from __future__ import annotations
from datetime import datetime, timezone
from uuid import UUID

from fastapi import APIRouter, Depends, HTTPException, Request as FastapiRequest
from sqlalchemy import func
from sqlalchemy.orm import Session

from app.core.deps import get_public_session
from app.db.session import get_db
from app.models.attachment import Attachment
from app.models.message import Message
from app.models.request import Request
from app.models.request_data_requirement import RequestDataRequirement
from app.schemas.public import PublicMessageCreate
from app.services.chat_presence import list_typing_presence, set_typing_presence
from app.services.notifications import EVENT_REQUEST_DATA as NOTIFICATION_EVENT_REQUEST_DATA, notify_request_event, unread_client_summary
from app.services.chat_secure_service import (
    DEFAULT_CHAT_WINDOW_LIMIT,
    clamp_chat_window_limit,
    create_client_message,
    get_chat_activity_summary,
    list_messages_for_request_window,
    list_messages_for_request,
    mark_messages_delivered_for_client,
    mark_messages_read_for_client,
    serialize_message,
    serialize_messages_for_request,
)
from app.services.request_read_markers import EVENT_REQUEST_DATA, mark_unread_for_lawyer
from app.services.origin_guard import enforce_public_origin_or_403
from app.services.security_audit import extract_client_ip, record_pii_access_event

router = APIRouter()


def _parse_cursor(raw: str | None) -> datetime | None:
    value = str(raw or "").strip()
    if not value:
        return None
    normalized = value.replace("Z", "+00:00")
    try:
        dt = datetime.fromisoformat(normalized)
    except ValueError:
        return None
    if dt.tzinfo is None:
        return dt.replace(tzinfo=timezone.utc)
    return dt.astimezone(timezone.utc)


def _iso_or_none(dt: datetime | None) -> str | None:
    if dt is None:
        return None
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=timezone.utc)
    else:
        dt = dt.astimezone(timezone.utc)
    return dt.isoformat()


def _as_utc_datetime(value) -> datetime | None:
    if value is None:
        return None
    if isinstance(value, datetime):
        if value.tzinfo is None:
            return value.replace(tzinfo=timezone.utc)
        return value.astimezone(timezone.utc)
    if isinstance(value, str):
        return _parse_cursor(value)
    return None


def _attachment_meta_for_public(req: Request, value_text: str | None, db: Session) -> dict | None:
    raw = str(value_text or "").strip()
    if not raw:
        return None
    try:
        attachment_uuid = UUID(raw)
    except ValueError:
        return None
    attachment = db.get(Attachment, attachment_uuid)
    if attachment is None or attachment.request_id != req.id:
        return None
    return {
        "attachment_id": str(attachment.id),
        "file_name": attachment.file_name,
        "mime_type": attachment.mime_type,
        "size_bytes": int(attachment.size_bytes or 0),
        "download_url": f"/api/public/uploads/object/{attachment.id}",
    }


def _serialize_public_attachment(row: Attachment) -> dict:
    return {
        "id": str(row.id),
        "request_id": str(row.request_id),
        "message_id": str(row.message_id) if row.message_id else None,
        "file_name": row.file_name,
        "mime_type": row.mime_type,
        "size_bytes": int(row.size_bytes or 0),
        "created_at": _iso_or_none(row.created_at),
        "download_url": f"/api/public/uploads/object/{row.id}",
    }


def _normalize_phone(raw: str | None) -> str:
    value = str(raw or "").strip()
    if not value:
        return ""
    allowed = {"+", "(", ")", "-", " "}
    return "".join(ch for ch in value if ch.isdigit() or ch in allowed).strip()


def _normalize_track(raw: str | None) -> str:
    return str(raw or "").strip().upper()


def _require_view_session_or_403(session: dict) -> str:
    purpose = str(session.get("purpose") or "").strip().upper()
    subject = str(session.get("sub") or "").strip()
    if purpose != "VIEW_REQUEST" or not subject:
        raise HTTPException(status_code=403, detail="Нет доступа к заявке")
    return subject


def _public_actor_subject(session: dict) -> str:
    subject = _require_view_session_or_403(session)
    normalized_track = _normalize_track(subject)
    if normalized_track.startswith("TRK-"):
        return normalized_track
    normalized_phone = _normalize_phone(subject)
    return normalized_phone or subject


