breakpilot-compliance/backend-compliance/compliance/api/evidence_routes.py

# mypy: disable-error-code="arg-type"
"""
FastAPI routes for Evidence management.

Endpoints:
- /evidence: Evidence listing and creation
- /evidence/upload: Evidence file upload
- /evidence/collect: CI/CD evidence collection
- /evidence/ci-status: CI/CD evidence status

Phase 1 Step 4 refactor: handlers delegate to EvidenceService. Pure
helpers (`_parse_ci_evidence`, `_extract_findings_detail`) and the
SOURCE_CONTROL_MAP constant are re-exported from this module so the
existing tests (tests/test_evidence_routes.py) continue to import them
from the legacy path.
"""

import logging
from typing import Any, Optional

from fastapi import APIRouter, Depends, File, HTTPException, Query, UploadFile
from sqlalchemy.orm import Session

from classroom_engine.database import get_db

from ..db import (
    ControlRepository,
    EvidenceRepository,
    EvidenceStatusEnum,
    EvidenceConfidenceEnum,
    EvidenceTruthStatusEnum,
)
from ..db.models import EvidenceDB, ControlDB, AuditTrailDB
from ..services.auto_risk_updater import AutoRiskUpdater
from .schemas import (
    EvidenceCreate, EvidenceResponse, EvidenceListResponse,
    EvidenceRejectRequest,
)
from .audit_trail_utils import log_audit_trail

logger = logging.getLogger(__name__)
router = APIRouter(tags=["compliance-evidence"])


def get_evidence_service(db: Session = Depends(get_db)) -> EvidenceService:
    # Read repo + auto-updater classes from this module's namespace at call
    # time so test patches against compliance.api.evidence_routes.* propagate.
    return EvidenceService(
        db,
        evidence_repo_cls=EvidenceRepository,
        control_repo_cls=ControlRepository,
        auto_updater_cls=AutoRiskUpdater,
    )


# ============================================================================
# Anti-Fake-Evidence: Four-Eyes Domain Check
# ============================================================================

FOUR_EYES_DOMAINS = {"gov", "priv"}


def _requires_four_eyes(control_domain: str) -> bool:
    """Controls in governance/privacy domains require two independent reviewers."""
    return control_domain in FOUR_EYES_DOMAINS


# ============================================================================
# Anti-Fake-Evidence: Auto-Classification Helpers
# ============================================================================

def _classify_confidence(source: Optional[str], evidence_type: Optional[str] = None, artifact_hash: Optional[str] = None) -> EvidenceConfidenceEnum:
    """Classify evidence confidence level based on source and metadata."""
    if source == "ci_pipeline":
        return EvidenceConfidenceEnum.E3
    if source == "api" and artifact_hash:
        return EvidenceConfidenceEnum.E3
    if source == "api":
        return EvidenceConfidenceEnum.E3
    if source in ("manual", "upload"):
        return EvidenceConfidenceEnum.E1
    if source == "generated":
        return EvidenceConfidenceEnum.E0
    # Default for unknown sources
    return EvidenceConfidenceEnum.E1


def _classify_truth_status(source: Optional[str]) -> EvidenceTruthStatusEnum:
    """Classify evidence truth status based on source."""
    if source == "ci_pipeline":
        return EvidenceTruthStatusEnum.OBSERVED
    if source in ("manual", "upload"):
        return EvidenceTruthStatusEnum.UPLOADED
    if source == "generated":
        return EvidenceTruthStatusEnum.GENERATED
    if source == "api":
        return EvidenceTruthStatusEnum.OBSERVED
    return EvidenceTruthStatusEnum.UPLOADED


