// The e-mail server's SMTP and POP3 dialogues (apps/emailServer.ts) against
// Java FILIUS' own: tools/java-oracle's MailCases fed Java's workers with the
// messages of email-server.cases.txt (email-server.<de|en>.java.json). After
// each message: what was sent, the window's lines, whether the connection
// was closed, and the accounts must be Java's, in both languages, except
// where Java errs.

import { readFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { describe, expect, it } from 'vitest';
import {
  addressEntry,
  EMAIL_SERVER_ACCOUNTS_FILE,
  serverAccountsFileText,
  VirtualFileSystem,
  deviceConfiguration,
  NetworkRuntimeEngine,
  topologySnapshot,
  type TopologySnapshotInput,
  addressText,
  formatMail,
  isMailAddress,
  mailboxEntry,
  MailServerState,
  mailSize,
  parseMail,
  Pop3Session,
  SmtpSession,
  type EmailServerLogEntry,
  type MailAccount,
  type PageLanguage,
  type Steps,
} from '../src/index.js';
import { link, pc, uuid } from './fixtures.js';
import { MAIL_ACCOUNTS } from './mailAccounts.js';
import { emailServerText } from './programLines.js';

const here = dirname(fileURLToPath(import.meta.url));

type JavaAccounts = [string, [string, boolean, boolean][]][];

interface JavaStep {
  message: string | null;
  sent: string[];
  lines: string[];
  closed: boolean;
  thrown: string | null;
  accounts: JavaAccounts;
}

interface JavaCase {
  name: string;
  protocol: 'smtp' | 'pop3';
  steps: JavaStep[];
}

const CLIENT = '192.168.0.20';

/** Without a network, no mail goes to another domain (MailCases: Java's server thread never runs). */
const NO_OUTBOX = {
  forward: () => undefined,
  *lookUpAndSend(): Steps<string[]> {
    return [];
  },
};

/** Runs a dialogue's steps to their end: nothing waits here, the connection sends at once. */
function run(steps: Steps): void {
  for (let next = steps.next(); next.done !== true; next = steps.next()) throw new Error('a step waited');
}

/** The session's own run of a case: each step as MailCases writes Java's. */
function play(javaCase: JavaCase, language: PageLanguage): JavaStep[] {
  const lines: EmailServerLogEntry[] = [];
  const accounts: MailAccount[] = MAIL_ACCOUNTS.map((account) => ({ ...account, mailbox: account.mailbox.map(mailboxEntry) }));
  const state = new MailServerState(
    'filius.de',
    accounts,
    language,
    (entry) => lines.push(entry),
    () => undefined,
    () => '192.168.0.30',
    () => 0,
    NO_OUTBOX,
  );
  const sent: string[] = [];
  const connection = {
    address: CLIENT,
    *send(text: string): Steps<boolean> {
      sent.push(text);
      return true;
    },
  };
  const session = javaCase.protocol === 'smtp' ? new SmtpSession(state, connection) : new Pop3Session(state, connection);
  const step = (text: string | null): JavaStep => {
    const result: JavaStep = {
      message: text,
      sent: [...sent],
      lines: lines.map((entry) => emailServerText(entry, language)),
      closed: session.closed,
      thrown: null,
      accounts: accounts.map((account) => [account.username, account.mailbox.map((entry) => [formatMail(entry.mail), entry.isNew, entry.isMarkedForDeletion])]),
    };
    sent.length = 0;
    lines.length = 0;
    return result;
  };
  run(session.begin());
  const steps = [step(null)];
  for (const each of javaCase.steps.slice(1)) {
    run(session.receive(each.message!));
    steps.push(step(each.message));
  }
  return steps;
}

/** Java's date of a notice, in its locale and time: a placeholder. */
const withoutDate = (text: string) => text.replace(/\nDate: [^\n]*\n/g, '\nDate: <date>\n');

const stored = (username: string, language: PageLanguage) => emailServerText({ kind: 'stored', username }, language);

