import { describe, it, expect, afterEach, beforeEach } from 'vitest';
import { getCellDimensions } from '../src/cell-dimensions.js';
import { createMockTerminal } from './helpers.js';
import type { XtermTerminal } from '../src/types.js';

let cleanups: (() => void)[] = [];

afterEach(() => {
  for (const fn of cleanups) fn();
  cleanups = [];
});

describe('getCellDimensions', () => {
  describe('v5 private API (mock _core._renderService)', () => {
    it('returns cell width and height from css.cell', () => {
      const mock = createMockTerminal({ cellWidth: 8.4, cellHeight: 19 });
      cleanups.push(mock.cleanup);
      const dims = getCellDimensions(mock.terminal as unknown as XtermTerminal);
      expect(dims).not.toBeNull();
      expect(dims!.width).toBe(8.4);
      expect(dims!.height).toBe(19);
    });

    it('returns charTop from device.char.top divided by DPR', () => {
      const mock = createMockTerminal({
        cellWidth: 8,
        cellHeight: 19,
        deviceCharTop: 2,
      });
      cleanups.push(mock.cleanup);
      const dims = getCellDimensions(mock.terminal as unknown as XtermTerminal);
      expect(dims).not.toBeNull();
      // DPR=1 in jsdom, so charTop = 2 / 1 = 2
      expect(dims!.charTop).toBe(2);
    });

    it('returns charHeight from device.char.height divided by DPR', () => {
      const mock = createMockTerminal({
        cellWidth: 8,
        cellHeight: 19,
        deviceCharHeight: 16,
      });
      cleanups.push(mock.cleanup);
      const dims = getCellDimensions(mock.terminal as unknown as XtermTerminal);
      expect(dims).not.toBeNull();
      // DPR=1, so charHeight = 16 / 1 = 16
      expect(dims!.charHeight).toBe(16);
    });

    it('defaults charTop to 0 when device.char not present', () => {
      // Default mock has deviceCharTop=0
      const mock = createMockTerminal({ cellWidth: 8, cellHeight: 19 });
      cleanups.push(mock.cleanup);
      const dims = getCellDimensions(mock.terminal as unknown as XtermTerminal);
      expect(dims!.charTop).toBe(0);
    });

    it('defaults charHeight to cellH when device.char.height not set', () => {
      // Default mock has deviceCharHeight=cellH
      const mock = createMockTerminal({ cellWidth: 8, cellHeight: 19 });
      cleanups.push(mock.cleanup);
      const dims = getCellDimensions(mock.terminal as unknown as XtermTerminal);
      expect(dims!.charHeight).toBe(19);
    });
  });

  describe('DPR simulation', () => {
    const originalDPR = globalThis.devicePixelRatio;

    beforeEach(() => {
      // Set DPR=2 to test division
      Object.defineProperty(globalThis, 'devicePixelRatio', {
        value: 2,
        writable: true,
        configurable: true,
      });
    });

    afterEach(() => {
      Object.defineProperty(globalThis, 'devicePixelRatio', {
        value: originalDPR,
        writable: true,
        configurable: true,
      });
    });

    it('divides device.char.top by DPR', () => {
      const mock = createMockTerminal({
        cellWidth: 16,
        cellHeight: 38,
        deviceCharTop: 4,
        deviceCharHeight: 32,
      });
      cleanups.push(mock.cleanup);
      const dims = getCellDimensions(mock.terminal as unknown as XtermTerminal);
      expect(dims).not.toBeNull();
      // charTop = 4 / 2 = 2
      expect(dims!.charTop).toBe(2);
      // charHeight = 32 / 2 = 16
      expect(dims!.charHeight).toBe(16);
    });
  });

  describe('null cases', () => {
    it('returns null for terminal without _core', () => {
      const terminal = {
        element: document.createElement('div'),
        cols: 80,
        rows: 24,
        options: {},
        buffer: { active: { viewportY: 0, baseY: 0, getLine: () => undefined } },
      } as unknown as XtermTerminal;
      const dims = getCellDimensions(terminal);
      expect(dims).toBeNull();
    });

    it('returns null for terminal with no dimensions', () => {
      const terminal = {
        element: document.createElement('div'),
        cols: 80,
        rows: 24,
        options: {},
        buffer: { active: { viewportY: 0, baseY: 0, getLine: () => undefined } },
        _core: { _renderService: {} },
      } as unknown as XtermTerminal;
      const dims = getCellDimensions(terminal);
      expect(dims).toBeNull();
    });
  });
});