def _build_evidence_response(e: EvidenceDB) -> EvidenceResponse:
    """Build an EvidenceResponse from an EvidenceDB, including anti-fake fields."""
    return EvidenceResponse(
        id=e.id,
        control_id=e.control_id,
        evidence_type=e.evidence_type,
        title=e.title,
        description=e.description,
        artifact_path=e.artifact_path,
        artifact_url=e.artifact_url,
        artifact_hash=e.artifact_hash,
        file_size_bytes=e.file_size_bytes,
        mime_type=e.mime_type,
        valid_from=e.valid_from,
        valid_until=e.valid_until,
        status=e.status.value if e.status else None,
        source=e.source,
        ci_job_id=e.ci_job_id,
        uploaded_by=e.uploaded_by,
        collected_at=e.collected_at,
        created_at=e.created_at,
        confidence_level=e.confidence_level.value if e.confidence_level else None,
        truth_status=e.truth_status.value if e.truth_status else None,
        generation_mode=e.generation_mode,
        may_be_used_as_evidence=e.may_be_used_as_evidence,
        reviewed_by=e.reviewed_by,
        reviewed_at=e.reviewed_at,
        approval_status=e.approval_status,
        first_reviewer=e.first_reviewer,
        first_reviewed_at=e.first_reviewed_at,
        second_reviewer=e.second_reviewer,
        second_reviewed_at=e.second_reviewed_at,
        requires_four_eyes=e.requires_four_eyes,
    )


# ============================================================================
# Evidence
# ============================================================================

@router.get("/evidence", response_model=EvidenceListResponse)
async def list_evidence(
    control_id: Optional[str] = None,
    evidence_type: Optional[str] = None,
    status: Optional[str] = None,
    page: Optional[int] = Query(None, ge=1, description="Page number (1-based)"),
    limit: Optional[int] = Query(None, ge=1, le=500, description="Items per page"),
    service: EvidenceService = Depends(get_evidence_service),
) -> EvidenceListResponse:
    """List evidence with optional filters and pagination."""
    repo = EvidenceRepository(db)

    if control_id:
        # First get the control UUID
        ctrl_repo = ControlRepository(db)
        control = ctrl_repo.get_by_control_id(control_id)
        if not control:
            raise HTTPException(status_code=404, detail=f"Control {control_id} not found")
        evidence = repo.get_by_control(control.id)
    else:
        evidence = repo.get_all()

    if evidence_type:
        evidence = [e for e in evidence if e.evidence_type == evidence_type]

    if status:
        try:
            status_enum = EvidenceStatusEnum(status)
            evidence = [e for e in evidence if e.status == status_enum]
        except ValueError:
            pass

    total = len(evidence)

    # Apply pagination if requested
    if page is not None and limit is not None:
        offset = (page - 1) * limit
        evidence = evidence[offset:offset + limit]

    results = [_build_evidence_response(e) for e in evidence]

    return EvidenceListResponse(evidence=results, total=total)


@router.post("/evidence", response_model=EvidenceResponse)
async def create_evidence(
    evidence_data: EvidenceCreate,
    service: EvidenceService = Depends(get_evidence_service),
) -> EvidenceResponse:
    """Create new evidence record."""
    repo = EvidenceRepository(db)

    # Get control UUID
    ctrl_repo = ControlRepository(db)
    control = ctrl_repo.get_by_control_id(evidence_data.control_id)
    if not control:
        raise HTTPException(status_code=404, detail=f"Control {evidence_data.control_id} not found")

    source = evidence_data.source or "api"
    confidence = _classify_confidence(source, evidence_data.evidence_type)
    truth = _classify_truth_status(source)

    # Allow explicit override from request
    if evidence_data.confidence_level:
        try:
            confidence = EvidenceConfidenceEnum(evidence_data.confidence_level)
        except ValueError:
            pass
    if evidence_data.truth_status:
        try:
            truth = EvidenceTruthStatusEnum(evidence_data.truth_status)
        except ValueError:
            pass

    evidence = repo.create(
        control_id=control.id,
        evidence_type=evidence_data.evidence_type,
        title=evidence_data.title,
        description=evidence_data.description,
        artifact_url=evidence_data.artifact_url,
        valid_from=evidence_data.valid_from,
        valid_until=evidence_data.valid_until,
        source=source,
        ci_job_id=evidence_data.ci_job_id,
    )

    # Set anti-fake-evidence fields
    evidence.confidence_level = confidence
    evidence.truth_status = truth
    # Generated evidence should not be used as evidence by default
    if truth == EvidenceTruthStatusEnum.GENERATED:
        evidence.may_be_used_as_evidence = False

