#!/bin/bash

# This script automates the backporting of ostree packages for Ubuntu Noble and Debian Trixie.
# Ubuntu: Pulls source from Ubuntu Questing
# Debian: Pulls source from Debian sid
#
# ⚠️  WARNING: This script modifies system libraries. Use with caution!
#    - Test in a VM first
#    - Have a system backup
#    - Be prepared for potential side effects with Flatpak and other ostree-dependent software

# Exit immediately if a command exits with a non-zero status.
set -e

# --- Configuration ---
OSTREE_VERSION="2025.2"
OSTREE_DEBIAN_REVISION="1"

# Distribution-specific configurations
declare -A DISTRO_CONFIGS
DISTRO_CONFIGS["noble"]="ubuntu|questing|noble|~noble1|http://archive.ubuntu.com/ubuntu/pool/universe/o/ostree/"
DISTRO_CONFIGS["trixie"]="debian|sid|trixie|~trixie1|http://deb.debian.org/debian/pool/main/o/ostree/"

# Default to noble if no distribution specified
TARGET_DISTRO=${1:-noble}

# Validate target distribution
if [[ ! ${DISTRO_CONFIGS[$TARGET_DISTRO]} ]]; then
    echo "Error: Unsupported distribution '$TARGET_DISTRO'"
    echo "Supported distributions: ${!DISTRO_CONFIGS[@]}"
    exit 1
fi

# Parse distribution config
IFS='|' read -r DISTRO_TYPE SOURCE_RELEASE TARGET_RELEASE BACKPORT_SUFFIX POOL_URL <<< "${DISTRO_CONFIGS[$TARGET_DISTRO]}"

# Set working directory based on distribution
BACKPORT_DIR="${BACKPORT_DIR:-/opt/Projects/ostree-backport-${TARGET_DISTRO}}"

# --- Functions ---
log_info() {
    echo -e "\n\e[1;34m[INFO]\e[0m $1"
}

log_success() {
    echo -e "\n\e[1;32m[SUCCESS]\e[0m $1"
}

log_warning() {
    echo -e "\n\e[1;33m[WARNING]\e[0m $1"
}

log_error() {
    echo -e "\n\e[1;31m[ERROR]\e[0m $1" >&2
    exit 1
}

cleanup() {
    log_info "Cleaning up temporary files..."
    # Remove the added source list file
    sudo rm -f /etc/apt/sources.list.d/${TARGET_RELEASE}-sources.list
    # Remove the entire backport working directory
    sudo rm -rf "${BACKPORT_DIR}"
    sudo apt update >/dev/null 2>&1 || true
    log_success "Cleanup completed."
}

# Safety check function
safety_check() {
    log_info "Performing safety checks..."

    # Check if we're running as root (shouldn't be)
    if [ "$EUID" -eq 0 ]; then
        log_error "This script should not be run as root. Please run as a regular user with sudo privileges."
    fi

    # Check if we're in a VM (recommended)
    if ! grep -q "VMware\|VirtualBox\|QEMU\|KVM" /sys/class/dmi/id/product_name 2>/dev/null; then
        log_warning "This doesn't appear to be running in a VM. Consider testing in a VM first."
        read -p "Continue anyway? (y/N): " -n 1 -r
        echo
        if [[ ! $REPLY =~ ^[Yy]$ ]]; then
            log_info "Aborted by user."
            exit 0
        fi
    fi

    # Check if we have enough disk space (rough estimate: 500MB)
    AVAILABLE_SPACE=$(df /opt | awk 'NR==2 {print $4}')
    if [ "$AVAILABLE_SPACE" -lt 500000 ]; then
        log_error "Insufficient disk space. Need at least 500MB available in /opt"
    fi

    log_success "Safety checks passed."
}

# Set trap to ensure cleanup runs on exit
# Commented out for debugging - uncomment when script is working
# trap cleanup EXIT

# --- Main Script ---

log_info "Starting ostree backport process for ${DISTRO_TYPE^} ${TARGET_RELEASE}..."
log_info "Source: ${SOURCE_RELEASE} → Target: ${TARGET_RELEASE}"

# Safety checks
safety_check

# Step 0: Clean up any existing backport directory
log_info "Step 0: Cleaning up any existing backport directory..."
if [ -d "${BACKPORT_DIR}" ]; then
    log_info "Removing existing backport directory: ${BACKPORT_DIR}"
    sudo rm -rf "${BACKPORT_DIR}"
fi
log_success "Cleanup completed."

# Step 1: Install Required Tools
log_info "Step 1: Installing essential build tools (devscripts, build-essential)..."
sudo apt update || log_error "Failed to update apt cache."
sudo apt install -y devscripts build-essential || log_error "Failed to install build tools."
log_success "Build tools installed."

# Step 1.5: Add Source Repositories
log_info "Step 1.5: Adding source repositories for build dependencies..."
if [[ "$DISTRO_TYPE" == "ubuntu" ]]; then
    echo "deb-src http://us.archive.ubuntu.com/ubuntu/ ${TARGET_RELEASE} main universe" | sudo tee /etc/apt/sources.list.d/${TARGET_RELEASE}-sources.list
else
    echo "deb-src http://deb.debian.org/debian/ ${TARGET_RELEASE} main contrib non-free" | sudo tee /etc/apt/sources.list.d/${TARGET_RELEASE}-sources.list
fi
sudo apt update || log_error "Failed to update apt cache with source repositories."
log_success "Source repositories added."

