"""
FastAPI routes for Compliance Escalations.

Endpoints:
  GET    /escalations           — list with filters (status, priority, limit, offset)
  POST   /escalations           — create new escalation
  GET    /escalations/stats     — counts per status and priority
  GET    /escalations/{id}      — get single escalation
  PUT    /escalations/{id}      — update escalation
  PUT    /escalations/{id}/status — update status only
  DELETE /escalations/{id}      — delete escalation
"""

import logging
from datetime import datetime
from typing import Optional, List, Any, Dict

from fastapi import APIRouter, Depends, HTTPException, Query, Header
from pydantic import BaseModel
from sqlalchemy import text
from sqlalchemy.orm import Session

from classroom_engine.database import get_db

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/escalations", tags=["escalations"])


# =============================================================================
# Pydantic Schemas
# =============================================================================

class EscalationCreate(BaseModel):
    title: str
    description: Optional[str] = None
    priority: str = 'medium'  # low|medium|high|critical
    category: Optional[str] = None  # dsgvo_breach|ai_act|vendor|internal|other
    assignee: Optional[str] = None
    reporter: Optional[str] = None
    source_module: Optional[str] = None
    source_id: Optional[str] = None
    due_date: Optional[datetime] = None


class EscalationUpdate(BaseModel):
    title: Optional[str] = None
    description: Optional[str] = None
    priority: Optional[str] = None
    status: Optional[str] = None
    category: Optional[str] = None
    assignee: Optional[str] = None
    due_date: Optional[datetime] = None


class EscalationStatusUpdate(BaseModel):
    status: str
    resolved_at: Optional[datetime] = None


def _row_to_dict(row) -> Dict[str, Any]:
    """Convert a SQLAlchemy row to a serialisable dict."""
    result = dict(row._mapping)
    for key, val in result.items():
        if isinstance(val, datetime):
            result[key] = val.isoformat()
        elif hasattr(val, '__str__') and not isinstance(val, (str, int, float, bool, type(None))):
            result[key] = str(val)
    return result


# =============================================================================
# Routes
# =============================================================================

@router.get("")
async def list_escalations(
    status: Optional[str] = Query(None),
    priority: Optional[str] = Query(None),
    limit: int = Query(50, ge=1, le=500),
    offset: int = Query(0, ge=0),
    tenant_id: Optional[str] = Header(None, alias="x-tenant-id"),
    db: Session = Depends(get_db),
):
    """List escalations with optional filters."""
    tid = tenant_id or 'default'

    where_clauses = ["tenant_id = :tenant_id"]
    params: Dict[str, Any] = {"tenant_id": tid, "limit": limit, "offset": offset}

    if status:
        where_clauses.append("status = :status")
        params["status"] = status
    if priority:
        where_clauses.append("priority = :priority")
        params["priority"] = priority

    where_sql = " AND ".join(where_clauses)

    rows = db.execute(
        text(
            f"SELECT * FROM compliance_escalations WHERE {where_sql} "
            f"ORDER BY created_at DESC LIMIT :limit OFFSET :offset"
        ),
        params,
    ).fetchall()

    total_row = db.execute(
        text(f"SELECT COUNT(*) FROM compliance_escalations WHERE {where_sql}"),
        {k: v for k, v in params.items() if k not in ("limit", "offset")},
    ).fetchone()

    return {
        "items": [_row_to_dict(r) for r in rows],
        "total": total_row[0] if total_row else 0,
        "limit": limit,
        "offset": offset,
    }


@router.post("", status_code=201)
async def create_escalation(
    request: EscalationCreate,
    tenant_id: Optional[str] = Header(None, alias="x-tenant-id"),
    db: Session = Depends(get_db),
):
    """Create a new escalation."""
    tid = tenant_id or 'default'

    row = db.execute(
        text(
            """
            INSERT INTO compliance_escalations
                (tenant_id, title, description, priority, status, category,
                 assignee, reporter, source_module, source_id, due_date)
            VALUES
                (:tenant_id, :title, :description, :priority, 'open', :category,
                 :assignee, :reporter, :source_module, :source_id, :due_date)
            RETURNING *
            """
        ),
        {
            "tenant_id": tid,
            "title": request.title,
            "description": request.description,
            "priority": request.priority,
            "category": request.category,
            "assignee": request.assignee,
            "reporter": request.reporter,
            "source_module": request.source_module,
            "source_id": request.source_id,
            "due_date": request.due_date,
        },
    ).fetchone()

    db.commit()
    return _row_to_dict(row)