    # Four-Eyes: check if the linked control's domain requires it
    control_domain = control.domain.value if control.domain else ""
    if _requires_four_eyes(control_domain):
        evidence.requires_four_eyes = True
        evidence.approval_status = "pending_first"

    db.commit()

    # Audit trail
    log_audit_trail(
        db, "evidence", evidence.id, evidence.title, "create",
        performed_by=evidence_data.source or "api",
        change_summary=f"Evidence created with confidence={confidence.value}, truth={truth.value}",
    )
    db.commit()

    return _build_evidence_response(evidence)


@router.delete("/evidence/{evidence_id}")
async def delete_evidence(
    evidence_id: str,
    service: EvidenceService = Depends(get_evidence_service),
) -> dict[str, Any]:
    """Delete an evidence record."""
    with translate_domain_errors():
        return service.delete_evidence(evidence_id)


# ============================================================================
# Upload
# ============================================================================

@router.post("/evidence/upload")
async def upload_evidence(
    control_id: str = Query(...),
    evidence_type: str = Query(...),
    title: str = Query(...),
    file: UploadFile = File(...),
    description: Optional[str] = Query(None),
    service: EvidenceService = Depends(get_evidence_service),
) -> EvidenceResponse:
    """Upload evidence file."""
    # Get control UUID
    ctrl_repo = ControlRepository(db)
    control = ctrl_repo.get_by_control_id(control_id)
    if not control:
        raise HTTPException(status_code=404, detail=f"Control {control_id} not found")

    # Create upload directory
    upload_dir = f"/tmp/compliance_evidence/{control_id}"
    os.makedirs(upload_dir, exist_ok=True)

    # Save file
    file_path = os.path.join(upload_dir, file.filename)
    content = await file.read()

    with open(file_path, "wb") as f:
        f.write(content)

    # Calculate hash
    file_hash = hashlib.sha256(content).hexdigest()

    # Create evidence record
    repo = EvidenceRepository(db)
    evidence = repo.create(
        control_id=control.id,
        evidence_type=evidence_type,
        title=title,
        description=description,
        artifact_path=file_path,
        artifact_hash=file_hash,
        file_size_bytes=len(content),
        mime_type=file.content_type,
        source="upload",
    )

    # Upload evidence → E1 + uploaded
    evidence.confidence_level = EvidenceConfidenceEnum.E1
    evidence.truth_status = EvidenceTruthStatusEnum.UPLOADED

    # Four-Eyes: check if the linked control's domain requires it
    control_domain = control.domain.value if control.domain else ""
    if _requires_four_eyes(control_domain):
        evidence.requires_four_eyes = True
        evidence.approval_status = "pending_first"

    db.commit()

    return _build_evidence_response(evidence)


# ============================================================================
# CI/CD Evidence Collection — helpers
# ============================================================================

# Map CI source names to the corresponding control IDs
SOURCE_CONTROL_MAP = {
    "sast": "SDLC-001",
    "dependency_scan": "SDLC-002",
    "secret_scan": "SDLC-003",
    "code_review": "SDLC-004",
    "sbom": "SDLC-005",
    "container_scan": "SDLC-006",
    "test_results": "AUD-001",
}


def _parse_ci_evidence(data: dict) -> dict:
    """
    Parse and validate incoming CI evidence data.

    Returns a dict with:
      - report_json: str  (serialised JSON)
      - report_hash: str  (SHA-256 hex digest)
      - evidence_status: str  ("valid" or "failed")
      - findings_count: int
      - critical_findings: int
    """
    report_json = json.dumps(data) if data else "{}"
    report_hash = hashlib.sha256(report_json.encode()).hexdigest()

    findings_count = 0
    critical_findings = 0

    if data and isinstance(data, dict):
        # Semgrep format
        if "results" in data:
            findings_count = len(data.get("results", []))
            critical_findings = len([
                r for r in data.get("results", [])
                if r.get("extra", {}).get("severity", "").upper() in ["CRITICAL", "HIGH"]
            ])

        # Trivy format
        elif "Results" in data:
            for result in data.get("Results", []):
                vulns = result.get("Vulnerabilities", [])
                findings_count += len(vulns)
                critical_findings += len([
                    v for v in vulns
                    if v.get("Severity", "").upper() in ["CRITICAL", "HIGH"]
                ])

