#!/usr/bin/env python3
"""
Repackage iotg-rpi4-config .deb for Debian Buster+ compatibility.

Changes:
- Updates CONFIG path from /boot/config.txt to /boot/firmware/config.txt
- Relocates overlays from /boot/overlays/ to /boot/firmware/overlays/
"""

import shutil
import subprocess
import tempfile
from pathlib import Path


def run_cmd(cmd: list[str], cwd: Path | None = None) -> None:
    """Run shell command and handle errors."""
    result = subprocess.run(cmd, cwd=cwd, capture_output=True, text=True)
    if result.returncode != 0:
        raise RuntimeError(f"Command failed: {' '.join(cmd)}\n{result.stderr}")


def modify_functions_file(functions_path: Path) -> None:
    """Update CONFIG path in iotg-rpi4-functions."""
    content = functions_path.read_text()

    # Replace the CONFIG path
    modified = content.replace(
        "CONFIG=/boot/config.txt",
        "CONFIG=/boot/firmware/config.txt"
    )

    # Also update the backup path reference (it uses ${CONFIG} so should be fine)
    # But let's verify the change was made
    if modified == content:
        raise RuntimeError("Failed to modify CONFIG path - pattern not found")

    functions_path.write_text(modified)
    print(f"✓ Modified {functions_path.name}")


def relocate_overlays(extract_dir: Path) -> None:
    """Move overlays from /boot/overlays to /boot/firmware/overlays."""
    old_path = extract_dir / "boot" / "overlays" / "iotg-rpi4"
    new_path = extract_dir / "boot" / "firmware" / "overlays" / "iotg-rpi4"

    if not old_path.exists():
        raise RuntimeError(f"Overlay directory not found: {old_path}")

    # Create new directory structure
    new_path.parent.mkdir(parents=True, exist_ok=True)

    # Move the iotg-rpi4 directory
    shutil.move(str(old_path), str(new_path))

    # Remove old empty directories
    (extract_dir / "boot" / "overlays").rmdir()

    print(f"✓ Relocated overlays to boot/firmware/overlays/iotg-rpi4/")


def repackage_deb(original_deb: Path, output_deb: Path) -> None:
    """Extract, modify, and repackage the .deb file."""

    with tempfile.TemporaryDirectory() as tmpdir:
        work_dir = Path(tmpdir)
        extract_dir = work_dir / "package"
        control_dir = work_dir / "DEBIAN"

        extract_dir.mkdir()
        control_dir.mkdir()

        print(f"Extracting {original_deb.name}...")
        run_cmd(["dpkg-deb", "-x", str(original_deb), str(extract_dir)])
        run_cmd(["dpkg-deb", "-e", str(original_deb), str(control_dir)])

        # Modify the functions file
        functions_file = extract_dir / "usr" / "local" / "bin" / "iotg-rpi4-functions"
        modify_functions_file(functions_file)

        # Relocate overlays
        relocate_overlays(extract_dir)

        # Update control file version
        control_file = control_dir / "control"
        control_content = control_file.read_text()
        control_content = control_content.replace(
            "Version: 1.3-1",
            "Version: 1.3-1buster1"
        )
        control_file.write_text(control_content)
        print("✓ Updated control file version")

        # Copy DEBIAN directory into extract_dir
        shutil.copytree(control_dir, extract_dir / "DEBIAN")

        # Build new .deb
        print(f"Building {output_deb.name}...")
        run_cmd(["dpkg-deb", "-b", str(extract_dir), str(output_deb)])

    print(f"\n✓ Successfully created {output_deb}")


def main() -> None:
    """Main entry point."""
    script_dir = Path(__file__).parent
    original_deb = script_dir / "iotg-rpi4-config_1.3-1_all.deb"
    output_deb = script_dir / "iotg-rpi4-config_1.3-1buster1_all.deb"

    if not original_deb.exists():
        raise FileNotFoundError(f"Original .deb not found: {original_deb}")

    if output_deb.exists():
        print(f"Removing existing {output_deb.name}...")
        output_deb.unlink()

    print("Repackaging for Debian Buster+ compatibility\n")
    repackage_deb(original_deb, output_deb)

    print("\nChanges made:")
    print("  • CONFIG=/boot/config.txt → CONFIG=/boot/firmware/config.txt")
    print("  • Overlays moved from /boot/overlays/ → /boot/firmware/overlays/")
    print("  • Version updated to 1.3-1buster1")
    print(f"\nInstall with: sudo dpkg -i {output_deb.name}")


if __name__ == "__main__":
    main()