# backend/routers/file_chat.py — chat (#169, #190)
"""Chat endpoints: history read + message post with SSE fan-out.

- ``GET/POST /api/file/{vault_name}/chat`` — per-file chat: auth + vault
  access + path traversal check (``resolve_safe_path`` raises
  ``ServiceError`` mapped by the app-level handler).
- ``GET/POST /api/chat`` — the **general chat** (#190), not bound to a file.
- ``POST /api/chat/upload`` / ``GET /api/chat/attachment/{name}`` (#190):
  image/video attachments (extension allow-list, size cap, UUID name).

Every post is broadcast on the existing SSE channel (``chat_message``) so
all connected clients update live without a second WebSocket.
"""

from __future__ import annotations

from pathlib import Path
from typing import Any

from fastapi import APIRouter, Body, Depends, File, HTTPException, UploadFile
from fastapi.responses import FileResponse

from backend import file_chat as _store
from backend.auth.middleware import check_vault_access, require_auth
from backend.indexer import get_vault_data
from backend.schemas import ChatHistoryResponse, ChatMessageResponse
from backend.services.paths import resolve_safe_path
from backend.sse import sse_manager

router = APIRouter()  # tags dérivés de `tag_for_path` → « Files »


def _check(vault_name: str, path: str, current_user: dict[str, Any]) -> None:
    """Authz + traversal guard shared by both verbs."""
    if not check_vault_access(vault_name, current_user):
        raise HTTPException(403, f"Accès refusé à la vault '{vault_name}'")
    vault_data = get_vault_data(vault_name)
    if not vault_data:
        raise HTTPException(404, "Vault not found")
    resolve_safe_path(Path(vault_data["path"]), path)  # ServiceError → 403/500


@router.get("/api/file/{vault_name}/chat", response_model=ChatHistoryResponse)
async def api_file_chat_history(
    vault_name: str,
    path: str,
    current_user: dict[str, Any] = Depends(require_auth),
):
    """Return the chat history for a file (chronological)."""
    _check(vault_name, path, current_user)
    return {"messages": _store.get_messages(vault_name, path)}


@router.post("/api/file/{vault_name}/chat", response_model=ChatMessageResponse)
async def api_file_chat_post(
    vault_name: str,
    body: dict[str, Any] = Body(...),
    current_user: dict[str, Any] = Depends(require_auth),
):
    """Post a chat message and broadcast it on SSE (``chat_message``)."""
    path = str(body.get("path") or "")
    text = str(body.get("text") or "")
    if not path:
        raise HTTPException(400, "path is required")
    if not text.strip():
        raise HTTPException(400, "text is required")
    _check(vault_name, path, current_user)
    msg = _store.add_message(vault_name, path, current_user.get("username", ""), text)
    await sse_manager.broadcast("chat_message", {"vault": vault_name, "path": path, "message": msg})
    return {"message": msg, "status": "ok"}


# --- #190 : chat général ----------------------------------------------------

def _attachment(body: dict[str, Any]) -> dict[str, Any] | None:
    """Validate the optional ``attachment`` object sent by the client."""
    raw = body.get("attachment")
    if not raw or not isinstance(raw, dict):
        return None
    name = str(raw.get("name") or "")
    # Only an already-uploaded file (or an http(s) URL) may travel along.
    if not _store.attachment_path(name) and not str(raw.get("url", "")).startswith(("http://", "https://", "/api/")):
        raise HTTPException(400, "attachment inconnu")
    return {
        "name": name,
        "url": str(raw.get("url") or ""),
        "mime": str(raw.get("mime") or ""),
        "kind": str(raw.get("kind") or "file"),
    }


@router.get("/api/chat", response_model=ChatHistoryResponse)
async def api_chat_history(current_user: dict[str, Any] = Depends(require_auth)):
    """Return the general chat history (#190, chronological)."""
    return {"messages": _store.get_global_messages()}


@router.post("/api/chat", response_model=ChatMessageResponse)
async def api_chat_post(
    body: dict[str, Any] = Body(...),
    current_user: dict[str, Any] = Depends(require_auth),
):
    """Post to the general chat and broadcast it on SSE (``chat_message``)."""
    text = str(body.get("text") or "")
    if not text.strip():
        raise HTTPException(400, "text is required")
    msg = _store.add_global_message(
        current_user.get("username", ""), text, _attachment(body)
    )
    await sse_manager.broadcast(
        "chat_message",
        {"vault": _store.GLOBAL_VAULT, "path": _store.GLOBAL_PATH, "message": msg},
    )
    return {"message": msg, "status": "ok"}


@router.post("/api/chat/upload")
async def api_chat_upload(
    file: UploadFile = File(...),
    current_user: dict[str, Any] = Depends(require_auth),
):
    """Store an image/video attachment (#190). Returns ``{attachment}``."""
    data = await file.read()
    try:
        info = _store.save_attachment(file.filename or "", data)
    except ValueError as e:
        raise HTTPException(400, str(e)) from e
    return {"attachment": info}


@router.get("/api/chat/attachment/{name}")
async def api_chat_attachment(name: str, current_user: dict[str, Any] = Depends(require_auth)):
    """Serve an uploaded attachment (name validated against the allow-list)."""
    path = _store.attachment_path(name)
    if not path:
        raise HTTPException(404, "Attachment not found")
    info = _store._MIME_BY_EXT.get(path.suffix.lower(), "application/octet-stream")
    return FileResponse(str(path), media_type=info)