import base64
import re

from auth import require_auth
from database import events_collection
from fastapi import APIRouter, Depends, HTTPException, Query
from models.api import FilterOptionsResponse, PaginatedEventResponse

router = APIRouter(dependencies=[Depends(require_auth)])


def _encode_cursor(timestamp: str, oid: str) -> str:
    payload = f"{timestamp}|{oid}"
    return base64.b64encode(payload.encode()).decode()


def _decode_cursor(cursor: str) -> tuple[str, str]:
    try:
        payload = base64.b64decode(cursor.encode()).decode()
        timestamp, oid = payload.split("|", 1)
        return timestamp, oid
    except Exception as exc:
        raise HTTPException(status_code=400, detail="Invalid cursor") from exc


@router.get("/events", response_model=PaginatedEventResponse)
def list_events(
    service: str | None = None,
    actor: str | None = None,
    operation: str | None = None,
    result: str | None = None,
    start: str | None = None,
    end: str | None = None,
    search: str | None = None,
    cursor: str | None = None,
    page_size: int = Query(default=50, ge=1, le=500),
):
    filters = []

    if service:
        filters.append({"service": service})
    if actor:
        actor_safe = re.escape(actor)
        filters.append(
            {
                "$or": [
                    {"actor_display": {"$regex": actor_safe, "$options": "i"}},
                    {"actor_upn": {"$regex": actor_safe, "$options": "i"}},
                    {"actor.user.userPrincipalName": {"$regex": actor_safe, "$options": "i"}},
                    {"actor.user.id": actor},
                ]
            }
        )
    if operation:
        filters.append({"operation": {"$regex": re.escape(operation), "$options": "i"}})
    if result:
        filters.append({"result": {"$regex": re.escape(result), "$options": "i"}})
    if start or end:
        time_filter = {}
        if start:
            time_filter["$gte"] = start
        if end:
            time_filter["$lte"] = end
        filters.append({"timestamp": time_filter})
    if search:
        search_safe = re.escape(search)
        filters.append(
            {
                "$or": [
                    {"raw_text": {"$regex": search_safe, "$options": "i"}},
                    {"display_summary": {"$regex": search_safe, "$options": "i"}},
                    {"actor_display": {"$regex": search_safe, "$options": "i"}},
                    {"target_displays": {"$elemMatch": {"$regex": search_safe, "$options": "i"}}},
                    {"operation": {"$regex": search_safe, "$options": "i"}},
                ]
            }
        )

    if cursor:
        try:
            cursor_ts, cursor_oid = _decode_cursor(cursor)
        except HTTPException:
            raise
        filters.append(
            {
                "$or": [
                    {"timestamp": {"$lt": cursor_ts}},
                    {"timestamp": cursor_ts, "_id": {"$lt": cursor_oid}},
                ]
            }
        )

    query = {"$and": filters} if filters else {}

    safe_page_size = max(1, min(page_size, 500))

    try:
        total = events_collection.count_documents(query) if not cursor else -1
        cursor_query = (
            events_collection.find(query)
            .sort([("timestamp", -1), ("_id", -1)])
            .limit(safe_page_size)
        )
        events = list(cursor_query)
    except Exception as exc:
        raise HTTPException(status_code=500, detail=f"Failed to query events: {exc}") from exc

    next_cursor = None
    if len(events) == safe_page_size:
        last = events[-1]
        next_cursor = _encode_cursor(last["timestamp"], str(last["_id"]))

    for e in events:
        e["_id"] = str(e["_id"])
    return {
        "items": events,
        "total": total,
        "page_size": safe_page_size,
        "next_cursor": next_cursor,
    }


@router.get("/filter-options", response_model=FilterOptionsResponse)
def filter_options(limit: int = Query(default=200, ge=1, le=1000)):
    """
    Provide distinct values for UI filters (best-effort, capped).
    """
    safe_limit = max(1, min(limit, 1000))
    try:
        services = sorted(events_collection.distinct("service"))[:safe_limit]
        operations = sorted(events_collection.distinct("operation"))[:safe_limit]
        results = sorted([r for r in events_collection.distinct("result") if r])[:safe_limit]
        actors = sorted([a for a in events_collection.distinct("actor_display") if a])[:safe_limit]
        actor_upns = sorted([a for a in events_collection.distinct("actor_upn") if a])[:safe_limit]
        devices = sorted([a for a in events_collection.distinct("target_displays") if isinstance(a, str)])[:safe_limit]
    except Exception as exc:
        raise HTTPException(status_code=500, detail=f"Failed to load filter options: {exc}") from exc

    return {
        "services": services,
        "operations": operations,
        "results": results,
        "actors": actors,
        "actor_upns": actor_upns,
        "devices": devices,
    }