@router.get("/stats")
async def get_stats(
    tenant_id: Optional[str] = Header(None, alias="x-tenant-id"),
    db: Session = Depends(get_db),
):
    """Return counts per status and priority."""
    tid = tenant_id or 'default'

    status_rows = db.execute(
        text(
            "SELECT status, COUNT(*) as cnt FROM compliance_escalations "
            "WHERE tenant_id = :tenant_id GROUP BY status"
        ),
        {"tenant_id": tid},
    ).fetchall()

    priority_rows = db.execute(
        text(
            "SELECT priority, COUNT(*) as cnt FROM compliance_escalations "
            "WHERE tenant_id = :tenant_id GROUP BY priority"
        ),
        {"tenant_id": tid},
    ).fetchall()

    total_row = db.execute(
        text("SELECT COUNT(*) FROM compliance_escalations WHERE tenant_id = :tenant_id"),
        {"tenant_id": tid},
    ).fetchone()

    active_row = db.execute(
        text(
            "SELECT COUNT(*) FROM compliance_escalations "
            "WHERE tenant_id = :tenant_id AND status NOT IN ('resolved', 'closed')"
        ),
        {"tenant_id": tid},
    ).fetchone()

    by_status = {"open": 0, "in_progress": 0, "escalated": 0, "resolved": 0, "closed": 0}
    for r in status_rows:
        key = r[0] if r[0] in by_status else r[0]
        by_status[key] = r[1]

    by_priority = {"low": 0, "medium": 0, "high": 0, "critical": 0}
    for r in priority_rows:
        if r[0] in by_priority:
            by_priority[r[0]] = r[1]

    return {
        "by_status": by_status,
        "by_priority": by_priority,
        "total": total_row[0] if total_row else 0,
        "active": active_row[0] if active_row else 0,
    }


@router.get("/{escalation_id}")
async def get_escalation(
    escalation_id: str,
    tenant_id: Optional[str] = Header(None, alias="x-tenant-id"),
    db: Session = Depends(get_db),
):
    """Get a single escalation by ID."""
    tid = tenant_id or 'default'
    row = db.execute(
        text(
            "SELECT * FROM compliance_escalations "
            "WHERE id = :id AND tenant_id = :tenant_id"
        ),
        {"id": escalation_id, "tenant_id": tid},
    ).fetchone()
    if not row:
        raise HTTPException(status_code=404, detail=f"Escalation {escalation_id} not found")
    return _row_to_dict(row)


@router.put("/{escalation_id}")
async def update_escalation(
    escalation_id: str,
    request: EscalationUpdate,
    tenant_id: Optional[str] = Header(None, alias="x-tenant-id"),
    db: Session = Depends(get_db),
):
    """Update an escalation's fields."""
    tid = tenant_id or 'default'

    existing = db.execute(
        text(
            "SELECT id FROM compliance_escalations "
            "WHERE id = :id AND tenant_id = :tenant_id"
        ),
        {"id": escalation_id, "tenant_id": tid},
    ).fetchone()
    if not existing:
        raise HTTPException(status_code=404, detail=f"Escalation {escalation_id} not found")

    updates = request.dict(exclude_none=True)
    if not updates:
        row = db.execute(
            text("SELECT * FROM compliance_escalations WHERE id = :id"),
            {"id": escalation_id},
        ).fetchone()
        return _row_to_dict(row)

    set_clauses = ", ".join(f"{k} = :{k}" for k in updates.keys())
    updates["id"] = escalation_id
    updates["updated_at"] = datetime.utcnow()

    row = db.execute(
        text(
            f"UPDATE compliance_escalations SET {set_clauses}, updated_at = :updated_at "
            f"WHERE id = :id RETURNING *"
        ),
        updates,
    ).fetchone()
    db.commit()
    return _row_to_dict(row)


@router.put("/{escalation_id}/status")
async def update_status(
    escalation_id: str,
    request: EscalationStatusUpdate,
    tenant_id: Optional[str] = Header(None, alias="x-tenant-id"),
    db: Session = Depends(get_db),
):
    """Update only the status of an escalation."""
    tid = tenant_id or 'default'

    existing = db.execute(
        text(
            "SELECT id FROM compliance_escalations "
            "WHERE id = :id AND tenant_id = :tenant_id"
        ),
        {"id": escalation_id, "tenant_id": tid},
    ).fetchone()
    if not existing:
        raise HTTPException(status_code=404, detail=f"Escalation {escalation_id} not found")

    resolved_at = request.resolved_at
    if request.status in ('resolved', 'closed') and resolved_at is None:
        resolved_at = datetime.utcnow()

    row = db.execute(
        text(
            "UPDATE compliance_escalations "
            "SET status = :status, resolved_at = :resolved_at, updated_at = :updated_at "
            "WHERE id = :id RETURNING *"
        ),
        {
            "status": request.status,
            "resolved_at": resolved_at,
            "updated_at": datetime.utcnow(),
            "id": escalation_id,
        },
    ).fetchone()
    db.commit()
    return _row_to_dict(row)


@router.delete("/{escalation_id}")
async def delete_escalation(
    escalation_id: str,
    tenant_id: Optional[str] = Header(None, alias="x-tenant-id"),
    db: Session = Depends(get_db),
):
    """Delete an escalation."""
    tid = tenant_id or 'default'

    existing = db.execute(
        text(
            "SELECT id FROM compliance_escalations "
            "WHERE id = :id AND tenant_id = :tenant_id"
        ),
        {"id": escalation_id, "tenant_id": tid},
    ).fetchone()
    if not existing:
        raise HTTPException(status_code=404, detail=f"Escalation {escalation_id} not found")

    db.execute(
        text("DELETE FROM compliance_escalations WHERE id = :id"),
        {"id": escalation_id},
    )
    db.commit()
    return {"success": True, "message": f"Escalation {escalation_id} deleted"}