import { execSync } from 'node:child_process';
import { existsSync } from 'node:fs';
import { homedir, platform } from 'node:os';
import { join } from 'node:path';
import { serverLog } from './server-logger';
import { posixUserBinDirs, probeViaLoginShell } from './cli-resolver-helpers';

const isWindows = platform() === 'win32';

/** Windows npm global installs may create .cmd or .ps1 wrappers — try both */
function winNpmCandidates(dir: string, name: string): string[] {
  return [join(dir, `${name}.cmd`), join(dir, `${name}.ps1`)];
}

/** On Windows, `where` may return an extensionless shell script — prefer .cmd/.ps1/.exe */
function resolveWinExtension(binPath: string): string {
  if (!isWindows) return binPath;
  if (/\.(cmd|ps1|exe)$/i.test(binPath)) return binPath;
  for (const ext of ['.cmd', '.ps1', '.exe']) {
    if (existsSync(binPath + ext)) return binPath + ext;
  }
  return binPath;
}

/**
 * Resolve the absolute path to the standalone `claude` binary.
 *
 * When Nitro bundles @anthropic-ai/claude-agent-sdk, the SDK's internal
 * `import.meta.url`-based resolution to find its own `cli.js` breaks.
 * Instead we locate the standalone native binary and pass it via
 * `pathToClaudeCodeExecutable` — the SDK detects non-.js paths as native
 * binaries and spawns them directly (no `node` wrapper needed).
 */
export function resolveClaudeCli(): string | undefined {
  serverLog.info(
    `[resolve-claude-cli] platform=${platform()}, isWindows=${isWindows}, SHELL=${process.env.SHELL ?? 'unset'}`,
  );
  serverLog.info(`[resolve-claude-cli] PATH=${(process.env.PATH ?? '').slice(0, 400)}`);

  // 1. Try PATH lookup
  try {
    const cmd = isWindows ? 'where claude 2>nul' : 'which claude 2>/dev/null';
    serverLog.info(`[resolve-claude-cli] PATH lookup: ${cmd}`);
    const raw = execSync(cmd, {
      encoding: 'utf-8',
      timeout: 3000,
    }).trim();
    const p = raw.split(/\r?\n/)[0]; // `where` on Windows may return multiple lines
    serverLog.info(
      `[resolve-claude-cli] PATH lookup result: "${p}" (exists=${p ? existsSync(p) : false})`,
    );
    if (p && existsSync(p)) return resolveWinExtension(p);
  } catch (err) {
    serverLog.info(
      `[resolve-claude-cli] PATH lookup failed: ${err instanceof Error ? err.message : err}`,
    );
  }

  // 2. On macOS/Linux, ask the user's login shell — Electron does not
  //    inherit the user's shell config, so nvm/pnpm/bun/mise/asdf shims are
  //    invisible to a bare `which`. This is the single most common cause of
  //    "CLI installed but OpenPencil can't find it" reports on Mac.
  if (!isWindows) {
    const viaShell = probeViaLoginShell('claude', 'resolve-claude-cli');
    if (viaShell) return viaShell;
  }

  // 3. Try `npm prefix -g` to find actual npm global bin directory
  //    On Windows, must use `npm.cmd` since Electron spawns cmd.exe
  if (isWindows) {
    try {
      serverLog.info('[resolve-claude-cli] trying npm.cmd prefix -g');
      const prefix = execSync('npm.cmd prefix -g', {
        encoding: 'utf-8',
        timeout: 5000,
      }).trim();
      serverLog.info(`[resolve-claude-cli] npm global prefix: "${prefix}"`);
      if (prefix) {
        for (const bin of winNpmCandidates(prefix, 'claude')) {
          serverLog.info(
            `[resolve-claude-cli] checking npm global bin: "${bin}" (exists=${existsSync(bin)})`,
          );
          if (existsSync(bin)) return bin;
        }
      }
    } catch (err) {
      serverLog.info(
        `[resolve-claude-cli] npm prefix -g failed: ${err instanceof Error ? err.message : err}`,
      );
    }
  }

  // 4. Common install locations
  const candidates = isWindows
    ? [
        // npm global (.cmd + .ps1)
        ...winNpmCandidates(join(process.env.APPDATA || '', 'npm'), 'claude'),
        // nvm-windows / fnm
        ...winNpmCandidates(join(process.env.NVM_SYMLINK || ''), 'claude'),
        ...winNpmCandidates(join(process.env.FNM_MULTISHELL_PATH || ''), 'claude'),
        // Native .exe install locations
        join(process.env.LOCALAPPDATA || '', 'Programs', 'claude-code', 'claude.exe'),
        join(process.env.LOCALAPPDATA || '', 'Microsoft', 'WinGet', 'Links', 'claude.exe'),
        join(homedir(), '.claude', 'local', 'claude.exe'),
        join(homedir(), 'AppData', 'Local', 'Programs', 'claude-code', 'claude.exe'),
      ]
    : posixUserBinDirs().map((dir) => join(dir, 'claude'));
  for (const c of candidates) {
    const exists = c ? existsSync(c) : false;
    serverLog.info(`[resolve-claude-cli] candidate: "${c}" (exists=${exists})`);
    if (c && exists) return c;
  }

  serverLog.warn(
    '[resolve-claude-cli] no claude binary found after PATH, login-shell probe, and candidate scan',
  );
  return undefined;
}