/**
 * Where somebody has got to in store setup, and what they have typed so far.
 *
 * Two different things are kept, for two different reasons:
 *
 *  - **Progress** — which steps are finished. Derived from the backend wherever
 *    it can be (a shop with a name and a licence has done Store Information),
 *    because a stored flag can claim work that was never done. What cannot be
 *    derived is *intent*: which steps were deliberately skipped, and whether
 *    setup was finished or abandoned.
 *  - **The draft** — half-typed answers. A form somebody spent five minutes on
 *    must survive a refresh, a closed laptop, or a phone call. This is the only
 *    place drafts live until they are saved.
 *
 * Per browser, per person, per shop. Deliberately not synced: an unsent draft
 * is a private half-thought, and two people editing one shop's setup from
 * different desks should not overwrite each other's typing.
 */

const KEY = 'nearle.onboarding';

export type StepId = 'welcome' | 'store' | 'catalogue' | 'inventory' | 'delivery' | 'review' | 'done';

/** The five that appear in the progress indicator. Welcome and Done bracket them. */
export const PROGRESS_STEPS: readonly StepId[] = ['store', 'catalogue', 'inventory', 'delivery', 'review'];

export const STEP_LABEL: Record<StepId, string> = {
  welcome: 'Welcome',
  store: 'Store',
  catalogue: 'Catalogue',
  inventory: 'Inventory',
  delivery: 'Delivery',
  review: 'Review',
  done: 'Done',
};

export interface StoreDraft {
  tenantname: string;
  tenantimage: string;
  primaryemail: string;
  primarycontact: string;
  address: string;
  city: string;
  postcode: string;
  state: string;
  tenanttype: string;
  opentime: string;
  closetime: string;
}

export interface DeliveryDraft {
  offersDelivery: boolean | null;
  radiusKm: string;
  minOrder: string;
  charge: string;
  freeAbove: string;
  mins: string;
  startTime: string;
  endTime: string;
}

export interface OnboardingState {
  /** Where to put them back when they return. */
  step: StepId;
  /** Steps they finished, so the indicator can tick them. */
  completed: StepId[];
  /** Steps they chose to pass over. Never counted as completed. */
  skipped: StepId[];
  /** True once they have reached the end — the offer is not made again. */
  finished: boolean;
  /** True once they have been offered setup at all. */
  started: boolean;
  store: StoreDraft;
  delivery: DeliveryDraft;
}

export const EMPTY_STORE: StoreDraft = {
  tenantname: '',
  tenantimage: '',
  primaryemail: '',
  primarycontact: '',
  address: '',
  city: '',
  postcode: '',
  state: '',
  tenanttype: '',
  // Sensible for a neighbourhood shop, and both are required — an empty time
  // picker asks a question the shopkeeper has to think about before they have
  // decided anything else.
  opentime: '08:00',
  closetime: '22:00',
};

export const EMPTY_DELIVERY: DeliveryDraft = {
  offersDelivery: null,
  radiusKm: '',
  minOrder: '',
  charge: '',
  freeAbove: '',
  mins: '',
  startTime: '09:00',
  endTime: '21:00',
};

const EMPTY: OnboardingState = {
  step: 'welcome',
  completed: [],
  skipped: [],
  finished: false,
  started: false,
  store: EMPTY_STORE,
  delivery: EMPTY_DELIVERY,
};

function scope(userid: number, tenantid: number): string {
  return `${userid}:${tenantid}`;
}

function readAll(): Record<string, OnboardingState> {
  try {
    const raw = localStorage.getItem(KEY);
    const parsed: unknown = raw ? JSON.parse(raw) : {};
    return parsed && typeof parsed === 'object' ? (parsed as Record<string, OnboardingState>) : {};
  } catch {
    // A private window, cleared site data, or storage the browser refuses.
    // Losing a draft is a nuisance; throwing on read would take the page down.
    return {};
  }
}

export function readOnboarding(userid: number, tenantid: number): OnboardingState {
  const stored = readAll()[scope(userid, tenantid)];
  if (!stored) return EMPTY;
  // Merged over the defaults so a state written by an older build — before a
  // field existed — does not arrive with `undefined` where a form expects a
  // string and React switches the input to uncontrolled.
  return {
    ...EMPTY,
    ...stored,
    store: { ...EMPTY_STORE, ...(stored.store ?? {}) },
    delivery: { ...EMPTY_DELIVERY, ...(stored.delivery ?? {}) },
    completed: Array.isArray(stored.completed) ? stored.completed : [],
    skipped: Array.isArray(stored.skipped) ? stored.skipped : [],
  };
}

export function writeOnboarding(
  userid: number,
  tenantid: number,
  next: OnboardingState,
): OnboardingState {
  const all = readAll();
  try {
    localStorage.setItem(KEY, JSON.stringify({ ...all, [scope(userid, tenantid)]: next }));
  } catch {
    /* Storage refused. The change still applies to this session; losing it on
       reload is a smaller failure than the write throwing mid-keystroke. */
  }
  return next;
}

/** Mark a step finished and move on. Completing twice is not an error. */
export function completeStep(state: OnboardingState, id: StepId, next: StepId): OnboardingState {
  return {
    ...state,
    step: next,
    completed: [...new Set([...state.completed, id])],
    // Finishing a step it was previously skipped clears the skip — the work is
    // done, and leaving it marked "skipped" would misreport the review page.
    skipped: state.skipped.filter((entry) => entry !== id),
    started: true,
  };
}

/** Pass over a step without doing it. Never counts as completed. */
export function skipStep(state: OnboardingState, id: StepId, next: StepId): OnboardingState {
  return {
    ...state,
    step: next,
    skipped: [...new Set([...state.skipped, id])],
    started: true,
  };
}

/**
 * How far along, for the welcome screen and the progress bar.
 *
 * Counts only the five real steps. Welcome is not an achievement and Done is
 * the result of the others, so including either would show progress before
 * anything had been done.
 */
export function progressOf(state: OnboardingState): { done: number; total: number } {
  const done = PROGRESS_STEPS.filter((id) => state.completed.includes(id)).length;
  return { done, total: PROGRESS_STEPS.length };
}

/** The step to resume on: where they left off, unless that is already finished. */
export function resumeStep(state: OnboardingState): StepId {
  if (state.finished) return 'done';
  return state.step;
}