"""The activity log: everything users did, newest first (administrators)."""
import csv
import io

from fastapi import APIRouter, Depends
from fastapi.responses import Response
from sqlalchemy import func, or_, select
from sqlalchemy.orm import Session

from ..db import get_db
from ..models import AuditEntry, BudgetYear, Department, User
from ..security import require
from .mail import _date

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


def _query(q, user_id, entity, action, year_id, date_from, date_to):
    query = select(AuditEntry)
    if user_id:
        query = query.where(AuditEntry.user_id == user_id)
    if entity:
        query = query.where(AuditEntry.entity == entity)
    if action:
        query = query.where(AuditEntry.action == action)
    if year_id:
        query = query.where(AuditEntry.year_id == year_id)
    if date_from:
        query = query.where(AuditEntry.at >= _date(date_from))
    if date_to:
        query = query.where(AuditEntry.at < _date(date_to, end=True))
    if q:
        like = f"%{q.strip().lower()}%"
        query = query.where(or_(func.lower(AuditEntry.summary).like(like),
                                AuditEntry.user_id.in_(select(User.id).where(func.lower(User.name).like(like)))))
    return query


def _rows(db: Session, entries: list[AuditEntry]) -> list[dict]:
    year_ids = {a.year_id for a in entries if a.year_id}
    labels = {y.id: f"{d.name} {y.year}" for y, d in db.execute(
        select(BudgetYear, Department).join(Department).where(BudgetYear.id.in_(year_ids)))} if year_ids else {}
    return [{"id": a.id, "at": a.at.isoformat(), "user": a.user.name if a.user else None, "user_id": a.user_id,
             "entity": a.entity, "entity_id": a.entity_id, "action": a.action, "summary": a.summary,
             "changes": a.changes, "year_id": a.year_id,
             "budget": labels.get(a.year_id) if a.year_id else None,
             "budget_exists": a.year_id in labels} for a in entries]


@router.get("/activity")
def activity(q: str | None = None, user_id: int | None = None, entity: str | None = None, action: str | None = None,
             year_id: int | None = None, date_from: str | None = None, date_to: str | None = None,
             limit: int = 100, offset: int = 0, db: Session = Depends(get_db), _: User = Depends(require("admin"))):
    query = _query(q, user_id, entity, action, year_id, date_from, date_to)
    total = db.scalar(select(func.count()).select_from(query.subquery()))
    entries = db.scalars(query.order_by(AuditEntry.at.desc(), AuditEntry.id.desc())
                         .limit(min(max(limit, 1), 500)).offset(max(offset, 0))).all()
    kinds = db.execute(select(AuditEntry.entity, AuditEntry.action).distinct()).all()
    return {"total": total, "rows": _rows(db, entries),
            "entities": sorted({e for e, _ in kinds}), "actions": sorted({a for _, a in kinds})}


@router.get("/activity.csv")
def activity_csv(q: str | None = None, user_id: int | None = None, entity: str | None = None,
                 action: str | None = None, year_id: int | None = None, date_from: str | None = None,
                 date_to: str | None = None, db: Session = Depends(get_db), _: User = Depends(require("admin"))):
    entries = db.scalars(_query(q, user_id, entity, action, year_id, date_from, date_to)
                         .order_by(AuditEntry.at.desc(), AuditEntry.id.desc())).all()
    out = io.StringIO()
    w = csv.writer(out, delimiter=";")
    w.writerow(["date", "user", "area", "action", "budget", "summary", "changes"])
    for r in _rows(db, entries):
        w.writerow([r["at"], r["user"] or "", r["entity"], r["action"], r["budget"] or "", r["summary"],
                    "" if not r["changes"] else str(r["changes"])])
    return Response("" + out.getvalue(), media_type="text/csv; charset=utf-8",
                    headers={"Content-Disposition": 'attachment; filename="activity_log.csv"'})