#!/usr/bin/env bash
# verify_biometric_erasure — confirm that a biometric erasure completed cleanly.
#
# Specification: docs/runbooks/BIPA_DESTRUCTION_RUNBOOK.md §3 step 3.
# Spec: docs/PHASE_1_6_BIPA_GATES.md §1 Gate 5.
#
# Why this exists: when an operator runs the erasure curl call against
# /biometric/subject/{id}/erase, they need a defensible artifact proving
# destruction completed. This script produces that artifact by checking
# four things:
#
#   1. SubjectManifest.biometric_collection is null  (catalogd cleared the row)
#   2. data/biometric/uploads/<safe_id>/  is empty or absent  (photo file gone)
#   3. Most recent audit row has accessor.kind in {biometric_erasure, full_erasure}
#      AND result is "erased" or "success"  (the chain logged the erasure intent)
#   4. audit_log.chain_verified is true  (HMAC chain still intact end-to-end)
#
# All four must pass for an operator to mark the destruction complete.
#
# Usage:
#   verify_biometric_erasure.sh <candidate_id> [--from ISO] [--to ISO]
#
# Environment:
#   GATEWAY_URL        — default http://localhost:3100
#   LEGAL_TOKEN_FILE   — default /etc/lakehouse/legal_audit.token
#   UPLOADS_ROOT       — default data/biometric/uploads (relative to repo root)
#   OUT_DIR            — default reports/biometric (where the verification report lands)
#
# Exit codes:
#   0 — all four checks pass; erasure verified
#   1 — one or more checks failed; do NOT mark destruction complete; escalate
#   2 — script error (missing tools, network failure, bad token)

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

if [ "$#" -lt 1 ]; then
  echo "usage: verify_biometric_erasure.sh <candidate_id> [--from ISO] [--to ISO]" >&2
  exit 2
fi

CANDIDATE_ID="$1"
shift
FROM=""
TO=""
while [ "$#" -gt 0 ]; do
  case "$1" in
    --from) FROM="$2"; shift 2 ;;
    --to) TO="$2"; shift 2 ;;
    *) echo "unknown flag: $1" >&2; exit 2 ;;
  esac
done

GATEWAY_URL="${GATEWAY_URL:-http://localhost:3100}"
LEGAL_TOKEN_FILE="${LEGAL_TOKEN_FILE:-/etc/lakehouse/legal_audit.token}"
UPLOADS_ROOT="${UPLOADS_ROOT:-data/biometric/uploads}"
OUT_DIR="${OUT_DIR:-reports/biometric}"

# Dependency gates — fail fast with clear errors rather than producing
# a misleading "evidence" file from missing tools.
for cmd in curl jq sha256sum; do
  if ! command -v "$cmd" >/dev/null 2>&1; then
    echo "[verify] FAIL: required tool '$cmd' not found in PATH" >&2
    exit 2
  fi
done

if [ ! -r "$LEGAL_TOKEN_FILE" ]; then
  echo "[verify] FAIL: cannot read legal token at $LEGAL_TOKEN_FILE" >&2
  echo "[verify]   This script requires legal-tier auth to query /audit/subject/." >&2
  exit 2
fi
LEGAL_TOKEN=$(tr -d '[:space:]' < "$LEGAL_TOKEN_FILE")
if [ -z "$LEGAL_TOKEN" ]; then
  echo "[verify] FAIL: legal token file is empty" >&2
  exit 2
fi

# safe_id matches catalogd::biometric_endpoint::sanitize_for_path:
# any non-[A-Za-z0-9_.-] char is replaced with underscore.
SAFE_ID=$(printf '%s' "$CANDIDATE_ID" | sed 's/[^A-Za-z0-9_.\-]/_/g')

mkdir -p "$OUT_DIR"
DATE=$(date -u +%Y-%m-%dT%H-%M-%SZ)
OUT="$OUT_DIR/erasure_verify_${SAFE_ID}_${DATE}.md"
EVIDENCE=$(mktemp)
trap 'rm -f "$EVIDENCE"' EXIT

