import type { JsonObject } from "../protocol";
import type { SurfaceInstance } from "./surface-instance-manager";

export type SurfaceHostCallbacks = Readonly<{
  ready: (instanceID: string) => void;
  event: (instanceID: string, event: "cancel") => void;
}>;

type HostedSurface = {
  readonly instance: SurfaceInstance;
  readonly frame: HTMLIFrameElement;
  ready: boolean;
  cancelSent: boolean;
};

const BRIDGE_VERSION = 1;
const READY_TYPE = "lineup.surface.v1.ready";
const STATE_TYPE = "lineup.surface.v1.state";

/**
 * M2-03 Web Reference Host.  The frame is deliberately an opaque sandbox
 * origin: it receives no same-origin access to the chat page, its storage,
 * the Tauri bridge, or browser network credentials.  Its only connection to
 * the parent is the narrow postMessage bridge below.
 */
export class IsolatedSurfaceHost {
  private readonly surfaces = new Map<string, HostedSurface>();

  public constructor(private readonly mountPoint: HTMLElement, private readonly callbacks: SurfaceHostCallbacks) {
    window.addEventListener("message", this.receiveMessage);
  }

  public mount(instance: SurfaceInstance): void {
    const current = this.surfaces.get(instance.instance_id);
    if (current) {
      current.frame.dataset.surfaceState = JSON.stringify(instance.state);
      if (current.ready) this.sendState(current, instance.state);
      return;
    }
    const frame = document.createElement("iframe");
    frame.className = "isolated-surface-frame";
    frame.title = `LineUp Surface ${instance.app_id}`;
    frame.setAttribute("sandbox", "allow-scripts");
    frame.setAttribute("referrerpolicy", "no-referrer");
    frame.setAttribute("aria-label", "受限扩展界面");
    // srcdoc comes only from this module's static source.  No Envelope field,
    // manifest field, Agent content or remote response can alter it.
    frame.srcdoc = surfaceDocument(instance.instance_id);
    const hosted: HostedSurface = { instance, frame, ready: false, cancelSent: false };
    this.surfaces.set(instance.instance_id, hosted);
    this.mountPoint.append(frame);
  }

  public update(instance: SurfaceInstance): void {
    const hosted = this.surfaces.get(instance.instance_id);
    if (!hosted || hosted.instance.app_id !== instance.app_id || hosted.instance.version !== instance.version) return;
    if (hosted.ready) this.sendState(hosted, instance.state);
  }

  public unmount(instanceID: string): void {
    const hosted = this.surfaces.get(instanceID);
    if (!hosted) return;
    this.surfaces.delete(instanceID);
    hosted.frame.remove();
  }

  public destroy(): void {
    window.removeEventListener("message", this.receiveMessage);
    for (const instanceID of [...this.surfaces.keys()]) this.unmount(instanceID);
  }

  private readonly receiveMessage = (event: MessageEvent<unknown>): void => {
    const message = parseBridgeMessage(event.data);
    if (!message) return;
    const hosted = this.surfaces.get(message.instance_id);
    // An opaque sandbox needs targetOrigin="*" to receive a postMessage, so
    // the source Window identity and instance id are mandatory checks here.
    if (!hosted || event.source !== hosted.frame.contentWindow) return;
    if (message.type === READY_TYPE) {
      if (hosted.ready) return;
      hosted.ready = true;
      this.sendState(hosted, hosted.instance.state);
      this.callbacks.ready(hosted.instance.instance_id);
      return;
    }
    if (!hosted.ready || hosted.cancelSent) return;
    hosted.cancelSent = true;
    this.callbacks.event(hosted.instance.instance_id, "cancel");
  };

  private sendState(hosted: HostedSurface, state: JsonObject): void {
    // The sandbox has an opaque origin; Window identity was captured at mount
    // and all incoming traffic is checked above. No privileged data is sent.
    hosted.frame.contentWindow?.postMessage({ v: BRIDGE_VERSION, type: STATE_TYPE, instance_id: hosted.instance.instance_id, state }, "*");
  }
}

