/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {EnvironmentProviders, inject, InjectionToken, makeEnvironmentProviders, Provider} from '@angular/core';

import {HttpBackend, HttpHandler} from './backend';
import {HttpClient} from './client';
import {HTTP_INTERCEPTOR_FNS, HttpInterceptorFn, HttpInterceptorHandler, legacyInterceptorFnFactory} from './interceptor';
import {jsonpCallbackContext, JsonpCallbackContext, JsonpClientBackend, jsonpInterceptorFn} from './jsonp';
import {HttpXhrBackend} from './xhr';
import {HttpXsrfCookieExtractor, HttpXsrfTokenExtractor, XSRF_COOKIE_NAME, XSRF_ENABLED, XSRF_HEADER_NAME, xsrfInterceptorFn} from './xsrf';

/**
 * Identifies a particular kind of `HttpFeature`.
 *
 * @publicApi
 */
export enum HttpFeatureKind {
  Interceptors,
  LegacyInterceptors,
  CustomXsrfConfiguration,
  NoXsrfProtection,
  JsonpSupport,
  RequestsMadeViaParent,
}

/**
 * A feature for use when configuring `provideHttpClient`.
 *
 * @publicApi
 */
export interface HttpFeature<KindT extends HttpFeatureKind> {
  ɵkind: KindT;
  ɵproviders: Provider[];
}

function makeHttpFeature<KindT extends HttpFeatureKind>(
    kind: KindT, providers: Provider[]): HttpFeature<KindT> {
  return {
    ɵkind: kind,
    ɵproviders: providers,
  };
}

/**
 * Configures Angular's `HttpClient` service to be available for injection.
 *
 * By default, `HttpClient` will be configured for injection with its default options for XSRF
 * protection of outgoing requests. Additional configuration options can be provided by passing
 * feature functions to `provideHttpClient`. For example, HTTP interceptors can be added using the
 * `withInterceptors(...)` feature.
 *
 * @see withInterceptors
 * @see withInterceptorsFromDi
 * @see withXsrfConfiguration
 * @see withNoXsrfProtection
 * @see withJsonpSupport
 * @see withRequestsMadeViaParent
 */
export function provideHttpClient(...features: HttpFeature<HttpFeatureKind>[]):
    EnvironmentProviders {
  if (ngDevMode) {
    const featureKinds = new Set(features.map(f => f.ɵkind));
    if (featureKinds.has(HttpFeatureKind.NoXsrfProtection) &&
        featureKinds.has(HttpFeatureKind.CustomXsrfConfiguration)) {
      throw new Error(
          ngDevMode ?
              `Configuration error: found both withXsrfConfiguration() and withNoXsrfProtection() in the same call to provideHttpClient(), which is a contradiction.` :
              '');
    }
  }

  const providers: Provider[] = [
    HttpClient,
    HttpXhrBackend,
    HttpInterceptorHandler,
    {provide: HttpHandler, useExisting: HttpInterceptorHandler},
    {provide: HttpBackend, useExisting: HttpXhrBackend},
    {
      provide: HTTP_INTERCEPTOR_FNS,
      useValue: xsrfInterceptorFn,
      multi: true,
    },
    {provide: XSRF_ENABLED, useValue: true},
    {provide: HttpXsrfTokenExtractor, useClass: HttpXsrfCookieExtractor},
  ];

  for (const feature of features) {
    providers.push(...feature.ɵproviders);
  }

  return makeEnvironmentProviders(providers);
}

/**
 * Adds one or more functional-style HTTP interceptors to the configuration of the `HttpClient`
 * instance.
 *
 * @see HttpInterceptorFn
 * @see provideHttpClient
 * @publicApi
 */
export function withInterceptors(interceptorFns: HttpInterceptorFn[]):
    HttpFeature<HttpFeatureKind.Interceptors> {
  return makeHttpFeature(HttpFeatureKind.Interceptors, interceptorFns.map(interceptorFn => {
    return {
      provide: HTTP_INTERCEPTOR_FNS,
      useValue: interceptorFn,
      multi: true,
    };
  }));
}

const LEGACY_INTERCEPTOR_FN = new InjectionToken<HttpInterceptorFn>('LEGACY_INTERCEPTOR_FN');

