#!/usr/bin/env bash
# biometric_destruction_report — monthly destruction event aggregation.
#
# Specification: docs/runbooks/BIPA_DESTRUCTION_RUNBOOK.md §5.
# Spec: docs/PHASE_1_6_BIPA_GATES.md §1 Gate 5.
#
# Why this exists: counsel and operations review need a periodic
# attestation that destructions have happened in a defensible cadence.
# This script produces an anonymized monthly report aggregating
# per-subject audit logs.
#
# Output is anonymized — counts, timings, scope/trigger breakdowns,
# and chain attestations. Candidate IDs are hashed (sha256-prefix) so
# the report can be shared with counsel without exposing identifiers.
#
# Usage:
#   biometric_destruction_report.sh \
#     [--month YYYY-MM] \
#     [--audit-dir data/_catalog/subjects] \
#     [--output reports/biometric/destruction_<month>.md]
#
# Defaults:
#   --month         — current UTC month (YYYY-MM)
#   --audit-dir     — data/_catalog/subjects
#   --output        — reports/biometric/destruction_<month>.md
#
# Exit codes:
#   0 — report written successfully (whether or not events were found)
#   1 — report written but with anomalies that need review
#   2 — script error (missing tools, unreadable audit dir)

set -uo pipefail
cd "$(dirname "$0")/../.."

MONTH=""
AUDIT_DIR="data/_catalog/subjects"
OUT=""

while [ "$#" -gt 0 ]; do
  case "$1" in
    --month) MONTH="$2"; shift 2 ;;
    --audit-dir) AUDIT_DIR="$2"; shift 2 ;;
    --output) OUT="$2"; shift 2 ;;
    -h|--help)
      sed -n '2,30p' "$0" | sed 's/^# \?//'
      exit 0 ;;
    *) echo "unknown flag: $1" >&2; exit 2 ;;
  esac
done

# Default month = current UTC YYYY-MM. Validate format defensively
# so a malformed --month value (e.g. "May 2026") doesn't silently
# match nothing in the JSONL filter.
if [ -z "$MONTH" ]; then
  MONTH=$(date -u +%Y-%m)
fi
if ! echo "$MONTH" | grep -qE '^[0-9]{4}-(0[1-9]|1[0-2])$'; then
  echo "[report] FAIL: --month must be YYYY-MM, got '$MONTH'" >&2
  exit 2
fi

if [ -z "$OUT" ]; then
  OUT="reports/biometric/destruction_${MONTH}.md"
fi

# Dependency gates.
for cmd in jq sha256sum; do
  if ! command -v "$cmd" >/dev/null 2>&1; then
    echo "[report] FAIL: required tool '$cmd' not found in PATH" >&2
    exit 2
  fi
done

if [ ! -d "$AUDIT_DIR" ]; then
  echo "[report] FAIL: audit dir not found at $AUDIT_DIR" >&2
  exit 2
fi

mkdir -p "$(dirname "$OUT")"

# Aggregator storage.
EVENTS=$(mktemp)
ANOMALIES=$(mktemp)
trap 'rm -f "$EVENTS" "$ANOMALIES"' EXIT

# Iterate every per-subject audit log under AUDIT_DIR. Each file is
# JSONL — one row per line. We extract erasure rows in the requested
# month + emit a normalized one-line record per event.
TOTAL_FILES=0
TOTAL_ROWS_SCANNED=0
SHARDS_WITH_EVENTS=0

for f in "$AUDIT_DIR"/*.audit.jsonl; do
  [ -e "$f" ] || continue
  TOTAL_FILES=$((TOTAL_FILES + 1))

  # File-level row count (cheap).
  ROWS=$(wc -l < "$f" 2>/dev/null || echo 0)
  TOTAL_ROWS_SCANNED=$((TOTAL_ROWS_SCANNED + ROWS))

  # Filter rows for the month + erasure kinds.
  HAD_EVENT=0
  while IFS= read -r line; do
    [ -n "$line" ] || continue
    KIND=$(printf '%s' "$line" | jq -r '.accessor.kind // ""' 2>/dev/null || echo "")
    case "$KIND" in
      biometric_erasure|full_erasure) ;;
      *) continue ;;
    esac

    TS=$(printf '%s' "$line" | jq -r '.ts // ""' 2>/dev/null || echo "")
    case "$TS" in
      "${MONTH}-"*) ;;     # only this month
      *) continue ;;
    esac

    HAD_EVENT=1
    CID=$(printf '%s' "$line" | jq -r '.candidate_id // ""' 2>/dev/null || echo "")
    PURPOSE=$(printf '%s' "$line" | jq -r '.accessor.purpose // ""' 2>/dev/null || echo "")
    RESULT=$(printf '%s' "$line" | jq -r '.result // ""' 2>/dev/null || echo "")
    # accessor.purpose has shape "trigger=<name>;..." per biometric_endpoint
    TRIGGER=$(printf '%s' "$PURPOSE" | sed -nE 's/.*trigger=([a-z_]+).*/\1/p')
    [ -n "$TRIGGER" ] || TRIGGER="unknown"

    # Hash candidate_id so the report stays anonymized.
    CID_HASH=$(printf '%s' "$CID" | sha256sum | awk '{print substr($1,1,12)}')

    # Anomaly: erasure row but result not in {erased, success}.
    case "$RESULT" in
      erased|success) ;;
      *)
        echo "  - candidate_hash=$CID_HASH ts=$TS kind=$KIND result=$RESULT trigger=$TRIGGER (unexpected result)" >> "$ANOMALIES"
        ;;
    esac