/**
 * A step as Java means it: the answers given, the window's lines rebuilt
 * from them (received, sent, then the mails stored), the accounts as given.
 */
function fixed(
  step: JavaStep,
  language: PageLanguage,
  changes: { sent?: string[]; stored?: string[]; accounts?: JavaAccounts; closed?: boolean },
): JavaStep {
  const sent = changes.sent ?? step.sent;
  const storedLines = changes.stored?.map((username) => stored(username, language)) ?? step.lines.filter((line) => !line.startsWith(`${CLIENT}`));
  return {
    ...step,
    sent,
    lines: [`${CLIENT}< ${step.message}`, ...sent.map((text) => `${CLIENT}> ${text}`), ...storedLines],
    closed: changes.closed ?? step.closed,
    thrown: null,
    accounts: changes.accounts ?? step.accounts,
  };
}

type Fix = (steps: JavaStep[], language: PageLanguage) => JavaStep[];

/** Each step from `from` on with the accounts given (a mail Java stores differently changes every later step). */
const accountsFrom = (steps: JavaStep[], from: number, accounts: JavaAccounts) => steps.map((step, index) => (index >= from ? { ...step, accounts } : step));

const order = (language: PageLanguage) => (language === 'de' ? '503 Falsche Reihenfolge der Kommandos.' : '503 Wrong order of commands.');
const queued = '250 Mail queued for delivery';
const noSuchMessage = '-ERR no such message';
const unknownCommand = '-ERR unknown command';

function addTo(accounts: JavaAccounts, username: string, ...mails: [string, boolean, boolean][]): JavaAccounts {
  return accounts.map(([name, mailbox]) => [name, name === username ? [...mailbox, ...mails] : mailbox]);
}

