"""Epic roll-up read model — ADP P4 / Backlog-Hierarchie.

Fortschritt eines Epics = Aggregation committeter/erledigter Stories im Subbaum.
Kein Gate-Status; Leading bleibt Action.
"""

from __future__ import annotations

from typing import Any, Literal

EpicRollupStatus = Literal["empty", "intake_only", "in_progress", "done"]

_DONE_ACTION = frozenset({"done"})
_ACTIVE_ACTION = frozenset({"open", "ready", "in_progress", "blocked", "review_required"})
_CHILD_EXCLUDE = frozenset({"rejected"})


def _action_status(actions_by_id: dict[str, dict[str, Any]], action_id: Any) -> str | None:
    if not action_id:
        return None
    row = actions_by_id.get(str(action_id))
    return row.get("status") if row else None


def compute_epic_rollup(
    *,
    backlog_items: list[dict[str, Any]],
    actions: list[dict[str, Any]],
) -> list[dict[str, Any]]:
    """Roll-up pro Epic-BacklogItem (item_kind=epic, nicht rejected)."""
    actions_by_id = {str(a["id"]): a for a in actions if a.get("id")}
    epics = [
        b
        for b in backlog_items
        if b.get("item_kind") == "epic" and b.get("status") not in _CHILD_EXCLUDE
    ]

    rollups: list[dict[str, Any]] = []
    for epic in epics:
        epic_id = str(epic["id"])
        children = [
            b
            for b in backlog_items
            if b.get("parent_backlog_id")
            and str(b["parent_backlog_id"]) == epic_id
            and b.get("item_kind") != "epic"
            and b.get("status") not in _CHILD_EXCLUDE
        ]

        child_total = len(children)
        committed: list[dict[str, Any]] = []
        uncommitted: list[dict[str, Any]] = []
        for child in children:
            if child.get("status") == "converted" or child.get("converted_action_id"):
                committed.append(child)
            else:
                uncommitted.append(child)

        actions_done = actions_in_progress = actions_open = 0
        for child in committed:
            status = _action_status(actions_by_id, child.get("converted_action_id"))
            if status in _DONE_ACTION:
                actions_done += 1
            elif status in _ACTIVE_ACTION:
                actions_in_progress += 1
                actions_open += 1
            elif status:
                actions_open += 1

        if child_total == 0:
            rollup_status: EpicRollupStatus = "empty"
        elif len(committed) == 0:
            rollup_status = "intake_only"
        elif actions_done == child_total:
            rollup_status = "done"
        else:
            rollup_status = "in_progress"

        completion_ratio = actions_done / child_total if child_total else None
        commit_ratio = len(committed) / child_total if child_total else None

        rollups.append(
            {
                "epic_backlog_id": epic_id,
                "epic_title": epic.get("title") or "Epic",
                "child_total": child_total,
                "child_uncommitted": len(uncommitted),
                "child_committed": len(committed),
                "actions_done": actions_done,
                "actions_in_progress": actions_in_progress,
                "actions_open": actions_open,
                "completion_ratio": completion_ratio,
                "commit_ratio": commit_ratio,
                "status": rollup_status,
                "data_source": "epic_rollup_v0.1",
            }
        )

    rollups.sort(key=lambda r: (r["status"] != "in_progress", r["epic_title"].lower()))
    return rollups


def epic_rollup_attention_items(
    *,
    initiative_id: str,
    rollups: list[dict[str, Any]],
) -> list[dict[str, Any]]:
    """Attention aus Epic-Roll-up — Steuerung, nicht nur Anzeige."""
    items: list[dict[str, Any]] = []

    for rollup in rollups:
        epic_id = rollup["epic_backlog_id"]
        title = rollup["epic_title"]
        child_total = rollup["child_total"]
        if child_total == 0:
            continue

        if rollup["child_committed"] == 0:
            items.append(
                {
                    "kind": "epic_awaiting_commit",
                    "severity": "info",
                    "title": title,
                    "summary": (
                        f"Epic hat {rollup['child_uncommitted']} Item(s) im Eingang — "
                        "noch keine committete Arbeit"
                    ),
                    "scope_type": "backlog",
                    "scope_id": epic_id,
                    "initiative_id": initiative_id,
                    "reason_code": "epic_awaiting_commit",
                    "data_source": "epic_rollup",
                }
            )
            continue

        if rollup["child_uncommitted"] > 0 and rollup["actions_in_progress"] > 0:
            items.append(
                {
                    "kind": "epic_uncommitted_during_execution",
                    "severity": "warning",
                    "title": title,
                    "summary": (
                        f"{rollup['child_uncommitted']} Item(s) noch im Eingang, "
                        f"während {rollup['actions_in_progress']} Arbeitspaket(e) laufen"
                    ),
                    "scope_type": "backlog",
                    "scope_id": epic_id,
                    "initiative_id": initiative_id,
                    "reason_code": "epic_uncommitted_during_execution",
                    "data_source": "epic_rollup",
                }
            )

        if rollup["status"] == "done":
            items.append(
                {
                    "kind": "epic_complete",
                    "severity": "info",
                    "title": title,
                    "summary": "Alle Stories im Epic erledigt",
                    "scope_type": "backlog",
                    "scope_id": epic_id,
                    "initiative_id": initiative_id,
                    "reason_code": "epic_complete",
                    "data_source": "epic_rollup",
                }
            )

    return items