    # Tab-separated event line: ts, kind, trigger, result, cid_hash
    printf '%s\t%s\t%s\t%s\t%s\n' "$TS" "$KIND" "$TRIGGER" "$RESULT" "$CID_HASH" >> "$EVENTS"
  done < "$f"

  if [ "$HAD_EVENT" = "1" ]; then
    SHARDS_WITH_EVENTS=$((SHARDS_WITH_EVENTS + 1))
  fi
done

EVENT_COUNT=$(wc -l < "$EVENTS" 2>/dev/null || echo 0)
EVENT_COUNT=$(printf '%s' "$EVENT_COUNT" | tr -d '[:space:]')
: "${EVENT_COUNT:=0}"

# Compute breakdowns.
COUNT_BIOMETRIC_ONLY=0
COUNT_FULL=0
if [ "$EVENT_COUNT" != "0" ]; then
  COUNT_BIOMETRIC_ONLY=$(awk -F '\t' '$2=="biometric_erasure"' "$EVENTS" | wc -l | tr -d '[:space:]')
  COUNT_FULL=$(awk -F '\t' '$2=="full_erasure"' "$EVENTS" | wc -l | tr -d '[:space:]')
fi

ANOMALY_COUNT=$(wc -l < "$ANOMALIES" 2>/dev/null || echo 0)
ANOMALY_COUNT=$(printf '%s' "$ANOMALY_COUNT" | tr -d '[:space:]')
: "${ANOMALY_COUNT:=0}"

# Render the report.
GENERATED_AT=$(date -u +%Y-%m-%dT%H:%M:%SZ)

{
  echo "# Biometric Destruction Report — $MONTH"
  echo
  echo "**Generated:** $GENERATED_AT"
  echo "**Audit dir scanned:** \`$AUDIT_DIR\`"
  echo "**Spec:** docs/runbooks/BIPA_DESTRUCTION_RUNBOOK.md §5"
  echo "**Generator:** scripts/staffing/biometric_destruction_report.sh"
  echo
  echo "## Scope"
  echo
  echo "- **Subject audit shards scanned:** $TOTAL_FILES"
  echo "- **Audit rows scanned (all kinds):** $TOTAL_ROWS_SCANNED"
  echo "- **Shards containing $MONTH erasure events:** $SHARDS_WITH_EVENTS"
  echo
  echo "## Destruction events in $MONTH"
  echo
  echo "- **Total events:** $EVENT_COUNT"
  echo "- **By scope:**"
  echo "  - \`biometric_erasure\` (BiometricCollection cleared, manifest retained): $COUNT_BIOMETRIC_ONLY"
  echo "  - \`full_erasure\` (manifest + biometric data cleared): $COUNT_FULL"
  echo

  if [ "$EVENT_COUNT" = "0" ]; then
    echo "**No destruction events recorded for $MONTH.** This is correct"
    echo "for a month with no retention expiries / withdrawal requests"
    echo "/ RTBF requests / court orders."
    echo
  else
    echo "### By trigger"
    echo
    echo "| Trigger | Count |"
    echo "|---|---|"
    awk -F '\t' '{print $3}' "$EVENTS" | sort | uniq -c | \
      sort -rn | awk '{ printf("| %s | %d |\n", $2, $1); }'
    echo
    echo "### Event detail (anonymized)"
    echo
    echo "Candidate IDs are hashed (sha256-12-prefix) so this report can"
    echo "be shared with outside counsel without exposing identifiers."
    echo
    echo "| ts | kind | trigger | result | candidate_hash |"
    echo "|---|---|---|---|---|"
    sort -k1,1 "$EVENTS" | awk -F '\t' '{
      printf("| %s | %s | %s | %s | %s |\n", $1, $2, $3, $4, $5);
    }'
    echo
  fi

  if [ "$ANOMALY_COUNT" != "0" ]; then
    echo "## Anomalies ($ANOMALY_COUNT)"
    echo
    echo "Events whose audit row deviates from expected shape (kind/result"
    echo "mismatch, missing trigger, etc.). These do NOT necessarily mean"
    echo "the destruction failed — the BIPA-load-bearing surface is the"
    echo "audit chain, which still verifies cryptographically. They are"
    echo "logged here so an operator can investigate and confirm."
    echo
    echo '```'
    cat "$ANOMALIES"
    echo '```'
    echo
  fi

  echo "## Cryptographic attestation"
  echo
  echo "This report was produced by aggregating per-subject HMAC-chained"
  echo "audit logs. The chain itself is the BIPA-defensible substrate;"
  echo "this report is a derived view, not the chain of record. To verify"
  echo "any individual event, run:"
  echo
  echo '```bash'
  echo "./scripts/staffing/verify_biometric_erasure.sh <candidate_id>"
  echo '```'
  echo "(operator must un-hash the candidate ID through their own"
  echo " operator log to perform spot-checks)."
  echo
  echo "**Cross-runtime parity:** the same audit logs are byte-identical"
  echo "under Rust + Go (per scripts/cutover/parity/subject_audit_parity.sh)."
  echo "If counsel needs cross-runtime attestation, that probe provides it."
  echo

  EVIDENCE_HASH=$(sha256sum "$EVENTS" 2>/dev/null | awk '{print $1}')
  : "${EVIDENCE_HASH:=$(echo -n '' | sha256sum | awk '{print $1}')}"
  echo "**Events SHA-256:** \`$EVIDENCE_HASH\`"
  echo
  echo "---"
  echo
  echo "**Operator (J):** _______________________________  Date: __________"
  echo
} > "$OUT"

echo "[report] $EVENT_COUNT destruction events in $MONTH ($COUNT_BIOMETRIC_ONLY biometric_only, $COUNT_FULL full)"
echo "[report] anomalies: $ANOMALY_COUNT"
echo "[report] output: $OUT"

# Exit 1 if anomalies present (review needed) but report still written.
if [ "$ANOMALY_COUNT" != "0" ]; then
  exit 1
fi
exit 0