import { existsSync } from 'node:fs'
import * as os from 'node:os'
import * as path from 'node:path'
import process from 'node:process'

/**
 * 解析 claude 可执行文件绝对路径；找不到返回 null。
 *
 * 顺序：env.PATH 各目录下的 claude → 官方/常见绝对路径候选。
 * GUI 启动的 VS Code 常缺 ~/.local/bin，不能只靠 spawn('claude')。
 */
export function resolveClaudeBin(
  env: NodeJS.ProcessEnv = process.env,
  homeDir?: string,
): string | null {
  const home = homeDir ?? env.HOME ?? os.homedir()

  for (const dir of (env.PATH ?? '').split(path.delimiter)) {
    if (!dir)
      continue
    const candidate = path.join(dir, 'claude')
    if (existsSync(candidate))
      return candidate
  }

  const fallbacks = [
    path.join(home, '.local', 'bin', 'claude'),
    '/usr/local/bin/claude',
    '/usr/bin/claude',
    path.join(home, '.claude', 'local', 'claude'),
  ]
  for (const candidate of fallbacks) {
    if (existsSync(candidate))
      return candidate
  }
  return null
}