/**
 * Includes class-based interceptors configured using a multi-provider in the current injector into
 * the configured `HttpClient` instance.
 *
 * Prefer `withInterceptors` and functional interceptors instead, as support for DI-provided
 * interceptors may be phased out in a later release.
 *
 * @see HttpInterceptor
 * @see HTTP_INTERCEPTORS
 * @see provideHttpClient
 */
export function withInterceptorsFromDi(): HttpFeature<HttpFeatureKind.LegacyInterceptors> {
  // Note: the legacy interceptor function is provided here via an intermediate token
  // (`LEGACY_INTERCEPTOR_FN`), using a pattern which guarantees that if these providers are
  // included multiple times, all of the multi-provider entries will have the same instance of the
  // interceptor function. That way, the `HttpINterceptorHandler` will dedup them and legacy
  // interceptors will not run multiple times.
  return makeHttpFeature(HttpFeatureKind.LegacyInterceptors, [
    {
      provide: LEGACY_INTERCEPTOR_FN,
      useFactory: legacyInterceptorFnFactory,
    },
    {
      provide: HTTP_INTERCEPTOR_FNS,
      useExisting: LEGACY_INTERCEPTOR_FN,
      multi: true,
    }
  ]);
}

/**
 * Customizes the XSRF protection for the configuration of the current `HttpClient` instance.
 *
 * This feature is incompatible with the `withNoXsrfProtection` feature.
 *
 * @see provideHttpClient
 */
export function withXsrfConfiguration(
    {cookieName, headerName}: {cookieName?: string, headerName?: string}):
    HttpFeature<HttpFeatureKind.CustomXsrfConfiguration> {
  const providers: Provider[] = [];
  if (cookieName !== undefined) {
    providers.push({provide: XSRF_COOKIE_NAME, useValue: cookieName});
  }
  if (headerName !== undefined) {
    providers.push({provide: XSRF_HEADER_NAME, useValue: headerName});
  }

  return makeHttpFeature(HttpFeatureKind.CustomXsrfConfiguration, providers);
}

/**
 * Disables XSRF protection in the configuration of the current `HttpClient` instance.
 *
 * This feature is incompatible with the `withXsrfConfiguration` feature.
 *
 * @see provideHttpClient
 */
export function withNoXsrfProtection(): HttpFeature<HttpFeatureKind.NoXsrfProtection> {
  return makeHttpFeature(HttpFeatureKind.NoXsrfProtection, [
    {
      provide: XSRF_ENABLED,
      useValue: false,
    },
  ]);
}

/**
 * Add JSONP support to the configuration of the current `HttpClient` instance.
 *
 * @see provideHttpClient
 */
export function withJsonpSupport(): HttpFeature<HttpFeatureKind.JsonpSupport> {
  return makeHttpFeature(HttpFeatureKind.JsonpSupport, [
    JsonpClientBackend,
    {provide: JsonpCallbackContext, useFactory: jsonpCallbackContext},
    {provide: HTTP_INTERCEPTOR_FNS, useValue: jsonpInterceptorFn, multi: true},
  ]);
}

/**
 * Configures the current `HttpClient` instance to make requests via the parent injector's
 * `HttpClient` instead of directly.
 *
 * By default, `provideHttpClient` configures `HttpClient` in its injector to be an independent
 * instance. For example, even if `HttpClient` is configured in the parent injector with
 * one or more interceptors, they will not intercept requests made via this instance.
 *
 * With this option enabled, once the request has passed through the current injector's
 * interceptors, it will be delegated to the parent injector's `HttpClient` chain instead of
 * dispatched directly, and interceptors in the parent configuration will be applied to the request.
 *
 * If there are several `HttpClient` instances in the injector hierarchy, it's possible for
 * `withRequestsMadeViaParent` to be used at multiple levels, which will cause the request to
 * "bubble up" until either reaching the root level or an `HttpClient` which was not configured with
 * this option.
 *
 * @see provideHttpClient
 * @developerPreview
 */
export function withRequestsMadeViaParent(): HttpFeature<HttpFeatureKind.RequestsMadeViaParent> {
  return makeHttpFeature(HttpFeatureKind.RequestsMadeViaParent, [
    {
      provide: HttpBackend,
      useFactory: () => {
        const handlerFromParent = inject(HttpHandler, {skipSelf: true, optional: true});
        if (ngDevMode && handlerFromParent === null) {
          throw new Error(
              'withRequestsMadeViaParent() can only be used when the parent injector also configures HttpClient');
        }
        return handlerFromParent;
      },
    },
  ]);
}