/**
 * Where Java errs, the case as Java means it (the core's departures, see
 * emailServer.ts).
 */
const JAVA_BUGS: Record<string, Fix> = {
  // After a mail Java answers the next command 503 and keeps sender,
  // recipients and text: the second mail went to anna too, with the first's text.
  smtpTwice: (steps, language) => {
    const start = steps[0]!.accounts;
    const first = steps[6]!.accounts.find(([name]) => name === 'anna')![1].at(-1)!;
    const second: [string, boolean, boolean] = ['From: <anna@filius.de>\nTo: <bob@filius.de>\nSubject: Zwei\n\nan Bob', true, false];
    const result = steps.map((step, index) => (index === 7 ? fixed(step, language, { sent: ['250 Sender OK'] }) : step));
    result[11] = fixed(steps[11]!, language, { stored: ['bob'] });
    return accountsFrom(result, 11, addTo(addTo(start, 'anna', first), 'bob', second));
  },
  // A command the state does not take: Java answers nothing.
  smtpStart: (steps, language) => steps.map((step, index) => (index === 1 || index === 2 ? fixed(step, language, { sent: [order(language)] }) : step)),
  // HELO again: Java answers nothing; the core begins anew.
  smtpHelo: (steps, language) => steps.map((step, index) => (index === 3 ? fixed(step, language, { sent: ['250 Hello wieder'] }) : step)),
  // "MAIL  FROM" (two spaces) and HELO again: Java answers nothing. After
  // HELO the envelope is new: DATA and the text are out of order, nothing is stored.
  smtpEnvelope: (steps, language) => {
    const result = steps.map((step, index) => {
      if (index === 3) return fixed(step, language, { sent: [order(language)] });
      if (index === 8) return fixed(step, language, { sent: ['250 Hello noch einmal'] });
      if (index === 9 || index === 10) return fixed(step, language, { sent: [order(language)], stored: [] });
      return step;
    });
    return accountsFrom(result, 10, steps[0]!.accounts);
  },
  // Java compares the domain exactly and sends the mail on; anna@FILIUS.DE is anna's.
  smtpDomainCase: (steps, language) => {
    const mail: [string, boolean, boolean] = ['Subject: Gross\n\nText', true, false];
    const result = steps.map((step, index) => (index === 5 ? fixed(step, language, { stored: ['anna'] }) : step));
    return accountsFrom(result, 5, addTo(steps[0]!.accounts, 'anna', mail));
  },
  // A field Java does not know ends its header, and Subject became text.
  smtpUnknownHeader: (steps) => accountsFrom(steps, 5, addTo(steps[0]!.accounts, 'anna', ['From: <bob@filius.de>\nSubject: Betreff\n\nText', true, false])),
  // A line without a field name (": leer") ends Java's header and is dropped; the core's text begins with it.
  smtpColonFirst: (steps) => accountsFrom(steps, 5, addTo(steps[0]!.accounts, 'anna', ['Subject: vorn\n\n: leer\n\nText', true, false])),
  // Without a header Java drops the first line.
  smtpNoHeader: (steps) => accountsFrom(steps, 5, addTo(steps[0]!.accounts, 'anna', ['\nHallo\nWelt', true, false])),
  // "quit" during DATA: Java ends the connection; it is the mail's text.
  smtpQuitInData: (steps, language) => steps.map((step, index) => (index === 6 ? { ...fixed(step, language, { sent: [], closed: false }), lines: [`${CLIENT}< quit`] } : step)),
  // An empty sender: Java's notice throws (NullPointerException); none is sent.
  smtpEmptySender: (steps, language) => steps.map((step, index) => (index === 5 ? fixed(step, language, {}) : step)),
  // A recipient without "@": Java's delivery throws; the core sends the sender a notice, to the
  // envelope's sender, as the mail has no From.
  smtpWithoutAt: (steps, language) => {
    const notice: [string, boolean, boolean] = [
      'From: <noreply@filius.de>\nTo: <bob@filius.de>\nSubject: Non Delivery Notification\n\n' +
        'The mail could not be delivered either because user or mail domain is unknown.\nMessage could not be delivered to the following recipients:\n\tanna\n\n' +
        'Date: <date>\nMail-Server: 192.168.0.30\n\n______________________________________________________________________\nSubject: Ohne\n\nText',
      true,
      false,
    ];
    const result = steps.map((step, index) => (index === 5 ? fixed(step, language, { sent: [queued], stored: ['bob'] }) : step));
    return accountsFrom(result, 5, addTo(steps[0]!.accounts, 'bob', notice));
  },
  // RETR of a message retrieved before: Java refuses.
  pop3Again: (steps, language) => steps.map((step, index) => (index === 4 ? fixed(step, language, { sent: steps[3]!.sent }) : step)),
  // After DELE 0, Java's LIST numbers the other message 0; RETR 0 still means the deleted one.
  pop3Numbers: (steps, language) => steps.map((step, index) => (index === 4 ? fixed(step, language, { sent: ['+OK 1 89\n1 89\n'] }) : step)),
  // LIST without messages: Java's list fails.
  pop3EmptyList: (steps, language) => steps.map((step, index) => (index === 4 ? fixed(step, language, { sent: ['+OK 0 0\n'] }) : step)),
  // Before log-in Java answers empty.
  pop3Before: (steps, language) =>
    steps.map((step, index) => (index >= 1 && index <= 5 ? fixed(step, language, { sent: [unknownCommand] }) : index === 7 ? fixed(step, language, { sent: ['+OK'] }) : step)),
  // A message that is not there: Java sends an empty mail or an empty
  // answer; LIST 0 lists all; RETR x throws and ends the connection.
  pop3BadArguments: (steps, language) =>
    steps.map((step, index) => {
      if (index === 3 || index === 4 || index === 5 || index === 9) return fixed(step, language, { sent: [noSuchMessage] });
      if (index === 6) return fixed(step, language, { sent: ['+OK 0 80'] });
      return step;
    }),
  // USER without a name: Java throws and ends the connection.
  pop3NoArgument: (steps, language) => steps.map((step, index) => (index === 1 ? fixed(step, language, { sent: ['-ERR user or password wrong'] }) : step)),
  // Two spaces before the number: Java throws and ends the connection.
  pop3TwoSpaces: (steps, language) => steps.map((step, index) => (index === 3 ? fixed(step, language, { sent: [noSuchMessage] }) : step)),
};

function javaCases(language: PageLanguage): JavaCase[] {
  return JSON.parse(readFileSync(join(here, `email-server.${language}.java.json`), 'utf8')) as JavaCase[];
}

const placeholders = (step: JavaStep): JavaStep => ({
  ...step,
  accounts: step.accounts.map(([name, mailbox]) => [name, mailbox.map(([text, isNew, deleted]) => [withoutDate(text), isNew, deleted])]),
});

describe("the e-mail server's dialogues as Java FILIUS answers them", () => {
  for (const language of ['de', 'en'] as const) {
    const cases = javaCases(language);

