"""Tech debt summary read model — P7."""

from __future__ import annotations

from datetime import datetime, timedelta, timezone
from typing import Any

from steering.eval_context import SteeringEvalContext

_OPEN_BACKLOG = frozenset({"new", "triaged", "accepted"})
_OPEN_ACTION = frozenset({"open", "ready", "in_progress", "blocked", "review_required"})


def _parse_ts(value: Any) -> datetime | None:
    if not value:
        return None
    if isinstance(value, datetime):
        return value if value.tzinfo else value.replace(tzinfo=timezone.utc)
    try:
        text = str(value).replace("Z", "+00:00")
        parsed = datetime.fromisoformat(text)
        return parsed if parsed.tzinfo else parsed.replace(tzinfo=timezone.utc)
    except ValueError:
        return None


def compute_tech_debt_summary(ctx: SteeringEvalContext) -> dict[str, Any]:
    vocabulary = ctx.backlog_vocabulary
    if "tech_debt" not in (vocabulary.get("kinds") or []):
        return {
            "enabled": False,
            "backlog_items": [],
            "actions": [],
            "total_open": 0,
            "stale_count": 0,
        }

    stale_days = int(ctx.agent_slot_config.get("stale_debt_days") or 30)
    cutoff = datetime.now(timezone.utc) - timedelta(days=stale_days)

    backlog_items: list[dict[str, Any]] = []
    for item in ctx.backlog_items:
        if item.get("item_kind") != "tech_debt":
            continue
        if item.get("status") not in _OPEN_BACKLOG:
            continue
        created = _parse_ts(item.get("created_at"))
        stale = created is not None and created < cutoff
        backlog_items.append(
            {
                "id": str(item["id"]),
                "title": item.get("title") or "Technische Schuld",
                "status": item.get("status"),
                "stale": stale,
                "created_at": item.get("created_at"),
            }
        )

    actions: list[dict[str, Any]] = []
    for action in ctx.actions:
        if action.get("action_kind") != "tech_debt":
            continue
        if action.get("status") not in _OPEN_ACTION:
            continue
        created = _parse_ts(action.get("created_at"))
        stale = created is not None and created < cutoff
        actions.append(
            {
                "id": str(action["id"]),
                "title": action.get("title") or "Technische Schuld",
                "status": action.get("status"),
                "stale": stale,
                "created_at": action.get("created_at"),
            }
        )

    stale_count = sum(1 for row in backlog_items if row["stale"]) + sum(
        1 for row in actions if row["stale"]
    )

    return {
        "enabled": True,
        "backlog_items": backlog_items,
        "actions": actions,
        "total_open": len(backlog_items) + len(actions),
        "stale_count": stale_count,
        "stale_days": stale_days,
    }