"""Compliance routes — AI registry, DPIA template, incident register, retention policies.

All endpoints are admin-only (require_permission('system:admin')).
"""

from __future__ import annotations

import uuid
from datetime import UTC, datetime
from typing import Any

from fastapi import APIRouter, Depends, HTTPException, Query
from pydantic import BaseModel, Field
from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from app.ai.ai_use_case import AIUseCaseMetadata, validate_ai_use_case
from app.core.db import get_db
from app.deps import require_permission
from app.models.audit import AuditLog
from app.models.compliance import ComplianceIncident
from app.plugins.builtins.automation.models import AgentDefinition

router = APIRouter(prefix="/api/v1/compliance", tags=["compliance"])


# ─── Schemas ───


class AIRegistryEntry(BaseModel):
    agent_id: str
    name: str
    description: str
    is_active: bool
    llm_model: str
    ai_use_case_metadata: dict[str, Any]
    validation_warnings: list[str]


class AIRegistryResponse(BaseModel):
    items: list[AIRegistryEntry]
    total: int


class DPIATemplateSection(BaseModel):
    section: str
    content: str | dict[str, Any] | list[Any]


class DPIATemplateResponse(BaseModel):
    use_case_id: str
    agent_name: str
    intended_purpose: str
    owner: str
    risk_class: str
    oversight_policy: str
    data_categories: list[str]
    allowed_providers: list[str]
    allowed_models: list[str]
    allowed_actions: list[str]
    human_review_required: bool
    validation_warnings: list[str]
    disclaimer: str


class IncidentCreate(BaseModel):
    incident_type: str = Field(default="ai", max_length=30)
    title: str = Field(max_length=300)
    description: str = Field(default="", max_length=5000)
    affected_use_cases: list[str] = Field(default_factory=list)
    affected_versions: list[str] = Field(default_factory=list)
    provider: str = Field(default="", max_length=100)
    measures_taken: str = Field(default="", max_length=5000)
    evidence_refs: list[str] = Field(default_factory=list)
    status: str = Field(default="open", max_length=20)


class IncidentUpdate(BaseModel):
    title: str | None = None
    description: str | None = None
    incident_type: str | None = None
    affected_use_cases: list[str] | None = None
    affected_versions: list[str] | None = None
    provider: str | None = None
    measures_taken: str | None = None
    evidence_refs: list[str] | None = None
    status: str | None = None


class IncidentResponse(BaseModel):
    id: str
    incident_type: str
    title: str
    description: str
    affected_use_cases: list[Any]
    affected_versions: list[Any]
    provider: str
    measures_taken: str
    evidence_refs: list[Any]
    status: str
    created_by: str | None
    resolved_by: str | None
    resolved_at: str | None
    created_at: str | None
    updated_at: str | None


class RetentionPolicyEntry(BaseModel):
    key: str
    label: str
    description: str
    default_days: int
    current_days: int
    editable: bool


class RetentionPolicyUpdate(BaseModel):
    days: int = Field(ge=1, le=3650)


# ─── Helpers ───


_VALID_INCIDENT_TYPES = {"ai", "privacy", "security"}
_VALID_INCIDENT_STATUS = {"open", "resolved", "closed"}


def _incident_to_dict(c: ComplianceIncident) -> dict:
    return {
        "id": str(c.id),
        "incident_type": c.incident_type,
        "title": c.title,
        "description": c.description,
        "affected_use_cases": c.affected_use_cases or [],
        "affected_versions": c.affected_versions or [],
        "provider": c.provider,
        "measures_taken": c.measures_taken,
        "evidence_refs": c.evidence_refs or [],
        "status": c.status,
        "created_by": str(c.created_by) if c.created_by else None,
        "resolved_by": str(c.resolved_by) if c.resolved_by else None,
        "resolved_at": c.resolved_at.isoformat() if c.resolved_at else None,
        "created_at": c.created_at.isoformat() if c.created_at else None,
        "updated_at": c.updated_at.isoformat() if c.updated_at else None,
    }