PASS=0
FAIL=0
note() { echo "$1" >> "$EVIDENCE"; }
mark_pass() { PASS=$((PASS+1)); note "  - PASS: $1"; }
mark_fail() { FAIL=$((FAIL+1)); note "  - FAIL: $1"; }

note "## Verification target"
note ""
note "- **candidate_id:** \`$CANDIDATE_ID\`"
note "- **safe_id (filesystem):** \`$SAFE_ID\`"
note "- **gateway:** \`$GATEWAY_URL\`"
note "- **uploads root:** \`$UPLOADS_ROOT\`"
note "- **window:** ${FROM:-unbounded}  →  ${TO:-unbounded}"
note ""

# ── Fetch the audit response ────────────────────────────────────────
QUERY=""
if [ -n "$FROM" ]; then QUERY="from=$FROM"; fi
if [ -n "$TO" ]; then
  if [ -n "$QUERY" ]; then QUERY="${QUERY}&to=$TO"; else QUERY="to=$TO"; fi
fi
URL="$GATEWAY_URL/audit/subject/$CANDIDATE_ID"
if [ -n "$QUERY" ]; then URL="$URL?$QUERY"; fi

RESP_FILE=$(mktemp)
HTTP_CODE=$(curl -sS -o "$RESP_FILE" -w '%{http_code}' \
  -H "X-Lakehouse-Legal-Token: $LEGAL_TOKEN" \
  -H "Accept: application/json" \
  "$URL" 2>&1) || HTTP_CODE="000"

if [ "$HTTP_CODE" != "200" ]; then
  echo "[verify] FAIL: GET $URL returned HTTP $HTTP_CODE" >&2
  echo "[verify] response head:" >&2
  head -c 500 "$RESP_FILE" >&2
  echo >&2
  rm -f "$RESP_FILE"
  exit 2
fi

# Schema sanity — refuse to evaluate against an unrecognized response shape.
SCHEMA=$(jq -r '.schema // ""' < "$RESP_FILE")
if [ "$SCHEMA" != "subject_audit_response.v1" ]; then
  echo "[verify] FAIL: unexpected response schema '$SCHEMA' (want subject_audit_response.v1)" >&2
  rm -f "$RESP_FILE"
  exit 2
fi

# ── Check 1: manifest.biometric_collection is null ──────────────────
note "## Check 1 — Subject manifest biometric_collection is null"
note ""
BIO_COLL=$(jq -c '.manifest.biometric_collection // null' < "$RESP_FILE")
note "**manifest.biometric_collection:** \`$BIO_COLL\`"
note ""
if [ "$BIO_COLL" = "null" ]; then
  mark_pass "biometric_collection field is null on the subject manifest"
else
  mark_fail "biometric_collection is still populated — erasure incomplete"
fi
note ""

# ── Check 2: filesystem uploads dir is empty/absent ─────────────────
note "## Check 2 — Quarantined upload directory empty or absent"
note ""
UPLOAD_DIR="$UPLOADS_ROOT/$SAFE_ID"
note "**path:** \`$UPLOAD_DIR\`"
if [ ! -e "$UPLOAD_DIR" ]; then
  note "**state:** absent (directory was removed during erasure or never existed)"
  note ""
  mark_pass "upload directory is absent"
elif [ ! -d "$UPLOAD_DIR" ]; then
  note "**state:** path exists but is not a directory — investigate"
  note ""
  mark_fail "upload path exists and is not a directory: $UPLOAD_DIR"
else
  REMAINING=$(find "$UPLOAD_DIR" -maxdepth 1 -mindepth 1 2>/dev/null | wc -l | tr -d '[:space:]')
  : "${REMAINING:=0}"
  note "**state:** directory exists with $REMAINING remaining entries"
  note ""
  if [ "$REMAINING" = "0" ]; then
    mark_pass "upload directory is empty (no residual photo files)"
  else
    mark_fail "$REMAINING file(s) remain under $UPLOAD_DIR — must be unlinked"
    note "### Residual files"
    note ""
    note '```'
    find "$UPLOAD_DIR" -maxdepth 2 >> "$EVIDENCE"
    note '```'
    note ""
  fi
fi

