#!/bin/bash

# Package List Update Script
# Detects the running OS and updates the package index only (no upgrades).

set -euo pipefail

#==============================================================================
# CONFIGURATION
#==============================================================================

readonly NC='\033[0m'
readonly RED='\033[1;31m'
readonly GREEN='\033[1;32m'
readonly LIGHT_GREEN='\033[1;32m'
readonly LIGHT_BLUE='\033[1;34m'
readonly LIGHT_GREY='\033[0;37m'
readonly YELLOW='\033[1;33m'

readonly SCRIPT_NAME="$(basename "$0")"

#==============================================================================
# UTILITY FUNCTIONS
#==============================================================================

log_info()    { echo -e "${LIGHT_GREY}[i] $1${NC}"; }
log_success() { echo -e "${LIGHT_GREEN}[✓] $1${NC}"; }
log_warning() { echo -e "${YELLOW}[!] $1${NC}"; }
log_error()   { echo -e "${RED}[x] $1${NC}" >&2; }
log_step()    { echo -e "${LIGHT_BLUE}[i] $1${NC}"; }

die() {
    log_error "$1"
    exit 1
}

command_exists() {
    command -v "$1" >/dev/null 2>&1
}

# Detect the running OS and its ID string.
# Prints two values: the distro id (lowercase) and the family id (lowercase).
detect_os() {
    local id=""
    local family=""

    if [[ -f /etc/os-release ]]; then
        # shellcheck disable=SC1091
        . /etc/os-release
        id="${ID:-unknown}"
        family="${ID_LIKE:-}"
    elif [[ -f /etc/alpine-release ]]; then
        id="alpine"
        family="alpine"
    else
        # Fall back to package manager detection
        if command_exists apk; then
            id="alpine"; family="alpine"
        elif command_exists pacman; then
            id="arch"; family="arch"
        elif command_exists apt-get; then
            id="debian"; family="debian"
        elif command_exists dnf; then
            id="fedora"; family="rhel"
        elif command_exists yum; then
            id="centos"; family="rhel"
        elif command_exists zypper; then
            id="opensuse"; family="suse"
        elif command_exists xbps-install; then
            id="void"; family="void"
        elif command_exists emerge; then
            id="gentoo"; family="gentoo"
        else
            id="unknown"; family="unknown"
        fi
    fi

    echo "${id} ${family}"
}

#==============================================================================
# OS-SPECIFIC UPDATE FUNCTIONS
#==============================================================================

update_alpine() {
    if ! command_exists apk; then
        log_warning "apk not found on Alpine-type system"
        return 0
    fi

    log_info "Running apk update..."
    if apk update 2>&1; then
        log_success "Alpine package index updated"
    else
        log_warning "apk update failed"
    fi
}

update_arch() {
    if ! command_exists pacman; then
        log_warning "pacman not found on Arch-type system"
        return 0
    fi

    log_info "Refreshing pacman database (pacman -Sy)..."
    # -S = sync, -y = refresh local database only (no package installation)
    if pacman -Sy --noconfirm 2>&1; then
        log_success "Arch package database refreshed"
    else
        log_warning "pacman -Sy failed"
    fi
}

update_debian() {
    if ! command_exists apt-get; then
        log_warning "apt-get not found on Debian-type system"
        return 0
    fi

    log_info "Running apt-get update..."
    if apt-get update 2>&1; then
        log_success "Debian/Ubuntu package index updated"
    else
        log_warning "apt-get update failed"
    fi
}

update_rhel() {
    if command_exists dnf; then
        log_info "Running dnf makecache..."
        if dnf makecache 2>&1; then
            log_success "RHEL/Fedora metadata cache refreshed (dnf)"
        else
            log_warning "dnf makecache failed"
        fi
    elif command_exists yum; then
        log_info "Running yum makecache..."
        if yum makecache fast 2>&1; then
            log_success "CentOS/RHEL metadata cache refreshed (yum)"
        else
            log_warning "yum makecache failed"
        fi
    else
        log_warning "No DNF or YUM found on RHEL-type system"
    fi
}

update_suse() {
    if ! command_exists zypper; then
        log_warning "zypper not found on openSUSE-type system"
        return 0
    fi

    log_info "Running zypper refresh..."
    if zypper --non-interactive refresh 2>&1; then
        log_success "openSUSE repositories refreshed"
    else
        log_warning "zypper refresh failed"
    fi
}

update_void() {
    if ! command_exists xbps-install; then
        log_warning "xbps-install not found on Void system"
        return 0
    fi

    log_info "Running xbps-install -S (sync repository index)..."
    if xbps-install -S 2>&1; then
        log_success "Void package index synced"
    else
        log_warning "xbps-install -S failed"
    fi
}

update_gentoo() {
    if ! command_exists emerge; then
        log_warning "emerge not found on Gentoo system"
        return 0
    fi

    log_info "Running emaint sync -a..."
    if emaint sync -a 2>&1; then
        log_success "Gentoo Portage tree synced"
    else
        log_warning "emaint sync failed"
    fi
}

#==============================================================================
# MAIN EXECUTION
#==============================================================================

main() {
    log_step "Starting package list update (${SCRIPT_NAME})"
    echo

    # Detect the OS
    local distro_info distro_id family_id
    distro_info="$(detect_os)"
    distro_id="${distro_info%% *}"
    family_id="${distro_info##* }"

    log_info "Detected OS: ${distro_id}"
    if [[ -n "${family_id}" && "${family_id}" != "${distro_id}" ]]; then
        log_info "OS family: ${family_id}"
    fi
    echo

    # Dispatch to the correct handler based on distro family
    # Check distro_id first, then fall back to family_id for aliases
    case "${distro_id}" in
        alpine)
            update_alpine
            ;;
        arch|artix|manjaro|garuda)
            update_arch
            ;;
        debian|ubuntu|linuxmint|kali|raspbian|pop)
            update_debian
            ;;
        fedora|rhel|centos|rocky|almalinux|amazon|oracle|clear-linux-os)
            update_rhel
            ;;
        opensuse*|suse|sles)
            update_suse
            ;;
        void)
            update_void
            ;;
        gentoo|funtoo)
            update_gentoo
            ;;
        *)
            # Try matching on family ID as fallback
            case "${family_id}" in
                *alpine*)
                    update_alpine
                    ;;
                *arch*)
                    update_arch
                    ;;
                *debian*|*ubuntu*)
                    update_debian
                    ;;
                *rhel*|*fedora*|*centos*)
                    update_rhel
                    ;;
                *suse*|*opensuse*)
                    update_suse
                    ;;
                *void*)
                    update_void
                    ;;
                *gentoo*)
                    update_gentoo
                    ;;
                *)
                    die "Unsupported OS: ${distro_id} (${family_id}). Cannot update package index."
                    ;;
            esac
            ;;
    esac

    echo
    log_success "Package list update completed!"
}

main "$@"