# ─── K-REG: AI System / Use-Case Register ───


@router.get(
    "/ai-registry",
    response_model=AIRegistryResponse,
    dependencies=[Depends(require_permission("system:admin"))],
)
async def list_ai_registry(
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("system:admin")),
):
    """List all AI agents with their use-case metadata. Admin only."""
    tenant_id = uuid.UUID(current_user["tenant_id"])

    q = (
        select(AgentDefinition)
        .where(
            AgentDefinition.tenant_id == tenant_id,
            AgentDefinition.deleted_at.is_(None),
        )
        .order_by(AgentDefinition.name)
    )
    result = await db.execute(q)
    agents = result.scalars().all()

    items: list[AIRegistryEntry] = []
    for a in agents:
        metadata = AIUseCaseMetadata.from_dict(a.ai_use_case_metadata or {})
        warnings = validate_ai_use_case(metadata, a)
        items.append(
            AIRegistryEntry(
                agent_id=str(a.id),
                name=a.name,
                description=a.description or "",
                is_active=a.is_active,
                llm_model=a.llm_model,
                ai_use_case_metadata=metadata.to_dict(),
                validation_warnings=warnings,
            )
        )

    return AIRegistryResponse(items=items, total=len(items))


# ─── K-DPIA: DPIA / AI Impact Template ───


@router.get(
    "/dpia-template",
    response_model=DPIATemplateResponse,
    dependencies=[Depends(require_permission("system:admin"))],
)
async def get_dpia_template(
    agent_id: str = Query(..., description="Agent ID to generate DPIA template for"),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("system:admin")),
):
    """Generate a pre-filled DPIA template from an agent's ai_use_case_metadata.

    This is a structured data export — no automatic legal assessment.
    """
    tenant_id = uuid.UUID(current_user["tenant_id"])

    try:
        aid = uuid.UUID(agent_id)
    except ValueError:
        raise HTTPException(400, detail={"detail": "Invalid agent_id", "code": "invalid_id"}) from None

    q = select(AgentDefinition).where(
        AgentDefinition.id == aid,
        AgentDefinition.tenant_id == tenant_id,
        AgentDefinition.deleted_at.is_(None),
    )
    result = await db.execute(q)
    agent = result.scalar_one_or_none()
    if agent is None:
        raise HTTPException(404, detail={"detail": "Agent not found", "code": "not_found"})

    metadata = AIUseCaseMetadata.from_dict(agent.ai_use_case_metadata or {})
    warnings = validate_ai_use_case(metadata, agent)

    return DPIATemplateResponse(
        use_case_id=str(agent.id),
        agent_name=agent.name,
        intended_purpose=metadata.intended_purpose,
        owner=metadata.owner,
        risk_class=metadata.risk_class,
        oversight_policy=metadata.oversight_policy,
        data_categories=metadata.data_categories,
        allowed_providers=metadata.allowed_providers,
        allowed_models=metadata.allowed_models,
        allowed_actions=metadata.allowed_actions,
        human_review_required=metadata.human_review_required,
        validation_warnings=warnings,
        disclaimer=(
            "This template is a structured data export from the platform's AI use-case metadata. "
            "It does NOT constitute a legal assessment or legal advice. "
            "A qualified DPO or legal counsel must review and complete the DPIA."
        ),
    )


