"""REST API for packages (distinct packages across scans)."""

import csv
import io

from fastapi import APIRouter, Depends, HTTPException, Query, Response
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from ..constants import (
    CSV_MEDIA_TYPE,
    DEFAULT_OFFSET,
    DEFAULT_PAGE_SIZE,
    DEFAULT_SORT_BY_PACKAGES,
    DEFAULT_SORT_DIR,
    MAX_PAGE_SIZE,
)
from ..core.nexus import parse_package_path
from ..db.engine import get_session
from ..db.models import Scan
from ..db.queries import build_package_list_query
from ..schemas import PackageDetailOut, PackageListResponse, serialize_finding

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


@router.get("", response_model=PackageListResponse)
async def list_packages(
    limit: int = Query(DEFAULT_PAGE_SIZE, le=MAX_PAGE_SIZE),
    offset: int = Query(DEFAULT_OFFSET, ge=0),
    ecosystem: str | None = Query(None),
    flagged: bool | None = Query(None),
    search: str | None = Query(None),
    repository: str | None = Query(None),
    sort_by: str = Query(DEFAULT_SORT_BY_PACKAGES),
    sort_dir: str = Query(DEFAULT_SORT_DIR),
    session: AsyncSession = Depends(get_session),
) -> dict:
    rows_q, total_q = build_package_list_query(
        flagged=flagged,
        ecosystem=ecosystem,
        repository=repository,
        search=search,
        sort_by=sort_by,
        sort_dir=sort_dir,
        limit=limit,
        offset=offset,
    )
    total = await session.scalar(total_q)
    rows = (await session.execute(rows_q)).all()

    return {
        "total": total,
        "limit": limit,
        "offset": offset,
        "packages": [
            {
                "name": r.pkg_name,
                "version": r.pkg_ver,
                "ecosystem": r.ecosystem,
                "repository": r.repository,
                "last_scanned_at": r.last_scan.isoformat() if r.last_scan else None,
                "flagged": bool(r.is_flagged),
                "total_findings": r.findings_sum,
                "latest_scan_id": r.sid,
            }
            for r in rows
        ],
    }


@router.get("/export")
async def export_packages_csv(
    flagged: bool | None = Query(None),
    search: str | None = Query(None),
    session: AsyncSession = Depends(get_session),
) -> Response:
    rows_q, _total_q = build_package_list_query(
        flagged=flagged,
        search=search,
        sort_by=DEFAULT_SORT_BY_PACKAGES,
        sort_dir=DEFAULT_SORT_DIR,
        limit=MAX_PAGE_SIZE,
        offset=0,
    )
    rows = (await session.execute(rows_q)).all()

    output = io.StringIO()
    writer = csv.writer(output)
    writer.writerow(
        [
            "name",
            "version",
            "ecosystem",
            "repository",
            "last_scanned_at",
            "flagged",
            "total_findings",
        ]
    )
    for r in rows:
        writer.writerow(
            [
                r.pkg_name,
                r.pkg_ver,
                r.ecosystem,
                r.repository,
                r.last_scan.isoformat() if r.last_scan else "",
                bool(r.is_flagged),
                r.findings_sum,
            ]
        )

    return Response(
        content=output.getvalue(),
        media_type=CSV_MEDIA_TYPE,
        headers={"Content-Disposition": "attachment; filename=packages_export.csv"},
    )


@router.get("/{name:path}", response_model=PackageDetailOut)
async def get_package(
    name: str,
    session: AsyncSession = Depends(get_session),
) -> dict:
    pkg_name, pkg_version = parse_package_path(name)

    scans = (
        (
            await session.execute(
                select(Scan)
                .where(Scan.package_name == pkg_name, Scan.package_version == pkg_version)
                .options(selectinload(Scan.findings))
                .order_by(Scan.started_at.desc())
            )
        )
        .scalars()
        .all()
    )

    if not scans:
        raise HTTPException(status_code=404, detail="Package not found")

    all_findings: list[dict] = []
    for s in scans:
        for f in s.findings:
            all_findings.append(serialize_finding(f))

    return {
        "name": scans[0].package_name,
        "version": scans[0].package_version,
        "ecosystem": scans[0].ecosystem,
        "repository": scans[0].repository,
        "flagged": any(s.flagged for s in scans),
        "scans": [
            {
                "id": s.id,
                "status": s.status,
                "total_findings": s.total_findings,
                "flagged": s.flagged,
                "started_at": s.started_at.isoformat() if s.started_at else None,
            }
            for s in scans
        ],
        "findings": all_findings,
    }