import { mkdirSync, mkdtempSync, readFileSync, rmSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { afterEach, describe, expect, it } from 'vitest';
import {
  GPU_CRASH_THRESHOLD,
  GPU_CRASH_WINDOW_MS,
  readGpuFallbackState,
  recordGpuCrash,
  shouldUseSoftwareRendering,
} from '../../electron/main/gpu-fallback';

const temporaryDirectories: string[] = [];

afterEach(() => {
  for (const directory of temporaryDirectories.splice(0)) {
    rmSync(directory, { recursive: true, force: true });
  }
});

describe('GPU fallback policy', () => {
  it('enables software rendering only after repeated recent GPU failures', () => {
    const now = 1_000_000;
    expect(shouldUseSoftwareRendering({ state: null, now })).toBe(false);
    expect(shouldUseSoftwareRendering({
      state: { crashCount: GPU_CRASH_THRESHOLD, lastCrashAt: now, reason: 'crashed:1' },
      now,
    })).toBe(true);
    expect(shouldUseSoftwareRendering({
      state: {
        crashCount: GPU_CRASH_THRESHOLD,
        lastCrashAt: now - GPU_CRASH_WINDOW_MS - 1,
        reason: 'crashed:1',
      },
      now,
    })).toBe(false);
    expect(shouldUseSoftwareRendering({ cliDisabled: true, now })).toBe(true);
  });

  it('persists an atomic crash counter and ignores malformed state', () => {
    const directory = mkdtempSync(join(tmpdir(), 'makelore-gpu-'));
    temporaryDirectories.push(directory);
    const filePath = join(directory, 'nested', 'gpu-fallback.json');
    const first = recordGpuCrash(filePath, 'crashed:9', 10);
    const second = recordGpuCrash(filePath, 'oom:137', 20);
    expect(first.crashCount).toBe(1);
    expect(second.crashCount).toBe(2);
    expect(readGpuFallbackState(filePath, 20)).toEqual(second);
    expect(JSON.parse(readFileSync(filePath, 'utf8'))).toEqual(second);

    mkdirSync(join(directory, 'bad'), { recursive: true });
    const malformedPath = join(directory, 'bad', 'gpu-fallback.json');
    expect(readGpuFallbackState(malformedPath)).toBeNull();
  });
});