import { signal, computed, effect } from "@preact/signals-core";
import { DirectedGraph } from "graphology";

const IDLE: NodeStatus = "idle";
const WAITING: NodeStatus = "waiting";
const READY: NodeStatus = "ready";
const RUNNING: NodeStatus = "running";
const COMPLETED: NodeStatus = "completed";
const FAILED: NodeStatus = "failed";
const ABORTED: NodeStatus = "aborted";
const SKIPPED: NodeStatus = "skipped";

type NodeStatus =
  | "idle"
  | "waiting"
  | "ready"
  | "running"
  | "completed"
  | "failed"
  | "aborted"
  | "skipped";

export interface TestReactiveRoot {
  statusMap: Map<string, ReturnType<typeof signal<NodeStatus>>>;
  preconditions: Map<string, ReturnType<typeof computed<boolean>>>;
  blockedByFailure: Map<string, ReturnType<typeof computed<boolean>>>;
  dispose: () => void;
}

export function createTestReactiveRoot(graph: DirectedGraph): TestReactiveRoot {
  const statusMap = new Map<string, ReturnType<typeof signal<NodeStatus>>>();
  const preconditions = new Map<string, ReturnType<typeof computed<boolean>>>();
  const blockedByFailure = new Map<string, ReturnType<typeof computed<boolean>>>();
  const disposers: (() => void)[] = [];

  for (const node of graph.nodes()) {
    const predecessors = graph.inNeighbors(node);

    const status = signal<NodeStatus>(IDLE);
    const preconditionsComputed = computed(() => {
      return predecessors.every((pred: string) => {
        const predStatus = statusMap.get(pred);
        return (
          predStatus !== undefined &&
          (predStatus.value === COMPLETED || predStatus.value === SKIPPED)
        );
      });
    });
    const blockedByFailureComputed = computed(() => {
      return predecessors.some((pred: string) => {
        const predStatus = statusMap.get(pred);
        return (
          predStatus !== undefined &&
          (predStatus.value === FAILED || predStatus.value === ABORTED)
        );
      });
    });

    const blockerDisposer = effect(() => {
      if (blockedByFailureComputed.value) {
        if (status.value === IDLE || status.value === WAITING) {
          status.value = ABORTED;
        }
      }
    });

    disposers.push(blockerDisposer);
    statusMap.set(node, status);
    preconditions.set(node, preconditionsComputed);
    blockedByFailure.set(node, blockedByFailureComputed);
  }

  return {
    statusMap,
    preconditions,
    blockedByFailure,
    dispose: () => {
      for (const disposer of disposers) {
        disposer();
      }
      statusMap.clear();
      preconditions.clear();
      blockedByFailure.clear();
    },
  };
}

export function assertStatus(
  root: TestReactiveRoot,
  nodeId: string,
  expected: NodeStatus,
): void {
  const status = root.statusMap.get(nodeId);
  if (!status) {
    throw new Error(`Node ${nodeId} not found in statusMap`);
  }
  if (status.value !== expected) {
    throw new Error(
      `Node ${nodeId} status: expected ${expected}, got ${status.value}`,
    );
  }
}

export function assertPreconditions(
  root: TestReactiveRoot,
  nodeId: string,
  expected: boolean,
): void {
  const preconditions = root.preconditions.get(nodeId);
  if (!preconditions) {
    throw new Error(`Node ${nodeId} not found in preconditions`);
  }
  if (preconditions.value !== expected) {
    throw new Error(
      `Node ${nodeId} preconditions: expected ${expected}, got ${preconditions.value}`,
    );
  }
}

export function assertBlockedByFailure(
  root: TestReactiveRoot,
  nodeId: string,
  expected: boolean,
): void {
  const blocked = root.blockedByFailure.get(nodeId);
  if (!blocked) {
    throw new Error(`Node ${nodeId} not found in blockedByFailure`);
  }
  if (blocked.value !== expected) {
    throw new Error(
      `Node ${nodeId} blockedByFailure: expected ${expected}, got ${blocked.value}`,
    );
  }
}

export type { NodeStatus };