declare global {
  interface Window {
    __IMAGEFIND_BASE__?: string;
  }
}

function normaliseBase(value: string | undefined) {
  const base = value?.trim() || "/";
  return `/${base.replace(/^\/+|\/+$/g, "")}${base === "/" ? "" : "/"}`;
}

export const appBase = normaliseBase(window.__IMAGEFIND_BASE__);

export function appUrl(value: string | undefined): string {
  if (!value) return "";
  if (/^(?:[a-z][a-z\d+.-]*:|\/\/|#)/i.test(value)) return value;
  const target = `${appBase}${value.replace(/^\/+/, "")}`;
  const path = `/${value.replace(/^\/+/, "")}`;
  const mediaPath = /^\/api\/v1\/(?:frames\/[^/]+\/thumbnail|faces\/[^/]+\/thumbnail|videos\/[^/]+\/(?:stream|download)|previews\/)/.test(path);
  if (appBase === "/" || !gatewayMediaToken || !mediaPath) return target;
  return `${target}${target.includes("?") ? "&" : "?"}media_token=${encodeURIComponent(gatewayMediaToken)}`;
}

let csrfToken = sessionStorage.getItem("imagefind:csrf") || "";
let gatewaySessionToken = sessionStorage.getItem("imagefind:gateway-session") || "";
let gatewayMediaToken = sessionStorage.getItem("imagefind:gateway-media-token") || "";
let gatewayRenewal: Promise<void> | null = null;
const inflightReads = new Map<string, Promise<unknown>>();

export function appMediaUrl(value: string | undefined): string {
  if (!value) return "";
  if (/^(?:[a-z][a-z\d+.-]*:|\/\/|#)/i.test(value)) return value;
  const target = appUrl(value);
  if (appBase === "/" || !gatewayMediaToken) return target;
  const hashAt = target.indexOf("#");
  const body = hashAt >= 0 ? target.slice(0, hashAt) : target;
  const hash = hashAt >= 0 ? target.slice(hashAt) : "";
  if (/(?:^|[?&])media_token=/.test(body)) return target;
  const separator = body.includes("?") ? "&" : "?";
  return `${body}${separator}media_token=${encodeURIComponent(gatewayMediaToken)}${hash}`;
}

export function setCsrf(token: string) {
  csrfToken = token;
  if (token) sessionStorage.setItem("imagefind:csrf", token);
  else sessionStorage.removeItem("imagefind:csrf");
}

export function setGatewaySession(token: string) {
  gatewaySessionToken = token;
  if (token) sessionStorage.setItem("imagefind:gateway-session", token);
  else sessionStorage.removeItem("imagefind:gateway-session");
}

export function setGatewayMediaToken(token: string) {
  gatewayMediaToken = token;
  if (token) sessionStorage.setItem("imagefind:gateway-media-token", token);
  else sessionStorage.removeItem("imagefind:gateway-media-token");
}

async function renewGatewaySession(): Promise<void> {
  if (appBase === "/") throw new Error("需要管理员登录");
  if (!gatewayRenewal) {
    gatewayRenewal = fetch(appUrl("/api/v1/auth/gateway"), {
      method: "POST",
      credentials: "same-origin",
      headers: { "Content-Type": "application/json" },
      body: "{}",
    }).then(async response => {
      if (!response.ok) throw new Error("飞牛管理员会话需要重新建立");
      const value = await response.json() as {
        csrf_token: string;
        gateway_session_token: string;
        gateway_media_token: string;
      };
      setGatewaySession(value.gateway_session_token);
      setGatewayMediaToken(value.gateway_media_token);
      setCsrf(value.csrf_token);
      window.dispatchEvent(new CustomEvent("imagefind-gateway-renewed"));
    }).finally(() => { gatewayRenewal = null; });
  }
  return gatewayRenewal;
}

