# BastionGuard init-system selection.
#
# BASTIONGUARD_INIT_SYSTEM may be AUTO, SYSTEMD, OPENRC, SYSVINIT or DINIT.
# AUTO is suitable for local builds. Distribution packages should pass an
# explicit value because the build host/chroot init may differ from the target.

set(BASTIONGUARD_INIT_SYSTEM "AUTO" CACHE STRING
    "Init system used by BastionGuard: AUTO, SYSTEMD, OPENRC, SYSVINIT or DINIT")
set_property(CACHE BASTIONGUARD_INIT_SYSTEM PROPERTY STRINGS
    AUTO SYSTEMD OPENRC SYSVINIT DINIT)

function(bastionguard_detect_init_system out_var)
    string(TOUPPER "${BASTIONGUARD_INIT_SYSTEM}" _requested)

    if(NOT _requested MATCHES "^(AUTO|SYSTEMD|OPENRC|SYSVINIT|DINIT)$")
        message(FATAL_ERROR
            "Invalid BASTIONGUARD_INIT_SYSTEM='${BASTIONGUARD_INIT_SYSTEM}'. "
            "Use AUTO, SYSTEMD, OPENRC, SYSVINIT or DINIT.")
    endif()

    if(NOT _requested STREQUAL "AUTO")
        set(${out_var} "${_requested}" PARENT_SCOPE)
        return()
    endif()

    find_program(_BG_RC_SERVICE rc-service)
    find_program(_BG_OPENRC_RUN openrc-run)
    find_program(_BG_SYSTEMCTL systemctl)
    find_program(_BG_DINITCTL dinitctl)
    find_program(_BG_SERVICE service)
    find_program(_BG_UPDATE_RC_D update-rc.d)
    find_program(_BG_CHKCONFIG chkconfig)

    # Prefer runtime markers, then the configured PID 1 implementation.
    # Tool presence alone is only a fallback because compatibility commands
    # can coexist with another init system.
    set(_BG_INIT_REAL "")
    if(EXISTS "/sbin/init")
        get_filename_component(_BG_INIT_REAL "/sbin/init" REALPATH)
    elseif(EXISTS "/usr/sbin/init")
        get_filename_component(_BG_INIT_REAL "/usr/sbin/init" REALPATH)
    endif()
    string(TOLOWER "${_BG_INIT_REAL}" _BG_INIT_REAL_LOWER)

    if(EXISTS "/run/openrc")
        set(_detected "OPENRC")
    elseif(EXISTS "/run/systemd/system")
        set(_detected "SYSTEMD")
    elseif(EXISTS "/dev/dinitctl" OR EXISTS "/run/dinitctl")
        set(_detected "DINIT")
    elseif(_BG_INIT_REAL_LOWER MATCHES "openrc")
        set(_detected "OPENRC")
    elseif(_BG_INIT_REAL_LOWER MATCHES "systemd")
        set(_detected "SYSTEMD")
    elseif(_BG_INIT_REAL_LOWER MATCHES "(^|/)dinit($|[-.])")
        set(_detected "DINIT")
    elseif(_BG_INIT_REAL_LOWER MATCHES "sysvinit")
        set(_detected "SYSVINIT")
    elseif(_BG_RC_SERVICE AND _BG_OPENRC_RUN)
        set(_detected "OPENRC")
    elseif(_BG_DINITCTL AND NOT _BG_SYSTEMCTL)
        set(_detected "DINIT")
        message(WARNING
            "No active init marker found; selecting DINIT because dinitctl is "
            "available and systemctl is not. Set -DBASTIONGUARD_INIT_SYSTEM "
            "explicitly for reproducible packages.")
    elseif(_BG_SYSTEMCTL)
        # Packaging fallback when configuring in a chroot without a running
        # PID 1. Pass an explicit value for reproducible packages.
        set(_detected "SYSTEMD")
        message(WARNING
            "No active init marker found; selecting SYSTEMD because systemctl "
            "is available. Set -DBASTIONGUARD_INIT_SYSTEM explicitly for "
            "reproducible packages.")
    elseif(EXISTS "/etc/init.d" AND
           (_BG_SERVICE OR _BG_UPDATE_RC_D OR _BG_CHKCONFIG))
        set(_detected "SYSVINIT")
    else()
        message(FATAL_ERROR
            "Unable to detect the init system. Set "
            "-DBASTIONGUARD_INIT_SYSTEM=SYSTEMD|OPENRC|SYSVINIT|DINIT.")
    endif()

    set(${out_var} "${_detected}" PARENT_SCOPE)
endfunction()