Improve SRS installer preflight output and readiness summary

install-update-srs.sh

@@ -476,9 +476,28 @@ show_apt_plan() {
    printf '   New packages......................: %s\n' "$packages"
 }
 
+# Color only interactive --check output. Redirected logs stay free of ANSI codes.
+# Colorization is presentation-only; it does not affect readiness decisions.
+colorize_check_output() {
+   if [[ -t 1 && ! -v NO_COLOR && "${TERM:-}" != dumb ]]; then
+      local line green=$'\033[32m' yellow=$'\033[33m' red=$'\033[31m' reset=$'\033[0m'
+      while IFS= read -r line || [[ -n "$line" ]]; do
+         line="${line//\[ ok \]/${green}[ ok ]${reset}}"
+         line="${line//\[ missing \]/${yellow}[ missing ]${reset}}"
+         line="${line//\[ blocked \]/${red}[ blocked ]${reset}}"
+         line="${line//: OK/: ${green}OK${reset}}"
+         printf '%s\n' "$line"
+      done
+   else
+      cat
+   fi
+}
+
 # Read-only inventory. Deliberately does not call init_srs_runtime().
 read_only_check() {
-   local cmd file unit
+   local cmd file unit apt_preview mail_env reason
+   local cmake_missing=false ctest_missing=false apt_plan_safe=false
+   local -a blockers=()
    echo
    echo 'Selective SRS installer - read-only inventory'
    echo "   Host..............................: $(hostname -f)"
@@ -490,6 +509,7 @@ read_only_check() {
    echo '   Public SRS DNS validation (authoritative nameservers):'
    if ! verify_srs_domain_dns; then
       echo '   [ warning ] Public DNS is not ready; --install is blocked.'
+      blockers+=("Public SRS DNS validation or Postfix diagnostics failed")
    fi
    echo
 
@@ -498,26 +518,66 @@ read_only_check() {
          printf '   [ ok ]      %s\n' "$cmd"
       else
          printf '   [ missing ] %s\n' "$cmd"
+         case "$cmd" in
+            cmake) cmake_missing=true ;;
+            ctest) ctest_missing=true ;;
+            *) blockers+=("Required command is missing: ${cmd}") ;;
+         esac
       fi
    done
+   # An installed CMake must also satisfy the version required by --install.
+   if ! $cmake_missing; then
+      local cmake_ver cmake_major cmake_minor
+      cmake_ver="$(cmake --version 2>/dev/null | head -n 1)"
+      if [[ "$cmake_ver" =~ ([0-9]+)\.([0-9]+)\.([0-9]+) ]]; then
+         cmake_major="${BASH_REMATCH[1]}"
+         cmake_minor="${BASH_REMATCH[2]}"
+         if ((10#$cmake_major < 3 || (10#$cmake_major == 3 && 10#$cmake_minor < 24))); then
+            blockers+=("Installed CMake is older than the required version 3.24")
+         fi
+      else
+         blockers+=("Installed CMake version cannot be determined")
+      fi
+   fi
    if ! command -v cmake >/dev/null 2>&1; then
       echo
       echo '   Read-only APT simulation for missing cmake/ctest:'
       if command -v apt-get >/dev/null 2>&1; then
-         local apt_preview
          if apt_preview="$(LC_ALL=C apt-get -s install --no-install-recommends cmake)"; then
-            show_apt_plan "$apt_preview" || true
+            if show_apt_plan "$apt_preview" &&
+               grep -Eq '^0 upgraded, [1-9][0-9]* newly installed, 0 to remove and [0-9]+ not upgraded\.$' <<< "$apt_preview"; then
+               apt_plan_safe=true
+            else
+               blockers+=("CMake/CTest APT transaction needs manual review")
+            fi
          else
             echo '   [ warning ] APT simulation failed; prerequisite cannot yet be installed.'
+            blockers+=("CMake/CTest APT simulation failed")
          fi
       else
          echo '   [ warning ] apt-get is unavailable.'
+         blockers+=("Cannot install missing CMake/CTest without apt-get")
       fi
       echo
    fi
-   check_templates && echo '   [ ok ]      SRS configuration templates' || echo '   [ missing ] SRS configuration templates'
+   if check_templates; then
-   check_python_sources && echo '   [ ok ]      Four SRS Python source files' || echo '   [ missing ] SRS Python sources'
+      echo '   [ ok ]      SRS configuration templates'
-   [[ -r "$SRS_DNS_CHECKER" ]] && echo '   [ ok ]      Public DNS preflight helper' || echo '   [ missing ] Public DNS preflight helper'
+   else
+      echo '   [ missing ] SRS configuration templates'
+      blockers+=("SRS configuration templates are missing")
+   fi
+   if check_python_sources; then
+      echo '   [ ok ]      Four SRS Python source files'
+   else
+      echo '   [ missing ] SRS Python sources'
+      blockers+=("SRS Python source files are missing")
+   fi
+   if [[ -r "$SRS_DNS_CHECKER" ]]; then
+      echo '   [ ok ]      Public DNS preflight helper'
+   else
+      echo '   [ missing ] Public DNS preflight helper'
+      blockers+=("Public DNS preflight helper is missing")
+   fi
    echo
 
