// The pages of FILIUS' routers and home routers (filius.software.system:
// VermittlungsrechnerBetriebssystem, GatewayFirmware; the web server's
// plug-ins FirewallWebLog and VermittlungWeb), written as Java writes them:
// from its templates (tmpl/vermittlung_index, gateway_index, routing) and the
// texts of its message bundle, in the project's language. The pages go over
// the simulated network as they are, so they are written here, not by the
// editor.
//
// Departure from Java: the German log page closes its title with </title>
// (Java's bundle writes </titel>).

import type { FirewallRule } from '../config.js';
import type { FirewallLogEntry } from '../engine.js';
import { formatIPv4, maskAddress, parseIPv4 } from '../ipv4.js';
import type { RouteRow } from '../routeTable.js';
import { DIRECTLY_CONNECTED_SOURCE_MARKER } from '../config.js';

/** The languages FILIUS' pages come in (Java also has French). */
export type PageLanguage = 'de' | 'en';

/** Java's templates as its WebServer and WebServerPlugIn read them: each line ended by "\n". */
const TEMPLATES: Record<'routerIndex' | 'gatewayIndex' | 'routing', Record<PageLanguage, string>> = {
  routerIndex: {
    de: "<html>\n  <head>\n    <title>Administration des Vermittlungsrechners</title>\n  </head>\n  <body>\n\n    <h1>Firewall-Administration</h1>\n    <p> <a href=\"konfig\">Konfiguration</a> </p>\n    <p> <a href=\"log\">Log-Eintr&auml;ge anzeigen</a> </p>\n\n    <h1> Weiterleitung/Routing </h1>\n    <p> <a href=\"routes\"> Anzeige des aktuellen Status der Weiterleitungs-/Routing-Tabelle </a></p>\n  </body>\n</html>\n",
    en: "<html>\n  <head>\n    <title>Router Administration</title>\n  </head>\n  <body>\n    <h1>Firewall Administration</h1>\n    <p> <a href=\"konfig\">Configuration</a> </p>\n    <p> <a href=\"log\">Show Log</a> </p>\n\n    <h1> Routing/Forwarding </h1>\n    <p> <a href=\"routes\"> Show current routing/forwarding table </a> </p>\n    \n  </body>\n</html>\n",
  },
  gatewayIndex: {
    de: "<html>\n  <head>\n    <title>Administration des Gateways</title>\n  </head>\n  <body>\n    <h1>Firewall-Administration</h1>\n    <p> <a href=\"konfig\">Konfiguration</a> </p>\n    <p> <a href=\"log\">Log-Eintr&auml;ge anzeigen</a> </p>\n  </body>\n</html>\n",
    en: "<html>\n  <head>\n    <title>Gateway Administration</title>\n  </head>\n  <body>\n    <h1>Firewall Administration</h1>\n    <p> <a href=\"konfig\">Configuration</a> </p>\n    <p> <a href=\"log\">Show Log</a> </p>    \n  </body>\n</html>\n",
  },
  routing: {
    de: "<html>\n  <head>\n    <title>\n:title:\n    </title>\n  </head>\n  <body>\n    <h1>\n:title:\n    </h1>\n\n    <table border=1>\n      <tr>\n        <th colspan=2>Rechnernetz</th>\n        <th>Hops</th>\n        <th>G&uuml;ltigkeit</th>\n        <th colspan=2>N&auml;chster Hop</th>\n      </tr>\n      <tr>\n        <th>Adresse</th>\n        <th>Netzmaske</th>\n        <th></th>\n        <th>(sec)</th>\n        <th>Ziel</th>\n        <th>&Ouml;ffentliche Adresse</th>\n      </tr>\n\n:routing_entries:\n\n    </table>\n    <p>\n:hint:\n    </p>\n  </body>\n</html>\n",
    en: "<html>\n  <head>\n    <title>\n:title:\n    </title>\n  </head>\n  <body>\n    <h1>\n:title:\n    </h1>\n\n    <table border=1>\n      <tr>\n        <th colspan=2>Network</th>\n        <th>Hops</th>\n        <th>Validity</th>\n        <th colspan=2>Next Hop</th>\n      </tr>\n      <tr>\n        <th>Address</th>\n        <th>Netmask</th>\n        <th></th>\n        <th>(sec)</th>\n        <th>Target</th>\n        <th>Public Address</th>\n      </tr>\n\n:routing_entries:\n\n    </table>\n    <p>\n:hint:\n    </p>\n  </body>\n</html>\n",
  },
};

