#!/bin/bash
# lto-rebuild-ng - Modern replacement for Gentoo LTO rebuild after GCC upgrade
# Works with official Gentoo LTO (no overlay needed)

set -euo pipefail

display_help() {
    echo -e "
Usage: $(basename "$0") [OPTION]

Rebuild static archives (.a files) built with a different GCC version.
Best used after major GCC upgrades when using -flto.

Options:
  -h    Show this help
  -a    List only affected static archives
  -l    List only packages that would be rebuilt (recommended first)
  -r    Rebuild packages with emerge --ask --oneshot
  -f    Force rebuild of ALL packages containing static libs (nuclear option)
"
}

get_current_gcc_ver() {
    gcc -dumpversion
}

perform_action() {
    local mode="${1:-}"
    local gcc_ver
    gcc_ver=$(get_current_gcc_ver)
    
    echo "Current GCC version: $gcc_ver"
    echo "Searching for static archives built with different GCC version..."

    # More efficient search using scanelf + readelf only when needed
    mapfile -t archives < <(
        find /usr/lib{,32,64} /opt/*/lib{,64} -name "*.a" -type f 2>/dev/null | \
        xargs -r -P "$(nproc)" -I {} bash -c '
            if readelf -p .comment "$1" 2>/dev/null | grep -q "GCC:"; then
                if ! readelf -p .comment "$1" 2>/dev/null | grep -q "GCC:.*'"$gcc_ver"'"; then
                    echo "$1"
                fi
            fi
        ' _ {} 
    )

    if [[ ${#archives[@]} -eq 0 ]]; then
        echo "No mismatched LTO static archives found. You're good!"
        exit 0
    fi

    if [[ "$mode" == "-a" ]]; then
        echo -e "\nMismatched static archives:"
        printf '%s\n' "${archives[@]}"
        exit 0
    fi

    # Get unique packages
    mapfile -t packages < <(qfile -qS "${archives[@]}" 2>/dev/null | sort -u)

    case "$mode" in
        "-l")
            echo -e "\nPackages that need rebuilding:"
            printf '%s\n' "${packages[@]}"
            ;;
        "-r")
            if [[ ${#packages[@]} -eq 0 ]]; then
                echo "No packages found via qfile."
                exit 1
            fi
            echo -e "\nRebuilding ${#packages[@]} packages..."
            emerge -1a "${packages[@]}"
            ;;
        "-f")
            echo -e "\nForcing rebuild of all packages with static libs..."
            emerge -1a "${packages[@]}"
            ;;
        *)
            echo "Invalid mode"
            exit 1
            ;;
    esac
}

case "${1:-}" in
    "" | "-h")
        display_help
        ;;
    "-a" | "-l" | "-r" | "-f")
        perform_action "$1"
        ;;
    *)
        echo "Unknown option. Use -h for help."
        exit 1
        ;;
esac