def _audit_public_chat_read(
    db: Session,
    *,
    session: dict,
    http_request: FastapiRequest,
    req: Request,
    action: str,
    details: dict | None = None,
) -> None:
    record_pii_access_event(
        db,
        actor_role="CLIENT",
        actor_subject=_public_actor_subject(session),
        actor_ip=extract_client_ip(http_request),
        action=action,
        scope="CHAT",
        request_id=req.id,
        details=details or {},
        responsible="Клиент",
        persist_now=True,
    )


def _request_for_track_or_404(db: Session, track_number: str) -> Request:
    req = db.query(Request).filter(Request.track_number == _normalize_track(track_number)).first()
    if req is None:
        raise HTTPException(status_code=404, detail="Заявка не найдена")
    return req


def _ensure_view_access_or_403(session: dict, req: Request) -> None:
    subject = _require_view_session_or_403(session)
    subject_track = _normalize_track(subject)
    if subject_track.startswith("TRK-") and subject_track != _normalize_track(req.track_number):
        raise HTTPException(status_code=404, detail="Заявка не найдена")
    if subject_track == _normalize_track(req.track_number):
        return
    if _normalize_phone(subject) and _normalize_phone(subject) == _normalize_phone(req.client_phone):
        return
    # Return 404 to avoid exposing existence of чужой заявки.
    raise HTTPException(status_code=404, detail="Заявка не найдена")


@router.get("/requests/{track_number}/messages")
def list_messages_by_track(
    track_number: str,
    http_request: FastapiRequest,
    db: Session = Depends(get_db),
    session: dict = Depends(get_public_session),
):
    req = _request_for_track_or_404(db, track_number)
    _ensure_view_access_or_403(session, req)
    mark_messages_read_for_client(db, request_id=req.id)
    rows = list_messages_for_request(db, req.id)
    payload = serialize_messages_for_request(db, req.id, rows)
    _audit_public_chat_read(
        db,
        session=session,
        http_request=http_request,
        req=req,
        action="READ_CHAT_MESSAGES",
        details={"rows": len(rows)},
    )
    return payload


@router.get("/requests/{track_number}/messages-window")
def list_messages_window_by_track(
    track_number: str,
    http_request: FastapiRequest,
    before_count: int = 0,
    limit: int = DEFAULT_CHAT_WINDOW_LIMIT,
    db: Session = Depends(get_db),
    session: dict = Depends(get_public_session),
):
    req = _request_for_track_or_404(db, track_number)
    _ensure_view_access_or_403(session, req)
    mark_messages_read_for_client(db, request_id=req.id)
    rows, total, has_more, loaded_count = list_messages_for_request_window(
        db,
        req.id,
        limit=limit,
        before_count=before_count,
    )
    payload = {
        "rows": serialize_messages_for_request(db, req.id, rows),
        "total": total,
        "has_more": has_more,
        "loaded_count": loaded_count,
        "limit": clamp_chat_window_limit(limit),
    }
    _audit_public_chat_read(
        db,
        session=session,
        http_request=http_request,
        req=req,
        action="READ_CHAT_MESSAGES",
        details={"rows": len(rows), "window": True},
    )
    return payload


@router.post("/requests/{track_number}/messages", status_code=201)
def create_message_by_track(
    track_number: str,
    payload: PublicMessageCreate,
    http_request: FastapiRequest,
    db: Session = Depends(get_db),
    session: dict = Depends(get_public_session),
):
    enforce_public_origin_or_403(http_request, endpoint="/api/public/chat/requests/{track_number}/messages")
    req = _request_for_track_or_404(db, track_number)
    _ensure_view_access_or_403(session, req)
    row = create_client_message(db, request=req, body=payload.body)
    return serialize_message(row)