/** The texts of Java's message bundle the pages use. */
interface PageTexts {
  readonly logHead: string;
  readonly logBody: string;
  readonly ruleMatched: string;
  readonly icmpDropped: string;
  readonly accept: string;
  readonly drop: string;
  readonly ripHint: string;
  readonly unlimited: string;
  readonly forwardingHint: string;
  readonly forwardingTitle: string;
  readonly ripTitle: string;
}

const TEXTS: Record<PageLanguage, PageTexts> = {
  de: {
    /** sw_firewallweblog_msg1, msg2 (</title>, where Java writes </titel>). */
    logHead: '<html>\n\t<head>\n\t\t<title>Log-Einträge der Firewall</title>',
    logBody: '\n\t</head>\n\t<body>\n\t\t<h2>Log-Eintr&auml;ge der Firewall</h2>',
    /** sw_firewall_msg8, firewallthread_msg1, jfirewalldialog_msg33, msg34. */
    ruleMatched: 'Firewall-Regel hat gegriffen:',
    icmpDropped: 'ICMP-Paket verworfen:',
    accept: 'akzeptieren',
    drop: 'verwerfen',
    /** sw_vermittlungweb_msg1, msg3, msg4, msg5, msg6. */
    ripHint: 'Diese Tabelle wird durch das Routing Information Protocol (RIP) aufgebaut und aktualisiert.',
    unlimited: 'unbegrenzt',
    forwardingHint: 'Diese Tabelle wurde aus der IP-Konfiguration des Vermittlungsrechners und manuellen Einträgen erstellt.',
    forwardingTitle: 'Routing-/Weiterleitungs-Tabelle',
    ripTitle: 'Routing-Tabelle',
  },
  en: {
    logHead: '<html>\n\t<head>\n\t\t<title>Log-data set entry of the firewall</title>',
    logBody: '\n\t</head>\n\t<body>\n\t\t<h2>Log-data set entry of the firewall</h2>',
    ruleMatched: 'Firewall rule matched:',
    icmpDropped: 'Dropped ICMP packet:',
    accept: 'accept',
    drop: 'drop',
    ripHint: 'This table is generated and updated by the Routing Information Protocol (RIP).',
    unlimited: 'unlimited',
    forwardingHint: 'This table was created from the IP configuration of the router and manually added entries of the forwarding table.',
    forwardingTitle: 'Routing/Forwarding Table',
    ripTitle: 'Routing Table',
  },
};

/** The index page a router or home router keeps in /webserver (WebServer.erzeugeIndexDatei). */
export function routerIndexPage(kind: 'router' | 'gateway', language: PageLanguage): string {
  return TEMPLATES[kind === 'router' ? 'routerIndex' : 'gatewayIndex'][language];
}

/** FirewallRule.toString(nics): the rule as the log names it. */
export function firewallRuleText(rule: FirewallRule, firstInterface: { readonly ipAddress: string; readonly subnetMask: string } | undefined): string {
  const sameNetwork = rule.sourceIPAddress === DIRECTLY_CONNECTED_SOURCE_MARKER && firstInterface !== undefined;
  let text = '';
  if (rule.sourceIPAddress === '') {
    text += '*/';
  } else if (sameNetwork) {
    const address = parseIPv4(firstInterface.ipAddress);
    const mask = parseIPv4(firstInterface.subnetMask);
    const network = address === undefined || mask === undefined ? firstInterface.ipAddress : formatIPv4(maskAddress(address, mask));
    text += `${network}/${firstInterface.subnetMask} -> `;
  } else {
    text += `${rule.sourceIPAddress}/`;
  }
  if (!sameNetwork) text += rule.sourceSubnetMask === '' ? '* -> ' : `${rule.sourceSubnetMask} -> `;
  text += rule.destinationIPAddress === '' ? '*/' : `${rule.destinationIPAddress}/`;
  text += rule.destinationSubnetMask === '' ? '*; ' : `${rule.destinationSubnetMask}; `;
  text += rule.protocol === 'all' ? '*:' : rule.protocol === 'tcp' ? 'TCP:' : rule.protocol === 'udp' ? 'UDP:' : '?:';
  text += rule.port >= 0 ? `${rule.port}  => ` : '*  => ';
  return text + (rule.action === 'accept' ? 'ACCEPT' : 'DROP');
}

