import { Component, inject, input, output, signal } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { firstValueFrom } from 'rxjs';
import { apiError } from '../core/api-error';

interface Preview {
  name: string;
  dancers: number;
  groups: number;
  shows: number;
  existingId: number | null;
  existingName: string | null;
  existingRevision: number | null;
}
@Component({
  selector: 'app-school-transfer',
  template: `
    <div class="quick-actions">
      @if (schoolId() !== undefined) {
        <button type="button" class="button secondary" (click)="download()" [disabled]="busy()">
          JSON exporteren
        </button>
      }
      <label
        >JSON importeren
        <input
          type="file"
          accept=".json,application/json"
          [disabled]="busy()"
          (change)="select($event)"
      /></label>
    </div>
    @if (error()) {
      <p class="alert error" role="alert">{{ error() }}</p>
    }
    @if (notice()) {
      <p role="status">{{ notice() }}</p>
    }
    @if (preview(); as p) {
      <section class="panel" aria-label="Importvoorbeeld">
        <h2>{{ p.name }}</h2>
        <p>{{ p.dancers }} dansers · {{ p.groups }} dansgroepen · {{ p.shows }} shows</p>
        @if (p.existingId !== null) {
          <p>
            De bestaande school {{ p.existingName }} wordt volledig vervangen. Alle huidige gegevens
            van deze school verdwijnen.
          </p>
          <button type="button" class="button primary" [disabled]="busy()" (click)="confirm()">
            Volledig vervangen bevestigen
          </button>
          <button
            type="button"
            class="button secondary"
            [disabled]="busy()"
            (click)="notice.set('Samenvoegen wordt nog niet ondersteund.')"
          >
            Samenvoegen
          </button>
        } @else {
          <button type="button" class="button primary" [disabled]="busy()" (click)="confirm()">
            School toevoegen bevestigen
          </button>
        }
        <button type="button" class="button secondary" [disabled]="busy()" (click)="cancel()">
          Annuleren
        </button>
      </section>
    }
  `,
})
export class SchoolTransfer {
  readonly schoolId = input<number>();
  readonly imported = output<void>();
  private readonly http = inject(HttpClient);
  readonly preview = signal<Preview | null>(null);
  readonly busy = signal(false);
  readonly error = signal('');
  readonly notice = signal('');
  private json = '';
  private readonly base = '/api/dance-schools';

  cancel(): void {
    this.preview.set(null);
    this.json = '';
    this.notice.set('');
  }
  async select(event: Event): Promise<void> {
    const input = event.target as HTMLInputElement;
    const file = input.files?.[0];
    input.value = '';
    this.cancel();
    this.error.set('');
    if (!file) return;
    this.busy.set(true);
    try {
      this.json = await file.text();
      this.preview.set(
        await firstValueFrom(
          this.http.post<Preview>(`${this.base}/import/preview`, this.json, {
            headers: { 'Content-Type': 'application/json' },
          }),
        ),
      );
    } catch (e) {
      this.error.set(
        `Import niet gelukt: ${e instanceof Error && !('status' in e) ? e.message : apiError(e)}`,
      );
    } finally {
      this.busy.set(false);
    }
  }
  async confirm(): Promise<void> {
    const p = this.preview();
    if (!p || this.busy()) return;
    this.busy.set(true);
    this.error.set('');
    try {
      const query = p.existingId === null ? '' : `?replaceId=${p.existingId}`;
      await firstValueFrom(
        this.http.post(`${this.base}/import${query}`, this.json, {
          headers: {
            'Content-Type': 'application/json',
            ...(p.existingRevision === null
              ? {}
              : { 'X-School-Revision': String(p.existingRevision) }),
          },
        }),
      );
      this.cancel();
      this.notice.set('School geïmporteerd.');
      this.imported.emit();
    } catch (e) {
      this.error.set(`Import niet gelukt: ${apiError(e)}`);
      this.preview.set(null);
    } finally {
      this.busy.set(false);
    }
  }
  async download(): Promise<void> {
    this.error.set('');
    this.busy.set(true);
    try {
      const blob = await firstValueFrom(
        this.http.get(`${this.base}/${this.schoolId()}/export`, { responseType: 'blob' }),
      );
      const url = URL.createObjectURL(blob);
      const link = document.createElement('a');
      link.href = url;
      link.download = `school-${this.schoolId()}.json`;
      link.click();
      setTimeout(() => URL.revokeObjectURL(url), 1000);
    } catch (e) {
      this.error.set(`Export niet gelukt: ${apiError(e)}`);
    } finally {
      this.busy.set(false);
    }
  }
}