# ─── K-INC: AI/Privacy Incident Register ───


@router.get(
    "/incidents",
    dependencies=[Depends(require_permission("system:admin"))],
)
async def list_incidents(
    status: str | None = Query(None),
    incident_type: str | None = Query(None),
    limit: int = Query(50, ge=1, le=200),
    offset: int = Query(0, ge=0),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("system:admin")),
):
    """List compliance incidents. Admin only."""
    tenant_id = uuid.UUID(current_user["tenant_id"])

    q = select(ComplianceIncident).where(
        ComplianceIncident.tenant_id == tenant_id,
        ComplianceIncident.deleted_at.is_(None),
    )
    if status:
        q = q.where(ComplianceIncident.status == status)
    if incident_type:
        q = q.where(ComplianceIncident.incident_type == incident_type)

    count_q = select(func.count()).select_from(q.subquery())
    total = (await db.execute(count_q)).scalar() or 0

    q = q.order_by(ComplianceIncident.created_at.desc()).offset(offset).limit(limit)
    result = await db.execute(q)
    incidents = result.scalars().all()

    return {"items": [_incident_to_dict(c) for c in incidents], "total": total}


@router.post(
    "/incidents",
    status_code=201,
    dependencies=[Depends(require_permission("system:admin"))],
)
async def create_incident(
    body: IncidentCreate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("system:admin")),
):
    """Create a compliance incident. Admin only."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    if body.incident_type not in _VALID_INCIDENT_TYPES:
        raise HTTPException(400, detail={"detail": f"Invalid incident_type. Must be one of {_VALID_INCIDENT_TYPES}", "code": "invalid_type"})
    if body.status not in _VALID_INCIDENT_STATUS:
        raise HTTPException(400, detail={"detail": f"Invalid status. Must be one of {_VALID_INCIDENT_STATUS}", "code": "invalid_status"})

    incident = ComplianceIncident(
        tenant_id=tenant_id,
        incident_type=body.incident_type,
        title=body.title,
        description=body.description,
        affected_use_cases=body.affected_use_cases,
        affected_versions=body.affected_versions,
        provider=body.provider,
        measures_taken=body.measures_taken,
        evidence_refs=body.evidence_refs,
        status=body.status,
        created_by=user_id,
    )
    db.add(incident)
    await db.flush()

    # Audit log
    audit = AuditLog(
        tenant_id=tenant_id,
        user_id=user_id,
        action="create",
        entity_type="compliance_incident",
        entity_id=incident.id,
        changes={"title": body.title, "incident_type": body.incident_type, "status": body.status},
    )
    db.add(audit)
    await db.flush()
    result = _incident_to_dict(incident)
    await db.commit()
    return result


@router.patch(
    "/incidents/{incident_id}",
    dependencies=[Depends(require_permission("system:admin"))],
)
async def update_incident(
    incident_id: str,
    body: IncidentUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("system:admin")),
):
    """Update a compliance incident. Admin only."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    try:
        iid = uuid.UUID(incident_id)
    except ValueError:
        raise HTTPException(400, detail={"detail": "Invalid incident_id", "code": "invalid_id"}) from None

    q = select(ComplianceIncident).where(
        ComplianceIncident.id == iid,
        ComplianceIncident.tenant_id == tenant_id,
        ComplianceIncident.deleted_at.is_(None),
    )
    result = await db.execute(q)
    incident = result.scalar_one_or_none()
    if incident is None:
        raise HTTPException(404, detail={"detail": "Incident not found", "code": "not_found"})

    changes: dict[str, Any] = {}
    update_data = body.model_dump(exclude_unset=True)

    if "incident_type" in update_data and update_data["incident_type"] not in _VALID_INCIDENT_TYPES:
        raise HTTPException(400, detail={"detail": f"Invalid incident_type. Must be one of {_VALID_INCIDENT_TYPES}", "code": "invalid_type"})
    if "status" in update_data and update_data["status"] not in _VALID_INCIDENT_STATUS:
        raise HTTPException(400, detail={"detail": f"Invalid status. Must be one of {_VALID_INCIDENT_STATUS}", "code": "invalid_status"})

    for field, value in update_data.items():
        old_val = getattr(incident, field)
        setattr(incident, field, value)
        changes[field] = {"old": old_val, "new": value}

    # If status changed to resolved/closed, set resolved_by and resolved_at
    if update_data.get("status") in ("resolved", "closed") and incident.resolved_at is None:
        incident.resolved_by = user_id
        incident.resolved_at = datetime.now(UTC)
        changes["resolved_by"] = {"old": None, "new": str(user_id)}
        changes["resolved_at"] = {"old": None, "new": incident.resolved_at.isoformat()}

