"""
REST routes — upload, download, session info, delete.
"""
from __future__ import annotations

import os
from fastapi import APIRouter, UploadFile, File, HTTPException
from fastapi.responses import FileResponse

from models.schemas import UploadResponse, SessionInfo, ErrorResponse
from services import file_manager, session_manager, audit_service

router = APIRouter(tags=["file operations"])


# ── Upload ─────────────────────────────────────────────────────────

@router.post(
    "/upload",
    response_model=UploadResponse,
    responses={400: {"model": ErrorResponse}, 413: {"model": ErrorResponse}},
    summary="Upload CSV / Excel / Parquet file",
)
async def upload_file(file: UploadFile = File(...)):
    content = await file.read()
    try:
        result = file_manager.handle_upload(content, file.filename or "unknown.csv")
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Upload failed: {e}")
    return UploadResponse(**result)


# ── Download ───────────────────────────────────────────────────────

@router.get(
    "/download/{session_id}",
    responses={404: {"model": ErrorResponse}},
    summary="Download file as CSV",
)
async def download_file(session_id: str):
    csv_path = file_manager.export_to_csv(session_id)
    if csv_path is None:
        raise HTTPException(status_code=404, detail="Session not found")
    return FileResponse(
        path=csv_path,
        media_type="text/csv",
        filename=f"{session_id}.csv",
    )


# ── Session info ───────────────────────────────────────────────────

@router.get(
    "/session/{session_id}",
    response_model=SessionInfo,
    responses={404: {"model": ErrorResponse}},
    summary="Get session metadata",
)
async def get_session(session_id: str):
    meta = session_manager.get(session_id)
    if meta is None:
        raise HTTPException(status_code=404, detail="Session not found")
    return SessionInfo(
        session_id=meta.session_id,
        file_name=meta.file_name,
        file_size_bytes=meta.file_size_bytes,
        columns=meta.columns,
        row_count=meta.row_count,
        status=meta.status,
    )


# ── Delete session ─────────────────────────────────────────────────

@router.delete(
    "/session/{session_id}",
    summary="Delete session and its data",
)
async def delete_session(session_id: str):
    ok = file_manager.delete_session(session_id)
    if not ok:
        raise HTTPException(status_code=404, detail="Session not found")
    return {"detail": "Session deleted"}


# ── Audit history ──────────────────────────────────────────────────

@router.get(
    "/history/{session_id}",
    summary="Get command history for a session",
)
async def get_history(session_id: str, limit: int = 50):
    history = await audit_service.get_history(session_id, limit)
    return {"history": history}