import {
  ChangeDetectionStrategy,
  Component,
  HostListener,
  computed,
  input,
  output,
} from '@angular/core';
import { CommonModule } from '@angular/common';
import { ImportPreviewResponse, ImportResultResponse } from '../../../core/services/admin.service';

@Component({
  selector: 'app-challenge-import-modal',
  standalone: true,
  changeDetection: ChangeDetectionStrategy.OnPush,
  imports: [CommonModule],
  styles: [`
    .modal-overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.4); display: flex; align-items: center; justify-content: center; z-index: 70; }
    .modal { background: var(--color-surface, #fff); padding: 16px; border-radius: 8px; width: min(520px, 90vw); }
    .actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 12px; }
    .error { color: var(--color-danger, #f00); margin-top: 8px; }
    .warnings { color: var(--color-warning, #b45309); margin-top: 8px; }
    .result { color: var(--color-success, #065f46); margin-top: 8px; }
    ul { margin: 0; padding-left: 18px; }
    .spinner { display: inline-block; width: 12px; height: 12px; border: 2px solid currentColor; border-right-color: transparent; border-radius: 50%; animation: spin 0.6s linear infinite; }
    @keyframes spin { to { transform: rotate(360deg); } }
  `],
  template: `
    @if (open()) {
      <div class="modal-overlay" data-testid="challenge-import-overlay">
        <div class="modal" role="dialog" aria-modal="true" aria-labelledby="ci-title" data-testid="challenge-import-modal">
          <h3 id="ci-title">Import challenges</h3>

          @if (result(); as r) {
            <p class="result" data-testid="challenge-import-result">
              Imported {{ r.imported }} challenge{{ r.imported === 1 ? '' : 's' }}.
              @if (r.skipped.length > 0) { (Skipped {{ r.skipped.length }}.) }
              @if (r.warnings.length > 0) { ({{ r.warnings.length }} warning(s).) }
            </p>
            @if (r.skipped.length > 0) {
              <ul data-testid="challenge-import-skipped">
                @for (s of r.skipped; track s.name) { <li>{{ s.name }} — {{ s.reason }}</li> }
              </ul>
            }
            <div class="actions">
              <button type="button" (click)="onCancel()" data-testid="challenge-import-close">Close</button>
            </div>
          } @else if (preview()) {
            @if (preview(); as p) {
              <p data-testid="challenge-import-preview">
                Import {{ p.total }} challenge{{ p.total === 1 ? '' : 's' }}.
                Existing challenges with matching names will be overwritten.
                New categories referenced but missing locally will be skipped with a warning.
                Continue?
              </p>
              @if (p.conflicts.length > 0) {
                <p>Will overwrite:</p>
                <ul>
                  @for (name of p.conflicts; track name) { <li>{{ name }}</li> }
                </ul>
              }
              @if (p.unknownCategories.length > 0) {
                <p class="warnings">Missing categories (will be skipped):</p>
                <ul>
                  @for (key of p.unknownCategories; track key) { <li>{{ key }}</li> }
                </ul>
              }
            }
            @if (errorMessage(); as msg) {
              <p class="error" role="alert" data-testid="challenge-import-error">{{ msg }}</p>
            }
            <div class="actions">
              <button type="button" (click)="onCancel()" [disabled]="submitting()" data-testid="challenge-import-cancel">Cancel</button>
              <button type="button" (click)="onConfirm()" [disabled]="submitting()" data-testid="challenge-import-confirm">
                <span *ngIf="submitting()" class="spinner" aria-hidden="true"></span>
                Overwrite &amp; Import
              </button>
            </div>
          } @else if (errorMessage()) {
            <p class="error" role="alert" data-testid="challenge-import-error">{{ msg }}</p>
            <div class="actions">
              <button type="button" (click)="onCancel()" data-testid="challenge-import-close">Close</button>
            </div>
          } @else {
            <p>Reading file…</p>
          }
        </div>
      </div>
    }
  `,
})
export class ChallengeImportModalComponent {
  readonly open = input(false);
  readonly document = input<unknown>(null);
  readonly preview = input<ImportPreviewResponse | null>(null);
  readonly result = input<ImportResultResponse | null>(null);
  readonly submitting = input(false);
  readonly errorMessage = input<string | null>(null);

  readonly cancel = output<void>();
  readonly confirm = output<void>();

  readonly summary = computed(() => this.preview());

  @HostListener('document:keydown.escape')
  onEscape(): void {
    if (this.open() && !this.submitting() && !this.result()) this.onCancel();
  }

  onCancel(): void {
    if (this.submitting()) return;
    this.cancel.emit();
  }

  onConfirm(): void {
    if (this.submitting() || this.result()) return;
    this.confirm.emit();
  }
}