import { AadHttpClient, HttpClientResponse } from '@microsoft/sp-http';

// Ответ бэкенда всегда в конверте { data: T } на успехе (Api/Common/ApiResponse.cs)
// и { messages: string[] } на ошибке (ApiError). 204 No Content возвращается без тела.
interface IApiEnvelope<T> {
  data?: T;
  messages?: string[];
}

export class ApiClientError extends Error {
  public readonly status: number;
  public readonly messages: string[];

  constructor(status: number, messages: string[]) {
    super(messages.join('; ') || `HTTP ${status}`);
    this.status = status;
    this.messages = messages;
  }
}

export type QueryParams = Record<string, string | number | boolean | undefined>;

export interface IHttpClient {
  get<T>(path: string, query?: QueryParams): Promise<T>;
  post<T>(path: string, body?: unknown): Promise<T>;
  put<T>(path: string, body?: unknown): Promise<T>;
  patch<T>(path: string, body?: unknown): Promise<T>;
  delete(path: string): Promise<void>;
}

function buildUrl(baseUrl: string, path: string, query?: QueryParams): string {
  const normalizedBase = baseUrl.endsWith('/') ? baseUrl : `${baseUrl}/`;
  const url = new URL(path.replace(/^\//, ''), normalizedBase);
  if (query) {
    Object.keys(query).forEach(key => {
      const value = query[key];
      if (value !== undefined && value !== '') {
        url.searchParams.set(key, String(value));
      }
    });
  }
  return url.toString();
}

interface IMinimalResponse {
  ok: boolean;
  status: number;
  text(): Promise<string>;
}

async function parseResponse<T>(response: IMinimalResponse): Promise<T> {
  if (response.status === 204) {
    return undefined as T;
  }

  const text = await response.text();
  let json: IApiEnvelope<T> | undefined;
  try {
    json = text ? JSON.parse(text) : undefined;
  } catch {
    // Ответ пришёл не в конверте ApiResponse/ApiError (например, "сырая" страница
    // необработанного исключения ASP.NET Core или ошибка от прокси перед API).
    if (!response.ok) {
      throw new ApiClientError(response.status, [text || `HTTP ${response.status}`]);
    }
    throw new ApiClientError(response.status, ['Сервер вернул не-JSON ответ.']);
  }

  if (!response.ok) {
    const messages = json?.messages ?? [`HTTP ${response.status}`];
    throw new ApiClientError(response.status, messages);
  }

  return (json?.data as T) ?? (undefined as T);
}

/**
 * Прод/staging: вызовы через AAD-защищённое SPFx-подключение (AadHttpClient).
 * Требует webApiPermissionRequests в package-solution.json и админского
 * согласия в SharePoint admin center → Advanced → API access.
 */
export class AadApiHttpClient implements IHttpClient {
  constructor(private readonly client: AadHttpClient, private readonly baseUrl: string) {}

  public get<T>(path: string, query?: QueryParams): Promise<T> {
    const url = buildUrl(this.baseUrl, path, query);
    return this.client
      .get(url, AadHttpClient.configurations.v1)
      .then((r: HttpClientResponse) => parseResponse<T>(r));
  }

  public post<T>(path: string, body?: unknown): Promise<T> {
    return this.send<T>('POST', path, body);
  }

  public put<T>(path: string, body?: unknown): Promise<T> {
    return this.send<T>('PUT', path, body);
  }

  public patch<T>(path: string, body?: unknown): Promise<T> {
    return this.send<T>('PATCH', path, body);
  }

  public async delete(path: string): Promise<void> {
    await this.send<void>('DELETE', path);
  }

  private send<T>(method: string, path: string, body?: unknown): Promise<T> {
    const url = buildUrl(this.baseUrl, path);
    return this.client
      .fetch(url, AadHttpClient.configurations.v1, {
        method,
        headers: { 'Content-Type': 'application/json' },
        body: body !== undefined ? JSON.stringify(body) : undefined
      })
      .then((r: HttpClientResponse) => parseResponse<T>(r));
  }
}