    it(`corrects Java only where it errs (${language})`, () => {
      for (const [name, fix] of Object.entries(JAVA_BUGS)) {
        const javaCase = cases.find((each) => each.name === name)!;
        expect(JSON.stringify(fix(javaCase.steps, language)), name).not.toBe(JSON.stringify(javaCase.steps));
      }
    });

    for (const javaCase of cases) {
      it(`${javaCase.name} (${language})`, () => {
        const expected = (JAVA_BUGS[javaCase.name]?.(javaCase.steps, language) ?? javaCase.steps).map(placeholders);
        const actual = play(javaCase, language).map(placeholders);
        for (const [index, step] of expected.entries()) expect(actual[index], `step ${index}: ${JSON.stringify(step.message)}`).toEqual(step);
      });
    }
  }
});

describe('e-mail as Java writes it', () => {
  it('reads addresses as AddressEntry does', () => {
    expect(addressEntry(' Anna Muster <anna@filius.de> ')).toEqual({ name: 'Anna Muster', mailAddress: 'anna@filius.de' });
    expect(addressEntry('<anna@filius.de>')).toEqual({ name: null, mailAddress: 'anna@filius.de' });
    expect(addressEntry('anna@filius.de')).toEqual({ name: null, mailAddress: 'anna@filius.de' });
    expect(addressEntry('Anna')).toEqual({ name: 'Anna', mailAddress: null });
    expect(addressEntry('a>b<c')).toEqual({ name: 'a>b<c', mailAddress: null });
    expect(addressText({ name: null, mailAddress: null })).toBeNull();
  });

  it("checks an address as Java's pattern does: an address, or a name and an address in angle brackets", () => {
    expect(isMailAddress('anna@filius.de')).toBe(true);
    expect(isMailAddress('Anna Muster <anna.m-x_1@filius.de.>')).toBe(true);
    expect(isMailAddress('anna@filius.de x')).toBe(false);
    expect(isMailAddress('Anna <anna@filius.de> x')).toBe(false);
    expect(isMailAddress('anna@')).toBe(false);
    expect(isMailAddress('anna..b@filius.de')).toBe(false);
  });

  it('writes no Bcc, and counts a size as Java does', () => {
    const mail = parseMail('From: A <a@b.de>\nTo: x@y.de, Y <y@z.de>\nBcc: geheim@b.de\nSubject:  Hallo \n\nText\n');
    expect(mail.bcc).toEqual([{ name: null, mailAddress: 'geheim@b.de' }]);
    expect(formatMail(mail)).toBe('From: A <a@b.de>\nTo: <x@y.de>, Y <y@z.de>\nSubject: Hallo\n\nText');
    expect(mailSize(mail)).toBe('Text\n'.length + 'A <a@b.de>'.length + 'Hallo'.length + '[<x@y.de>, Y <y@z.de>]'.length);
    expect(mailSize(parseMail('\nx'))).toBe('x\n'.length + 'null'.length * 2 + '[]'.length);
  });
});

const SERVER = uuid(0x5001);
const HOST = uuid(0x5002);

function mailNetwork(): TopologySnapshotInput {
  return {
    nodes: [pc(SERVER, uuid(0x5011)), pc(HOST, uuid(0x5012))],
    links: [link(SERVER, uuid(0x5011), HOST, uuid(0x5012))],
    deviceConfigurations: new Map([
      [SERVER, deviceConfiguration('10.0.0.1', '255.255.255.0', '', '')],
      [HOST, deviceConfiguration('10.0.0.2', '255.255.255.0', '', '')],
    ]),
    emailServersByNodeId: new Map([[SERVER, { domain: 'filius.de', accounts: MAIL_ACCOUNTS, isActive: true }]]),
  };
}