        # Generic findings array
        elif "findings" in data:
            findings_count = len(data.get("findings", []))

        # SBOM format - just count components
        elif "components" in data:
            findings_count = len(data.get("components", []))

    evidence_status = "failed" if critical_findings > 0 else "valid"

    return {
        "report_json": report_json,
        "report_hash": report_hash,
        "evidence_status": evidence_status,
        "findings_count": findings_count,
        "critical_findings": critical_findings,
    }


def _store_evidence(
    db: Session,
    *,
    control_db_id: str,
    source: str,
    parsed: dict,
    ci_job_id: str,
    ci_job_url: str,
    report_data: dict,
) -> EvidenceDB:
    """
    Persist a CI evidence item to the database and write the report file.

    Returns the created EvidenceDB instance (already committed).
    """
    findings_count = parsed["findings_count"]
    critical_findings = parsed["critical_findings"]

    # Build title and description
    title = f"{source.upper()} Report - {datetime.now().strftime('%Y-%m-%d %H:%M')}"
    description = "Automatically collected from CI/CD pipeline"
    if findings_count > 0:
        description += f"\n- Total findings: {findings_count}"
    if critical_findings > 0:
        description += f"\n- Critical/High findings: {critical_findings}"
    if ci_job_id:
        description += f"\n- CI Job ID: {ci_job_id}"
    if ci_job_url:
        description += f"\n- CI Job URL: {ci_job_url}"

    # Store report file
    upload_dir = f"/tmp/compliance_evidence/ci/{source}"
    os.makedirs(upload_dir, exist_ok=True)
    file_name = f"{source}_{datetime.now().strftime('%Y%m%d_%H%M%S')}_{parsed['report_hash'][:8]}.json"
    file_path = os.path.join(upload_dir, file_name)

    with open(file_path, "w") as f:
        json.dump(report_data or {}, f, indent=2)

    # Create evidence record with anti-fake-evidence classification
    evidence = EvidenceDB(
        id=str(uuid_module.uuid4()),
        control_id=control_db_id,
        evidence_type=f"ci_{source}",
        title=title,
        description=description,
        artifact_path=file_path,
        artifact_hash=parsed["report_hash"],
        file_size_bytes=len(parsed["report_json"]),
        mime_type="application/json",
        source="ci_pipeline",
        ci_job_id=ci_job_id,
        valid_from=datetime.utcnow(),
        valid_until=datetime.utcnow() + timedelta(days=90),
        status=EvidenceStatusEnum(parsed["evidence_status"]),
        # CI pipeline evidence → E3 observed (system-observed, hash-verified)
        confidence_level=EvidenceConfidenceEnum.E3,
        truth_status=EvidenceTruthStatusEnum.OBSERVED,
        may_be_used_as_evidence=True,
    )
    db.add(evidence)
    db.commit()
    db.refresh(evidence)

    return evidence


def _extract_findings_detail(report_data: dict) -> dict:
    """
    Extract severity-bucketed finding counts from report data.

    Returns dict with keys: critical, high, medium, low.
    """
    findings_detail = {
        "critical": 0,
        "high": 0,
        "medium": 0,
        "low": 0,
    }

    if not report_data:
        return findings_detail

    # Semgrep format
    if "results" in report_data:
        for r in report_data.get("results", []):
            severity = r.get("extra", {}).get("severity", "").upper()
            if severity == "CRITICAL":
                findings_detail["critical"] += 1
            elif severity == "HIGH":
                findings_detail["high"] += 1
            elif severity == "MEDIUM":
                findings_detail["medium"] += 1
            elif severity in ["LOW", "INFO"]:
                findings_detail["low"] += 1

    # Trivy format
    elif "Results" in report_data:
        for result in report_data.get("Results", []):
            for v in result.get("Vulnerabilities", []):
                severity = v.get("Severity", "").upper()
                if severity == "CRITICAL":
                    findings_detail["critical"] += 1
                elif severity == "HIGH":
                    findings_detail["high"] += 1
                elif severity == "MEDIUM":
                    findings_detail["medium"] += 1
                elif severity == "LOW":
                    findings_detail["low"] += 1

