import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
import { Container } from "@mariozechner/pi-tui";

// Parse CSI ? 997 ; N n response (colour scheme notification).
function parseColourSchemeNotification(data: string): "light" | "dark" | null {
  const match = data.match(/^\x1b\[\?997;(\d)n$/);
  if (!match) return null;

  const value = match[1];
  if (value === "1") return "dark";
  if (value === "2") return "light";
  return null;
}

export default function (pi: ExtensionAPI) {
  let currentTheme: "dark" | "light" | undefined;
  let initialized = false;

  pi.on("session_start", (event, ctx) => {
    if (!ctx.hasUI || initialized) return;
    initialized = true;

    // Listen for future colour scheme changes.
    ctx.ui.onTerminalInput((data) => {
      const newTheme = parseColourSchemeNotification(data);
      if (!newTheme) return undefined;

      if (currentTheme !== newTheme) {
        currentTheme = newTheme;
        ctx.ui.setTheme(newTheme);
        ctx.ui.notify(`Switched to ${newTheme} theme`, "info");
      }

      return undefined;
    });

    // HACK: get access to the terminal object.
    ctx.ui.setWidget("auto-theme", (tui) => {
      // Enable unsolicited palette change notifications.
      tui.terminal.write("\x1b[?2031h");

      // Query current colour scheme (CSI ? 996 n).
      tui.terminal.write("\x1b[?996n");
      return new Container();
    });
  });
}