"""
The dashboard's numbers in one call: lists and people, mailboxes and their health, recent
sends and how they went, forms and presets. Read-only, and every count comes from the same
stores the other pages read, so the dashboard never disagrees with them.
"""

from __future__ import annotations

from datetime import datetime, timedelta, timezone

from backend import collect, databases, mailboxes, orgs, presets, sending

_RECENT_DAYS = 30


def _parse(ts: str | None) -> datetime | None:
    if not ts:
        return None
    try:
        return datetime.fromisoformat(ts)
    except ValueError:
        return None


def get_overview(org_id: str, actor_uid: str) -> dict:
    orgs.require_permission(org_id, actor_uid)

    lists = [{"database_id": did, **d} for did, d in databases.list_databases(org_id).items()]
    boxes = list(mailboxes.list_mailboxes(org_id).values())
    sends = sending.list_sends(org_id, actor_uid, limit=500)
    forms = [k for k in collect.list_keys(org_id, actor_uid) if not k.get("revoked")]
    saved_presets = presets.list_presets(org_id, actor_uid)

    cutoff = datetime.now(timezone.utc) - timedelta(days=_RECENT_DAYS)
    recent = [s for s in sends if (_parse(s["sent_at"]) or cutoff) > cutoff]
    delivered = sum(s["sent"] for s in recent)
    failed = sum(s["failed"] for s in recent)

    # One point per day for the last 30 days, oldest first, for the activity chart.
    by_day: dict[str, int] = {}
    for s in recent:
        day = (_parse(s["sent_at"]) or cutoff).date().isoformat()
        by_day[day] = by_day.get(day, 0) + s["sent"]
    today = datetime.now(timezone.utc).date()
    activity = [
        {"day": (today - timedelta(days=i)).isoformat(), "sent": by_day.get((today - timedelta(days=i)).isoformat(), 0)}
        for i in range(_RECENT_DAYS - 1, -1, -1)
    ]

    names = {d["database_id"]: d["name"] for d in lists}
    return {
        "people": sum(d.get("row_count", 0) for d in lists if not d.get("disabled")),
        "lists": len(lists),
        "mailboxes": {
            "total": len(boxes),
            "verified": sum(1 for b in boxes if b.get("status") == "verified"),
            "needs_attention": sum(1 for b in boxes if b.get("status") not in ("verified", "pending_verification") and not b.get("dismissed")),
        },
        "sends_30d": {"campaigns": len(recent), "delivered": delivered, "failed": failed},
        "forms": len(forms),
        "presets": len(saved_presets),
        "activity": activity,
        "recent_sends": [s | {"list_name": names.get(s["database_id"], "Deleted list")} for s in sends[:8]],
        "largest_lists": sorted(
            ({"database_id": d["database_id"], "name": d["name"], "row_count": d.get("row_count", 0)} for d in lists),
            key=lambda d: d["row_count"], reverse=True,
        )[:5],
    }