_args=""
    for tag in "${tags[@]}"; do
        tag_args="$tag_args --tag $tag"
    done
    
    # Cache configuration
    local cache_from="${REGISTRY}/${REGISTRY_PATH}/${repo_name}:buildcache"
    local cache_to="${REGISTRY}/${REGISTRY_PATH}/${repo_name}:buildcache"
    
    log "Tags: ${tags[*]}"
    log "Cache from/to: $cache_from"
    
    # Build command
    docker buildx build \
        --platform "$PLATFORMS" \
        --build-arg UBUNTU_VER="$version" \
        $tag_args \
        --cache-from "type=registry,ref=$cache_from" \
        --cache-to "type=registry,ref=$cache_to,mode=max" \
        --push \
        .
    
    success "Ubuntu ${version} build completed successfully"
    
    # Clear local builder cache to save disk space (registry cache is preserved)
    log "Clearing local builder cache for Ubuntu ${version}..."
    docker buildx prune --filter type=exec.cachemount --filter type=regular --force >/dev/null 2>&1 || true
}

# Function to validate Docker buildx setup
validate_setup() {
    log "Validating Docker buildx setup..."
    
    if ! command -v docker &> /dev/null; then
        error "Docker is not installed or not in PATH"
        exit 1
    fi
    
    if ! docker buildx version &> /dev/null; then
        error "Docker buildx is not available"
        exit 1
    fi
    
    # Always use multiarch builder for consistency and reliability
    # Reasons: better registry caching, isolated BuildKit, predictable multi-arch behavior
    log "Setting up multiarch builder for optimal registry caching and multi-platform support..."
    
    # Install binfmt for cross-platform emulation
    log "Setting up cross-platform emulation..."
    docker run --privileged --rm tonistiigi/binfmt --install all
    
    # Create or reuse multiarch builder
    if docker buildx ls | grep -q "^multiarch"; then
        log "Using existing multiarch builder"
        docker buildx use multiarch
    else
        log "Creating new multiarch builder"
        docker buildx create --name multiarch --driver docker-container --use
    fi
    
    # Bootstrap the builder
    docker buildx inspect --bootstrap
    
    success "Multiarch builder setup completed"
}

# Function to show build summary
show_summary() {
    log "Build Summary:"
    echo "Registry: $REGISTRY"
    echo "Date tag: $DATE_TAG"
    echo "Platforms: $PLATFORMS"
    echo "Ubuntu versions: ${UBUNTU_VERSIONS[*]}"
    echo ""
    
    echo "Images that will be built:"
    for version in "${UBUNTU_VERSIONS[@]}"; do
        echo "  ${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}-${version}:latest"
        echo "  ${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}-${version}:${DATE_TAG}"
        echo "  ${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}-${version}:buildcache (cache)"
        if [[ "$version" == "$LATEST_VERSION" ]]; then
            echo "  ${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}:latest"
        fi
        echo ""
    done
}

# Main execution
main() {
    log "Starting Ubuntu Docker images build process"
    
    # Validate environment
    validate_setup
    
    # Show what will be built
    show_summary
    
    # Confirm before proceeding
    read -p "Proceed with build? (y/N): " -n 1 -r
    echo
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        warn "Build cancelled by user"
        exit 0
    fi
    
    # Build each version
    for version in "${UBUNTU_VERSIONS[@]}"; do
        build_ubuntu_version "$version"
    done
    
    success "All Ubuntu images built successfully!"
    
    log "Available images:"
    for version in "${UBUNTU_VERSIONS[@]}"; do
        echo "  ${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}-${version}:latest"
        echo "  ${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}-${version}:${DATE_TAG}"
    done
    echo "  ${REGISTRY}/${REGISTRY_PATH}/${REPO_PREFIX}:latest (→ Ubuntu ${LATEST_VERSION})"
}

# Help function
show_help() {
    echo "Ubuntu Docker Build Script"
    echo ""
    echo "Usage: $0 [OPTIONS]"
    echo ""
    echo "Environment Variables:"
    echo "  REGISTRY       Docker registry (default: gitea.ahkhan.me)"
    echo "  REGISTRY_PATH  Registry path (default: docker)"
    echo "  REPO_PREFIX    Repository prefix (default: ubuntu)"
    echo "  PLATFORMS      Target platforms (default: linux/amd64,linux/arm64)"
    echo ""
    echo "Examples:"
    echo "  REGISTRY=myregistry.com ./build.sh"
    echo "  PLATFORMS=linux/amd64 ./build.sh"
    echo ""
}

# Handle arguments
case "${1:-}" in
    -h|--help)
        show_help
        exit 0
        ;;
    *)
        main "$@"
        ;;
esac