    # Generic findings with severity
    elif "findings" in report_data:
        for f in report_data.get("findings", []):
            severity = f.get("severity", "").upper()
            if severity == "CRITICAL":
                findings_detail["critical"] += 1
            elif severity == "HIGH":
                findings_detail["high"] += 1
            elif severity == "MEDIUM":
                findings_detail["medium"] += 1
            else:
                findings_detail["low"] += 1

    return findings_detail


def _update_risks(db: Session, *, source: str, control_id: str, ci_job_id: str, report_data: dict):
    """
    Update risk status based on new evidence.

    Uses AutoRiskUpdater to update Control status and linked Risks based on
    severity-bucketed findings.  Returns the update result or None on error.
    """
    findings_detail = _extract_findings_detail(report_data)

    try:
        auto_updater = AutoRiskUpdater(db)
        risk_update_result = auto_updater.process_evidence_collect_request(
            tool=source,
            control_id=control_id,
            evidence_type=f"ci_{source}",
            timestamp=datetime.utcnow().isoformat(),
            commit_sha=report_data.get("commit_sha", "unknown") if report_data else "unknown",
            ci_job_id=ci_job_id,
            findings=findings_detail,
        )


# ============================================================================
# CI/CD Evidence Collection
# ============================================================================

def _update_risks(
    db: Session,
    *,
    source: str,
    control_id: str,
    ci_job_id: Optional[str],
    report_data: Optional[dict[str, Any]],
) -> Any:
    """Thin wrapper so test patches against this module's _update_risks take effect."""
    return _update_risks_impl(
        db,
        source=source,
        control_id=control_id,
        ci_job_id=ci_job_id,
        report_data=report_data,
        auto_updater_cls=AutoRiskUpdater,
    )


@router.post("/evidence/collect")
async def collect_ci_evidence(
    source: str = Query(
        ...,
        description="Evidence source: sast, dependency_scan, sbom, container_scan, test_results",
    ),
    ci_job_id: Optional[str] = Query(None, description="CI/CD Job ID for traceability"),
    ci_job_url: Optional[str] = Query(None, description="URL to CI/CD job"),
    report_data: Optional[dict[str, Any]] = None,
    db: Session = Depends(get_db),
) -> dict[str, Any]:
    """
    Collect evidence from CI/CD pipeline.

    Handler stays inline so tests can patch
    ``compliance.api.evidence_routes._store_evidence`` /
    ``compliance.api.evidence_routes._update_risks`` directly.
    """
    if source not in SOURCE_CONTROL_MAP:
        raise HTTPException(
            status_code=400,
            detail=f"Unknown source '{source}'. Supported: {list(SOURCE_CONTROL_MAP.keys())}",
        )

    control_id = SOURCE_CONTROL_MAP[source]
    ctrl_repo = ControlRepository(db)
    control = ctrl_repo.get_by_control_id(control_id)
    if not control:
        raise HTTPException(
            status_code=404,
            detail=f"Control {control_id} not found. Please seed the database first.",
        )

    parsed = _parse_ci_evidence(report_data or {})
    evidence = _store_evidence(
        db,
        control_db_id=control.id,
        source=source,
        parsed=parsed,
        ci_job_id=ci_job_id,
        ci_job_url=ci_job_url,
        report_data=report_data,
    )
    risk_update_result = _update_risks(
        db,
        source=source,
        control_id=control_id,
        ci_job_id=ci_job_id,
        report_data=report_data,
    )

    return {
        "success": True,
        "evidence_id": evidence.id,
        "control_id": control_id,
        "source": source,
        "status": parsed["evidence_status"],
        "findings_count": parsed["findings_count"],
        "critical_findings": parsed["critical_findings"],
        "artifact_path": evidence.artifact_path,
        "message": f"Evidence collected successfully for control {control_id}",
        "auto_risk_update": (
            {
                "enabled": True,
                "control_updated": risk_update_result.control_updated,
                "old_status": risk_update_result.old_status,
                "new_status": risk_update_result.new_status,
                "risks_affected": risk_update_result.risks_affected,
                "alerts_generated": risk_update_result.alerts_generated,
            }
            if risk_update_result
            else {"enabled": False, "error": "Auto-update skipped"}
        ),
    }


