import { Component, computed, effect, inject, input, untracked } from '@angular/core';
import { ButtonComponent } from '@shared/ui/atoms/button/button.component';
import { ConfirmationComponent } from '@shared/ui/molecules/confirmation/confirmation.component';
import {
  WizardShellComponent,
  WizardError,
  WizardPhase,
  naarStapLabel,
} from '@shared/layout/wizard-shell/wizard-shell.component';
import { toWizardErrors } from '@shared/layout/wizard-shell/wizard-errors';
import { createStore } from '@shared/application/store';
import { whenTag } from '@shared/kernel/fp';
import { BigProfileStore } from '@registratie/application/big-profile.store';
import {
  IntakeState,
  IntakeMsg,
  Answers,
  Errors,
  StepId,
  initial,
  reduce,
  STEPS,
  hasProgress,
  SCHOLING_THRESHOLD_DEFAULT,
} from '@herregistratie/domain/intake.machine';
import { createDraftSync } from '@registratie/application/draft-sync';
import { IntakePolicyStore } from '@herregistratie/application/intake-policy.store';
import { BuitenlandStep } from './buitenland.step';
import { WerkStep } from './werk.step';
import { ReviewStep } from './review.step';

/** Organism: a BRANCHING intake questionnaire. All state lives in one signal
    driven by the pure `reduce` (intake.machine.ts). Which step renders is derived
    from the answers via `visibleSteps`, never stored — so editing an earlier
    answer immediately changes the remaining steps. The draft persists to the
    backend as a Concept aanvraag (createDraftSync), so a reload — or a "Verder
    gaan" from the dashboard via `?aanvraag=<id>` — resumes progress. */
@Component({
  selector: 'app-intake-wizard',
  imports: [
    ButtonComponent,
    ConfirmationComponent,
    WizardShellComponent,
    BuitenlandStep,
    WerkStep,
    ReviewStep,
  ],
  template: `
    <app-wizard-shell
      [steps]="stepLabels"
      [current]="cursor()"
      [stepTitle]="stepTitle()"
      i18n-processName="@@intake.processName"
      processName="Herregistratie-intake"
      [phase]="phase()"
      [primaryLabel]="primaryLabel()"
      [canGoBack]="cursor() > 0"
      [errors]="errorList()"
      (primary)="dispatch({ tag: 'Primary' })"
      (back)="dispatch({ tag: 'Back' })"
      (cancel)="restart()"
      (retry)="dispatch({ tag: 'Retry' })"
      (goToStep)="dispatch({ tag: 'GaNaarStap', cursor: $event })"
    >
      @switch (step()) {
        @case ('buitenland') {
          <app-intake-buitenland-step
            [answers]="answers()"
            [errors]="errors()"
            (answerChange)="dispatch({ tag: 'SetAnswer', key: $event.key, value: $event.value })"
          />
        }
        @case ('werk') {
          <app-intake-werk-step
            [answers]="answers()"
            [errors]="errors()"
            [scholingThreshold]="scholingThreshold()"
            (answerChange)="dispatch({ tag: 'SetAnswer', key: $event.key, value: $event.value })"
          />
        }
        @case ('review') {
          <app-intake-review-step
            [answers]="answers()"
            [scholingThreshold]="scholingThreshold()"
            (edit)="dispatch({ tag: 'GaNaarStap', cursor: $event })"
          />
        }
      }

      <div wizardSuccess>
        <app-confirmation
          i18n-title="@@intake.success.title"
          title="Uw aanvraag tot herregistratie is ontvangen"
        >
          <div class="app-section">
            <app-button variant="secondary" (click)="restart()" i18n="@@intake.opnieuw"
              >Opnieuw beginnen</app-button
            >
          </div>
        </app-confirmation>
      </div>
    </app-wizard-shell>
  `,
})
export class IntakeWizardComponent {
  private profile = inject(BigProfileStore);
  // Server-owned policy (scholing threshold): fetched from the backend via the
  // application facade, not hardcoded. The backend stays the authority on submit.
  private policyStore = inject(IntakePolicyStore);

  /** Optional seed so Storybook / the showcase can mount any state directly. */
  seed = input<IntakeState>(initial);

  // --- The store: all state in one signal, changed only by a pure reduce -----
  // The effect fires once, on the `Answering -> Submitting` transition. `Seed` is exempt,
  // so a story that mounts straight into `Submitting` does not call the network.
  // `draftSync` is declared below (both callbacks are deferred, so the cycle is safe).
  private store = createStore<IntakeState, IntakeMsg>(initial, reduce, {
    Submitting: async (s, store) => {
      this.profile.beginHerregistratie();
      // The scholing answer rides along so the server can re-validate it as the
      // authority (IntakePolicy.RejectIncompleteScholing) — undefined members are dropped by
      // JSON.stringify, so a wizard above the threshold sends neither field.
      const r = await this.draftSync.submit({
        uren: s.data.uren,
        aanvullendeScholing: s.data.aanvullendeScholing,
        scholingPunten: s.data.punten,
      });
      if (r.ok) {
        store.dispatch({ tag: 'SubmitConfirmed' });
        this.profile.confirmHerregistratie();
      } else {
        store.dispatch({ tag: 'SubmitFailed', error: r.error });
        this.profile.rollbackHerregistratie();
      }
    },
  });

  readonly state = this.store.model;
  readonly dispatch = this.store.dispatch;

