import { getPageSignFromUrl } from "./oauth";

export const preloadDefaultMcp = async (): Promise<File | null> => {
  try {
    const res = await fetch("/demo-mcp.json", { cache: "no-store" });
    if (!res.ok) return null;
    const blob = await res.blob();
    return new File([blob], "demo-mcp.json", { type: "application/json" });
  } catch (err) {
    console.error(err);
    return null;
  }
};

export const readFileAsText = (file: File): Promise<string> => {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onerror = () => reject(new Error("File reading failed"));
    reader.onload = () => resolve(String(reader.result || ""));
    reader.readAsText(file);
  });
};

export interface StartDemoPayload {
  model: string;
  provider: string;
  user: string;
  mcp: string | null;
  sign: string | null;
}

export const startDemo = async (
  payload: StartDemoPayload,
  accessToken: string | null,
): Promise<{ iframe_url: string; health_url: string }> => {
  const headers: Record<string, string> = {
    "Content-Type": "application/json",
  };
  if (accessToken) headers["Authorization"] = `Bearer ${accessToken}`;

  const res = await fetch("/api/start", {
    method: "POST",
    headers,
    body: JSON.stringify(payload),
  });

  if (!res.ok) {
    let message = `Error while starting (${res.status}${res.statusText ? ` ${res.statusText}` : ""})`;
    try {
      const clone = res.clone();
      try {
        const data = await res.json();
        const parts = [];
        if (data && data.error) parts.push(String(data.error));
        if (data && data.detail) parts.push(String(data.detail));
        if (parts.length)
          message = `Error while starting: ${parts.join(" — ")}`;
      } catch (_e) {
        const txt = await clone.text();
        if (txt && txt.trim())
          message = `Error while starting: ${txt.trim().slice(0, 300)}`;
      }
    } catch (_ignore) {}
    throw new Error(message);
  }

  const data = await res.json();
  if (!data || !data.iframe_url || !data.health_url) {
    throw new Error("Invalid server response - missing required URLs.");
  }

  return data;
};

export const createStartDemoPayload = (
  model: string,
  provider: string,
  loginLabel: string,
  mcpText: string | null,
): StartDemoPayload => ({
  model: model.trim(),
  provider: provider.trim(),
  user: loginLabel,
  mcp: mcpText,
  sign: getPageSignFromUrl(),
});