    if [[ -L "$POSTSRSD_LINK" ]]; then
@@ -533,13 +593,16 @@ read_only_check() {
    done
    if [[ -f "$SRS_CONF_FILE" && -z "$CONFIG_DOMAIN_HINT" ]]; then
       printf '   [ warning ] Existing SRS config has no simple readable _SRS_DOMAIN setting\n'
+      blockers+=("Existing SRS configuration has no readable _SRS_DOMAIN")
    elif [[ -n "$CONFIG_DOMAIN_HINT" && "$CONFIG_DOMAIN_HINT" != "$SELECTED_SRS_DOMAIN" ]]; then
       printf '   [ conflict ] Existing config domain: %s\n' "$CONFIG_DOMAIN_HINT"
+      blockers+=("Chosen SRS domain conflicts with existing configuration")
    fi
    if [[ -f "$SRS_CONF_FILE" && -z "$CONFIG_MX_HINT" ]]; then
       printf '   [ legacy ] Existing config has no _MX_HOST; maintenance-update will add it.\n'
    elif [[ -n "$CONFIG_MX_HINT" && "$CONFIG_MX_HINT" != "$SELECTED_MX_HOST" ]]; then
       printf '   [ conflict ] Existing MX hostname: %s\n' "$CONFIG_MX_HINT"
+      blockers+=("Chosen public MX hostname conflicts with existing configuration")
    fi
    echo
    for unit in "$POSTSRSD_SERVICE" "$SRS_REVERSE_MAP_SERVICE"; do
@@ -559,12 +622,54 @@ read_only_check() {
    fi
    echo
    echo '   Delivery service MAIL_CONFIG (if defined):'
-   systemctl show -P Environment "$SRS_DELIVERY_SERVICE" 2>/dev/null || true
+   mail_env="$(systemctl show -P Environment "$SRS_DELIVERY_SERVICE" 2>/dev/null || true)"
+   if [[ -n "$mail_env" ]]; then
+      printf '      %s\n' "${mail_env//$'\n'/$'\n'      }"
+   else
+      echo '      (not defined)'
+   fi
+
+   echo
+   echo '   ------------------------------------------------------------'
+   echo '   Installation readiness summary'
+   echo '   ------------------------------------------------------------'
+   if $cmake_missing; then
+      if $apt_plan_safe; then
+         echo '   [ missing ] CMake/CTest: --install can install these after explicit APT approval.'
+      else
+         echo '   [ missing ] CMake/CTest: APT prerequisites require manual review.'
+      fi
+   elif $ctest_missing; then
+      echo '   [ missing ] CTest is unavailable although CMake is installed.'
+      blockers+=("CTest is missing despite installed CMake")
+   fi
+   if ((${#blockers[@]})); then
+      echo '   [ blocked ] INSTALLATION PREREQUISITES NOT SATISFIED.'
+      echo '   Resolve the following issues before proceeding:'
+      for reason in "${blockers[@]}"; do
+         printf '      - %s\n' "$reason"
+      done
+      echo '   Re-run ./install-update-srs.sh --check after fixing the issues.'
+   else
+      if $cmake_missing; then
+         echo '   [ ok ] READY TO START INSTALLATION (CMake/CTest approval required).'
+      else
+         echo '   [ ok ] ALL CHECKED INSTALLATION PREREQUISITES ARE SATISFIED.'
+         echo '   [ ok ] READY TO START INSTALLATION.'
+      fi
+      echo
+      echo '   Installation command:'
+      printf '      ./install-update-srs.sh --install --version %s\n' "$POSTSRSD_VERSION"
+      echo
+      echo '   --install repeats safety checks and requests confirmation.'
+      echo '   Installation does NOT activate SRS in the main Postfix instance.'
+   fi
+   echo '   Missing SRS installation files/services are normal before first installation.'
    echo
    echo 'No changes made.'
 }
 
-[[ "$MODE" == '--check' ]] && { read_only_check; exit 0; }
+[[ "$MODE" == '--check' ]] && { read_only_check | colorize_check_output; exit 0; }
 
 # CMake 3.24+ is required by the pinned PostSRSd build. The Debian
 # package "cmake" also supplies ctest. Never install any packages in --check.