# Step 2: Create Backport Directory Structure
log_info "Step 2: Creating backport directory structure at ${BACKPORT_DIR}..."
mkdir -p "${BACKPORT_DIR}" || log_error "Failed to create directory ${BACKPORT_DIR}."
cd "${BACKPORT_DIR}" || log_error "Failed to change directory to ${BACKPORT_DIR}."
log_success "Directory structure created."

# Step 3: Download Source
log_info "Step 3: Downloading ostree ${OSTREE_VERSION}-${OSTREE_DEBIAN_REVISION} source from ${SOURCE_RELEASE}..."
# Construct the full filenames
DSC_FILE="ostree_${OSTREE_VERSION}-${OSTREE_DEBIAN_REVISION}.dsc"
ORIG_TAR_XZ_FILE="ostree_${OSTREE_VERSION}.orig.tar.xz"
DEBIAN_TAR_XZ_FILE="ostree_${OSTREE_VERSION}-${OSTREE_DEBIAN_REVISION}.debian.tar.xz"

# Check if files already exist to avoid re-downloading
for file in "${DSC_FILE}" "${ORIG_TAR_XZ_FILE}" "${DEBIAN_TAR_XZ_FILE}"; do
    if [ ! -f "$file" ]; then
        wget "${POOL_URL}${file}" || log_error "Failed to download ${file}."
    else
        log_info "File ${file} already exists, skipping download."
    fi
done
log_success "Source files downloaded."

# Step 4: Extract and Modify Source
log_info "Step 4: Extracting source and modifying debian/changelog..."
dpkg-source -x "${DSC_FILE}" || log_error "Failed to extract source package."
cd "ostree-${OSTREE_VERSION}" || log_error "Failed to change directory to ostree-${OSTREE_VERSION}."

# Create backport version entry in changelog
# For backports, we need to manually set the version and distribution
# Use -b to force the version change since backport versions are "less than" original
if ! dch --newversion "${OSTREE_VERSION}-${OSTREE_DEBIAN_REVISION}${BACKPORT_SUFFIX}" \
    --distribution "${TARGET_RELEASE}-backports" \
    -b \
    "Backport ostree ${OSTREE_VERSION}-${OSTREE_DEBIAN_REVISION} from ${SOURCE_RELEASE} for ${TARGET_RELEASE} compatibility."; then
    log_info "dch failed, attempting manual changelog update..."
    log_error "Manual changelog update not implemented. Please check debian/changelog format."
fi
log_success "Source extracted and changelog updated."

# Step 5: Install Build Dependencies
log_info "Step 5: Installing build dependencies for ostree..."
# This command relies on the debian/control file in the extracted source
sudo apt build-dep ./ || log_error "Failed to install build dependencies. Check debian/control or your ${TARGET_RELEASE} repositories."
log_success "Build dependencies installed."

# Step 6: Build the Backport
log_info "Step 6: Building the ostree backport for ${TARGET_RELEASE}..."
dpkg-buildpackage -us -uc -b || log_error "Failed to build the Debian package."
log_success "ostree backport built successfully."

# Step 7: Install the Backport
log_info "Step 7: Installing the built ostree packages..."
cd .. # Go back to the directory where the .deb files are

# Find all .deb files from the current build (more flexible)
OSTREE_DEBS=$(find . -maxdepth 1 -name "*ostree*${BACKPORT_SUFFIX}*.deb" -o -name "*libostree*${BACKPORT_SUFFIX}*.deb")

if [ -z "$OSTREE_DEBS" ]; then
    log_error "No .deb packages found to install. Build might have failed or naming is unexpected."
    log_info "Available .deb files:"
    ls -la *.deb 2>/dev/null || echo "No .deb files found"
    exit 1
fi

log_info "Found packages to install: $OSTREE_DEBS"
sudo dpkg -i ${OSTREE_DEBS} || log_error "Failed to install the backported .deb packages."
log_success "Backported ostree packages installed."

# Run apt --fix-broken install to handle any missed dependencies if dpkg -i failed to resolve them
log_info "Running apt --fix-broken install to resolve any lingering dependencies..."
sudo apt --fix-broken install -y || log_error "apt --fix-broken install failed."
log_success "Dependency resolution attempted."

# Step 8: Verify Installation
log_info "Step 8: Verifying installation..."
if dpkg -l | grep -q "ostree.*${BACKPORT_SUFFIX}"; then
    log_success "ostree backport successfully installed."
else
    log_warning "ostree backport installation verification failed, but continuing..."
fi

# Step 9: Test with bootc
log_info "Step 9: Now you can try building bootc with the newly installed ostree."
log_info "Example: (assuming bootc source is in /opt/Projects/bootc-deb/bootc)"
echo "cd /opt/Projects/bootc-deb/bootc"
echo "cargo build --release"
log_info "Remember to monitor for AppArmor denials during bootc operation if issues arise."

log_success "ostree backport process completed for ${DISTRO_TYPE^} ${TARGET_RELEASE}."
log_warning "⚠️  IMPORTANT: Please reboot your system if you experience any issues with applications that use ostree (e.g., Flatpak)."
log_info "If you encounter problems, you can revert by reinstalling the original ostree packages from the ${TARGET_RELEASE} repositories."