/** Route only validated xterm wheel reports to an alternate-screen dashboard PTY. */

const fs = require("node:fs");
const path = process.env.HERMES_CHAT_PAGE_PATH || "/opt/hermes/web/src/pages/ChatPage.tsx";
let source = fs.readFileSync(path, "utf8");

function replaceOnce(before, after, label) {
  const count = source.split(before).length - 1;
  if (count !== 1) {
    throw new Error(`${label} patch context changed: expected 1, found ${count}`);
  }
  source = source.replace(before, after);
}

replaceOnce(
  'import { api } from "@/lib/api";\n',
  'import { api } from "@/lib/api";\n' +
    'import { isSgrWheelReport } from "@/lib/dashboard-terminal-input";\n',
  "dashboard wheel input import",
);
replaceOnce(
  `    // Dashboard chat should scroll the browser-side transcript, not send
    // mouse-wheel protocol bytes through the PTY.
    term.attachCustomWheelEventHandler((ev) => {
      const delta = ev.deltaY;
      if (!delta) {
        return false;
      }

      const step = Math.max(1, Math.round(Math.abs(delta) / 50));
      term.scrollLines(delta > 0 ? step : -step);

      ev.preventDefault();
      ev.stopPropagation();
      return false;
    });

`,
  "",
  "browser-local wheel handler",
);
replaceOnce(
  `      // Browser-embedded chat runs the TUI in inline mode. Keep transcript
      // history in xterm.js so the browser wheel can scroll it directly.
      scrollback: 5000,
`,
  `      // Alternate-screen PTYs keep their own visible history. Retain a
      // modest xterm scrollback only for terminal protocol compatibility.
      scrollback: 5000,
`,
  "dashboard alternate-screen scrollback comment",
);
const inputCommentStart = source.indexOf("    // Keystrokes → PTY.");
const inputCommentEnd = source.indexOf(
  "      // eslint-disable-next-line no-control-regex",
  inputCommentStart,
);
if (inputCommentStart < 0 || inputCommentEnd < 0) {
  throw new Error("dashboard PTY input comment patch context changed");
}
source =
  source.slice(0, inputCommentStart) +
  `    // Keystrokes and paste retain their existing PTY path. Mouse reports
    // are fail-closed below: only a bounded SGR wheel report can pass.
` +
  source.slice(inputCommentEnd);
replaceOnce(
  String.raw`      // eslint-disable-next-line no-control-regex -- intentional ESC byte in xterm SGR mouse report parser
      const SGR_MOUSE_RE = /^\x1b\[<(\d+);(\d+);(\d+)([Mm])$/;
      onDataDisposable = term.onData((data) => {
        if (ws.readyState !== WebSocket.OPEN) return;

        if (SGR_MOUSE_RE.test(data)) {
          return;
        }

        ws.send(data);
      });
`,
  String.raw`    onDataDisposable = term.onData((data) => {
      if (ws.readyState !== WebSocket.OPEN) return;
      if (data.startsWith("\x1b[<") && !isSgrWheelReport(data)) return;
      if (data.startsWith("\x1b[M")) return;
      ws.send(data);
    });
`,
  "SGR wheel relay",
);
if (source.includes("attachCustomWheelEventHandler")) {
  throw new Error("dashboard wheel interception remained after patch");
}
fs.writeFileSync(path, source);