import { describe, expect, it } from "vitest";
import { onScreen, place, roomFor, viewport } from "../src/lib/place";
import type { Box } from "../src/lib/place";

const VIEW = { width: 1280, height: 800 };
const PANEL = { width: 320, height: 200 };
const row = (over: Partial<Box> = {}): Box => ({
  top: 300,
  left: 400,
  width: 500,
  height: 40,
  ...over,
});

describe("onScreen", () => {
  it("skips the copy that is hidden and has no box", () => {
    const hidden = row({ top: 0, left: 0, width: 0, height: 0 });
    const shown = row();
    expect(onScreen([hidden, shown])).toBe(shown);
  });

  it("takes the first one when several are on screen", () => {
    const first = row();
    expect(onScreen([first, row({ top: 500 })])).toBe(first);
  });

  it("says nothing when every copy is hidden", () => {
    expect(onScreen([row({ width: 0, height: 0 })])).toBeNull();
    expect(onScreen([])).toBeNull();
  });
});

describe("place", () => {
  it("sits just under the anchor", () => {
    expect(place(row(), PANEL, VIEW)).toEqual({ top: 346, left: 400 });
  });

  it("flips above when there is no room below", () => {
    expect(place(row({ top: 700 }), PANEL, VIEW)).toEqual({ top: 494, left: 400 });
  });

  it("stays inside the window when there is room neither way", () => {
    const tall = { width: 320, height: 780 };
    const spot = place(row({ top: 400 }), tall, VIEW);
    expect(spot.top).toBeGreaterThanOrEqual(10);
    expect(spot.top + tall.height).toBeLessThanOrEqual(VIEW.height);
  });

  it("pulls back from the right edge", () => {
    expect(place(row({ left: 1200 }), PANEL, VIEW).left).toBe(950);
  });

  it("never goes off the left edge", () => {
    expect(place(row({ left: -40 }), PANEL, VIEW).left).toBe(10);
  });

  it("centres rather than hiding in the corner with nothing to anchor to", () => {
    expect(place(null, PANEL, VIEW)).toEqual({ top: 300, left: 480 });
  });
});

// A phone's keyboard shrinks the visual viewport and leaves the window alone.
describe("place against a keyboard", () => {
  const SHRUNK = { width: 390, height: 400, top: 0, left: 0 };

  it("keeps the panel above the keyboard", () => {
    const spot = place(row({ top: 380, left: 10, width: 370 }), PANEL, SHRUNK);
    expect(spot.top + PANEL.height).toBeLessThanOrEqual(SHRUNK.height);
  });

  it("measures from where the visible area starts", () => {
    const scrolled = { width: 390, height: 400, top: 120, left: 0 };
    const spot = place(null, PANEL, scrolled);
    expect(spot.top).toBeGreaterThanOrEqual(scrolled.top);
    expect(spot.top + PANEL.height).toBeLessThanOrEqual(
      scrolled.top + scrolled.height
    );
  });

  it("comes back into view when the anchor itself is under the keyboard", () => {
    // The row the panel hangs off is at 650, the keyboard leaves 380: neither
    // above nor below the anchor is reachable, so the visible area wins.
    const spot = place(row({ top: 650, height: 40 }), PANEL, SHRUNK);
    expect(spot.top).toBeGreaterThanOrEqual(10);
    expect(spot.top + PANEL.height).toBeLessThanOrEqual(SHRUNK.height);
  });
});

describe("roomFor", () => {
  it("leaves the panel less height than the visible area", () => {
    expect(roomFor({ width: 390, height: 400 })).toBeLessThan(400);
  });

  it("never collapses to nothing when the keyboard takes almost everything", () => {
    expect(roomFor({ width: 390, height: 60 })).toBeGreaterThan(100);
  });
});

// Obsidian's phone navbar is not part of the visual viewport - it floats over
// it - so a panel sized to the viewport still ends up underneath it.
describe("viewport minus the floating navbar", () => {
  function fakeWin(navbarTop: number | null, height = 780): Window {
    const bar = {
      getBoundingClientRect: () => ({
        top: navbarTop ?? 0,
        bottom: height,
        height: height - (navbarTop ?? 0),
        left: 0,
        right: 390,
      }),
      offsetParent: {},
    };
    return {
      innerWidth: 390,
      innerHeight: height,
      visualViewport: { width: 390, height, offsetTop: 0, offsetLeft: 0 },
      document: {
        querySelector: (selector: string) =>
          selector === ".mobile-navbar" && navbarTop !== null ? bar : null,
      },
    } as unknown as Window;
  }

  it("takes the navbar off the bottom", () => {
    expect(viewport(fakeWin(724)).height).toBe(724);
  });

  it("leaves the height alone with no navbar in the way", () => {
    expect(viewport(fakeWin(null)).height).toBe(780);
  });

  it("still leaves a usable strip if a bar somehow covers everything", () => {
    expect(viewport(fakeWin(0)).height).toBeGreaterThanOrEqual(120);
  });
});