@router.get("/requests/{track_number}/live")
def get_live_chat_state_by_track(
    track_number: str,
    http_request: FastapiRequest,
    cursor: str | None = None,
    db: Session = Depends(get_db),
    session: dict = Depends(get_public_session),
):
    req = _request_for_track_or_404(db, track_number)
    _ensure_view_access_or_403(session, req)
    mark_messages_delivered_for_client(db, request_id=req.id)
    summary = get_chat_activity_summary(db, req.id)
    latest_activity_at = _as_utc_datetime(summary.get("latest_activity_at"))
    latest_activity_iso = _iso_or_none(latest_activity_at)
    cursor_dt = _parse_cursor(cursor)
    has_updates = bool(latest_activity_at and (cursor_dt is None or latest_activity_at > cursor_dt))
    delta_messages = []
    delta_attachments = []
    if has_updates and cursor_dt is not None:
        message_rows = (
            db.query(Message)
            .filter(
                Message.request_id == req.id,
                func.coalesce(Message.updated_at, Message.created_at) > cursor_dt,
            )
            .order_by(Message.created_at.asc(), Message.id.asc())
            .all()
        )
        attachment_rows = (
            db.query(Attachment)
            .filter(
                Attachment.request_id == req.id,
                func.coalesce(Attachment.updated_at, Attachment.created_at) > cursor_dt,
            )
            .order_by(Attachment.created_at.asc(), Attachment.id.asc())
            .all()
        )
        delta_messages = serialize_messages_for_request(db, req.id, message_rows)
        delta_attachments = [_serialize_public_attachment(row) for row in attachment_rows]

    subject = _require_view_session_or_403(session)
    actor_key = f"CLIENT:{_normalize_track(subject) or _normalize_phone(subject)}"
    typing_rows = list_typing_presence(request_key=str(req.id), exclude_actor_key=actor_key)
    payload = {
        "track_number": req.track_number,
        "cursor": latest_activity_iso,
        "has_updates": has_updates,
        "message_count": int(summary.get("message_count") or 0),
        "attachment_count": int(summary.get("attachment_count") or 0),
        "latest_message_at": _iso_or_none(_as_utc_datetime(summary.get("latest_message_at"))),
        "latest_attachment_at": _iso_or_none(_as_utc_datetime(summary.get("latest_attachment_at"))),
        "messages": delta_messages,
        "attachments": delta_attachments,
        "typing": typing_rows,
        "unread": unread_client_summary(
            db,
            track_number=req.track_number,
            request_id=req.id,
        ),
    }
    _audit_public_chat_read(
        db,
        session=session,
        http_request=http_request,
        req=req,
        action="READ_CHAT_LIVE_STATE",
        details={"has_updates": bool(has_updates)},
    )
    return payload


@router.post("/requests/{track_number}/typing")
def set_live_chat_typing_by_track(
    track_number: str,
    payload: dict,
    http_request: FastapiRequest,
    db: Session = Depends(get_db),
    session: dict = Depends(get_public_session),
):
    enforce_public_origin_or_403(http_request, endpoint="/api/public/chat/requests/{track_number}/typing")
    req = _request_for_track_or_404(db, track_number)
    _ensure_view_access_or_403(session, req)
    subject = _require_view_session_or_403(session)
    typing = bool((payload or {}).get("typing"))
    actor_key = f"CLIENT:{_normalize_track(subject) or _normalize_phone(subject)}"
    set_typing_presence(
        request_key=str(req.id),
        actor_key=actor_key,
        actor_label=str(req.client_name or "Клиент"),
        actor_role="CLIENT",
        typing=typing,
    )
    return {"status": "ok", "typing": typing}


@router.get("/requests/{track_number}/data-requests/{message_id}")
def get_data_request_by_message(
    track_number: str,
    message_id: str,
    http_request: FastapiRequest,
    db: Session = Depends(get_db),
    session: dict = Depends(get_public_session),
):
    req = _request_for_track_or_404(db, track_number)
    _ensure_view_access_or_403(session, req)
    try:
        message_uuid = UUID(str(message_id))
    except ValueError:
        raise HTTPException(status_code=400, detail="Некорректный идентификатор сообщения")
    message = db.get(Message, message_uuid)
    if message is None or message.request_id != req.id:
        raise HTTPException(status_code=404, detail="Сообщение запроса не найдено")
    rows = (
        db.query(RequestDataRequirement)
        .filter(
            RequestDataRequirement.request_id == req.id,
            RequestDataRequirement.request_message_id == message_uuid,
        )
        .order_by(RequestDataRequirement.sort_order.asc(), RequestDataRequirement.created_at.asc(), RequestDataRequirement.id.asc())
        .all()
    )
    if not rows:
        raise HTTPException(status_code=404, detail="Запрос данных не найден")
    payload = {
        "message_id": str(message.id),
        "request_id": str(req.id),
        "track_number": req.track_number,
        "items": [
            {
                "id": str(row.id),
                "key": row.key,
                "label": row.label,
                "field_type": str(row.field_type or "text"),
                "value_text": row.value_text,
                "value_file": _attachment_meta_for_public(req, row.value_text, db) if str(row.field_type or "").lower() == "file" else None,
                "is_filled": bool(str(row.value_text or "").strip()),
                "sort_order": int(row.sort_order or 0),
            }
            for row in rows
        ],
    }
    _audit_public_chat_read(
        db,
        session=session,
        http_request=http_request,
        req=req,
        action="READ_CHAT_DATA_REQUEST",
        details={"message_id": str(message.id), "rows": len(rows)},
    )
    return payload


