# os.sh — OS/distro detection, command_exists, version_ge
# Depends-On: colors.sh
# Requires-Vars: (none)
# Sets-Vars: $OS $DISTRO
# Include via: @include lib/os.sh

# Sets OS (macOS | Linux | Windows | Unknown) and DISTRO (ubuntu | debian | …)
detect_os() {
    case "$(uname -s)" in
        Linux*)  OS=Linux  ;;
        Darwin*) OS=macOS  ;;
        CYGWIN*) OS=Windows ;;
        MINGW*)  OS=Windows ;;
        *)       OS=Unknown ;;
    esac
    print_info "Detected OS: $OS"

    if [ "$OS" = "Linux" ] && [ -f /etc/os-release ]; then
        # shellcheck source=/dev/null
        . /etc/os-release
        DISTRO=$ID
        print_info "Detected Linux distribution: $DISTRO"
    else
        DISTRO=unknown
    fi
}

# Returns 0 if the given command is on PATH
command_exists() { command -v "$1" >/dev/null 2>&1; }

# Boolean helpers — use these in business logic instead of inline string comparisons
is_macos()     { [ "$OS" = "macOS" ]; }
is_linux_apt() { [ "$OS" = "Linux" ] && { [ "$DISTRO" = "ubuntu" ] || [ "$DISTRO" = "debian" ]; }; }

# Returns 0 (true) if $1 >= $2  (semantic version comparison)
version_ge() { printf '%s\n%s\n' "$2" "$1" | sort -V -C; }

# Assert that the current OS/distro is supported (macOS or Ubuntu/Debian).
# Optional $1: hint message printed on failure (e.g. manual install instructions).
# Exits with code 1 on unsupported OS or distro.
assert_supported_os() {
    local hint="${1:-}"
    if [ "$OS" = "Linux" ]; then
        if [ "$DISTRO" = "ubuntu" ] || [ "$DISTRO" = "debian" ]; then
            return 0
        fi
        print_error "Unsupported Linux distribution: $DISTRO"
        [ -n "$hint" ] && print_info "$hint"
        exit 1
    elif [ "$OS" = "macOS" ]; then
        return 0
    else
        print_error "Unsupported OS: $OS"
        [ -n "$hint" ] && print_info "$hint"
        exit 1
    fi
}