import { existsSync } from 'node:fs';
import { execFileSync } from 'node:child_process';
import { join, dirname } from 'node:path';
import { platform } from 'node:os';
import { createRequire } from 'node:module';

let glimpseAvailable: boolean | null = null;
let resolvedBinaryPath: string | null = null;

export function isGlimpseAvailable(): boolean {
  if (glimpseAvailable !== null) {
    return glimpseAvailable;
  }

  if (platform() !== 'darwin') {
    glimpseAvailable = false;

    return false;
  }

  resolvedBinaryPath = getGlimpseBinaryPath();
  glimpseAvailable = resolvedBinaryPath !== null;

  return glimpseAvailable;
}

function getGlimpseBinaryPath(): string | null {
  if (process.env.GLIMPSE_BINARY && existsSync(process.env.GLIMPSE_BINARY)) {
    return process.env.GLIMPSE_BINARY;
  }

  // Local node_modules
  try {
    const require = createRequire(import.meta.url);
    const glimpseuiPath = require.resolve('glimpseui');
    const binaryPath = join(dirname(glimpseuiPath), 'glimpse');

    if (existsSync(binaryPath)) {
      return binaryPath;
    }
  } catch {
    // Not installed in local node_modules; the global root is tried next.
  }

  // Global npm install
  try {
    const globalRoot = execFileSync('npm', ['root', '-g'], { encoding: 'utf-8' }).trim();
    const binaryPath = join(globalRoot, 'glimpseui', 'src', 'glimpse');

    if (existsSync(binaryPath)) {
      return binaryPath;
    }
  } catch {
    // Not installed globally either; the caller reports the dependency as missing.
  }

  return null;
}

export async function openGlimpseWindow(
  html: string,
  options: {
    title: string;
    width?: number;
    height?: number;
    onClosed: () => void;
  }
) {
  const modulePath = resolvedBinaryPath ? join(dirname(resolvedBinaryPath), 'glimpse.mjs') : 'glimpseui';
  const glimpse = await import(modulePath);

  let active = true;
  const win = glimpse.open(html, {
    width: options.width ?? 900,
    height: options.height ?? 700,
    title: options.title,
  });

  win.on('closed', () => {
    if (!active) {
      return;
    }

    active = false;
    options.onClosed();
  });

  return {
    close: () => {
      if (!active) {
        return;
      }

      active = false;
      win.close();
    },
  };
}