#!/usr/bin/env bash
# KNELPerf loop driver — baseline -> audit/benchmark -> tweak -> re-baseline.
#
# The heart of KNELPerf v2 (#826). One host, one cycle phase at a time:
#
#   perf-loop.sh baseline <host>       capture baseline bundle (cpu/net/storage/psi)
#   perf-loop.sh audit <host>          read-only audit vs baseline (alerts on drift)
#   perf-loop.sh tweak <host> <id>     apply a tweak (from tweaks/) after CR gate
#   perf-loop.sh rebaseline <host>     capture post-tweak bundle + diff report
#   perf-loop.sh compare <host> <a> <b>  diff two stored bundles
#
# Bundles live in data/baselines/<host>/<ts>/ and are plain TSV/JSON so diff
# and jq stay the toolchain. Nothing here mutates a host except `tweak`.
set -euo pipefail
REPO_ROOT=$(cd "$(dirname "$0")/.." && pwd)
DATA_DIR=${KNELPERF_DATA_DIR:-$REPO_ROOT/data/baselines}
SSH_OPTS=(-o ConnectTimeout=8 -o BatchMode=yes)

usage() { sed -n '2,12p' "$0"; exit 2; }
[ $# -ge 2 ] || usage
cmd=$1; host=$2

now() { date +%Y%m%d-%H%M%S; }
host_dir() { mkdir -p "$DATA_DIR/$1"; }

run_on_host() { # host script-path args...
  local h=$1 script=$2; shift 2
  case $h in
    local) bash "$REPO_ROOT/$script" "$@" ;;
    *) ssh "${SSH_OPTS[@]}" "root@$h" "bash -s" < "$REPO_ROOT/$script" "$@" ;;
  esac
}

case "$cmd" in
baseline|rebaseline)
  ts=$(now); dir="$DATA_DIR/$host/$ts"; host_dir "$host"; mkdir -p "$dir"
  echo "== KNELPerf $cmd: $host -> $dir"
  # shellcheck disable=SC2043  # single-part list by design; grows as legs are added
  for part in cpu-bench; do
    run_on_host "$host" "loop/$part.sh" > "$dir/$part.tsv" 2> "$dir/$part.err" \
      || echo "WARN: $part failed (see $dir/$part.err)"
  done
  # storage + network reuse the existing bench harness outputs
  run_on_host "$host" "bench/bench-run.sh" > "$dir/bench-run.tsv" 2> "$dir/bench.err" \
    || echo "WARN: bench-run failed (see $dir/bench.err)"
  echo "$cmd $host $ts" > "$dir/MANIFEST"
  echo "done: $(ls "$dir")"
  ;;
audit)
  latest=$(find "$DATA_DIR/$host" -maxdepth 1 -mindepth 1 -type d -printf '%f\n' 2>/dev/null | sort | tail -1)
  [ -n "$latest" ] || { echo "no baseline for $host" >&2; exit 3; }
  echo "== KNELPerf audit: $host vs baseline $latest"
  "$REPO_ROOT/loop/baseline-diff.sh" "$DATA_DIR/$host/$latest" "$host"
  ;;
tweak)
  [ $# -ge 3 ] || usage; tweak_id=$3
  echo "== KNELPerf tweak $tweak_id on $host (CR gate applies - see AGENTS.md)"
  run_on_host "$host" "tweaks/$tweak_id.sh"
  ;;
compare)
  [ $# -ge 4 ] || usage
  "$REPO_ROOT/loop/baseline-diff.sh" "$DATA_DIR/$host/$3" "$DATA_DIR/$host/$4"
  ;;
*) usage ;;
esac