/**
 * Cross-platform open-with-default-application used by the local GUI carrier.
 *
 * A document a browser RENDERS is opened with the user's default browser
 * rather than the default application for its type, when the platform can name
 * one: a developer who binds `.html` to an editor would otherwise click a
 * produced page and get source code. The contract is uniform — prefer the
 * default browser, fall back to the default application — while how completely
 * a platform can answer "which browser" differs, and every failure falls back
 * rather than surfacing.
 */

import { extname } from 'node:path'
import { runNativeCommand, type NativeCommandRunner } from '@deepseek-ai/dsh-native-command'

/** Testable command boundary; native implementations never invoke a shell. */
export type PathOpenerRunner = NativeCommandRunner

/** Injectable platform facts for deterministic adapter tests. */
export interface PathOpenerInternals {
  platform?: NodeJS.Platform
  run?: PathOpenerRunner
  /** Environment the linux browser convention reads; defaults to the process env. */
  env?: NodeJS.ProcessEnv
}

/** Documents a browser renders, as opposed to ones an editor merely edits. */
const BROWSER_DOCUMENTS = new Set(['.html', '.htm', '.xhtml', '.svg'])

/**
 * The macOS bundle registered for `https` — the default browser, as
 * LaunchServices records it. The nested version dict is stripped first
 * because it carries its own `LSHandlerRoleAll`.
 */
function macBundleForHttps(plist: string): string | undefined {
  const stripped = plist.replace(/LSHandlerPreferredVersions\s*=\s*\{[^}]*\};/g, '')
  const block = /\{[^{}]*LSHandlerURLScheme\s*=\s*"?https"?;[^{}]*\}/.exec(stripped)?.[0]
  if (block === undefined) return undefined
  return /LSHandlerRoleAll\s*=\s*"?([\w.-]+)"?;/.exec(block)?.[1]
}

/**
 * Open one browser-renderable document with the default browser.
 * @returns true when a browser took it; false when this platform cannot name
 * one, or naming it failed — the caller then uses the default application.
 */
async function openInBrowser(
  path: string, signal: AbortSignal, platform: NodeJS.Platform,
  run: PathOpenerRunner, env: NodeJS.ProcessEnv,
): Promise<boolean> {
  if (platform === 'darwin') {
    let bundle: string | undefined
    try {
      const { stdout } = await run(
        'defaults', ['read', 'com.apple.LaunchServices/com.apple.launchservices.secure'], signal)
      bundle = macBundleForHttps(stdout)
    } catch {
      // No LaunchServices record (a fresh account never changed a default):
      // the content-type handler is then the system's own choice anyway.
      return false
    }
    if (bundle === undefined) return false
    await run('open', ['-b', bundle, path], signal)
    return true
  }
  if (platform === 'linux') {
    // $BROWSER is the portable convention; desktop-entry resolution through
    // xdg-settings needs a launcher this package has no business shipping.
    const browser = env.BROWSER
    if (browser === undefined || browser === '') return false
    await run(browser, [path], signal)
    return true
  }
  // Windows names no browser without reading the UserChoice registry, and its
  // .html association is the browser in the ordinary case.
  return false
}

/** PowerShell single-quoted literal (doubles embedded quotes). */
function powershellLiteral(path: string): string {
  return `'${path.replace(/'/g, "''")}'`
}

/**
 * Open a filesystem path with the operating system's default application, or
 * with the default browser when the path names a document a browser renders.
 * @param path - absolute or host-resolvable path (caller owns resolution).
 * @param signal - caller/connection lifetime; abort terminates the native command.
 * @param internals - platform, environment, and runner seam for deterministic tests.
 */
export async function openNativePath(
  path: string,
  signal: AbortSignal,
  internals: PathOpenerInternals = {},
): Promise<void> {
  const platform = internals.platform ?? process.platform
  const run = internals.run ?? runNativeCommand
  const env = internals.env ?? process.env

  if (BROWSER_DOCUMENTS.has(extname(path).toLowerCase())
    && await openInBrowser(path, signal, platform, run, env)) return

  if (platform === 'darwin') {
    await run('open', [path], signal)
    return
  }

  if (platform === 'win32') {
    await run('powershell.exe', [
      '-NoProfile',
      '-Command',
      `Invoke-Item -LiteralPath ${powershellLiteral(path)}`,
    ], signal)
    return
  }

  if (platform === 'linux') {
    await run('xdg-open', [path], signal)
    return
  }

  throw new Error(`native path opener is unsupported on ${platform}`)
}