import { existsSync } from 'node:fs';

type Env = NodeJS.ProcessEnv;
type Check = (env: Env) => boolean;

const set =
  (...names: string[]): Check =>
  (env) =>
    names.some((name) => Boolean(env[name]));
const matches =
  (name: string, pattern: RegExp): Check =>
  (env) =>
    pattern.test(env[name] ?? '');
const noTTY =
  (check: Check): Check =>
  (env) =>
    !process.stdout.isTTY && check(env);

const AGENTS: Array<[name: string, check: Check]> = [
  [
    'cursor-cli',
    (env) => set('CURSOR_AGENT')(env) || env.CURSOR_EXTENSION_HOST_ROLE === 'agent-exec',
  ],
  ['kimi', set('KIMI_PLUGIN_ROOT')],
  ['grok', set('GROK_PLUGIN_ROOT', 'GROK_PLUGIN_DATA')],
  ['gemini_cli', set('GEMINI_CLI')],
  ['cline', set('CLINE_ACTIVE')],
  [
    'codex_cli',
    set('CODEX_SANDBOX', 'CODEX_CI', 'CODEX_THREAD_ID', 'CODEX_SANDBOX_NETWORK_DISABLED'),
  ],
  ['antigravity', set('ANTIGRAVITY_AGENT', 'ANTIGRAVITY_CLI_ALIAS')],
  ['augment-cli', set('AUGMENT_AGENT')],
  ['open_code', (env) => set('OPENCODE')(env) || noTTY(set('OPENCODE_CLIENT'))(env)],
  ['goose', noTTY(set('GOOSE_PROVIDER'))],
  ['junie', set('JUNIE_DATA', 'JUNIE_SHIM_PATH')],
  ['pi', matches('PATH', /\.pi[\\/]agent/)],
  ['cowork', (env) => set('CLAUDE_CODE_IS_COWORK')(env) && set('CLAUDECODE', 'CLAUDE_CODE')(env)],
  ['claude_code', (env) => set('CLAUDECODE', 'CLAUDE_CODE')(env) || env.TERM_PROGRAM === 'claude'],
  ['github-copilot', noTTY(set('COPILOT_MODEL', 'COPILOT_ALLOW_ALL'))],
  ['openclaw', set('OPENCLAW_SHELL')],
  ['devin', (env) => matches('EDITOR', /devin/)(env) || existsSync('/opt/.devin')],
  ['replit', noTTY(set('REPL_ID'))],
  ['kiro', noTTY(matches('TERM_PROGRAM', /kiro/))],
  ['cursor', noTTY(set('CURSOR_TRACE_ID'))],
];

export function detectAgent(env: Env = process.env): string | undefined {
  const explicit = (env.AI_AGENT || env.AGENT)?.trim();
  if (explicit) return explicit.toLowerCase();
  return AGENTS.find(([, check]) => check(env))?.[0];
}

export function isCI(env: Env = process.env): boolean {
  return Boolean(env.CI && env.CI !== 'false' && env.CI !== '0');
}