import fs from "node:fs";
import path from "node:path";
import { settings } from "./config.js";

const PROXY_TYPES = new Set([
  "vless",
  "vmess",
  "trojan",
  "shadowsocks",
  "hysteria2",
]);
const CUSTOM_OUTBOUNDS = new Set(["direct", "vpn", "block"]);

function clone(value) {
  return JSON.parse(JSON.stringify(value));
}

function findOutbound(subscriptionConfig, selectedTag) {
  const outbounds = Array.isArray(subscriptionConfig?.outbounds)
    ? subscriptionConfig.outbounds
    : [];
  const exact = outbounds.find(
    (outbound) =>
      outbound.tag === selectedTag && PROXY_TYPES.has(outbound.type),
  );
  if (exact) return exact;

  const trimmedTag = String(selectedTag || "").trim();
  return outbounds.find(
    (outbound) =>
      String(outbound.tag || "").trim() === trimmedTag &&
      PROXY_TYPES.has(outbound.type),
  );
}

function readCustomRuleSets() {
  try {
    if (!fs.existsSync(settings.customRuleSetsPath)) return [];
    const data = JSON.parse(
      fs.readFileSync(settings.customRuleSetsPath, "utf8"),
    );
    return Array.isArray(data) ? data : [];
  } catch {
    return [];
  }
}

function ruleSets(customRuleSets = []) {
  const builtIn = settings.routingRuDirect
    ? [
        {
          type: "remote",
          tag: "geoip-ru",
          format: "binary",
          url: "https://cdn.jsdelivr.net/gh/SagerNet/sing-geoip@rule-set/geoip-ru.srs",
          download_detour: "direct",
        },
        {
          type: "remote",
          tag: "geosite-category-ru",
          format: "binary",
          url: "https://cdn.jsdelivr.net/gh/SagerNet/sing-geosite@rule-set/geosite-category-ru.srs",
          download_detour: "direct",
        },
      ]
    : [];

  const custom = (Array.isArray(customRuleSets) ? customRuleSets : [])
    .filter((rs) => rs.tag && rs.url)
    .map((rs) => ({
      type: "remote",
      tag: String(rs.tag).trim(),
      format: rs.format || "binary",
      url: String(rs.url).trim(),
      download_detour: "direct",
    }));

  // Пользовательские rule-sets не должны дублировать встроенные
  const builtInTags = new Set(builtIn.map((rs) => rs.tag));
  const merged = [
    ...builtIn,
    ...custom.filter((rs) => !builtInTags.has(rs.tag)),
  ];
  return merged;
}

function uniqueClean(values) {
  return Array.from(
    new Set(
      (Array.isArray(values) ? values : [])
        .map((value) => String(value || "").trim())
        .filter(Boolean),
    ),
  );
}

function parsePorts(values) {
  return uniqueClean(values)
    .map((value) => Number.parseInt(value, 10))
    .filter((value) => Number.isInteger(value) && value > 0 && value <= 65535);
}

function toSingboxRule(customRule, vpnTag) {
  if (!customRule?.enabled) return null;
  if (!CUSTOM_OUTBOUNDS.has(customRule.outbound)) return null;

  const rule = {};
  const domains = uniqueClean(customRule.domains);
  const domainSuffixes = uniqueClean(customRule.domainSuffixes);
  const domainKeywords = uniqueClean(customRule.domainKeywords);
  const ipCidrs = uniqueClean(customRule.ipCidrs);
  const ports = parsePorts(customRule.ports);
  const networks = uniqueClean(customRule.networks).filter((network) =>
    ["tcp", "udp"].includes(network),
  );

  if (domains.length) rule.domain = domains;
  if (domainSuffixes.length) rule.domain_suffix = domainSuffixes;
  if (domainKeywords.length) rule.domain_keyword = domainKeywords;
  if (ipCidrs.length) rule.ip_cidr = ipCidrs;
  if (ports.length) rule.port = ports;
  if (networks.length) rule.network = networks;

  const ruleSetsRef = uniqueClean(customRule.ruleSets);
  if (ruleSetsRef.length) rule.rule_set = ruleSetsRef;

  if (
    !rule.domain &&
    !rule.domain_suffix &&
    !rule.domain_keyword &&
    !rule.ip_cidr &&
    !rule.port &&
    !rule.network &&
    !rule.rule_set
  ) {
    return null;
  }

  rule.outbound = customRule.outbound === "vpn" ? vpnTag : customRule.outbound;
  return rule;
}

function customRouteRules(customRules, vpnTag) {
  return (Array.isArray(customRules) ? customRules : [])
    .map((rule) => toSingboxRule(rule, vpnTag))
    .filter(Boolean);
}

function routeRules(customRules, vpnTag) {
  const rules = [
    {
      ip_is_private: true,
      outbound: "direct",
    },
  ];

  rules.push(...customRouteRules(customRules, vpnTag));

  if (settings.routingRuDirect) {
    rules.push({
      rule_set: ["geoip-ru", "geosite-category-ru"],
      outbound: "direct",
    });
  }

  return rules;
}

export function buildGatewayConfig(subscriptionConfig, selectedTag) {
  const selectedOutbound = findOutbound(subscriptionConfig, selectedTag);
  if (!selectedOutbound) {
    throw new Error(`Outbound не найден: ${selectedTag}`);
  }

  const vpnOutbound = clone(selectedOutbound);
  if (!vpnOutbound.tag) vpnOutbound.tag = "vpn-out";
  if (vpnOutbound.type === "vless" && !vpnOutbound.packet_encoding) {
    vpnOutbound.packet_encoding = "xudp";
  }

  const customRuleSets = readCustomRuleSets();

  return {
    log: {
      level: settings.logLevel,
      timestamp: true,
    },
    experimental: {
      cache_file: {
        enabled: true,
        path: settings.cachePath,
      },
    },
    dns: {
      independent_cache: true,
    },
    inbounds: [
      {
        type: "tproxy",
        tag: "tproxy-in",
        listen: "::",
        listen_port: settings.tproxyPort,
        sniff: true,
        sniff_override_destination: true,
      },
      {
        type: "mixed",
        tag: "mixed-in",
        listen: settings.bindIp,
        listen_port: settings.proxyPort,
        sniff: true,
        set_system_proxy: false,
      },
    ],
    outbounds: [
      vpnOutbound,
      { type: "direct", tag: "direct" },
      { type: "block", tag: "block" },
    ],
    route: {
      rule_set: ruleSets(customRuleSets),
      rules: routeRules(subscriptionConfig.customRules, vpnOutbound.tag),
      final: vpnOutbound.tag,
      auto_detect_interface: true,
    },
  };
}

export function writeSingboxConfig(config) {
  fs.mkdirSync(path.dirname(settings.configPath), { recursive: true });
  fs.writeFileSync(
    settings.configPath,
    JSON.stringify(config, null, 2),
    "utf8",
  );
}

export function readSingboxConfig() {
  if (!fs.existsSync(settings.configPath)) return null;
  try {
    return JSON.parse(fs.readFileSync(settings.configPath, "utf8"));
  } catch {
    return null;
  }
}

export function removeSingboxConfig() {
  if (fs.existsSync(settings.configPath)) {
    fs.rmSync(settings.configPath);
  }
}