@router.post("/requests/{track_number}/data-requests/{message_id}")
def save_data_request_values(
    track_number: str,
    message_id: str,
    payload: dict,
    http_request: FastapiRequest,
    db: Session = Depends(get_db),
    session: dict = Depends(get_public_session),
):
    enforce_public_origin_or_403(
        http_request,
        endpoint="/api/public/chat/requests/{track_number}/data-requests/{message_id}",
    )
    req = _request_for_track_or_404(db, track_number)
    _ensure_view_access_or_403(session, req)
    try:
        message_uuid = UUID(str(message_id))
    except ValueError:
        raise HTTPException(status_code=400, detail="Некорректный идентификатор сообщения")
    message = db.get(Message, message_uuid)
    if message is None or message.request_id != req.id:
        raise HTTPException(status_code=404, detail="Сообщение запроса не найдено")

    raw_items = (payload or {}).get("items")
    if not isinstance(raw_items, list):
        raise HTTPException(status_code=400, detail="Ожидается список items")

    rows = (
        db.query(RequestDataRequirement)
        .filter(
            RequestDataRequirement.request_id == req.id,
            RequestDataRequirement.request_message_id == message_uuid,
        )
        .all()
    )
    by_id = {str(row.id): row for row in rows}
    by_key = {str(row.key): row for row in rows}
    updated = 0
    for item in raw_items:
        if not isinstance(item, dict):
            continue
        target = None
        raw_id = str(item.get("id") or "").strip()
        if raw_id:
            target = by_id.get(raw_id)
        if target is None:
            raw_key = str(item.get("key") or "").strip()
            if raw_key:
                target = by_key.get(raw_key)
        if target is None:
            continue
        if str(target.field_type or "").lower() == "file":
            attachment_id_raw = str(item.get("attachment_id") or item.get("value_text") or "").strip()
            if attachment_id_raw:
                try:
                    attachment_uuid = UUID(attachment_id_raw)
                except ValueError:
                    raise HTTPException(status_code=400, detail="Некорректный attachment_id для файла")
                attachment = db.get(Attachment, attachment_uuid)
                if attachment is None or attachment.request_id != req.id:
                    raise HTTPException(status_code=400, detail="Файл для поля не найден или недоступен")
                normalized = str(attachment.id)
            else:
                normalized = ""
        else:
            value_text = item.get("value_text")
            normalized = str(value_text).strip() if value_text is not None else ""
        target.value_text = normalized or None
        target.responsible = "Клиент"
        db.add(target)
        updated += 1

    if updated:
        message.updated_at = datetime.now(timezone.utc)
        db.add(message)
        mark_unread_for_lawyer(req, EVENT_REQUEST_DATA)
        req.responsible = "Клиент"
        notify_request_event(
            db,
            request=req,
            event_type=NOTIFICATION_EVENT_REQUEST_DATA,
            actor_role="CLIENT",
            body=f"Клиент обновил дополнительные данные ({updated})",
            responsible="Клиент",
        )
        db.add(req)
        db.commit()
    else:
        db.rollback()

    messages = list_messages_for_request(db, req.id)
    serialized = serialize_messages_for_request(db, req.id, messages)
    current = next((item for item in serialized if str(item.get("id")) == str(message_uuid)), None)
    return {"updated": updated, "message": current}