from __future__ import annotations

from .models import TaskState


ALLOWED_TRANSITIONS: dict[TaskState, set[TaskState]] = {
    TaskState.DISCOVERED: {TaskState.CLAIMED, TaskState.CANCELLED},
    TaskState.CLAIMED: {TaskState.PLANNING, TaskState.FAILED, TaskState.BLOCKED, TaskState.CANCELLED},
    TaskState.PLANNING: {TaskState.IMPLEMENTING, TaskState.FAILED, TaskState.BLOCKED, TaskState.CANCELLED},
    TaskState.IMPLEMENTING: {TaskState.TESTING, TaskState.FAILED, TaskState.BLOCKED, TaskState.CANCELLED},
    TaskState.TESTING: {
        TaskState.PR_OPENED,
        TaskState.HUMAN_REVIEW_READY,
        TaskState.FAILED,
        TaskState.BLOCKED,
        TaskState.CANCELLED,
    },
    TaskState.PR_OPENED: {TaskState.REVIEWING, TaskState.FAILED, TaskState.CANCELLED},
    TaskState.REVIEWING: {TaskState.HUMAN_REVIEW_READY, TaskState.FAILED, TaskState.CANCELLED},
    TaskState.HUMAN_REVIEW_READY: {TaskState.DISCOVERED},
    TaskState.BLOCKED: {TaskState.DISCOVERED, TaskState.CANCELLED},
    TaskState.FAILED: {TaskState.DISCOVERED, TaskState.CANCELLED},
    TaskState.CANCELLED: {TaskState.DISCOVERED},
}


def validate_transition(from_state: TaskState, to_state: TaskState) -> None:
    if to_state not in ALLOWED_TRANSITIONS[from_state]:
        raise ValueError(f"invalid task transition: {from_state.value} -> {to_state.value}")