// @vitest-environment happy-dom
// Sidebar preview (docs/PREVIEW.md): highlighting a session shows it in the
// content pane without changing the layout the operator built.
import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";

import { addTab, emptyLayout, type Layout, splitLeaf } from "./layout.js";
import { serializeLayout } from "./persistence.js";
import { createMultiView, type MultiView } from "./multiview.js";
import type { ConnectionPool } from "./connections.js";
import type { SidebarHandle } from "./catalog.js";

function stubFetch(): void {
  vi.stubGlobal(
    "fetch",
    vi.fn(async (input: RequestInfo | URL) => {
      const url = String(input);
      const body = url.includes("/api/info")
        ? { hostname: "h", version: "0", home_dir: "/home/user", presets: [] }
        : undefined;
      return new Response(JSON.stringify(body), { status: 200 });
    }),
  );
}

interface Spy {
  pool: ConnectionPool;
  visible: () => string[];
  focusCalls: (string | null)[];
  mountedWithFocus: (boolean | undefined)[];
}

function fakePool(): Spy {
  let visible: string[] = [];
  const focusCalls: (string | null)[] = [];
  const mountedWithFocus: (boolean | undefined)[] = [];
  const pool = {
    setVisible(entries: { id: string }[], opts?: { focus?: boolean }) {
      visible = entries.map((e) => e.id);
      mountedWithFocus.push(opts?.focus);
    },
    setFocus(id: string | null) {
      focusCalls.push(id);
    },
  } as unknown as ConnectionPool;
  return { pool, visible: () => visible, focusCalls, mountedWithFocus };
}

/** Last value the controller pushed to `SidebarHandle.setPreview`. */
const previewRow: { id: string | null } = { id: null };
/** Last highlights the controller pushed to `SidebarHandle.setHighlights`. */
const rowHighlights: { open: Set<string>; focused: string | null } = {
  open: new Set(),
  focused: null,
};

function fakeSidebar(): SidebarHandle {
  return {
    el: document.createElement("aside"),
    setActive() {},
    setHighlights(h) {
      rowHighlights.open = h.open;
      rowHighlights.focused = h.focused;
    },
    setPreview(id: string | null) {
      previewRow.id = id;
    },
    focusList() {},
    hasListFocus() {
      return false;
    },
    dispose() {},
  };
}

function makeMv(layout: Layout, pool: ConnectionPool, onLayoutChange?: () => void): MultiView {
  const mv = createMultiView({
    pool,
    layout,
    sidebar: fakeSidebar(),
    infoFor: () => ({ name: "sess", command: "bash" }),
    onDisconnect: () => {},
    renderWelcome: () => document.createElement("div"),
    onLayoutChange,
  });
  document.body.appendChild(mv.el);
  mv.render();
  return mv;
}

/** Tab 1 holds `s1`; tab 2 holds `s2` and is the active one. */
function twoTabs(): Layout {
  const layout = emptyLayout();
  const first = layout.tabs[0];
  first.focusedLeafId = splitLeaf(first, "", "s1", "row", true);
  const second = addTab(layout);
  second.focusedLeafId = splitLeaf(second, "", "s2", "row", true);
  layout.activeTabId = second.id;
  return layout;
}

describe("sidebar preview", () => {
  beforeEach(() => {
    stubFetch();
    document.body.replaceChildren();
    previewRow.id = null;
    rowHighlights.open = new Set();
    rowHighlights.focused = null;
  });

  afterEach(() => {
    vi.unstubAllGlobals();
  });

  it("brings a session's own tab forward, then puts the layout back", () => {
    const layout = twoTabs();
    const before = serializeLayout(layout);
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);

    mv.previewSession("s1");
    expect(spy.visible()).toEqual(["s1"]);
    expect(mv.previewedSessionId()).toBe("s1");

    mv.previewSession(null);
    expect(spy.visible()).toEqual(["s2"]);
    expect(mv.previewedSessionId()).toBeNull();
    expect(serializeLayout(layout)).toEqual(before);
  });

  it("marks the previewed pane and its sidebar row, and unmarks them after", () => {
    const layout = twoTabs();
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);

    mv.previewSession("s1");
    expect(previewRow.id).toBe("s1");
    expect(mv.el.querySelectorAll(".mv-pane.is-preview")).toHaveLength(1);
    expect(
      (mv.el.querySelector(".mv-pane.is-preview") as HTMLElement).dataset.sessionId,
    ).toBe("s1");

    mv.previewSession(null);
    expect(previewRow.id).toBeNull();
    expect(mv.el.querySelectorAll(".mv-pane.is-preview")).toHaveLength(0);
  });

  it("leaves the accent on the session the pane actually holds", () => {
    const layout = twoTabs();
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);
    expect(rowHighlights.focused).toBe("s2");

