import { ChangeDetectionStrategy, Component, computed, input, signal } from '@angular/core';
import {
  type ContactFieldCopy,
  type ContactFieldId,
  type ContactPageCopy,
} from '../../core/content/content.contracts';
import { SITE_CONFIG } from '../../core/content/site-config';

const EMPTY_VALUES: Record<ContactFieldId, string> = {
  name: '',
  email: '',
  company: '',
  projectType: '',
  situation: '',
  timeframe: '',
};

@Component({
  selector: 'app-contact-briefing',
  changeDetection: ChangeDetectionStrategy.OnPush,
  templateUrl: './contact-briefing.html',
  styleUrl: './contact-briefing.scss',
})
export class ContactBriefing {
  readonly copy = input.required<ContactPageCopy>();

  protected readonly values = signal<Record<ContactFieldId, string>>({ ...EMPTY_VALUES });
  protected readonly touched = signal<Partial<Record<ContactFieldId, boolean>>>({});
  protected readonly contactEmail = SITE_CONFIG.contactEmail;
  protected readonly incompleteId = 'contact-incomplete';

  protected readonly missingLabels = computed(() => {
    const copy = this.copy();
    const values = this.values();
    return copy.fields
      .filter((field) => field.required && values[field.id].trim().length === 0)
      .map((field) => field.label);
  });

  protected readonly isComplete = computed(() => this.missingLabels().length === 0);

  protected readonly incompleteMessage = computed(() => {
    const missing = this.missingLabels();
    if (missing.length === 0) {
      return '';
    }

    return `${this.copy().incompleteHint} ${missing.join(', ')}`;
  });

  protected readonly mailtoHref = computed(() => {
    const copy = this.copy();
    const values = this.values();
    const body = this.assembleBody(copy, values);
    return `mailto:${SITE_CONFIG.contactEmail}?subject=${encodeURIComponent(copy.mailSubject)}&body=${encodeURIComponent(body)}`;
  });

  protected onInput(fieldId: ContactFieldId, event: Event): void {
    const target = event.target as HTMLInputElement | HTMLTextAreaElement | HTMLSelectElement;
    this.values.update((current) => ({ ...current, [fieldId]: target.value }));
    this.markTouched(fieldId);
  }

  protected onBlur(fieldId: ContactFieldId): void {
    this.markTouched(fieldId);
  }

  protected onDisabledSubmit(event: Event): void {
    event.preventDefault();
  }

  protected controlId(field: ContactFieldCopy): string {
    return `contact-${field.id}`;
  }

  protected showInvalid(field: ContactFieldCopy): boolean {
    return (
      field.required &&
      this.touched()[field.id] === true &&
      this.values()[field.id].trim().length === 0
    );
  }

  protected describedBy(field: ContactFieldCopy): string | null {
    const ids: string[] = [];
    if (field.hint) {
      ids.push(`${this.controlId(field)}-hint`);
    }
    if (this.showInvalid(field)) {
      ids.push(this.incompleteId);
    }
    return ids.length > 0 ? ids.join(' ') : null;
  }

  private markTouched(fieldId: ContactFieldId): void {
    this.touched.update((current) => ({ ...current, [fieldId]: true }));
  }

  private assembleBody(copy: ContactPageCopy, values: Record<ContactFieldId, string>): string {
    const lines = copy.fields.flatMap((field) => {
      const raw = values[field.id];
      if (!field.required && raw.trim().length === 0) {
        return [];
      }

      return [`${field.label}: ${this.displayValue(field, raw)}`];
    });
    return [copy.mailIntro, '', ...lines, '', copy.mailSignature].join('\n');
  }

  private displayValue(field: ContactFieldCopy, value: string): string {
    return field.options?.find((option) => option.value === value)?.label ?? value;
  }
}