// System-level actions Studio invokes by spawning the `fai`
// binary or asking the OS to open a file. Used by Doctor's
// daemon-control + open-paths affordances so Windows operators
// who never touch a shell can restart the daemon, apply an
// update, or open a log file from inside the GUI.
//
// Cross-platform notes:
// - macOS uses `open` for files + URLs.
// - Linux uses `xdg-open`.
// - Windows uses `explorer` (file manager) and a quoted CLI
//   call for processes.
//
// The `fai` binary is resolved from PATH first; falls back to
// `~/.fai/bin/fai` (Unix) or `%USERPROFILE%\.fai\bin\fai.exe`
// (Windows). The PowerShell installer puts both in PATH but
// some operators don't restart their shell after install — the
// fallback covers that case.

import 'dart:io';

class SystemActions {
  SystemActions._();

  /// Ask the OS to open [path] in the default handler. On macOS
  /// this opens text files in TextEdit, configs in the registered
  /// editor, etc. Returns true on a clean spawn (process exited
  /// non-zero is still surfaced as false).
  static Future<({bool ok, String stderr})> openInOs(String path) async {
    if (path.isEmpty) {
      return (ok: false, stderr: 'empty path');
    }
    final cmd = _openCommand();
    try {
      final r = await Process.run(cmd.executable, [...cmd.args, path]);
      if (r.exitCode == 0) return (ok: true, stderr: '');
      return (ok: false, stderr: r.stderr.toString().trim());
    } catch (e) {
      return (ok: false, stderr: e.toString());
    }
  }

  /// Run a `fai daemon ...` subcommand and surface the captured
  /// output. Used by Doctor's "Restart daemon" button.
  static Future<({bool ok, String stdout, String stderr})> faiDaemon(
    List<String> args,
  ) async {
    return _runFai(['daemon', ...args]);
  }

  /// Run `fai update apply --channel <c>`. Long-running on a slow
  /// network — caller should show a spinner.
  static Future<({bool ok, String stdout, String stderr})> faiUpdateApply(
    String channel,
  ) async {
    return _runFai(['update', 'apply', '--channel', channel]);
  }

  /// Switch the active channel pointer at `~/.fai/current-channel`.
  /// The CLI also restarts the daemon for the new channel, so the
  /// caller does not need a follow-up restart.
  static Future<({bool ok, String stdout, String stderr})> faiChannelSwitch(
    String channel,
  ) async {
    return _runFai(['channel', 'switch', channel]);
  }

  /// Install the platform-native autostart unit for [channel]
  /// (launchd plist on macOS, systemd-user unit on Linux). On
  /// Windows the platform CLI returns a "not supported" exit
  /// status that the caller surfaces as an error message.
  static Future<({bool ok, String stdout, String stderr})> faiDaemonEnable(
    String channel,
  ) async {
    return _runFai(['daemon', 'enable', '--channel', channel]);
  }

  /// Remove the autostart unit installed by [faiDaemonEnable].
  static Future<({bool ok, String stdout, String stderr})> faiDaemonDisable(
    String channel,
  ) async {
    return _runFai(['daemon', 'disable', '--channel', channel]);
  }

  static Future<({bool ok, String stdout, String stderr})> _runFai(
    List<String> args,
  ) async {
    final exe = _faiExecutable();
    if (exe == null) {
      return (
        ok: false,
        stdout: '',
        stderr: 'Could not locate the `fai` binary. Install via the '
            'platform installer or set FAI_BIN to its full path.',
      );
    }
    try {
      final r = await Process.run(exe, args);
      return (
        ok: r.exitCode == 0,
        stdout: r.stdout.toString(),
        stderr: r.stderr.toString(),
      );
    } catch (e) {
      return (ok: false, stdout: '', stderr: e.toString());
    }
  }

  static ({String executable, List<String> args}) _openCommand() {
    if (Platform.isMacOS) return (executable: 'open', args: const []);
    if (Platform.isWindows) return (executable: 'explorer', args: const []);
    return (executable: 'xdg-open', args: const []);
  }

  /// Locate the `fai` binary. Order: $FAI_BIN, PATH, fallback to
  /// the canonical install location under the user's home dir.
  static String? _faiExecutable() {
    final fromEnv = Platform.environment['FAI_BIN'];
    if (fromEnv != null && fromEnv.isNotEmpty && File(fromEnv).existsSync()) {
      return fromEnv;
    }

    final isWindows = Platform.isWindows;
    final fromPath = _whichFai(isWindows ? 'fai.exe' : 'fai');
    if (fromPath != null) return fromPath;

    final home = Platform.environment[isWindows ? 'USERPROFILE' : 'HOME'];
    if (home == null || home.isEmpty) return null;
    final fallback = isWindows
        ? '$home\\.fai\\bin\\fai.exe'
        : '$home/.fai/bin/fai';
    return File(fallback).existsSync() ? fallback : null;
  }

  /// Tiny PATH walker — we cannot rely on `which`/`where` being
  /// reachable via Process.run on every platform.
  static String? _whichFai(String name) {
    final pathEnv = Platform.environment['PATH'];
    if (pathEnv == null || pathEnv.isEmpty) return null;
    final sep = Platform.isWindows ? ';' : ':';
    final slash = Platform.isWindows ? '\\' : '/';
    for (final dir in pathEnv.split(sep)) {
      if (dir.isEmpty) continue;
      final candidate = '$dir$slash$name';
      if (File(candidate).existsSync()) return candidate;
    }
    return null;
  }
}