From 5ea02756f1da1a822ad3df87fe319eecb9ff1f95 Mon Sep 17 00:00:00 2001
From: George Georgalis <george@galis.org>
Date: Mon, 23 Oct 2023 14:43:58 -0700
Subject: [PATCH] init sequence.sh almost working

---
 boot/nbsd/sequence.sh | 164 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100755 boot/nbsd/sequence.sh

diff --git a/boot/nbsd/sequence.sh b/boot/nbsd/sequence.sh
new file mode 100755
index 0000000..3a75003
--- /dev/null
+++ b/boot/nbsd/sequence.sh
@@ -0,0 +1,164 @@
+#!/bin/sh
+
+# (C) 2023 George Georgalis <george@galis.org> unlimited use with this notice
+# 6536a4f43 foundation code based Claud 2 prompt to enhance rcorder functionality
+
+# given a bootstrap setup directory (arg1) with scripts annoted in
+# rcorder format, consider respective PROVIDE, REQUIRE, and BEFORE
+# metadata, and additional args denoting PROVIDE requirements from
+# the setup directory scripts, the required scripts in the proper
+# sequence, to satisfy the dependencies, are discovered and printed.
+#
+# Through the following key steps:
+# 
+# 1. Parse the input PROVIDE requirement into an array.
+# 
+# 2. Loop through each requirement and find scripts in the bootstrap
+#      setup directory that PROVIDE it. Add those scripts to a
+#      'required' array.
+#    - If no script provides a service, exit with error.
+# 
+# 3. Parse the BEFORE metadata for each required script and build
+#      a 'before' array with before/after pairs.
+#
+# 4. Perform a topological sort on the required scripts using the
+#      before dependency graph.
+#    - Handle the case of no BEFORE dependencies by using original
+#        required order.
+#    - Loop through required array and check for back edges to
+#        already visited nodes to detect cycles.
+#    - Track visited nodes and append to tsorted array in dep order.
+# 
+# 5. Print the sorted script list. 
+#    - For each script, print its REQUIRE dependencies.
+#    - Check required array for missing dependencies, exit if found.
+# 
+# This ensures we only print the minimum set of scripts needed
+# for the provided services, in the proper dependency order while
+# detecting cycles and errors.
+#
+# The key data structures are the 'required', 'provided', 'before'
+# and 'tsorted' arrays. By tracking them separately, we can build
+# the dependency graph and sort it for the correct output.
+
+
+rcd="$1"
+[ "$#" -gt 1 ] && shift
+provide=$@
+
+devnul() { return 0 ;}                                                 #:> drop args
+stderr() {  [ "$*" ] && echo "$*" 1>&2 || true ;}                      #:> args to stderr, or noop if null
+chkwrn() {  [ "$*" ] && { stderr    "^^^ $*" ; return $? ;} || true ;} #:> wrn stderr args return 0, noop if null
+chkerr() {  [ "$*" ] && { stderr    ">>> $*" ; return 1  ;} || true ;} #:> err stderr args return 1, noop if null
+
+[ "$rcd" ] || { chkerr "$0 : no rc.d (arg1) provided (6536a66a)" ; exit 1 ;}
+[ -d "$rcd" ] || { chkerr "$0 : rc.d (arg1) not a directory (6536a6a4)" ; exit 1 ;}
+cd "$rcd"
+[ "$provide" ] || provide='.'
+
+required=()
+provided=()
+before=()
+
+# set verb to chkwrn for debug output
+verb=devnul
+verb=chkwrn
+
+# Parse PROVIDED data
+for p in $provide; do
+  provided+=("$p")
+  done
+# verb
+for i in ${!provided[@]}; do
+  $verb "provided[$i] = ${provided[$i]}"
+  done
+
+# Find scripts that PROVIDE services
+for p in "${provided[@]}"; do
+  found=0
+  for f in *; do
+    [ -d "$f" ] || if grep -Eq "^# PROVIDE:.*( ${p} | ${p}$)" "$f"; then
+      required+=("$f")
+      found+=1
+      break
+    fi
+  done
+  [ $found -eq 0 ] && { chkerr "$0 : No script provides $p (6536c080)" ; exit 1 ;}
+  [ $found -gt 1 ] && { chkerr "$0 : Multiple scripts provide $p (6536c0c8)" ; exit 1 ;}
+done
+# verb
+for i in ${!required[@]}; do
+  $verb "required[$i] = ${required[$i]}"
+  done
+
+$verb "required: ${required[@]}"
+# Build BEFORE dependency graph
+for r in "${required[@]}"; do
+  deps=$(grep -E '^# BEFORE: ' "$r" | cut -d: -f2-)
+  for d in $deps; do
+    $verb "before get $d"
+    before+=("$r $d") 
+  done
+done
+# verb
+for i in ${!before[@]}; do
+  $verb "before[$i] = ${before[$i]}"
+  done
+
+$verb "Topological sort ${#required[@]}: ${required[@]}"
+# Topological sort
+tsorted=()
+[ ${#before[@]} -eq 0 ] \
+  && { # No BEFORE dependencies
+    tsorted=("${required[@]}")
+  } || { # With BEFORE dependencies
+    visited=()
+    for r in "${required[@]}"; do
+      for b in "${before[@]}"; do
+        read before after <<<"$b"
+        [ "$after" = "$r" ] && [[ " ${visited[@]} " =~ " ${before} " ]] && \
+          { chkerr "$0 : Dependency loop detected (6536c3b6)" ; exit 1 ;} 
+        done
+      visited+=("$r")
+      tsorted+=("$r")
+      done
+    required=("${tsorted[@]}")
+  } # With BEFORE dependencies
+
+
+$verb "sorted scripts ${tsorted[@]}" 
+
+
+revargs () {
+    local a out
+    out="$1" ; shift || true
+    while test $# -gt 0 ; do out="$1 $out" ; shift || true ; done
+    echo "$out"
+    }
+
+# # Print sorted scripts + REQUIRE deps
+# for ((i=${#tsorted[@]}-1; i>=0; i--)); do
+#   s=${tsorted[$i]}
+#   echo "$s"
+#   deps=$(grep '^# REQUIRE: ' "$s" | cut -d: -f2-)
+#   for d in $deps; do
+#   for d in $deps; do
+# 
+
+
+for s in "${tsorted[@]}"; do
+  echo "$s"
+  deps=$(grep '^# REQUIRE: ' "$s" | cut -d: -f2-)
+  for d in $deps; do
+    if [ ${#required[@]} -eq 0 ]; then
+      echo "Missing dependency: $d" >&2
+      exit 1  
+    fi
+    echo "$d"
+  done
+done
+
+
+$verb end
+exit 0
+