import { describe, it, expect } from "vitest";
import { h } from "../src/core/h.js";
import { createRoot as createHostRoot } from "../src/host/config.js";
import type { HostConfig } from "../src/host/config.js";
import { ReactiveRoot } from "../src/core/reactive.js";

function makeHost(): {
  host: HostConfig<string, string, Record<string, unknown>>;
  removes: { parent: string; child: string }[];
  finalizeInstanceCalls: string[];
  finalizeRootCalls: { count: number };
  emittedEvents: { type: string; id: string; payload: unknown }[];
  instances: { tag: string; props: Record<string, unknown> }[];
  appends: { parent: string; child: string }[];
} {
  const instances: { tag: string; props: Record<string, unknown> }[] = [];
  const appends: { parent: string; child: string }[] = [];
  const removes: { parent: string; child: string }[] = [];
  const finalizeInstanceCalls: string[] = [];
  const finalizeRootCalls: { count: number } = { count: 0 };
  const emittedEvents: { type: string; id: string; payload: unknown }[] = [];

  const host: HostConfig<string, string, Record<string, unknown>> = {
    name: "test",
    createRootContext: () => ({}),
    createInstance: (tag, props) => {
      const id = `${tag}_${instances.length}`;
      instances.push({ tag, props });
      return id;
    },
    createTextInstance: (text) => {
      instances.push({ tag: "#text", props: { text } });
      return `text_${instances.length}`;
    },
    appendChild: (parent, child) => {
      appends.push({ parent, child });
    },
    removeChild: (parent, child) => {
      removes.push({ parent, child });
    },
    finalizeInstance: (instance) => {
      finalizeInstanceCalls.push(instance as string);
    },
    finalizeRoot: () => {
      finalizeRootCalls.count++;
    },
    emit: (type, id, payload) => {
      emittedEvents.push({ type, id, payload });
    },
  };
  return { host, removes, finalizeInstanceCalls, finalizeRootCalls, emittedEvents, instances, appends };
}

describe("Root.unmount()", () => {
  it("cleans up all host instances via removeChild", () => {
    const { host, removes } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, h("span", null, "a"), h("em", null)));

    root.unmount();

    expect(removes.length).toBe(1);
  });

  it("clears rootFiber after unmount", () => {
    const { host } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, "hello"));

    expect(root.rootFiber).not.toBeNull();
    root.unmount();
    expect(root.rootFiber).toBeNull();
  });

  it("calls host.finalizeRoot after disposal and removal", () => {
    const { host, finalizeRootCalls } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, "hello"));

    expect(finalizeRootCalls.count).toBe(1);
    root.unmount();
    expect(finalizeRootCalls.count).toBe(2);
  });

  it("emits root.unmount event", () => {
    const { host, emittedEvents } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, "hello"));

    root.unmount();

    const unmountEvent = emittedEvents.find((e) => e.type === "root.unmount");
    expect(unmountEvent).toBeDefined();
  });

  it("unmount then re-render works (fresh mount)", () => {
    const { host, instances, appends } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, "hello"));

    const firstInstanceCount = instances.length;
    const firstAppendCount = appends.length;

    root.unmount();
    expect(root.rootFiber).toBeNull();

    root.render(h("div", null, "world"));
    expect(root.rootFiber).not.toBeNull();
    expect(root.rootFiber!.tag).toBe("#root");
    expect(root.rootFiber!.children.length).toBe(1);
    expect(root.rootFiber!.children[0]!.tag).toBe("div");
    expect(root.rootFiber!.disposed).toBe(false);

    expect(instances.length).toBeGreaterThan(firstInstanceCount);
  });

  it("double unmount is safe (idempotent)", () => {
    const { host, removes } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, "hello"));

    root.unmount();
    const removesAfterFirst = removes.length;

    root.unmount();
    expect(removes.length).toBe(removesAfterFirst);
    expect(root.rootFiber).toBeNull();
  });

  it("unmount with no prior render is safe", () => {
    const { host, removes } = makeHost();
    const root = createHostRoot(host, {});

    root.unmount();
    expect(root.rootFiber).toBeNull();
    expect(removes.length).toBe(0);
  });

  it("calls finalizeInstance for each fiber", () => {
    const { host, finalizeInstanceCalls } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, h("span", null, "a"), h("em", null)));

    root.unmount();

    expect(finalizeInstanceCalls.length).toBe(5);
  });

  it("signal subscriptions are cleaned up via disposeFiber", () => {
    const disposed: string[] = [];
    const { host } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, "hello"));

    const rootFiber = root.rootFiber!;
    const divFiber = rootFiber.children[0]!;
    divFiber.signalDisposers.push(() => disposed.push("div-disposed"));
    const textFiber = divFiber.children[0]!;
    textFiber.signalDisposers.push(() => disposed.push("text-disposed"));

    root.unmount();

    expect(disposed).toContain("div-disposed");
    expect(disposed).toContain("text-disposed");
  });

  it("does not auto-dispose ReactiveRoot — consumer responsibility", () => {
    const { host } = makeHost();
    const root = createHostRoot(host, {});
    root.render(h("div", null, "hello"));

    const reactiveRoot = new ReactiveRoot(h("span", null, "test"));
    const disposeSpy: string[] = [];
    const origDispose = reactiveRoot.dispose.bind(reactiveRoot);
    reactiveRoot.dispose = () => {
      disposeSpy.push("called");
      origDispose();
    };

    root.unmount();

    expect(disposeSpy.length).toBe(0);
    expect(reactiveRoot.value).toBeDefined();
  });
});