import {Location} from "@angular/common";
import {inject, Injectable, OnDestroy, Signal, signal} from "@angular/core";
import {MatDialog} from "@angular/material/dialog";
import {MatSnackBar} from "@angular/material/snack-bar";
import {ActivatedRoute} from "@angular/router";
import {debounceTime, distinctUntilChanged, Subscription} from "rxjs";
import {DEFAULT_PUBLICATION, Publication} from "../../core/rest-services/publications/model/publication";
import {PublicationRestService} from "../../core/rest-services/publications/publication.rest-service";
import {copy} from "../../core/utils/ObjectUtils";
import {CodeBlockDialog} from "./code-block-dialog/code-block-dialog.component";
import {PictureSelectionDialog} from "./picture-selection-dialog/picture-selection-dialog.component";
import {PreviewContentRequest} from "../../core/rest-services/publications/model/preview";
import {FormBuilder, FormControl, FormGroup, Validators} from "@angular/forms";

declare let Prism: any;

export class CursorPosition {
  start: number;
  end: number;
  selectedCharacters: number;

  constructor(start: number, end: number) {
    this.start = start;
    this.end = end;
    this.selectedCharacters = end - start;
  }
}

export interface PublicationEditionState {
  publication: Publication;
  cursorPosition: CursorPosition;
}

const DEFAULT_CURSOR_POSITION = new CursorPosition(0, 0);

const DEFAULT_STATE: PublicationEditionState = {
  publication: DEFAULT_PUBLICATION,
  cursorPosition: DEFAULT_CURSOR_POSITION
};

@Injectable()
export class PublicationEditionService implements OnDestroy {
  readonly #activatedRoute = inject(ActivatedRoute);
  readonly #dialog = inject(MatDialog);
  readonly #formBuilder = inject(FormBuilder);
  readonly #location = inject(Location);
  readonly #publicationRestService = inject(PublicationRestService);
  readonly #snackBar = inject(MatSnackBar);

  #isLoading = signal(false);
  #state = signal<PublicationEditionState>(copy(DEFAULT_STATE));
  #isSaving = signal<boolean>(false);
  #isPreviewing = signal<boolean>(false);
  #subscriptions: Subscription[] = [];

  publicationEditionForm: FormGroup = this.#formBuilder.group({
    title: new FormControl<string | undefined>('', [Validators.required]),
    description: new FormControl<string | undefined>('', [Validators.required]),
    text: new FormControl<string | undefined>('', [Validators.required]),
    illustrationId: new FormControl<string | undefined>('', [Validators.required]),
    categoryId: new FormControl<string | undefined>('', [Validators.required])
  });

  ngOnDestroy(): void {
    this.#subscriptions.forEach(subscription => subscription.unsubscribe());
  }

  #updateForm(): void {
    const state = this.#state();
    const publication = state.publication;

    this.publicationEditionForm.controls['title'].setValue(publication.title);
    this.publicationEditionForm.controls['description'].setValue(publication.description);
    this.publicationEditionForm.controls['text'].setValue(publication.text);
    this.publicationEditionForm.controls['illustrationId'].setValue(publication.illustrationId);
    this.publicationEditionForm.controls['categoryId'].setValue(publication.categoryId);
  }

  get isLoading(): Signal<boolean> {
    return this.#isLoading.asReadonly();
  }

  get isSaving(): Signal<boolean> {
    return this.#isSaving.asReadonly();
  }

  get isPreviewing(): Signal<boolean> {
    return this.#isPreviewing.asReadonly();
  }

  get state(): Signal<PublicationEditionState> {
    return this.#state.asReadonly();
  }

  get editedPublication(): Publication {
    return this.#state().publication;
  }

  loadPublication(): void {
    this.#isLoading.set(true);

    this.#activatedRoute.paramMap.subscribe(params => {
      const publicationId = params.get('publicationId');
      if (publicationId == undefined) {
        this.#snackBar.open($localize`A technical error occurred while loading publication data.`, $localize`Close`, {duration: 5000});
        this.#location.back();
      } else {
        this.#publicationRestService.getById(publicationId)
          .then(publication => {
            const state = this.#state();
            state.publication = publication;
            this.#state.set(state);
          })
          .catch(error => {
            const errorMessage = $localize`A technical error occurred while loading publication data.`;
            this.#snackBar.open(errorMessage, $localize`Close`, {duration: 5000});
            console.error(errorMessage, error)
          })
          .finally(() => this.#isLoading.set(false));
      }
    });
  }

  init(publication: Publication): void {
    const state = this.#state();
    state.publication = publication;
    this.#state.set(state);
    this.#updateForm();

    const formValueChangesSubscription = this.publicationEditionForm.valueChanges
      .pipe(
        debounceTime(200),
        distinctUntilChanged()
      )
      .subscribe(formValue => {
        const state = this.#state();
        const publication = state.publication;

