import { homedir } from 'node:os';

const EXPLICIT_AGENT_RUNTIMES = new Set([
  'claude_code',
  'claude_cowork',
  'codex',
  'cline',
  'cursor',
  'gemini',
  'antigravity',
  'windsurf',
  'unknown',
]);

function truthyEnv(name: string): boolean {
  return ['1', 'true', 'yes', 'on'].includes(
    String(process.env[name] ?? '')
      .trim()
      .toLowerCase(),
  );
}

export function normalizeAgentRuntime(
  value: string | undefined,
): string | null {
  const explicit = value?.trim().toLowerCase().replace(/-/g, '_');
  if (!explicit) return null;
  if (explicit === 'gemini_cli') return 'gemini';
  return EXPLICIT_AGENT_RUNTIMES.has(explicit) ? explicit : null;
}

export function isCoworkLikeSandbox(): boolean {
  const pluginMode = truthyEnv('DEEPLINE_PLUGIN_MODE');
  const claudeRemote = truthyEnv('CLAUDE_CODE_REMOTE');
  const projectDir = Boolean(process.env.CLAUDE_PROJECT_DIR?.trim());
  const pluginRoot = Boolean(process.env.DEEPLINE_PLUGIN_ROOT?.trim());
  const home = process.env.HOME?.trim() || homedir();
  const sessionHome = home === '/sessions' || home.startsWith('/sessions/');
  return (
    claudeRemote || sessionHome || ((pluginMode || pluginRoot) && projectDir)
  );
}

export function detectAgentRuntime(
  options: { defaultRuntime?: string; detectCowork?: boolean } = {},
): string {
  const explicit = normalizeAgentRuntime(process.env.DEEPLINE_AGENT_RUNTIME);
  if (explicit) return explicit;
  if (process.env.CODEX_THREAD_ID?.trim()) return 'codex';
  if (options.detectCowork !== false && isCoworkLikeSandbox()) {
    return 'claude_cowork';
  }
  if (process.env.CLAUDECODE?.trim() === '1') return 'claude_code';
  if (process.env.CLINE_ACTIVE?.trim().toLowerCase() === 'true') return 'cline';
  if (process.env.CURSOR_TRACE_ID?.trim() || process.env.CURSOR_AGENT?.trim()) {
    return 'cursor';
  }
  if (process.env.WINDSURF?.trim() || process.env.CASCADE?.trim()) {
    return 'windsurf';
  }
  if (
    process.env.ANTIGRAVITY?.trim() ||
    process.env.ANTIGRAVITY_CLI?.trim() ||
    process.env.ANTIGRAVITY_AGENT?.trim() ||
    process.env.ANTIGRAVITY_WORKSPACE?.trim()
  ) {
    return 'antigravity';
  }
  if (
    process.env.GEMINI_CLI?.trim() ||
    process.env.GEMINI_CLI_VERSION?.trim() ||
    process.env.GEMINI_SANDBOX?.trim() ||
    process.env.GEMINI_CONFIG_DIR?.trim()
  ) {
    return 'gemini';
  }
  return options.defaultRuntime ?? 'unknown';
}