  // --- Static copy: stepper labels and per-step headings ---------------------
  readonly stepLabels = [
    $localize`:@@intake.step.buitenland:Buitenland`,
    $localize`:@@intake.step.werk:Werk`,
    $localize`:@@intake.step.controle:Controle`,
  ];
  private stepTitles: Record<StepId, string> = {
    buitenland: $localize`:@@intake.title.buitenland:Werken in het buitenland`,
    werk: $localize`:@@intake.title.werk:Werkervaring in Nederland`,
    review: $localize`:@@intake.title.review:Controleren en indienen`,
  };

  // --- State projections: one narrow, then read-only views of it -------------
  private answering = computed(() => whenTag(this.state(), 'Answering'));
  /** Public so the showcase can render the (fixed) step list next to the wizard. */
  readonly steps = STEPS;
  protected cursor = computed(() => this.answering()?.cursor ?? 0);
  protected answers = computed<Answers>(() => this.answering()?.answers ?? {});
  protected step = computed<StepId>(() => STEPS[Math.min(this.cursor(), STEPS.length - 1)]);
  /** Server-owned threshold from the policy endpoint (mirrored into machine state). */
  protected scholingThreshold = computed(
    () => this.answering()?.scholingThreshold ?? SCHOLING_THRESHOLD_DEFAULT,
  );
  protected errors = computed<Errors>(() => this.answering()?.errors ?? {});

  // --- Controllers: persistence and uploads ----------------------------------
  // Create a Concept on first progress, then debounced-sync the snapshot.
  // `?aanvraag=<id>` resumes it. The intake has no uploads.
  private draftSync = createDraftSync({
    type: 'intake',
    snapshot: () => {
      const s = this.state();
      if (s.tag !== 'Answering' || !hasProgress(s)) return null;
      return { draft: s, stepIndex: s.cursor, stepCount: STEPS.length, documentIds: [] };
    },
    onResume: (draft) => this.dispatch({ tag: 'Seed', state: draft as IntakeState }),
    enabled: () => this.seed() === initial,
  });

  // --- Presentational wiring for the shared wizard shell ---------------------
  protected stepTitle = computed(() => this.stepTitles[this.step()]);
  protected primaryLabel = computed(() => {
    if (this.step() === 'review') return $localize`:@@intake.indienen:Aanvraag indienen`;
    const next = this.cursor() + 1;
    return naarStapLabel(next + 1, this.stepLabels[next]);
  });
  /** Maps this machine's own tags onto the shell's `WizardPhase` vocabulary,
      composing the localized failure prefix so the `Failed` message arrives intact. */
  protected phase = computed<WizardPhase>(() => {
    const s = this.state();
    switch (s.tag) {
      case 'Answering':
        return { tag: 'Editing' };
      case 'Submitting':
        return { tag: 'Submitting' };
      case 'Submitted':
        return { tag: 'Submitted' };
      case 'Failed':
        return {
          tag: 'Failed',
          message: $localize`:@@wizard.indienenMislukt:Indienen mislukt:` + ` ${s.error}`,
        };
    }
  });
  /** Current step's field errors, flattened for the shell's error summary. The
      field ids match the answer keys, so the summary anchors jump to the field. */
  protected errorList = computed<WizardError[]>(() =>
    toWizardErrors(this.answering()?.errors ?? {}),
  );

  constructor() {
    // An explicit seed (stories/tests) wins; otherwise resume the backend draft
    // (`?aanvraag=<id>`) or start fresh. Persistence is the draftSync controller's job.
    // Read `seed()` INSIDE the microtask: Angular binds inputs after the constructor
    // runs, so an eager read here always returns the `initial` default.
    queueMicrotask(() => {
      const seeded = this.seed();
      if (seeded !== initial) this.dispatch({ tag: 'Seed', state: seeded });
      else void this.draftSync.resume();
    });
    // Apply the server-owned threshold into machine state as it arrives. Track
    // only the policy value; untrack the dispatch (it reads the state signal
    // internally, which would otherwise make this effect loop on its own write).
    effect(() => {
      const scholingThreshold = this.policyStore.scholingThreshold();
      untracked(() => this.dispatch({ tag: 'SetPolicy', scholingThreshold }));
    });
  }

  restart() {
    this.draftSync.reset();
    this.dispatch({ tag: 'Seed', state: initial });
  }
}