@router.get("/evidence/ci-status")
async def get_ci_evidence_status(
    control_id: Optional[str] = Query(None, description="Filter by control ID"),
    days: int = Query(30, description="Look back N days"),
    service: EvidenceService = Depends(get_evidence_service),
) -> dict[str, Any]:
    """Get CI/CD evidence collection status overview."""
    with translate_domain_errors():
        return service.ci_status(control_id, days)


# ----------------------------------------------------------------------------
# Legacy re-exports for tests that import helpers directly.
# ----------------------------------------------------------------------------

    if control_id:
        ctrl_repo = ControlRepository(db)
        control = ctrl_repo.get_by_control_id(control_id)
        if control:
            query = query.filter(EvidenceDB.control_id == control.id)

    evidence_list = query.order_by(EvidenceDB.collected_at.desc()).limit(100).all()

    # Group by control and calculate stats
    control_stats = defaultdict(lambda: {
        "total": 0,
        "valid": 0,
        "failed": 0,
        "last_collected": None,
        "evidence": [],
    })

    for e in evidence_list:
        # Get control_id string
        control = db.query(ControlDB).filter(ControlDB.id == e.control_id).first()
        ctrl_id = control.control_id if control else "unknown"

        stats = control_stats[ctrl_id]
        stats["total"] += 1
        if e.status:
            if e.status.value == "valid":
                stats["valid"] += 1
            elif e.status.value == "failed":
                stats["failed"] += 1
        if not stats["last_collected"] or e.collected_at > stats["last_collected"]:
            stats["last_collected"] = e.collected_at

        # Add evidence summary
        stats["evidence"].append({
            "id": e.id,
            "type": e.evidence_type,
            "status": e.status.value if e.status else None,
            "collected_at": e.collected_at.isoformat() if e.collected_at else None,
            "ci_job_id": e.ci_job_id,
        })

    # Convert to list and sort
    result = []
    for ctrl_id, stats in control_stats.items():
        result.append({
            "control_id": ctrl_id,
            "total_evidence": stats["total"],
            "valid_count": stats["valid"],
            "failed_count": stats["failed"],
            "last_collected": stats["last_collected"].isoformat() if stats["last_collected"] else None,
            "recent_evidence": stats["evidence"][:5],
        })

    result.sort(key=lambda x: x["last_collected"] or "", reverse=True)

    return {
        "period_days": days,
        "total_evidence": len(evidence_list),
        "controls": result,
    }


# ============================================================================
# Evidence Review (Anti-Fake-Evidence)
# ============================================================================

from pydantic import BaseModel as _BaseModel

class _EvidenceReviewRequest(_BaseModel):
    confidence_level: Optional[str] = None
    truth_status: Optional[str] = None
    reviewed_by: str


@router.patch("/evidence/{evidence_id}/review", response_model=EvidenceResponse)
async def review_evidence(
    evidence_id: str,
    review: _EvidenceReviewRequest,
    db: Session = Depends(get_db),
):
    """
    Review evidence: upgrade confidence level and/or change truth status.

    For Four-Eyes evidence, the first reviewer sets first_reviewer and
    approval_status='first_approved'. A second (different) reviewer then
    sets second_reviewer and approval_status='approved'.
    """
    evidence = db.query(EvidenceDB).filter(EvidenceDB.id == evidence_id).first()
    if not evidence:
        raise HTTPException(status_code=404, detail=f"Evidence {evidence_id} not found")

    old_confidence = evidence.confidence_level.value if evidence.confidence_level else None
    old_truth = evidence.truth_status.value if evidence.truth_status else None

    if review.confidence_level:
        try:
            evidence.confidence_level = EvidenceConfidenceEnum(review.confidence_level)
        except ValueError:
            raise HTTPException(status_code=400, detail=f"Invalid confidence_level: {review.confidence_level}")

    if review.truth_status:
        try:
            evidence.truth_status = EvidenceTruthStatusEnum(review.truth_status)
        except ValueError:
            raise HTTPException(status_code=400, detail=f"Invalid truth_status: {review.truth_status}")