# ── Check 3: most recent audit row reflects erasure ─────────────────
note "## Check 3 — Audit log records the erasure event"
note ""
ROW_COUNT=$(jq '.audit_log.rows | length' < "$RESP_FILE")
note "**rows in window:** $ROW_COUNT"
if [ "$ROW_COUNT" = "0" ]; then
  mark_fail "no audit rows in the requested window — erasure should have appended one"
  note ""
else
  LAST_KIND=$(jq -r '.audit_log.rows | last | .accessor.kind // ""' < "$RESP_FILE")
  LAST_RESULT=$(jq -r '.audit_log.rows | last | .result // ""' < "$RESP_FILE")
  LAST_TS=$(jq -r '.audit_log.rows | last | .ts // ""' < "$RESP_FILE")
  note "**last row:** ts=\`$LAST_TS\` accessor.kind=\`$LAST_KIND\` result=\`$LAST_RESULT\`"
  note ""
  case "$LAST_KIND" in
    biometric_erasure|full_erasure)
      case "$LAST_RESULT" in
        erased|success)
          mark_pass "last audit row is an erasure event ($LAST_KIND/$LAST_RESULT)"
          ;;
        *)
          mark_fail "last row kind is $LAST_KIND but result is '$LAST_RESULT' (expected erased/success)"
          ;;
      esac
      ;;
    *)
      mark_fail "last audit row accessor.kind is '$LAST_KIND' (expected biometric_erasure or full_erasure)"
      ;;
  esac
fi
note ""

# ── Check 4: HMAC chain verifies end-to-end ─────────────────────────
note "## Check 4 — HMAC chain integrity"
note ""
CHAIN_VERIFIED=$(jq -r '.audit_log.chain_verified' < "$RESP_FILE")
CHAIN_ROOT=$(jq -r '.audit_log.chain_root // ""' < "$RESP_FILE")
CHAIN_ROWS=$(jq -r '.audit_log.chain_rows_total // 0' < "$RESP_FILE")
CHAIN_ERR=$(jq -r '.audit_log.chain_verification_error // ""' < "$RESP_FILE")
note "**chain_verified:** \`$CHAIN_VERIFIED\`"
note "**chain_rows_total:** $CHAIN_ROWS"
note "**chain_root:** \`$CHAIN_ROOT\`"
if [ -n "$CHAIN_ERR" ]; then
  note "**chain_verification_error:** \`$CHAIN_ERR\`"
fi
note ""
if [ "$CHAIN_VERIFIED" = "true" ]; then
  mark_pass "chain verifies end-to-end ($CHAIN_ROWS rows)"
else
  mark_fail "chain integrity broken — destruction is NOT defensible until investigated"
fi
note ""

# ── Render report ───────────────────────────────────────────────────
TOTAL=$((PASS + FAIL))
note "## Summary"
note ""
note "**$PASS / $TOTAL** verification checks pass."
note ""
if [ "$FAIL" -gt 0 ]; then
  note "**Status: ERASURE NOT VERIFIED.** Do NOT mark destruction complete. Escalate to engineering before responding to candidate / counsel."
  note ""
fi

# Hash response body so the report has a tamper-evident anchor.
RESP_HASH=$(sha256sum "$RESP_FILE" | awk '{print $1}')
EVIDENCE_HASH=$(sha256sum "$EVIDENCE" | awk '{print $1}')

{
  echo "# Biometric Erasure Verification — $CANDIDATE_ID"
  echo
  echo "**Date:** $DATE"
  echo "**Spec:** docs/runbooks/BIPA_DESTRUCTION_RUNBOOK.md §3 step 3"
  echo "**Generator:** scripts/staffing/verify_biometric_erasure.sh"
  echo
  cat "$EVIDENCE"
  echo "---"
  echo
  echo "**Audit response SHA-256:** \`$RESP_HASH\`"
  echo "**Evidence summary SHA-256:** \`$EVIDENCE_HASH\`"
  echo
} > "$OUT"

rm -f "$RESP_FILE"
echo "[verify] $PASS / $TOTAL checks pass — report: $OUT"
echo "[verify] response hash: $RESP_HASH"
[ "$FAIL" -eq 0 ]