        publication.title = formValue.title;
        publication.description = formValue.description;
        publication.categoryId = formValue.categoryId;
        publication.text = formValue.text;

        this.#state.set(state);
      });
    this.#subscriptions.push(formValueChangesSubscription);
  }

  private editIllustrationId(pictureId: string): void {
    const state = this.#state();
    state.publication.illustrationId = pictureId
    this.#state.set(state);
  }

  displayPictureSectionDialog(): void {
    const dialogRef = this.#dialog.open(PictureSelectionDialog);

    const afterDialogCloseSubscription = dialogRef.afterClosed()
      .subscribe(newPictureId => {
        if (newPictureId) {
          this.editIllustrationId(newPictureId);
        }
      });
    this.#subscriptions.push(afterDialogCloseSubscription);
  }

  displayCodeBlockDialog(): void {
    const dialogRef = this.#dialog.open(CodeBlockDialog, {width: '60em'});

    const afterDialogCloseSubscription = dialogRef.afterClosed()
      .subscribe(codeBlockWithLanguage => {
        if (codeBlockWithLanguage) {
          this.insertCodeBlock(codeBlockWithLanguage.programmingLanguage, codeBlockWithLanguage.codeBlock);
        }
      });
    this.#subscriptions.push(afterDialogCloseSubscription);
  }

  editCursorPosition(positionStart: number, positionEnd: number): void {
    const state = this.#state();

    state.cursorPosition.start = positionStart;
    state.cursorPosition.end = positionEnd;

    this.#state.set(state);
  }

  insertTitle(titleNumber: number): void {
    if (titleNumber >= 1 && titleNumber <= 3) {
      const state = this.#state();

      const publication = state.publication;

      const publicationTextLeftPart = publication.text.substring(0, state.cursorPosition.start);
      const publicationTextMiddlePart = publication.text.substring(state.cursorPosition.start, state.cursorPosition.end);
      const publicationTextRightPart = publication.text.substring(state.cursorPosition.end);
      const textWithTags = `${publicationTextLeftPart}[h${titleNumber}]${publicationTextMiddlePart}[/h${titleNumber}]${publicationTextRightPart}`;

      publication.text = textWithTags;

      this.#state.set(state);
      this.#updateForm();
    } else {
      console.error(`Bad value for parameter of function 'insertTitle': '${titleNumber}'.`);
    }
  }

  selectAPicture(): void {
    const dialogRef = this.#dialog.open(PictureSelectionDialog);

    const afterDialogCloseSubscription = dialogRef.afterClosed()
      .subscribe(newPictureId => {
        if (newPictureId) {
          this.insertPicture(newPictureId);
        }
      });
    this.#subscriptions.push(afterDialogCloseSubscription);
  }

  insertPicture(pictureId: string): void {
    const state = this.#state();

    const publication = state.publication;

    const publicationTextLeftPart = publication.text.substring(0, state.cursorPosition.start);
    const publicationTextRightPart = publication.text.substring(state.cursorPosition.start);
    const textWithTags = `${publicationTextLeftPart}[img src="/api/pictures/${pictureId}" /]${publicationTextRightPart}`;

    publication.text = textWithTags;

    this.#state.set(state);
    this.#updateForm();
  }

  insertLink(): void {
    const state = this.#state();

    const publication = state.publication;

    const publicationTextLeftPart = publication.text.substring(0, state.cursorPosition.start);
    const publicationTextMiddlePart = publication.text.substring(state.cursorPosition.start, state.cursorPosition.end);
    const publicationTextRightPart = publication.text.substring(state.cursorPosition.end);
    const textWithTags = `${publicationTextLeftPart}[link href="" txt="${publicationTextMiddlePart}" /]${publicationTextRightPart}`;

    publication.text = textWithTags;

    this.#state.set(state);
    this.#updateForm();
  }

  private insertCodeBlock(programmingLanguage: string, codeBlock: string): void {
    const state = this.#state();

    const publication = state.publication;

    const publicationTextLeftPart = publication.text.substring(0, state.cursorPosition.start);
    const publicationTextRightPart = publication.text.substring(state.cursorPosition.start);
    const codeBlockInstruction = `\n[code lg="${programmingLanguage}"]\n${codeBlock}\n[/code]\n\n`;
    const textWithTags = `${publicationTextLeftPart}${codeBlockInstruction}${publicationTextRightPart}`;

    publication.text = textWithTags;

    this.#state.set(state);
    this.#updateForm();
  }

  loadPreview(): void {
    const state = this.#state();

    this.#isPreviewing.set(true);
    const request: PreviewContentRequest = {
      text: state.publication.text
    };
    this.#publicationRestService.preview(request)
      .then(response => {
        state.publication.parsedText = response.text;
        this.#state.set(state);
        setTimeout(() => Prism.highlightAll(), 1000);
      })
      .catch(error => {
        console.error(error);
      })
      .finally(() => {
        this.#isPreviewing.set(false);
      });
  }
}