import { ipcMain } from "electron/main";
import type { IpcMainEvent, WebContents } from "electron/main";

interface RendererProxyRequest {
  url: string;
  method: string;
  headers?: Record<string, string>;
  body?: string;
}

interface RendererProxyResponse {
  ok: boolean;
  status: number;
  statusText: string;
  headers: Record<string, string>;
  bodyText: string;
  error?: string;
}

let rendererWebContents: WebContents | null = null;
let requestSequence = 0;
const pendingRequests = new Map<string, {
  resolve: (value: RendererProxyResponse) => void;
  reject: (error: Error) => void;
  timeout: ReturnType<typeof setTimeout>;
}>();
const rendererProxyRequestChannel = "desktop:renderer-devtools-proxy:request";
const rendererProxyResponseChannel = "desktop:renderer-devtools-proxy:response";

ipcMain.on(rendererProxyResponseChannel, handleRendererProxyResponse);

export function registerRendererDevtoolsProxyTarget(webContents: WebContents): void {
  rendererWebContents = webContents;
  webContents.once("destroyed", () => {
    if (rendererWebContents === webContents) {
      rendererWebContents = null;
    }
  });
}

export function canUseRendererDevtoolsProxy(): boolean {
  return Boolean(rendererWebContents && !rendererWebContents.isDestroyed());
}

export async function rendererDevtoolsFetch(
  request: RendererProxyRequest,
): Promise<RendererProxyResponse> {
  if (!rendererWebContents || rendererWebContents.isDestroyed()) {
    throw new Error("renderer_devtools_proxy_unavailable");
  }

  const requestId = `renderer-proxy-${Date.now()}-${requestSequence += 1}`;

  return await new Promise<RendererProxyResponse>((resolve, reject) => {
    const timeout = setTimeout(() => {
      pendingRequests.delete(requestId);
      reject(new Error("renderer_devtools_proxy_timeout"));
    }, 30_000);

    pendingRequests.set(requestId, {
      resolve,
      reject,
      timeout,
    });

    try {
      rendererWebContents?.send(rendererProxyRequestChannel, {
        requestId,
        request,
      });
    } catch (error) {
      clearTimeout(timeout);
      pendingRequests.delete(requestId);
      reject(error instanceof Error ? error : new Error("renderer_devtools_proxy_send_failed"));
    }
  });
}

function handleRendererProxyResponse(
  event: IpcMainEvent,
  payload: {
    requestId?: unknown;
    response?: unknown;
  },
): void {
  if (rendererWebContents && event.sender !== rendererWebContents) {
    return;
  }

  const requestId = typeof payload?.requestId === "string" ? payload.requestId : "";
  if (!requestId) {
    return;
  }

  const pending = pendingRequests.get(requestId);
  if (!pending) {
    return;
  }

  clearTimeout(pending.timeout);
  pendingRequests.delete(requestId);

  const response = payload.response;
  if (!isRendererProxyResponse(response)) {
    pending.reject(new Error("renderer_devtools_proxy_invalid_response"));
    return;
  }

  pending.resolve(response);
}

function isRendererProxyResponse(value: unknown): value is RendererProxyResponse {
  if (!value || typeof value !== "object") {
    return false;
  }

  const candidate = value as Partial<RendererProxyResponse>;
  return typeof candidate.ok === "boolean"
    && typeof candidate.status === "number"
    && typeof candidate.statusText === "string"
    && typeof candidate.bodyText === "string"
    && Boolean(candidate.headers && typeof candidate.headers === "object");
}