/** A line of the firewall's log, as Firewall tells its observers. */
export function firewallLogText(entry: FirewallLogEntry, language: PageLanguage): string {
  const texts = TEXTS[language];
  if (entry.kind === 'icmpDropped') {
    return `${texts.icmpDropped} ${entry.senderIPAddress} -> ${entry.receiverIPAddress} (code: ${entry.code}, type: ${entry.type})`;
  }
  return `${texts.ruleMatched} #${entry.ruleNumber} (${firewallRuleText(entry.rule, entry.firstInterface)})  -> ${entry.accepted ? texts.accept : texts.drop}`;
}

/** FirewallWebLog.holeHtmlSeite: the log since the engine was made. */
export function firewallLogPage(entries: readonly FirewallLogEntry[], language: PageLanguage): string {
  const texts = TEXTS[language];
  const lines = entries.map((entry) => `<br /> \n${firewallLogText(entry, language)}`).join('');
  return `${texts.logHead}${texts.logBody}\n\n${lines}\n\n\t</body>\n</html>`;
}

function routingPage(title: string, entries: string, hint: string, language: PageLanguage): string {
  return TEMPLATES.routing[language].replaceAll(':title:', title).replaceAll(':routing_entries:', entries).replaceAll(':hint:', hint);
}

/** VermittlungWeb.createForwardingTablePage: a router without RIP. */
export function forwardingTablePage(rows: readonly RouteRow[], language: PageLanguage): string {
  const texts = TEXTS[language];
  const entries = rows
    .map((row) => {
      const direct = row.nextHop === row.interfaceIPAddress;
      const localhost = row.interfaceIPAddress === '127.0.0.1';
      const cells =
        `<td>${row.destinationNetwork}</td><td>${row.subnetMask}</td>` +
        (direct || localhost ? '<td> 0 </td>' : '<td> ? </td>') +
        `<td>${texts.unlimited}</td>` +
        `<td><a href="http://${row.nextHop}/routes">${row.nextHop}</a></td><td> - </td>`;
      if (direct || localhost) return `<tr style='background-color:#aaffaa'>${cells}</tr>`;
      if (row.subnetMask === '0.0.0.0') return `<tr style='background-color:#aaaaff'>${cells}</tr>`;
      return `<tr>${cells}</tr>`;
    })
    .join('');
  return routingPage(texts.forwardingTitle, entries, texts.forwardingHint, language);
}

/** VermittlungWeb.createRoutingTablePage: a router with RIP; how long each learned route has left, in whole seconds. */
export function ripTablePage(rows: readonly RouteRow[], nowMilliseconds: number, language: PageLanguage): string {
  const texts = TEXTS[language];
  const entries = rows
    .map((row) => {
      const hops = row.metric ?? 16;
      const validity = row.expiresAtMilliseconds === undefined ? texts.unlimited : String(Math.trunc((row.expiresAtMilliseconds - nowMilliseconds) / 1_000));
      const publicAddress = row.hopPublicIPAddress ?? '';
      const cells =
        `<td>${row.destinationNetwork}</td><td>${row.subnetMask}</td><td>${hops}</td><td>${validity}</td><td>${row.nextHop}</td>` +
        `<td><a href="http://${publicAddress}/routes">${publicAddress}</a></td>`;
      if (hops === 0) return `<tr style='background-color:#aaffaa'>${cells}</tr>`;
      if (hops === 16) return `<tr style='background-color:#ffaaaa'>${cells}</tr>`;
      return `<tr>${cells}</tr>`;
    })
    .join('');
  return routingPage(texts.ripTitle, entries, texts.ripHint, language);
}