// Test-copy observations only: bracket the supervisor's inner timer before
// clean_session scans the host's /proc. Keep all shipped control flow intact.
import { readProbeSeconds } from './case-p10-timing-fixture.mjs';
export { readProbeSeconds };
const BEGIN = '# row253-supervisor-begin\n';
const END = '# row253-supervisor-end\n';
const TIMER = '"$sleep_bin" "$seconds" & timer=$!\n';
const FINISH = 'finish() {\n    local rc="$?"\n';
function unique(source, anchor) {
  const at=source.indexOf(anchor);
  if(at<0 || source.indexOf(anchor,at+anchor.length)>=0) throw new Error('inner observer anchor must occur exactly once');
  return at;
}
function innerObservers(clock) {
  // The literal path survives env -i in the fake sudo. It is a private scratch
  // file, never a product input. Quote even paths containing shell metacharacters.
  const file="'"+clock.replaceAll("'", "'\\''")+"'";
  return {
    begin:`# inner-observer-begin\n{ read -r timing2_up timing2_spare < /proc/uptime &&\n  printf 'begin %s\\n' "$timing2_up" >> ${file}; } 2>/dev/null || :\n# inner-observer-begin-end\n`,
    end:`    # inner-observer-end\n    { read -r timing2_up timing2_spare < /proc/uptime &&\n      printf 'end %s\\n' "$timing2_up" >> ${file}; } 2>/dev/null || :\n    # inner-observer-end-end\n`,
  };
}
export function instrumentInnerTimer(source,clock) {
  const from=unique(source,BEGIN),to=unique(source,END);
  if(to<=from)throw new Error('inner observer scope is reversed');
  let supervisor=source.slice(from,to);
  unique(supervisor,TIMER);unique(supervisor,FINISH);
  const blocks=innerObservers(clock);
  supervisor=supervisor.replace(TIMER,blocks.begin+TIMER).replace(FINISH,FINISH+blocks.end);
  return source.slice(0,from)+supervisor+source.slice(to);
}
export function removeInnerObservers(source,clock) {
  for(const block of Object.values(innerObservers(clock))){unique(source,block);source=source.replace(block,'');}
  return source;
}

// Reuse the timing2 finish-entry stamp, moving only the other observation.
// The end is in the supervisor, after clean_session and both waits, immediately
// before exit. Parent scheduling and process start-up never enter this pair.
export function instrumentCleanupTimer(source,clock) {
  const blocks=innerObservers(clock);
  let observed=instrumentInnerTimer(source,clock);
  const from=unique(observed,BEGIN),to=unique(observed,END);
  let supervisor=observed.slice(from,to);
  const exit='    exit "$rc"\n';
  unique(supervisor,exit);
  supervisor=supervisor.replace(blocks.begin,'').replace(blocks.end,blocks.begin);
  supervisor=supervisor.replace(exit,blocks.end+exit);
  return observed.slice(0,from)+supervisor+observed.slice(to);
}