// Libraries
import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Location } from '@angular/common';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

// Services
import { ConfigService } from '@app/core/config.service';

// Models
import { Note } from '@app/core/models/note';
import { Term } from '@app/core/models/term';
import { Course } from '@app/core/models/course';
import { DegreePlan } from '@app/core/models/degree-plan';
import { SavedForLaterCourse } from '@app/core/models/saved-for-later-course';

const HTTP_OPTIONS = {
  headers: new HttpHeaders({
    'Content-Type': 'application/json',
  }),
};

@Injectable({ providedIn: 'root' })
export class DegreePlannerApiService {
  constructor(private http: HttpClient, private config: ConfigService) {}

  public getSavedForLaterCourses(): Observable<SavedForLaterCourse[]> {
    return this.http.get<SavedForLaterCourse[]>(
      `${this.config.apiPlannerUrl}/favorites`,
    );
  }

  public getAllDegreePlans(): Observable<DegreePlan[]> {
    return this.http.get<DegreePlan[]>(this.degreePlanEndpoint());
  }

  public getPlan(roadmapId: number): Observable<DegreePlan> {
    return this.http.get<DegreePlan>(this.degreePlanEndpoint(roadmapId));
  }

  public getAllSubjects(): Observable<Object> {
    return this.http.get<Object>(this.searchEndpoint('subjectsMap/0000'));
  }

  public getActiveTerms(): Observable<Term[]> {
    return this.http.get<Term[]>(this.searchEndpoint('terms'));
  }

  public getAllNotes(roadmapId: number): Observable<Note[]> {
    return this.http.get<Note[]>(this.degreePlanEndpoint(roadmapId, 'notes'));
  }

  public getAllTermCourses(
    roadmapId: number,
  ): Observable<{ termCode: string; courses: Course[] }[]> {
    return this.http.get<{ termCode: string; courses: Course[] }[]>(
      this.degreePlanEndpoint(roadmapId, 'termcourses'),
    );
  }

  public updateCourseTerm(roadmapId, recordId, termCode): Observable<any> {
    return this.http.put<Course>(
      this.config.apiPlannerUrl +
        '/degreePlan/' +
        roadmapId +
        '/courses/' +
        recordId +
        '?termCode=' +
        termCode,
      HTTP_OPTIONS,
    );
  }

  public addCourse(
    planId: number,
    subjectCode: string,
    courseId: string,
    termCode: string,
  ): Observable<Course> {
    return this.http.post<Course>(
      this.config.apiPlannerUrl + '/degreePlan/' + planId + '/courses',
      { subjectCode, courseId, termCode },
      HTTP_OPTIONS,
    );
  }

  public removeCourse(planId: number, recordId: string) {
    return this.http.delete(
      this.config.apiPlannerUrl +
        '/degreePlan/' +
        planId +
        '/courses/' +
        recordId,
      HTTP_OPTIONS,
    );
  }

  public saveForLater(
    subjectCode: string,
    courseId: string,
  ): Observable<SavedForLaterCourse> {
    return this.http.post<SavedForLaterCourse>(
      this.config.apiPlannerUrl + '/favorites/' + subjectCode + '/' + courseId,
      HTTP_OPTIONS,
    );
  }

  public removeSavedForLater(
    subjectCode: string,
    courseId: string,
  ): Observable<SavedForLaterCourse> {
    return this.http.delete<SavedForLaterCourse>(
      this.config.apiPlannerUrl + '/favorites/' + subjectCode + '/' + courseId,
      HTTP_OPTIONS,
    );
  }

  public createNote(
    planId: number,
    termCode: string,
    noteText: string,
  ): Observable<Note> {
    const payload = {
      termCode: termCode,
      note: noteText,
    };

    return this.http.post<Note>(
      this.degreePlanEndpoint(planId, 'notes'),
      payload,
      HTTP_OPTIONS,
    );
  }

  public updateNote(
    planId: number,
    termCode: string,
    noteText: string,
    noteId: number,
  ): Observable<Note> {
    const payload = {
      termCode: termCode,
      note: noteText,
      id: noteId,
    };

    return this.http
      .put<null>(
        this.degreePlanEndpoint(planId, 'notes', noteId),
        payload,
        HTTP_OPTIONS,
      )
      .pipe(map(() => payload));
  }

  public deleteNote(planId: number, noteId: number): Observable<null> {
    return this.http.delete<null>(
      this.degreePlanEndpoint(planId, 'notes', noteId),
      HTTP_OPTIONS,
    );
  }

  /**
   * Helper function for building API endpoint URLs
   */
  private degreePlanEndpoint(...parts: any[]): string {
    return ['degreePlan']
      .concat(parts.map(part => part.toString()))
      .reduce((soFar, next) => {
        return Location.joinWithSlash(soFar, next);
      }, this.config.apiPlannerUrl);
  }

  private searchEndpoint(...parts: any[]): string {
    return parts
      .map(part => part.toString())
      .reduce((soFar, next) => {
        return Location.joinWithSlash(soFar, next);
      }, this.config.apiSearchUrl);
  }
}