#!/usr/bin/env bash
#
# Hardened LEARNINGS update verification helper.
#
# Previous verification gates used grep-only checks and could pass by matching
# an old file title (e.g. "Batch 6" appearing in the existing title). This helper
# snapshots the file mtime before a batch and checks it after, then verifies a
# fresh "Batch N" header appears in the first 5 lines.
#
# Usage:
#   scripts/verify-learnings-update.sh snapshot <agent-name> <baseline-epoch>
#   scripts/verify-learnings-update.sh check <agent-name> <batch-number>
#
# Conventions:
#   LEARNINGS path:  .learnings/<agent-name>/LEARNINGS.md
#   Baseline store:  .learnings/<agent-name>/.mtime-baseline
#
# Exit codes:
#   0  OK (file modified, batch header found)
#   1  FAIL (mtime unchanged or batch header missing)
#   2  WARNING / no baseline snapshot (needs manual review)
#
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"

usage() {
  cat <<EOF
Usage: $0 snapshot <agent-name> <baseline-epoch>
       $0 check <agent-name> <batch-number>

  snapshot  Capture the current mtime of .learnings/<agent-name>/LEARNINGS.md
            and write it to .learnings/<agent-name>/.mtime-baseline.
  check     Compare current mtime against the stored baseline and verify that
            a "Batch N" header appears in the first 5 lines.
EOF
}

log() {
  echo "[verify-learnings] $1"
}

main() {
  if [[ $# -lt 2 ]]; then
    usage
    exit 2
  fi

  local mode="$1"
  local agent="$2"
  local learnings="$PROJECT_ROOT/.learnings/$agent/LEARNINGS.md"
  local baseline="$PROJECT_ROOT/.learnings/$agent/.mtime-baseline"

  if [[ ! -f "$learnings" ]]; then
    log "ERROR: $learnings not found"
    exit 2
  fi

  case "$mode" in
    snapshot)
      if [[ $# -lt 3 ]]; then
        usage
        exit 2
      fi
      local epoch="$3"
      mkdir -p "$(dirname "$baseline")"
      echo "$epoch" > "$baseline"
      log "Snapshot for $agent: baseline epoch = $epoch"
      exit 0
      ;;

    check)
      if [[ $# -lt 3 ]]; then
        usage
        exit 2
      fi
      local batch="$3"

      if [[ ! -f "$baseline" ]]; then
        log "ERROR: no baseline snapshot for $agent — run snapshot mode first."
        exit 2
      fi

      local base_epoch
      base_epoch="$(cat "$baseline")"
      local cur_epoch
      cur_epoch="$(stat -c '%Y' "$learnings")"

      if [[ "$cur_epoch" -lt "$base_epoch" ]]; then
        log "WARNING: mtime regressed for $agent (baseline $base_epoch -> current $cur_epoch); manual review needed."
        exit 2
      fi

      if [[ "$cur_epoch" -eq "$base_epoch" ]]; then
        log "FAIL: $agent LEARNINGS untouched (epoch unchanged at $cur_epoch)"
        exit 1
      fi

      log "OK: $agent LEARNINGS updated (epoch: $base_epoch -> $cur_epoch)"

      if ! head -n 5 "$learnings" | grep -qE "^## Batch $batch|^### Batch $batch"; then
        log "FAIL: mtime updated but no Batch $batch header found in first 5 lines of $learnings"
        exit 1
      fi

      log "OK: Batch $batch header present in first 5 lines"
      exit 0
      ;;

    *)
      usage
      exit 2
      ;;
  esac
}

main "$@"