import { Component, Input, OnInit } from '@angular/core';
import { CdkDragDrop } from '@angular/cdk/drag-drop';
import { MatDialog, ErrorStateMatcher } from '@angular/material';
import { Observable } from 'rxjs';
import { filter, map, distinctUntilChanged } from 'rxjs/operators';
import { Store, select } from '@ngrx/store';
import { DegreePlannerState } from '@app/degree-planner/store/state';
import {
  ToggleCourseSearch,
  OpenCourseSearch,
} from '@app/degree-planner/store/actions/ui.actions';

// Models
import * as actions from '@app/degree-planner/store/actions/course.actions';
import * as selectors from '@app/degree-planner/store/selectors';
import { PlannedTerm, PlannedTermNote } from '@app/core/models/planned-term';
import { Note } from '@app/core/models/note';
import { Course } from '@app/core/models/course';
import {
  NotesDialogComponent,
  NotesDialogData,
} from '@app/degree-planner/dialogs/notes-dialog/notes-dialog.component';
import * as utils from '@app/degree-planner/shared/utils';
import { findSafariExecutable } from 'selenium-webdriver/safari';

const isntUndefined = <T>(thing: T | undefined): thing is T => {
  return thing !== undefined;
};

const sumCredits = (courses: Course[]): number => {
  return courses.reduce((sum, course) => {
    if (course.credits == undefined) {
      return sum + course.credits;
    }
    return 0;
  }, 0);
};

const sumCreditsInCart = (courses: Course[]): number => {
  return courses
    .filter(course => course.id && course.creditRange)
    .reduce((sum, course) => {
      return sum + parseInt(course.creditRange);
    }, 0);
};

@Component({
  selector: 'cse-term-container',
  templateUrl: './term-container.component.html',
  styleUrls: ['./term-container.component.scss'],
})
export class TermContainerComponent implements OnInit {
  @Input() yearCode: string;
  @Input() termName: 'fall' | 'spring' | 'summer';

  public termCode: string;
  public term$: Observable<PlannedTerm>;
  public note$: Observable<PlannedTermNote | undefined>;
  public courses$: Observable<Course[]>;
  public credits$: Observable<number>;
  public cartCredits$: Observable<number>;
  public isPastTerm$: Observable<boolean>;
  public dropZoneIds$: Observable<string[]>;
  public isCurrentTerm$: Observable<boolean>;

  constructor(
    public dialog: MatDialog,
    private store: Store<{ degreePlanner: DegreePlannerState }>,
  ) {}

  public ngOnInit() {
    const termOffset = { fall: 2, spring: 4, summer: 6 };
    this.termCode = `${this.yearCode}${termOffset[this.termName]}`;

    this.term$ = this.store.pipe(
      select(selectors.selectVisibleTerm, { termCode: this.termCode }),
      filter(isntUndefined),
      distinctUntilChanged(),
    );

    this.note$ = this.term$.pipe(
      map(term => term.note),
      distinctUntilChanged(),
    );

    this.courses$ = this.term$.pipe(
      map(term => term.courses),
      distinctUntilChanged(),
    );

    this.credits$ = this.courses$.pipe(
      map(sumCredits),
      distinctUntilChanged(),
    );

    this.cartCredits$ = this.courses$.pipe(
      map(sumCreditsInCart),
      distinctUntilChanged(),
    );

    this.isPastTerm$ = this.term$.pipe(
      map(term => term.era === 'past'),
      distinctUntilChanged(),
    );

    this.dropZoneIds$ = this.store.pipe(
      select(selectors.selectAllVisibleYears),
      utils.yearsToDropZoneIds(),
      distinctUntilChanged(utils.compareStringArrays),
    );

    this.isPastTerm$ = this.store.pipe(
      select(selectors.isPastTerm(this.termCode)),
    );

    this.isCurrentTerm$ = this.store.pipe(
      select(selectors.isCurrentTerm(this.termCode)),
    );
  }

  openNotesDialog(note?: PlannedTermNote) {
    if (note === undefined || note.isLoaded) {
      const termCode = this.termCode;
      const data: NotesDialogData = note
        ? {
            termCode,
            hasExistingNote: true,
            initialText: note.text,
            noteId: note.id,
          }
        : { termCode, hasExistingNote: false };
      this.dialog.open(NotesDialogComponent, { data });
    }
  }

  openCourseSearch() {
    this.store.dispatch(new OpenCourseSearch(this.termCode));
  }

  drop(event: CdkDragDrop<string>) {
    const newContainer = event.container.id;
    const previousContainer = event.previousContainer.id;

    if (newContainer === previousContainer) {
      const newIndex = event.currentIndex;
      const { id: recordId, termCode } = event.item.data as Course;

      if (recordId !== null) {
        const action = new actions.MoveCourseInsideTerm({
          termCode,
          recordId,
          newIndex,
        });
        this.store.dispatch(action);
      }
    } else if (previousContainer.indexOf('term-') === 0) {
      // If moving from term to term

      // Get the pervious and new term code, and the record ID
      const from = event.previousContainer.data;
      const to = event.container.data;
      const { id } = event.item.data;
      const newIndex = event.currentIndex;

      // Dispatch a new change request
      this.store.dispatch(
        new actions.MoveCourseBetweenTerms({ to, from, id, newIndex }),
      );
    } else if (previousContainer === 'saved-courses') {
      // If moving from saved courses to term

      // Get the term code from the new term dropzone's ID
      const termCode = newContainer.substr(5);
      const newIndex = event.currentIndex;
      // Pull the course data from the moved item
      const { subjectCode, courseId, title, catalogNumber } = event.item.data;

      this.store.dispatch(
        new actions.AddCourse({
          courseId,
          termCode,
          subjectCode,
          title,
          catalogNumber,
          newIndex,
        }),
      );
      this.store.dispatch(
        new actions.RemoveSaveForLater({ subjectCode, courseId }),
      );
    } else if (
      previousContainer === 'queried-courses-list' &&
      newContainer.indexOf('term-') === 0
    ) {
      const termCode = newContainer.substr(5);
      const newIndex = event.currentIndex;
      this.store.dispatch(
        new actions.AddCourse({
          courseId: event.item.data.courseId,
          termCode,
          subjectCode: event.item.data.subjectCode,
          title: event.item.data.title,
          catalogNumber: event.item.data.catalogNumber,
          newIndex,
        }),
      );
    }
  }
}