    # Audit log
    audit = AuditLog(
        tenant_id=tenant_id,
        user_id=user_id,
        action="update",
        entity_type="compliance_incident",
        entity_id=incident.id,
        changes=changes,
    )
    db.add(audit)
    await db.commit()
    await db.refresh(incident)

    return _incident_to_dict(incident)


# ─── K-RET: Retention Policies ───


_DEFAULT_RETENTION_POLICIES = [
    {"key": "audit_log", "label": "Audit Log", "description": "How long audit log entries are kept before automatic deletion", "default_days": 365, "editable": True},
    {"key": "backup", "label": "Backup Retention", "description": "How long backup files are retained before cleanup", "default_days": 7, "editable": True},
    {"key": "trash", "label": "Trash / Soft-Delete", "description": "How long soft-deleted records remain before permanent removal", "default_days": 30, "editable": True},
    {"key": "knowledge", "label": "Knowledge Base", "description": "Retention for knowledge base articles and extractions", "default_days": 365, "editable": True},
    {"key": "agent_memory", "label": "Agent Memory", "description": "How long AI agent memory embeddings are retained", "default_days": 90, "editable": True},
]


@router.get(
    "/retention-policies",
    dependencies=[Depends(require_permission("system:admin"))],
)
async def list_retention_policies(
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("system:admin")),
):
    """List all retention policies with their current configured days. Admin only."""
    tenant_id = uuid.UUID(current_user["tenant_id"])

    # Read current values from system_settings.retention_config JSONB
    from app.models.system_settings import SystemSettings

    q = select(SystemSettings).where(
        SystemSettings.tenant_id == tenant_id,
        SystemSettings.deleted_at.is_(None),
    )
    result = await db.execute(q)
    settings = result.scalar_one_or_none()
    retention_config = (settings.retention_config if settings and settings.retention_config else {}) or {}

    items: list[RetentionPolicyEntry] = []
    for policy in _DEFAULT_RETENTION_POLICIES:
        key = policy["key"]
        current_days = retention_config.get(key, policy["default_days"])
        items.append(
            RetentionPolicyEntry(
                key=key,
                label=policy["label"],
                description=policy["description"],
                default_days=policy["default_days"],
                current_days=int(current_days),
                editable=policy["editable"],
            )
        )

    return {"items": items, "total": len(items)}


@router.patch(
    "/retention-policies/{key}",
    dependencies=[Depends(require_permission("system:admin"))],
)
async def update_retention_policy(
    key: str,
    body: RetentionPolicyUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("system:admin")),
):
    """Update a retention policy's days value. Admin only."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    valid_keys = {p["key"] for p in _DEFAULT_RETENTION_POLICIES}
    if key not in valid_keys:
        raise HTTPException(400, detail={"detail": f"Invalid retention policy key. Must be one of {valid_keys}", "code": "invalid_key"})

    from app.models.system_settings import SystemSettings

    q = select(SystemSettings).where(
        SystemSettings.tenant_id == tenant_id,
        SystemSettings.deleted_at.is_(None),
    )
    result = await db.execute(q)
    settings = result.scalar_one_or_none()
    if settings is None:
        raise HTTPException(404, detail={"detail": "System settings not found. Configure company settings first.", "code": "settings_not_found"})

    retention_config = settings.retention_config or {}
    old_days = retention_config.get(key)
    retention_config[key] = body.days
    settings.retention_config = retention_config

    # Audit log
    audit = AuditLog(
        tenant_id=tenant_id,
        user_id=user_id,
        action="update",
        entity_type="retention_policy",
        entity_id=None,
        changes={"key": key, "old_days": old_days, "new_days": body.days},
    )
    db.add(audit)
    await db.commit()

    return {"key": key, "days": body.days, "message": "Retention policy updated"}