    // Walking past other rows never moves the accent off what the operator
    // picked: only a real open does (docs/PREVIEW.md).
    mv.previewSession("s1");
    expect(rowHighlights.focused).toBe("s2");
    expect(mv.focusedSessionId()).toBe("s2");

    mv.previewSession("s9");
    expect(rowHighlights.focused).toBe("s2");

    mv.previewSession(null);
    expect(rowHighlights.focused).toBe("s2");

    mv.openSession("s1");
    expect(rowHighlights.focused).toBe("s1");
  });

  it("shows a session no pane holds in a throwaway tab that leaves no trace", () => {
    const layout = twoTabs();
    const before = serializeLayout(layout);
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);

    mv.previewSession("s9");
    expect(spy.visible()).toEqual(["s9"]);
    expect(layout.tabs).toHaveLength(3);
    // The throwaway tab is not something the operator has open.
    expect(mv.openSessions().has("s9")).toBe(false);

    mv.previewSession(null);
    expect(layout.tabs).toHaveLength(2);
    expect(serializeLayout(layout)).toEqual(before);
  });

  it("stepping between previews leaves only the newest one on screen", () => {
    const layout = twoTabs();
    const before = serializeLayout(layout);
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);

    mv.previewSession("s9");
    mv.previewSession("s1");
    mv.previewSession("s8");
    expect(spy.visible()).toEqual(["s8"]);
    expect(layout.tabs).toHaveLength(3);

    mv.previewSession(null);
    expect(serializeLayout(layout)).toEqual(before);
  });

  it("opening what is previewed keeps it: the throwaway tab becomes real", () => {
    const layout = twoTabs();
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);

    mv.previewSession("s9");
    mv.openSession("s9");

    expect(mv.previewedSessionId()).toBeNull();
    expect(layout.tabs).toHaveLength(3);
    expect(mv.openSessions().has("s9")).toBe(true);
    expect(spy.visible()).toEqual(["s9"]);
    // Nothing the operator had open was evicted to make room.
    expect(mv.openSessions().has("s2")).toBe(true);
  });

  it("never persists, and saves again once the preview is settled", () => {
    const layout = twoTabs();
    const spy = fakePool();
    const saves = vi.fn();
    const mv = makeMv(layout, spy.pool, saves);
    saves.mockClear();

    mv.previewSession("s9");
    expect(saves).not.toHaveBeenCalled();

    mv.previewSession(null);
    expect(saves).toHaveBeenCalled();
  });

  it("never reports a previewed pane as focused to the daemon", () => {
    const layout = twoTabs();
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);
    spy.focusCalls.length = 0;

    mv.previewSession("s1");
    mv.previewSession("s9");
    expect(spy.focusCalls).toEqual([]);

    mv.previewSession(null);
    expect(spy.focusCalls).toEqual(["s2"]);
  });

  it("mounts a preview without taking the keyboard", () => {
    const layout = twoTabs();
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);
    spy.mountedWithFocus.length = 0;

    mv.previewSession("s1");
    expect(spy.mountedWithFocus).toEqual([false]);

    mv.openSession("s1");
    expect(spy.mountedWithFocus.at(-1)).toBe(true);
  });

  it("keeps the tab bar hidden while a lone tab is previewing", () => {
    const layout = emptyLayout();
    const tab = layout.tabs[0];
    tab.focusedLeafId = splitLeaf(tab, "", "s1", "row", true);
    const spy = fakePool();
    const mv = makeMv(layout, spy.pool);
    expect(mv.el.classList.contains("mv-solo-tab")).toBe(true);

    mv.previewSession("s9");
    expect(mv.el.classList.contains("mv-solo-tab")).toBe(true);
    expect(mv.el.classList.contains("mv-previewing")).toBe(true);

    mv.previewSession(null);
    expect(mv.el.classList.contains("mv-previewing")).toBe(false);
  });
});