// Drives `s3d login` through a pseudo-terminal. s3d reads the recovery phrase
// with term.ReadPassword, which needs a real console, so plain pipes fail.
// The phrase only ever lives in this process's memory: it is written to the
// pty and never logged or emitted except the one-time display of a phrase
// s3d generated, which the user has to copy down.

import { EventEmitter } from 'node:events';
import { spawn } from 'node:child_process';
import { loadPty } from './pty.js';

const ANSI = /\x1b\[[0-9;?]*[A-Za-z]|\x1b\][^\x07]*\x07/g;

export class LoginSession extends EventEmitter {
  // registration: async () => ({ registered, indexerUrl }), used to learn the
  // outcome when login ran in a console window we cannot read.
  // ptyDir: where terminal support may be downloaded if the host lacks it.
  constructor(daemon, { registration, ptyDir } = {}) {
    super();
    this.daemon = daemon;
    this.registration = registration;
    this.ptyDir = ptyDir;
    this.term = null;
    this.buffer = '';
    this.state = 'idle';
    // idle | indexer | phrase | confirm | approve | registering | done | already | failed
    this.info = {};
  }

  snapshot() { return { state: this.state, ...this.info }; }

  set(state, info = {}) {
    this.state = state;
    Object.assign(this.info, info);
    this.emit('state', this.snapshot());
  }

  async start({ indexerUrl, phrase }) {
    if (this.term) throw new Error('a login is already in progress');
    this.answers = { indexerUrl: indexerUrl || '', phrase: phrase || '' };
    // Kept in the state so "done" says which indexer this s3d now uses
    // (a blank answer means s3d's default, sia.storage).
    this.info = { indexerUrl: indexerUrl || 'https://sia.storage' };
    this.set('preparing');
    let pty = null;
    try {
      pty = await loadPty({ installDir: this.ptyDir });
    } catch (e) {
      this.lastError = e.message;
    }
    // Without terminal support, run s3d login in its own console window.
    if (!pty) return this.startInConsole();
    this.buffer = '';
    this.generated = null;
    this.lastError = null;
    const term = pty.spawn(this.daemon.binary, ['login'], {
      name: 'xterm', cols: 200, rows: 50, cwd: this.daemon.cwd(), env: this.daemon.env(),
    });
    this.term = term;
    this.set('starting');
    // A cancelled session's pty can still flush output or exit after a new
    // one started; only the current term may drive the state machine.
    term.onData((d) => {
      if (this.term !== term) return;
      try { this.onData(d); } catch (e) { this.fail(e.message); }
    });
    term.onExit(({ exitCode }) => {
      if (this.term !== term) return;
      this.term = null;
      this.answers = null;
      if (!['done', 'already'].includes(this.state)) {
        this.set('failed', { error: this.lastError || `s3d login exited with code ${exitCode}` });
      }
    });
    return this.snapshot();
  }

  // Fallback when the pty module is not shipped (the Theseus add-on): run
  // s3d login in its own console window and check the result when it closes.
  startInConsole() {
    if (process.platform !== 'win32') {
      throw new Error('run "s3d login" in a terminal on this machine, then reload this page');
    }
    // detached gives a console app its own visible console window on Windows.
    const child = spawn(this.daemon.binary, ['login'], {
      cwd: this.daemon.cwd(), env: this.daemon.env(), detached: true, stdio: 'ignore', windowsHide: false,
    });
    this.term = { kill: () => child.kill(), write() {} };
    const term = this.term;
    this.answers = null;
    this.set('terminal');
    child.on('error', (e) => { if (this.term === term) this.fail(e.message); });
    child.on('exit', async () => {
      if (this.term !== term) return;
      this.term = null;
      try {
        const r = await this.registration();
        if (r.registered) this.set('done', { indexerUrl: r.indexerUrl });
        else this.set('failed', { error: 'the login window closed before registration finished' });
      } catch (e) { this.set('failed', { error: e.message }); }
    });
    return this.snapshot();
  }

  // The user confirms they stored a phrase s3d generated; we echo it back.
  confirmGenerated() {
    if (this.state !== 'confirm' || !this.generated) throw new Error('nothing to confirm');
    this.write(this.generated);
    this.generated = null;
    this.info.generatedPhrase = undefined;
    this.set('approve-wait');
  }

  cancel() {
    if (this.term) { try { this.term.kill(); } catch {} }
    this.term = null;
    this.answers = null;
    this.generated = null;
    this.set('idle', { error: undefined, approvalUrl: undefined, generatedPhrase: undefined });
  }

  write(s) { this.term?.write(s + '\r'); }

  onData(chunk) {
    this.buffer += chunk.replace(ANSI, '');
    // Work line-by-line, but prompts have no trailing newline, so also look at
    // the unterminated tail.
    const text = this.buffer;

    // Checked first: s3d prints the error and re-prompts in the same chunk,
    // and answering that prompt with a blank would make it generate a phrase.
    const bad = text.match(/Invalid recovery phrase: (.+)$/m);
    if (bad) {
      // s3d would re-prompt forever; stop and let the user retype.
      return this.fail(`invalid recovery phrase: ${bad[1].trim()}`);
    }
    if (/already registered with (\S+?)\.?\s*$/m.test(text)) {
      const m = text.match(/already registered with (\S+?)\.?\s*$/m);
      this.buffer = '';
      return this.set('already', { indexerUrl: m[1] });
    }
    if (/Indexer URL \(default: [^)]*\):\s*$/.test(text)) {
      this.buffer = '';
      this.set('indexer');
      return this.write(this.answers.indexerUrl);
    }
    if (/Recovery Phrase:\s*(.+)$/m.test(text) && !this.generated) {
      // s3d generated a phrase because we sent a blank one.
      this.generated = text.match(/Recovery Phrase:\s*(.+)$/m)[1].trim();
    }
    if (/Confirm recovery phrase:\s*$/.test(text)) {
      this.buffer = '';
      if (!this.generated) return this.fail('could not read the generated recovery phrase');
      return this.set('confirm', { generatedPhrase: this.generated });
    }
    if (/Enter recovery phrase:\s*$/.test(text)) {
      this.buffer = '';
      this.set('phrase');
      const p = this.answers.phrase;
      this.answers.phrase = '';
      return this.write(p);
    }
    const url = text.match(/visiting the following URL:\s*(\S+)/);
    if (url) {
      this.buffer = text.slice(url.index + url[0].length);
      return this.set('approve', { approvalUrl: url[1] });
    }
    if (/Login successful/.test(text)) {
      this.buffer = '';
      return this.set('done');
    }
    if (/app connection was declined/.test(text)) {
      this.buffer = '';
      return this.fail('the connection was declined on the indexer');
    }
    const fatal = text.match(/^(failed to [^\n]+)$/m);
    if (fatal) this.lastError = fatal[1].trim();
    // Keep the tail bounded; anything we care about is short.
    if (this.buffer.length > 8192) this.buffer = this.buffer.slice(-2048);
  }

  fail(error) {
    const term = this.term;
    this.term = null;
    this.answers = null;
    this.generated = null;
    this.set('failed', { error, generatedPhrase: undefined });
    if (term) { try { term.kill(); } catch {} }
  }
}