import { Injectable, inject, resource } from '@angular/core';
import { Result, ok, err } from '@shared/kernel/fp';
import { DashboardViewDto, DashboardView } from '@registratie/contracts/dashboard-view.dto';
import { ApiClient } from '@shared/infrastructure/api-client';

/**
 * Infrastructure adapter for the screen-shaped ("BFF-lite") dashboard endpoint.
 * ONE call returns registration + person + server-computed decisions. The data
 * comes from the .NET backend (`GET /api/dashboard-view`) via the generated typed
 * client; the decisions (e.g. herregistratie eligibility) are computed there.
 */
@Injectable({ providedIn: 'root' })
export class DashboardViewAdapter {
  private client = inject(ApiClient);

  // The value is still untrusted JSON — parseDashboardView validates it at the
  // boundary and maps DTO → domain before the app uses it.
  //
  // SEAM (G5): retry-with-backoff for non-mutating reads wraps the loader here —
  // e.g. `loader: () => withBackoff(() => this.client.dashboardView())` — since the
  // adapter is the single place HTTP lives. Reads are safe to retry; MUTATING calls
  // (the submit-* commands) must NEVER auto-retry — and don't. Manual retry
  // (resource.reload via <app-async>) covers the UX today, so backoff stays unbuilt.
  dashboardViewResource() {
    return resource({ loader: () => this.client.dashboardView() });
  }
}

/**
 * Trust-boundary parse: validate the untrusted response shape and map the DTO
 * onto our own domain model. Hand-written on purpose — no Zod for a single
 * contract. ponytail: reach for a schema lib once the contract count grows.
 */
export function parseDashboardView(json: unknown): Result<string, DashboardView> {
  if (typeof json !== 'object' || json === null) return err('dashboard-view: not an object');
  const dto = json as Partial<DashboardViewDto>;

  const reg = dto.registration;
  if (!reg || typeof reg.bigNummer !== 'string' || !reg.status || typeof reg.status.tag !== 'string') {
    return err('dashboard-view: missing/invalid registration');
  }
  const person = dto.person;
  if (!person || !person.adres || typeof person.adres.postcode !== 'string') {
    return err('dashboard-view: missing/invalid person');
  }
  const d = dto.decisions;
  if (!d || typeof d.eligibleForHerregistratie !== 'boolean') {
    return err('dashboard-view: missing/invalid decisions');
  }

  return ok({
    profile: { registration: reg, person },
    decisions: { eligibleForHerregistratie: d.eligibleForHerregistratie, herregistratieReason: d.herregistratieReason },
  });
}