    # Four-Eyes branching
    if evidence.requires_four_eyes:
        status = evidence.approval_status or "none"
        if status in ("none", "pending_first"):
            evidence.first_reviewer = review.reviewed_by
            evidence.first_reviewed_at = datetime.utcnow()
            evidence.approval_status = "first_approved"
        elif status == "first_approved":
            if review.reviewed_by == evidence.first_reviewer:
                raise HTTPException(
                    status_code=400,
                    detail="Four-Eyes: second reviewer must be different from first reviewer",
                )
            evidence.second_reviewer = review.reviewed_by
            evidence.second_reviewed_at = datetime.utcnow()
            evidence.approval_status = "approved"
        elif status == "approved":
            raise HTTPException(status_code=400, detail="Evidence already approved")
        elif status == "rejected":
            raise HTTPException(status_code=400, detail="Evidence was rejected — create new evidence instead")

    evidence.reviewed_by = review.reviewed_by
    evidence.reviewed_at = datetime.utcnow()
    db.commit()

    # Audit trail
    new_confidence = evidence.confidence_level.value if evidence.confidence_level else None
    if old_confidence != new_confidence:
        log_audit_trail(
            db, "evidence", evidence_id, evidence.title, "review",
            performed_by=review.reviewed_by,
            field_changed="confidence_level",
            old_value=old_confidence,
            new_value=new_confidence,
        )
    new_truth = evidence.truth_status.value if evidence.truth_status else None
    if old_truth != new_truth:
        log_audit_trail(
            db, "evidence", evidence_id, evidence.title, "review",
            performed_by=review.reviewed_by,
            field_changed="truth_status",
            old_value=old_truth,
            new_value=new_truth,
        )
    db.commit()

    db.refresh(evidence)
    return _build_evidence_response(evidence)


@router.patch("/evidence/{evidence_id}/reject", response_model=EvidenceResponse)
async def reject_evidence(
    evidence_id: str,
    body: EvidenceRejectRequest,
    db: Session = Depends(get_db),
):
    """Reject evidence (sets approval_status='rejected')."""
    evidence = db.query(EvidenceDB).filter(EvidenceDB.id == evidence_id).first()
    if not evidence:
        raise HTTPException(status_code=404, detail=f"Evidence {evidence_id} not found")

    evidence.approval_status = "rejected"
    evidence.reviewed_by = body.reviewed_by
    evidence.reviewed_at = datetime.utcnow()
    db.commit()

    log_audit_trail(
        db, "evidence", evidence_id, evidence.title, "reject",
        performed_by=body.reviewed_by,
        change_summary=body.rejection_reason or "Evidence rejected",
    )
    db.commit()

    db.refresh(evidence)
    return _build_evidence_response(evidence)


# ============================================================================
# Audit Trail Query
# ============================================================================

@router.get("/audit-trail")
async def get_audit_trail(
    entity_type: Optional[str] = Query(None),
    entity_id: Optional[str] = Query(None),
    action: Optional[str] = Query(None),
    limit: int = Query(50, ge=1, le=200),
    db: Session = Depends(get_db),
):
    """Query audit trail entries for an entity."""
    query = db.query(AuditTrailDB)
    if entity_type:
        query = query.filter(AuditTrailDB.entity_type == entity_type)
    if entity_id:
        query = query.filter(AuditTrailDB.entity_id == entity_id)
    if action:
        query = query.filter(AuditTrailDB.action == action)

    records = query.order_by(AuditTrailDB.performed_at.desc()).limit(limit).all()

    return {
        "entries": [
            {
                "id": r.id,
                "entity_type": r.entity_type,
                "entity_id": r.entity_id,
                "entity_name": r.entity_name,
                "action": r.action,
                "field_changed": r.field_changed,
                "old_value": r.old_value,
                "new_value": r.new_value,
                "change_summary": r.change_summary,
                "performed_by": r.performed_by,
                "performed_at": r.performed_at.isoformat() if r.performed_at else None,
                "checksum": r.checksum,
            }
            for r in records
        ],
        "total": len(records),
    }