"""Admin-only backup: produce and download a restorable archive.

The archive is built on demand rather than served from a directory, so it always
reflects the database at the moment of the request.
"""
from __future__ import annotations

import shutil
import tempfile
from pathlib import Path

from fastapi import APIRouter, Depends, HTTPException, Request
from fastapi.responses import FileResponse, JSONResponse
from starlette.background import BackgroundTask

from ..auth import Ctx
from ..backup import export_backup
from ..db import record_audit
from ..deps import get_ctx

router = APIRouter()


@router.get("/v1/backup")
def download_backup(request: Request, ctx: Ctx = Depends(get_ctx)):
    """Admin: stream a full backup archive (database rows + plugin artifacts)."""
    admin = ctx.require_admin(request)
    # Build in the system temp dir, not data/backups: this one is a response
    # body, and leaving a copy behind on every click would fill the disk.
    tmpdir = Path(tempfile.mkdtemp(prefix="dsh-backup-"))
    try:
        archive = export_backup(ctx.cfg, tmpdir / "dsh-backup.tar.gz")
    except Exception as e:  # noqa: BLE001 - surface any failure as a 500 with context
        raise HTTPException(500, f"backup failed: {e}")
    record_audit(ctx.conn, admin["id"], "backup.download",
                 {"size_bytes": archive.stat().st_size})
    return FileResponse(
        archive,
        media_type="application/gzip",
        filename="dsh-backup.tar.gz",
        background=BackgroundTask(shutil.rmtree, tmpdir, ignore_errors=True),
    )


@router.get("/v1/backup/info")
def backup_info(request: Request, ctx: Ctx = Depends(get_ctx)):
    """Admin: what a backup would contain, without building one."""
    ctx.require_admin(request)
    counts = {}
    for table in ("users", "tokens", "settings", "plugins", "audit_log"):
        counts[table] = ctx.conn.execute(f"SELECT COUNT(*) AS c FROM {table}").fetchone()["c"]
    artifacts = 0
    for p in ctx.cfg.plugins_dir.rglob("*.tar.gz"):
        if p.is_file():
            artifacts += 1
    return JSONResponse({"row_counts": counts, "artifacts": artifacts})