#!/usr/bin/env bash
set -euo pipefail

# CASAN H5 Governance Harness
# Usage:
#   governance-check.sh <input-file> <output-file> [action-name]
#
# Non-interactive by default. High-risk actions are denied unless:
#   CASAN_APPROVAL_DECISION=approve CASAN_APPROVER=<name>

INPUT_FILE="${1:-}"
OUTPUT_FILE="${2:-}"
ACTION_NAME="${3:-agent_step}"

if [[ -z "$INPUT_FILE" || -z "$OUTPUT_FILE" ]]; then
  echo "Usage: governance-check.sh <input-file> <output-file> [action-name]" >&2
  exit 64
fi

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/../../.." && pwd)"
LOG_DIR="$PROJECT_ROOT/.specify/logs"
TRACE_DIR="$LOG_DIR/trace"
AUDIT_DIR="$LOG_DIR/audit"
mkdir -p "$TRACE_DIR" "$AUDIT_DIR" "$(dirname "$OUTPUT_FILE")"

if [[ ! -f "$INPUT_FILE" ]]; then
  echo "GOVERNANCE_DENIED: input file not found: $INPUT_FILE" >&2
  exit 1
fi

timestamp() {
  date -u +"%Y-%m-%dT%H:%M:%SZ"
}

new_trace_id() {
  if command -v uuidgen >/dev/null 2>&1; then
    uuidgen | tr '[:upper:]' '[:lower:]'
  else
    printf 'trace-%s-%s\n' "$(date +%s)" "$$"
  fi
}

hash_text() {
  if command -v sha256sum >/dev/null 2>&1; then
    sha256sum | awk '{print $1}'
  else
    shasum -a 256 | awk '{print $1}'
  fi
}

json_escape() {
  python -c 'import json,sys; print(json.dumps(sys.stdin.read()))' 2>/dev/null || sed 's/\\/\\\\/g; s/"/\\"/g'
}

TRACE_ID="$(new_trace_id)"
TIMESTAMP="$(timestamp)"
INPUT="$(cat "$INPUT_FILE")"
LOWER_INPUT="$(printf '%s' "$INPUT" | tr '[:upper:]' '[:lower:]')"
ACTOR="${CASAN_ACTOR:-developer}"
APPROVER="${CASAN_APPROVER:-}"
APPROVAL_DECISION="${CASAN_APPROVAL_DECISION:-auto}"
AUDIT_LOG="$AUDIT_DIR/audit.jsonl"

RISK_LEVEL="low"
REASONS=()

case "$ACTION_NAME" in
  deploy|launch|write_code|write_file|migration|db_write|external_api|tool_call)
    RISK_LEVEL="medium"
    REASONS+=("sensitive-action:$ACTION_NAME")
    ;;
esac

if printf '%s' "$LOWER_INPUT" | grep -Eq "(delete|drop table|password|api[_-]?key|secret|token|credential|migration|deploy|external api|shutdown|dump database)"; then
  RISK_LEVEL="high"
  REASONS+=("high-risk-content")
elif printf '%s' "$LOWER_INPUT" | grep -Eq "(internal|config|system|policy|permission)"; then
  [[ "$RISK_LEVEL" == "low" ]] && RISK_LEVEL="medium"
  REASONS+=("medium-risk-content")
fi

APPROVAL_STATUS="auto_approved"
DECISION="approved"

if [[ "$RISK_LEVEL" == "medium" ]]; then
  APPROVAL_STATUS="policy_auto_approved_with_audit"
fi

if [[ "$RISK_LEVEL" == "high" ]]; then
  if [[ "${CASAN_APPROVAL_STRICT:-0}" == "1" ]]; then
    # Approval-identity mode (V20): an env-var approver is NOT enough — the
    # reviewer must cryptographically SIGN this exact request and their role must
    # be authorized for the action. SoD (actor != approver) still enforced.
    if [[ "$APPROVAL_DECISION" == "approve" && -n "$APPROVER" && ( -n "${CASAN_APPROVAL_SIG:-}" || -n "${CASAN_APPROVAL_JWT:-}" ) ]]; then
      if [[ "$APPROVER" == "$ACTOR" ]]; then
        APPROVAL_STATUS="separation_of_duties_violation"
        DECISION="denied"
        REASONS+=("separation-of-duties:actor-equals-approver")
      else
        AV_RC=0
        AV_OUT="$(bash "$SCRIPT_DIR/approval-verify.sh" "$ACTION_NAME" "$ACTOR" "$INPUT_FILE" "$APPROVER" "${CASAN_APPROVAL_SIG:-"-"}" 2>/dev/null)" || AV_RC=$?
        if [[ "$AV_RC" -eq 0 ]]; then
          if printf '%s' "$AV_OUT" | grep -q "mechanism=oidc"; then
            APPROVAL_STATUS="human_approved_oidc"
          else
            APPROVAL_STATUS="human_approved_signed"
          fi
          DECISION="approved"
          REASONS+=("signed-approval:${AV_OUT#APPROVAL_OK }")
        else
          APPROVAL_STATUS="approval_signature_invalid"
          DECISION="denied"
          REASONS+=("signed-approval-failed")
        fi
      fi
    else
      APPROVAL_STATUS="approval_required_signed"
      DECISION="denied"
      REASONS+=("strict-requires-signed-approval")
    fi
  elif [[ "$APPROVAL_DECISION" == "approve" && -n "$APPROVER" ]]; then
    if [[ "$APPROVER" == "$ACTOR" ]]; then
      # Separation of duties: the submitter may not approve their own action.
      APPROVAL_STATUS="separation_of_duties_violation"
      DECISION="denied"
      REASONS+=("separation-of-duties:actor-equals-approver")
    else
      APPROVAL_STATUS="human_approved"
      DECISION="approved"
    fi
  else
    APPROVAL_STATUS="approval_required"
    DECISION="denied"
  fi
fi

