// ==UserScript==
// @name         Claude Cassia Checkout Mock
// @namespace    gothbreach.claude
// @version      1.0.0
// @description  Mock checkout_capabilities to cassia flow for Claude Max
// @match        *://claude.ai/*
// @match        *://*.claude.ai/*
// @run-at       document-start
// @grant        none
// ==/UserScript==

(function () {
  "use strict";

  const TARGET_HOST = "claude.ai";
  const TARGET_PATH = /^\/api\/organizations\/[^/]+\/subscription\/checkout_capabilities\/?$/;
  const MOCK_DATA = { checkout_flow: "cassia" };
  const MOCK_BODY = JSON.stringify(MOCK_DATA);
  const MOCK_LENGTH = new TextEncoder().encode(MOCK_BODY).byteLength;

  function getTargetUrl(input, method = "GET") {
    try {
      let rawUrl;
      if (typeof input === "string" || input instanceof URL) rawUrl = String(input);
      else if (input && typeof input.url === "string") rawUrl = input.url;
      else return null;
      const url = new URL(rawUrl, location.href);
      if (String(method).toUpperCase() !== "GET") return null;
      const hostMatched = url.hostname === TARGET_HOST || url.hostname.endsWith("." + TARGET_HOST);
      if (!hostMatched) return null;
      if (!TARGET_PATH.test(url.pathname)) return null;
      return url;
    } catch (error) { return null; }
  }

  function createMockResponse(originalResponse) {
    const headers = new Headers(originalResponse.headers);
    headers.delete("content-length"); headers.delete("content-encoding");
    headers.delete("etag"); headers.delete("content-md5");
    headers.set("content-type", "application/json; charset=utf-8");
    headers.set("content-length", String(MOCK_LENGTH));
    headers.set("cache-control", "no-store");
    const response = new Response(MOCK_BODY, { status: 200, statusText: "OK", headers });
    try {
      Object.defineProperties(response, {
        url: { value: originalResponse.url, configurable: true },
        redirected: { value: originalResponse.redirected, configurable: true },
        type: { value: originalResponse.type, configurable: true }
      });
    } catch (_) {}
    return response;
  }

  // Intercept Fetch
  const nativeFetch = window.fetch;
  window.fetch = async function (input, init) {
    const method = init?.method || (input instanceof Request ? input.method : "GET");
    const targetUrl = getTargetUrl(input, method);
    const originalResponse = await nativeFetch.apply(this, arguments);
    if (!targetUrl) return originalResponse;
    console.warn("[Cassia Mock] Fetch mocked:", targetUrl.href, MOCK_DATA);
    return createMockResponse(originalResponse);
  };

  // Intercept XMLHttpRequest
  const XhrPrototype = XMLHttpRequest.prototype;
  const xhrInfo = new WeakMap();
  const loggedXhrs = new WeakSet();
  const nativeOpen = XhrPrototype.open;
  const nativeSend = XhrPrototype.send;
  const nativeGetResponseHeader = XhrPrototype.getResponseHeader;
  const nativeGetAllResponseHeaders = XhrPrototype.getAllResponseHeaders;

  XhrPrototype.open = function (method, url) {
    let absoluteUrl;
    try { absoluteUrl = new URL(String(url), location.href).href; }
    catch (_) { absoluteUrl = String(url); }
    xhrInfo.set(this, { method: String(method || "GET").toUpperCase(), url: absoluteUrl });
    return nativeOpen.apply(this, arguments);
  };

  function getMatchedXhr(xhr) {
    const info = xhrInfo.get(xhr);
    if (!info || xhr.readyState !== XMLHttpRequest.DONE) return null;
    return getTargetUrl(info.url, info.method);
  }

  function replaceXhrGetter(propertyName, replacement) {
    const descriptor = Object.getOwnPropertyDescriptor(XhrPrototype, propertyName);
    if (!descriptor || typeof descriptor.get !== "function" || descriptor.configurable === false) return;
    const nativeGetter = descriptor.get;
    Object.defineProperty(XhrPrototype, propertyName, {
      ...descriptor,
      get: function () {
        if (!getMatchedXhr(this)) return nativeGetter.call(this);
        return replacement.call(this, nativeGetter);
      }
    });
  }

  replaceXhrGetter("responseText", function (nativeGetter) {
    if (this.responseType !== "" && this.responseType !== "text") return nativeGetter.call(this);
    return MOCK_BODY;
  });

  replaceXhrGetter("response", function (nativeGetter) {
    if (this.responseType === "json") return { checkout_flow: "cassia" };
    if (this.responseType === "" || this.responseType === "text") return MOCK_BODY;
    return nativeGetter.call(this);
  });

  replaceXhrGetter("status", function () { return 200; });
  replaceXhrGetter("statusText", function () { return "OK"; });

  XhrPrototype.getResponseHeader = function (name) {
    if (!getMatchedXhr(this)) return nativeGetResponseHeader.apply(this, arguments);
    switch (String(name).toLowerCase()) {
      case "content-type": return "application/json; charset=utf-8";
      case "content-length": return String(MOCK_LENGTH);
      case "cache-control": return "no-store";
      case "content-encoding": case "etag": case "content-md5": return null;
      default: return nativeGetResponseHeader.apply(this, arguments);
    }
  };

  XhrPrototype.getAllResponseHeaders = function () {
    const originalHeaders = nativeGetAllResponseHeaders.apply(this, arguments);
    if (!getMatchedXhr(this)) return originalHeaders;
    const headers = String(originalHeaders || "").split(/\r?\n/).filter(Boolean).filter(function (line) {
      const name = line.split(":", 1)[0].trim().toLowerCase();
      return !["content-type", "content-length", "content-encoding", "cache-control", "etag", "content-md5"].includes(name);
    });
    headers.push("content-type: application/json; charset=utf-8", `content-length: ${MOCK_LENGTH}`, "cache-control: no-store");
    return headers.join("\r\n") + "\r\n";
  };

  XhrPrototype.send = function () {
    this.addEventListener("readystatechange", function () {
      const targetUrl = getMatchedXhr(this);
      if (targetUrl && !loggedXhrs.has(this)) {
        loggedXhrs.add(this);
        console.warn("[Cassia Mock] XHR mocked:", targetUrl.href, MOCK_DATA);
      }
    });
    return nativeSend.apply(this, arguments);
  };

  // Status badge
  function showStatusBadge() {
    if (!document.documentElement) {
      document.addEventListener("DOMContentLoaded", showStatusBadge, { once: true });
      return;
    }
    if (document.getElementById("cassia-mock-badge")) return;
    const badge = document.createElement("div");
    badge.id = "cassia-mock-badge";
    badge.textContent = "Cassia Mock ON";
    Object.assign(badge.style, {
      position: "fixed", right: "12px", bottom: "12px", zIndex: "2147483647",
      padding: "7px 11px", color: "#ffffff", background: "#167c3a",
      borderRadius: "6px", fontSize: "12px", fontFamily: "sans-serif",
      boxShadow: "0 2px 8px rgba(0,0,0,.3)"
    });
    document.documentElement.appendChild(badge);
  }

  window.__cassiaMockInstalled = true;
  console.info("[Cassia Mock] Script loaded:", location.href);
  showStatusBadge();
})();