"""Task-Lebenszyklus (→ Konzept 9.2). Übergänge werden serverseitig geprüft."""

from app.core.errors import Invalid

QUEUED = "queued"
RUNNING = "running"
WAITING_APPROVAL = "waiting_approval"
WAITING_INPUT = "waiting_input"
COMPLETED = "completed"
FAILED = "failed"
CANCELLED = "cancelled"
BLOCKED_BY_GUARDRAIL = "blocked_by_guardrail"
NEEDS_RECONCILIATION = "needs_reconciliation"

TRANSITIONS: dict[str, set[str]] = {
    QUEUED: {RUNNING, CANCELLED},
    RUNNING: {QUEUED, WAITING_APPROVAL, WAITING_INPUT, COMPLETED, FAILED, CANCELLED, BLOCKED_BY_GUARDRAIL,
              NEEDS_RECONCILIATION},
    WAITING_APPROVAL: {QUEUED, CANCELLED},
    WAITING_INPUT: {QUEUED, CANCELLED},
    NEEDS_RECONCILIATION: {QUEUED, FAILED},
    FAILED: {QUEUED},
    COMPLETED: set(),
    CANCELLED: set(),
    BLOCKED_BY_GUARDRAIL: set(),
}

# Zustände, in denen ein Run ohne weiteres Zutun nichts mehr tut (für das Ende eines SSE-Streams)
RESTING = {WAITING_APPROVAL, WAITING_INPUT, COMPLETED, FAILED, CANCELLED, BLOCKED_BY_GUARDRAIL,
           NEEDS_RECONCILIATION}
FINAL = {COMPLETED, CANCELLED, BLOCKED_BY_GUARDRAIL}

LABELS = {QUEUED: "wartet", RUNNING: "läuft", WAITING_APPROVAL: "wartet auf Freigabe", WAITING_INPUT: "wartet auf Eingabe",
          COMPLETED: "fertig", FAILED: "fehlgeschlagen", CANCELLED: "abgebrochen",
          BLOCKED_BY_GUARDRAIL: "blockiert (Guardrail)", NEEDS_RECONCILIATION: "Abgleich nötig"}


def check(current: str, target: str) -> None:
    if target not in TRANSITIONS[current]:
        raise Invalid(f"Übergang {current} → {target} ist nicht erlaubt.")