import fs from "node:fs";
import path from "node:path";

const DEFAULT_CONFIG = {
  SERVER_HOST: "0.0.0.0",
  SERVER_PORT: 9736,
  MONGODB_HOST: "",
  MONGODB_PORT: 27017,
  MONGODB_DB: "arena",
  MONGODB_USER: "",
  MONGODB_PASS: "",
  MONGODB_URI: "",
  MONGODB_VISITOR_COLLECTION: "visitors",
  MONGODB_MAX_POOL_SIZE: 10,
  MONGODB_SERVER_SELECTION_TIMEOUT_MS: 5000,
  COOKIE_SECURE: false,
};

let config;

export function getConfig() {
  if (!config) {
    config = loadConfig();
  }

  return config;
}

export function loadConfig(filePath = path.resolve(process.cwd(), "config.json")) {
  const rawConfig = fs.existsSync(filePath)
    ? JSON.parse(fs.readFileSync(filePath, "utf8"))
    : {};

  return normalizeConfig(rawConfig);
}

export function hasMongoConfig() {
  const appConfig = getConfig();
  return Boolean(appConfig.MONGODB_URI || appConfig.MONGODB_HOST);
}

export function getMongoUri() {
  const appConfig = getConfig();

  if (appConfig.MONGODB_URI) {
    return appConfig.MONGODB_URI;
  }

  if (!appConfig.MONGODB_HOST) {
    throw new Error("MongoDB configuration is required for visitor tracking.");
  }

  const host = appConfig.MONGODB_HOST;
  const port = Number(appConfig.MONGODB_PORT || DEFAULT_CONFIG.MONGODB_PORT);
  const credentials = mongoCredentials(appConfig);

  return `mongodb://${credentials}${host}:${port}`;
}

function normalizeConfig(rawConfig) {
  const server = rawConfig.server || {};
  const mongodb = rawConfig.mongodb || {};

  return {
    SERVER_HOST: stringValue(rawConfig.SERVER_HOST, server.host, DEFAULT_CONFIG.SERVER_HOST),
    SERVER_PORT: numberValue(rawConfig.SERVER_PORT, server.port, DEFAULT_CONFIG.SERVER_PORT),
    MONGODB_HOST: stringValue(rawConfig.MONGODB_HOST, mongodb.host, DEFAULT_CONFIG.MONGODB_HOST),
    MONGODB_PORT: numberValue(rawConfig.MONGODB_PORT, mongodb.port, DEFAULT_CONFIG.MONGODB_PORT),
    MONGODB_DB: stringValue(rawConfig.MONGODB_DB, mongodb.db, DEFAULT_CONFIG.MONGODB_DB),
    MONGODB_USER: stringValue(rawConfig.MONGODB_USER, mongodb.user, DEFAULT_CONFIG.MONGODB_USER),
    MONGODB_PASS: stringValue(rawConfig.MONGODB_PASS, mongodb.pass, DEFAULT_CONFIG.MONGODB_PASS),
    MONGODB_URI: stringValue(rawConfig.MONGODB_URI, mongodb.uri, DEFAULT_CONFIG.MONGODB_URI),
    MONGODB_VISITOR_COLLECTION: stringValue(
      rawConfig.MONGODB_VISITOR_COLLECTION,
      mongodb.visitorCollection,
      DEFAULT_CONFIG.MONGODB_VISITOR_COLLECTION,
    ),
    MONGODB_MAX_POOL_SIZE: numberValue(
      rawConfig.MONGODB_MAX_POOL_SIZE,
      mongodb.maxPoolSize,
      DEFAULT_CONFIG.MONGODB_MAX_POOL_SIZE,
    ),
    MONGODB_SERVER_SELECTION_TIMEOUT_MS: numberValue(
      rawConfig.MONGODB_SERVER_SELECTION_TIMEOUT_MS,
      mongodb.serverSelectionTimeoutMs,
      DEFAULT_CONFIG.MONGODB_SERVER_SELECTION_TIMEOUT_MS,
    ),
    COOKIE_SECURE: booleanValue(rawConfig.COOKIE_SECURE, server.cookieSecure, DEFAULT_CONFIG.COOKIE_SECURE),
  };
}

function mongoCredentials(appConfig) {
  if (!appConfig.MONGODB_USER) {
    return "";
  }

  const user = encodeURIComponent(appConfig.MONGODB_USER);
  const pass = encodeURIComponent(appConfig.MONGODB_PASS || "");

  return `${user}:${pass}@`;
}

function stringValue(...values) {
  const value = values.find((candidate) => typeof candidate === "string" && candidate.length > 0);
  return value ?? "";
}

function numberValue(...values) {
  const value = values.find((candidate) => {
    const numericValue = Number(candidate);
    return Number.isFinite(numericValue) && numericValue > 0;
  });

  return Number(value);
}

function booleanValue(...values) {
  const value = values.find((candidate) => typeof candidate === "boolean" || candidate === "true" || candidate === "false");

  if (value === "true") {
    return true;
  }

  if (value === "false") {
    return false;
  }

  return Boolean(value);
}