INPUT_HASH="$(printf '%s' "$INPUT" | hash_text)"
OUTPUT_CONTENT="$INPUT"
OUTPUT_HASH="$(printf '%s' "$OUTPUT_CONTENT" | hash_text)"
PREV_HASH=""
if [[ -s "$AUDIT_LOG" ]]; then
  PREV_HASH="$(tail -n 1 "$AUDIT_LOG" | sed -n 's/.*"record_hash":"\([^"]*\)".*/\1/p')"
fi

REASONS_JSON="$(printf '%s\n' "${REASONS[@]:-}" | python -c 'import json,sys; print(json.dumps([x for x in sys.stdin.read().splitlines() if x]))')"
# approver and output_hash are part of the hashed core so they cannot be
# silently mutated after the fact.
RECORD_CORE="$(printf '%s|%s|%s|%s|%s|%s|%s|%s|%s|%s|%s' "$TIMESTAMP" "$TRACE_ID" "$ACTION_NAME" "$ACTOR" "$RISK_LEVEL" "$DECISION" "$APPROVAL_STATUS" "$APPROVER" "$INPUT_HASH" "$OUTPUT_HASH" "$PREV_HASH")"
RECORD_HASH="$(printf '%s' "$RECORD_CORE" | hash_text)"

TRACE_FILE="$TRACE_DIR/governance-$TRACE_ID.json"
cat > "$TRACE_FILE" <<EOF
{
  "trace_id": "$TRACE_ID",
  "timestamp": "$TIMESTAMP",
  "harness": "H5-governance",
  "action": "$ACTION_NAME",
  "actor": "$ACTOR",
  "risk_level": "$RISK_LEVEL",
  "decision": "$DECISION",
  "approval_status": "$APPROVAL_STATUS",
  "approver": "$APPROVER",
  "reasons": $REASONS_JSON,
  "input_hash": "$INPUT_HASH",
  "output_hash": "$OUTPUT_HASH",
  "previous_record_hash": "$PREV_HASH",
  "record_hash": "$RECORD_HASH"
}
EOF

printf '{"timestamp":"%s","trace_id":"%s","harness":"H5-governance","action":"%s","actor":"%s","risk_level":"%s","decision":"%s","approval_status":"%s","approver":"%s","input_hash":"%s","output_hash":"%s","previous_record_hash":"%s","record_hash":"%s"}\n' \
  "$TIMESTAMP" "$TRACE_ID" "$ACTION_NAME" "$ACTOR" "$RISK_LEVEL" "$DECISION" "$APPROVAL_STATUS" "$APPROVER" "$INPUT_HASH" "$OUTPUT_HASH" "$PREV_HASH" "$RECORD_HASH" >> "$AUDIT_LOG"

# --- External anchor: cryptographically sign the new chain head ---
# A re-forged chain (recomputed hashes) changes the head; without the private
# key the attacker cannot produce a matching signature, so verification fails.
# Production note: the private key must live off-repo (KMS/HSM). It is local
# here only for self-contained demonstration.
if command -v openssl >/dev/null 2>&1; then
  # Private signing key lives OFF-REPO (default ~/.casan/audit-keys); only the
  # public key is committed. Production: replace with KMS/HSM.
  PUB_DIR="$PROJECT_ROOT/.specify/level5/central-governance"
  PRIV_DIR="${CASAN_AUDIT_KEY_DIR:-$HOME/.casan/audit-keys}"
  AUDIT_PRIV="$PRIV_DIR/audit-private.pem"
  AUDIT_PUB="$PUB_DIR/audit-public.pem"
  mkdir -p "$PUB_DIR" "$PRIV_DIR"
  if [[ ! -f "$AUDIT_PRIV" ]]; then
    openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out "$AUDIT_PRIV" 2>/dev/null
    chmod 600 "$AUDIT_PRIV"
  fi
  # Always re-export the public key so it matches the private key we sign with.
  # Without this, a private key that PERSISTS on a CI runner drifts out of sync
  # with a freshly checked-out audit-public.pem (e.g. one committed after a
  # Vault-KMS signing), and verify-audit-chain.sh would reject a genuine head.
  openssl rsa -in "$AUDIT_PRIV" -pubout -out "$AUDIT_PUB" 2>/dev/null || true
  printf '%s' "$RECORD_HASH" > "$AUDIT_DIR/audit-head.txt"
  openssl dgst -sha256 -sign "$AUDIT_PRIV" -out "$AUDIT_DIR/audit-head.sig" "$AUDIT_DIR/audit-head.txt" 2>/dev/null || true
fi

if [[ "$DECISION" != "approved" ]]; then
  : > "$OUTPUT_FILE"
  echo "GOVERNANCE_DENIED trace_id=$TRACE_ID risk=$RISK_LEVEL approval_status=$APPROVAL_STATUS" >&2
  exit 2
fi

printf '%s\n' "$OUTPUT_CONTENT" > "$OUTPUT_FILE"
echo "GOVERNANCE_APPROVED trace_id=$TRACE_ID risk=$RISK_LEVEL approval_status=$APPROVAL_STATUS output=$OUTPUT_FILE"