/** Connects to the server's port and sends each message, each after the answer to the one before; the answers, the greeting first. */
function talk(engine: NetworkRuntimeEngine, port: number, ...messages: string[]): string[] {
  const socket = engine.openTcpClientSocket(HOST, '10.0.0.1', port)!;
  if (engine.connectTcpWithResult(socket) !== 'connected') return [];
  const answers: string[] = [];
  const receive = () => {
    engine.handle({ type: 'advance', toMilliseconds: engine.state.currentTimeMilliseconds + 2_000 });
    const answer = engine.receiveTcp(socket);
    if (answer !== undefined) answers.push(new TextDecoder().decode(answer));
  };
  receive();
  for (const message of messages) {
    engine.sendTcp(socket, new TextEncoder().encode(message));
    receive();
  }
  return answers;
}

describe('the e-mail server beyond the cases', () => {
  it('writes a failed answer as Java does (sw_smtpmitarbeiter_msg14)', () => {
    const lines: EmailServerLogEntry[] = [];
    const state = new MailServerState('filius.de', [], 'de', (entry) => lines.push(entry), () => undefined, () => '10.0.0.1', () => 0, NO_OUTBOX);
    const session = new SmtpSession(state, {
      address: '10.0.0.2',
      *send(): Steps<boolean> {
        return false;
      },
    });
    run(session.begin());
    expect(lines.map((entry) => emailServerText(entry))).toEqual(['----', 'Fehler beim Senden an 10.0.0.2']);
  });

  it("takes a model's message as Java loads it from its file: the date, the subject trimmed when written, no sender as an empty name", () => {
    const entry = mailboxEntry({ ...MAIL_ACCOUNTS[0]!.mailbox[0]!, subject: ' Termin ', receivedAtMilliseconds: 1_000, from: { name: null, mailAddress: null } });
    expect(formatMail(entry.mail)).toBe('From: \nTo: <anna@filius.de>\nSubject: Termin\nDate Received: 1000\n\nErste Zeile\nZweite Zeile');
    expect(entry.mail.subject).toBe(' Termin ');
  });
});

describe('the e-mail server in the engine', () => {
  it('switches SMTP and POP3 on and off together', () => {
    const engine = new NetworkRuntimeEngine(14);
    engine.handle({ type: 'start', snapshot: topologySnapshot(mailNetwork()), seed: 14, initialTimeMilliseconds: 0 });
    const server = engine.emailServer(SERVER)!;
    expect(server.isActive).toBe(true);
    server.setActive(false);
    engine.handle({ type: 'advance', toMilliseconds: 1_000 });
    expect(server.isActive).toBe(false);
    expect(talk(engine, 25)).toEqual([]);
    expect(talk(engine, 110)).toEqual([]);
    server.setActive(true);
    expect(talk(engine, 25, 'QUIT')).toEqual(['220 Willkommen bei filius.de', '221 Server beendet Verbindung.']);
    expect(talk(engine, 110, 'QUIT')).toEqual(['+OK POP3 server ready', '+OK']);
  });

  it('writes its account file from its accounts when it starts, over one that says otherwise', () => {
    const files = new VirtualFileSystem();
    files.createDirectory('/mailserver');
    files.writeTextFile(EMAIL_SERVER_ACCOUNTS_FILE, 'alt;filius.de;alt;Alt;Alt;\n');
    const engine = new NetworkRuntimeEngine(14);
    engine.handle({ type: 'start', snapshot: topologySnapshot({ ...mailNetwork(), fileSystemsByNodeId: new Map([[SERVER, files]]) }), seed: 14, initialTimeMilliseconds: 0 });
    expect(files.textFile(EMAIL_SERVER_ACCOUNTS_FILE)).toBe(serverAccountsFileText('filius.de', MAIL_ACCOUNTS));
  });