type SurfaceReadyMessage = Readonly<{ v: 1; type: typeof READY_TYPE; instance_id: string }>;
type SurfaceEventMessage = Readonly<{ v: 1; type: "lineup.surface.v1.event"; instance_id: string; event: "cancel" }>;

export function parseReadyMessage(value: unknown): SurfaceReadyMessage | undefined {
  const parsed = parseBridgeMessage(value);
  return parsed?.type === READY_TYPE ? parsed : undefined;
}

function parseBridgeMessage(value: unknown): SurfaceReadyMessage | SurfaceEventMessage | undefined {
  if (!isPlainObject(value) || value.v !== BRIDGE_VERSION || (value.type !== READY_TYPE && value.type !== "lineup.surface.v1.event") || typeof value.instance_id !== "string"
    || !/^[A-Za-z0-9._:-]{1,128}$/.test(value.instance_id)) return undefined;
  if (value.type === READY_TYPE && Object.keys(value).every(key => key === "v" || key === "type" || key === "instance_id")) return { v: 1, type: READY_TYPE, instance_id: value.instance_id };
  if (value.type === "lineup.surface.v1.event" && value.event === "cancel" && Object.keys(value).every(key => key === "v" || key === "type" || key === "instance_id" || key === "event")) return { v: 1, type: "lineup.surface.v1.event", instance_id: value.instance_id, event: "cancel" };
  return undefined;
}

/** A static boot document for the future host-local Task Dashboard bundle. */
export function surfaceDocument(instanceID: string): string {
  const safeID = JSON.stringify(instanceID);
  return `<!doctype html><html lang="zh-CN"><head><meta charset="utf-8"><meta name="referrer" content="no-referrer"><meta http-equiv="Content-Security-Policy" content="default-src 'none'; connect-src 'none'; img-src data:; style-src 'unsafe-inline'; script-src 'unsafe-inline'; base-uri 'none'; form-action 'none'; frame-src 'none'; object-src 'none'; navigate-to 'none'"><style>html,body{margin:0;background:#15231c;color:#e7f0eb;font:14px system-ui,sans-serif}main{padding:12px;display:grid;gap:10px}h2,p{margin:0}progress{width:100%}ul{margin:0;padding-left:20px}#logs{max-height:64px;overflow:auto;color:#b8cfc0;font-size:12px}button{justify-self:start;border:0;border-radius:7px;padding:8px 10px;background:#a9dfc4;color:#102018;font-weight:700}</style></head><body><main><h2 id="title">任务面板</h2><progress id="progress" max="100"></progress><p id="status">等待状态</p><ul id="steps"></ul><div id="logs" aria-label="日志摘要"></div><button id="cancel" type="button">请求取消</button></main><script>"use strict";const instanceId=${safeID},q=id=>document.getElementById(id),list=(id,items)=>q(id).replaceChildren(...(Array.isArray(items)?items.slice(0,12).map(x=>{const n=document.createElement(id==="logs"?"p":"li");n.textContent=typeof x==="string"?x:"";return n}):[]));q("cancel").onclick=()=>window.parent.postMessage({v:1,type:"lineup.surface.v1.event",instance_id:instanceId,event:"cancel"},"*");window.addEventListener("message",event=>{if(event.source!==window.parent)return;const d=event.data;if(!d||d.v!==1||d.type!=="lineup.surface.v1.state"||d.instance_id!==instanceId||!d.state||typeof d.state!=="object"||Array.isArray(d.state))return;const s=d.state;q("title").textContent=typeof s.title==="string"?s.title:"任务面板";q("progress").value=typeof s.percent==="number"?Math.max(0,Math.min(100,s.percent)):0;q("status").textContent=typeof s.status==="string"?s.status:"进行中";list("steps",s.steps);list("logs",s.logs);});window.parent.postMessage({v:1,type:"lineup.surface.v1.ready",instance_id:instanceId},"*");</script></body></html>`;
}

function isPlainObject(value: unknown): value is Record<string, unknown> {
  if (value === null || typeof value !== "object" || Array.isArray(value)) return false;
  const prototype = Object.getPrototypeOf(value);
  return prototype === Object.prototype || prototype === null;
}