async function request(path: string, options: RequestInit = {}): Promise<Response> {
  const send = () => {
  const headers = new Headers(options.headers);
  if (typeof options.body === "string" && !headers.has("Content-Type")) headers.set("Content-Type", "application/json");
  if (options.method && !["GET", "HEAD"].includes(options.method.toUpperCase()) && csrfToken) {
    headers.set("X-CSRF-Token", csrfToken);
  }
  if (appBase !== "/" && gatewaySessionToken) headers.set("X-ImageFind-Gateway-Session", gatewaySessionToken);
    return fetch(appUrl(`/api/v1${path}`), { ...options, headers, credentials: "same-origin" });
  };
  let response = await send();
  if (response.status === 401 && appBase !== "/" && path !== "/auth/gateway") {
    await renewGatewaySession();
    response = await send();
  }
  if (!response.ok) {
    let message = `${response.status} ${response.statusText}`;
    try {
      const payload = await response.json();
      message = typeof payload.detail === "string" ? payload.detail : payload.detail?.message || message;
    } catch { /* response is not JSON */ }
    throw new Error(message);
  }
  return response;
}

export async function api<T>(path: string, options: RequestInit = {}): Promise<T> {
  const method = String(options.method || "GET").toUpperCase();
  if (method === "GET" && options.body === undefined) {
    const existing = inflightReads.get(path);
    if (existing) return existing as Promise<T>;
    const pending = request(path, options).then(response =>
      response.status === 204 ? undefined : response.json()
    ).finally(() => inflightReads.delete(path));
    inflightReads.set(path, pending);
    return pending as Promise<T>;
  }
  const response = await request(path, options);
  if (response.status === 204) return undefined as T;
  return response.json() as Promise<T>;
}

export async function downloadBackup(scope: "keys" | "full", password: string) {
  const response = await request("/backups/export", {
    method: "POST",
    body: JSON.stringify({ scope, password }),
  });
  const disposition = response.headers.get("Content-Disposition") || "";
  const encoded = disposition.match(/filename\*=UTF-8''([^;]+)/i)?.[1];
  const plain = disposition.match(/filename="?([^";]+)"?/i)?.[1];
  const filename = encoded ? decodeURIComponent(encoded) : plain || `imagefind-backup-${scope}.ifbackup`;
  const blob = await response.blob();
  const url = URL.createObjectURL(blob);
  const anchor = document.createElement("a");
  anchor.href = url;
  anchor.download = filename;
  document.body.append(anchor);
  anchor.click();
  anchor.remove();
  window.setTimeout(() => URL.revokeObjectURL(url), 1000);
  return { filename, size_bytes: blob.size };
}

export async function downloadGeneratedBackup(exportId: string) {
  const response = await request(`/backups/${encodeURIComponent(exportId)}/download`);
  const disposition = response.headers.get("Content-Disposition") || "";
  const encoded = disposition.match(/filename\*=UTF-8''([^;]+)/i)?.[1];
  const plain = disposition.match(/filename="?([^";]+)"?/i)?.[1];
  const filename = encoded ? decodeURIComponent(encoded) : plain || `imagefind-backup-${exportId}.ifbackup`;
  const blob = await response.blob();
  const url = URL.createObjectURL(blob);
  const anchor = document.createElement("a");
  anchor.href = url;
  anchor.download = filename;
  document.body.append(anchor);
  anchor.click();
  anchor.remove();
  window.setTimeout(() => URL.revokeObjectURL(url), 1000);
  return { filename, size_bytes: blob.size };
}

export async function restoreBackup<T>(file: File, password: string, confirmed: boolean): Promise<T> {
  const form = new FormData();
  form.append("file", file);
  form.append("password", password);
  form.append("confirmed", String(confirmed));
  return api<T>("/backups/restore", { method: "POST", body: form });
}

export async function uploadImage(file: File): Promise<{ id: string }> {
  const form = new FormData();
  form.append("file", file);
  return api("/query-images", { method: "POST", body: form });
}