/**
 * @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 {ɵRuntimeError as RuntimeError} from '@angular/core';
import {Observable, of, throwError} from 'rxjs';

import {RuntimeErrorCode} from './errors';
import {NavigationCancellationCode} from './events';
import {LoadedRouterConfig, Route} from './models';
import {navigationCancelingError} from './navigation_canceling_error';
import {Params, PRIMARY_OUTLET} from './shared';
import {UrlSegment, UrlSegmentGroup, UrlSerializer, UrlTree} from './url_tree';

export class NoMatch {
  public segmentGroup: UrlSegmentGroup | null;

  constructor(segmentGroup?: UrlSegmentGroup) {
    this.segmentGroup = segmentGroup || null;
  }
}

export class AbsoluteRedirect extends Error {
  constructor(public urlTree: UrlTree) {
    super();
  }
}

export function noMatch(segmentGroup: UrlSegmentGroup): Observable<any> {
  return throwError(new NoMatch(segmentGroup));
}

export function absoluteRedirect(newTree: UrlTree): Observable<any> {
  return throwError(new AbsoluteRedirect(newTree));
}

export function namedOutletsRedirect(redirectTo: string): Observable<any> {
  return throwError(
    new RuntimeError(
      RuntimeErrorCode.NAMED_OUTLET_REDIRECT,
      (typeof ngDevMode === 'undefined' || ngDevMode) &&
        `Only absolute redirects can have named outlets. redirectTo: '${redirectTo}'`,
    ),
  );
}

export function canLoadFails(route: Route): Observable<LoadedRouterConfig> {
  return throwError(
    navigationCancelingError(
      (typeof ngDevMode === 'undefined' || ngDevMode) &&
        `Cannot load children because the guard of the route "path: '${route.path}'" returned false`,
      NavigationCancellationCode.GuardRejected,
    ),
  );
}

export class ApplyRedirects {
  constructor(
    private urlSerializer: UrlSerializer,
    private urlTree: UrlTree,
  ) {}

  lineralizeSegments(route: Route, urlTree: UrlTree): Observable<UrlSegment[]> {
    let res: UrlSegment[] = [];
    let c = urlTree.root;
    while (true) {
      res = res.concat(c.segments);
      if (c.numberOfChildren === 0) {
        return of(res);
      }

      if (c.numberOfChildren > 1 || !c.children[PRIMARY_OUTLET]) {
        return namedOutletsRedirect(route.redirectTo!);
      }

      c = c.children[PRIMARY_OUTLET];
    }
  }

  applyRedirectCommands(
    segments: UrlSegment[],
    redirectTo: string,
    posParams: {[k: string]: UrlSegment},
  ): UrlTree {
    const newTree = this.applyRedirectCreateUrlTree(
      redirectTo,
      this.urlSerializer.parse(redirectTo),
      segments,
      posParams,
    );
    if (redirectTo.startsWith('/')) {
      throw new AbsoluteRedirect(newTree);
    }
    return newTree;
  }

  applyRedirectCreateUrlTree(
    redirectTo: string,
    urlTree: UrlTree,
    segments: UrlSegment[],
    posParams: {[k: string]: UrlSegment},
  ): UrlTree {
    const newRoot = this.createSegmentGroup(redirectTo, urlTree.root, segments, posParams);
    return new UrlTree(
      newRoot,
      this.createQueryParams(urlTree.queryParams, this.urlTree.queryParams),
      urlTree.fragment,
    );
  }

  createQueryParams(redirectToParams: Params, actualParams: Params): Params {
    const res: Params = {};
    Object.entries(redirectToParams).forEach(([k, v]) => {
      const copySourceValue = typeof v === 'string' && v.startsWith(':');
      if (copySourceValue) {
        const sourceName = v.substring(1);
        res[k] = actualParams[sourceName];
      } else {
        res[k] = v;
      }
    });
    return res;
  }

  createSegmentGroup(
    redirectTo: string,
    group: UrlSegmentGroup,
    segments: UrlSegment[],
    posParams: {[k: string]: UrlSegment},
  ): UrlSegmentGroup {
    const updatedSegments = this.createSegments(redirectTo, group.segments, segments, posParams);

    let children: {[n: string]: UrlSegmentGroup} = {};
    Object.entries(group.children).forEach(([name, child]) => {
      children[name] = this.createSegmentGroup(redirectTo, child, segments, posParams);
    });

    return new UrlSegmentGroup(updatedSegments, children);
  }

  createSegments(
    redirectTo: string,
    redirectToSegments: UrlSegment[],
    actualSegments: UrlSegment[],
    posParams: {[k: string]: UrlSegment},
  ): UrlSegment[] {
    return redirectToSegments.map((s) =>
      s.path.startsWith(':')
        ? this.findPosParam(redirectTo, s, posParams)
        : this.findOrReturn(s, actualSegments),
    );
  }

  findPosParam(
    redirectTo: string,
    redirectToUrlSegment: UrlSegment,
    posParams: {[k: string]: UrlSegment},
  ): UrlSegment {
    const pos = posParams[redirectToUrlSegment.path.substring(1)];
    if (!pos)
      throw new RuntimeError(
        RuntimeErrorCode.MISSING_REDIRECT,
        (typeof ngDevMode === 'undefined' || ngDevMode) &&
          `Cannot redirect to '${redirectTo}'. Cannot find '${redirectToUrlSegment.path}'.`,
      );
    return pos;
  }

  findOrReturn(redirectToUrlSegment: UrlSegment, actualSegments: UrlSegment[]): UrlSegment {
    let idx = 0;
    for (const s of actualSegments) {
      if (s.path === redirectToUrlSegment.path) {
        actualSegments.splice(idx);
        return s;
      }
      idx++;
    }
    return redirectToUrlSegment;
  }
}