  it('keeps its mailboxes in the snapshot: a mail taken, a mail deleted; a new start begins from there', () => {
    const engine = new NetworkRuntimeEngine(14);
    engine.handle({ type: 'start', snapshot: topologySnapshot({ ...mailNetwork(), language: 'en' }), seed: 14, initialTimeMilliseconds: 0 });
    talk(engine, 25, 'HELO x', 'MAIL FROM:<anna@filius.de>', 'RCPT TO:<bob@filius.de>', 'DATA', 'Bcc: <bob@filius.de>\nSubject: Neu\n\nText\r\n.\r\n', 'QUIT');
    talk(engine, 25, 'HELO x', 'MAIL FROM:<anna@filius.de>', 'RCPT TO:<anna@filius.de>', 'DATA', 'Ohne Kopf\n.\n', 'QUIT');
    const mailbox = (username = 'bob') => engine.state.topologySnapshot.emailServersByNodeId.get(SERVER)!.accounts.find((account) => account.username === username)!.mailbox;
    // Stored as Java reads the mail anew: no Bcc, no "\r".
    expect(mailbox()).toEqual([expect.objectContaining({ id: 4, bcc: [], subject: 'Neu', body: 'Text\n', isNew: true, isMarkedForDeletion: false })]);
    expect(mailbox('anna').at(-1)).toEqual(expect.objectContaining({ from: { name: null, mailAddress: null }, subject: '', body: 'Ohne Kopf\n' }));
    expect(talk(engine, 110, 'USER bob', 'PASS passwort', 'RETR 0', 'DELE 0')).toEqual([
      '+OK POP3 server ready',
      '+OK enter password',
      '+OK Mailbox locked and ready',
      '+OK message follows \nSubject: Neu\n\nText',
      '+OK message marked for delete',
    ]);
    expect(mailbox()).toEqual([expect.objectContaining({ isNew: false, isMarkedForDeletion: true })]);
    engine.handle({ type: 'stop' });
    engine.handle({ type: 'start', snapshot: engine.state.topologySnapshot, seed: 14, initialTimeMilliseconds: 0 });
    // As Java loads its file: every message new, none deleted; no sender is an empty name ("Text\n", "", "Neu", "[]").
    expect(talk(engine, 110, 'USER bob', 'PASS passwort', 'STAT', 'DELE 0', 'QUIT')).toEqual([
      '+OK POP3 server ready',
      '+OK enter password',
      '+OK Mailbox locked and ready',
      '+OK 1 10',
      '+OK message marked for delete',
      '+OK',
    ]);
    expect(mailbox()).toEqual([]);
  });

  it('sends no notice to an empty sender, also when the recipient is unknown (Java: <> gets none)', () => {
    const engine = new NetworkRuntimeEngine(14);
    engine.handle({ type: 'start', snapshot: topologySnapshot(mailNetwork()), seed: 14, initialTimeMilliseconds: 0 });
    expect(talk(engine, 25, 'HELO x', 'MAIL FROM:<>', 'RCPT TO:<niemand@filius.de>', 'DATA', 'Subject: x\n\ny\n.\n', 'QUIT').at(-1)).toBe('221 Server beendet Verbindung.');
    expect(engine.emailServer(SERVER)!.log.all.filter((line) => line.kind === 'stored')).toEqual([]);
  });

  it("sends a notice to another domain's sender with an empty sender, and none back when that fails", () => {
    const engine = new NetworkRuntimeEngine(14);
    engine.handle({ type: 'start', snapshot: topologySnapshot(mailNetwork()), seed: 14, initialTimeMilliseconds: 0 });
    // nirgendwo.de has no mail exchange (no DNS server here): the notice goes nowhere, and its own failure tells no one.
    expect(talk(engine, 25, 'HELO x', 'MAIL FROM:<x@nirgendwo.de>', 'RCPT TO:<niemand@filius.de>', 'DATA', 'Subject: x\n\ny\n.\n', 'QUIT').at(-1)).toBe(
      '221 Server beendet Verbindung.',
    );
    expect(engine.emailServer(SERVER)!.log.all.filter((line) => line.kind === 'stored' || line.kind === 'connectionStarting')).toEqual([]);
  });

  it("writes a notice's date in the project's language, at the wall clock's time", () => {
    const at = new Date(2026, 9, 1, 18, 5).getTime();
    const notice = (language: PageLanguage) => {
      const accounts: MailAccount[] = MAIL_ACCOUNTS.map((account) => ({ ...account, mailbox: [] }));
      const state = new MailServerState('filius.de', accounts, language, () => undefined, () => undefined, () => '10.0.0.1', () => at, NO_OUTBOX);
      run(state.deliver(parseMail('Subject: x\n\ny\n'), 'anna@filius.de', ['niemand@filius.de']));
      return formatMail(accounts[0]!.mailbox[0]!.mail);
    };
    expect(notice('de')).toContain('\nDate: 01.10.26, 18:05\nMail-Server: 10.0.0.1\n');
    expect(notice('en')).toContain('\nDate: 01/10/2026, 18:05\n');
    expect(notice('de')).toContain('To: <anna@filius.de>\n');
  });
});