"""Attachment routes — upload (multipart), list, download, delete."""

from __future__ import annotations

import os
import uuid

from fastapi import APIRouter, Depends, File, Form, HTTPException, Request, UploadFile, status
from fastapi.responses import FileResponse
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.db import get_db
from app.core.rate_limit import RateLimitPolicy, check_rate_limit_policy
from app.deps import require_permission
from app.services import attachment_service

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


@router.post("", status_code=status.HTTP_201_CREATED)
async def upload_attachment(
    request: Request,
    file: UploadFile = File(...),
    entity_type: str = Form(...),
    entity_id: str = Form(...),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("attachments:write")),
):
    """Upload a file attachment. Multipart form data."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

    # Rate limit — UPLOAD policy
    await check_rate_limit_policy(
        f"rate:upload:attachments:{tenant_id}:{user_id}",
        RateLimitPolicy.UPLOAD,
    )

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

    mime_type = file.content_type or "application/octet-stream"

    try:
        return await attachment_service.save_attachment(
            db, tenant_id, user_id, entity_type, eid,
            file.filename or "unknown", file, mime_type,
            is_system_admin=is_admin,
        )
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e


@router.get("")
async def list_attachments(
    entity_type: str,
    entity_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("attachments:read")),
):
    """List attachments for a specific entity."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

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

    try:
        return await attachment_service.list_attachments(db, tenant_id, entity_type, eid, user_id=user_id, is_system_admin=is_admin)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e


@router.get("/{attachment_id}")
async def download_attachment(
    attachment_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("attachments:read")),
):
    """Download an attachment file."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

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

    try:
        data = await attachment_service.get_attachment(db, tenant_id, aid, user_id=user_id, is_system_admin=is_admin)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if data is None:
        raise HTTPException(404, detail={"detail": "Attachment not found", "code": "not_found"})

    # Get storage path from DMS file via new unified service
    storage_path = await attachment_service.get_attachment_download_path(
        db, tenant_id, aid, user_id=user_id, is_system_admin=is_admin
    )
    if storage_path is None:
        raise HTTPException(404, detail={"detail": "File not found in DMS", "code": "file_missing"})

    from app.core.storage import get_storage_backend
    storage = get_storage_backend()
    try:
        file_bytes = await storage.read(storage_path)
    except Exception:
        raise HTTPException(404, detail={"detail": "File not found in storage", "code": "file_missing"})

    from fastapi.responses import Response
    return Response(
        content=file_bytes,
        media_type=data["mime_type"],
        headers={"Content-Disposition": f'attachment; filename="{data["filename"]}"'},
    )


@router.delete("/{attachment_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_attachment(
    attachment_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("attachments:write")),
):
    """Delete an attachment."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_admin = current_user.get("is_system_admin", False)

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

    try:
        deleted = await attachment_service.delete_attachment(db, tenant_id, user_id, aid, is_system_admin=is_admin)
    except PermissionError as e:
        raise HTTPException(status_code=403, detail=str(e)) from e
    if not deleted:
        raise HTTPException(404, detail={"detail": "Attachment not found", "code": "not_found"})