/**
 * Pure progression logic for the v1.4 dashboard "Getting started"
 * checklist. Decoupled from React so it can be unit-tested without a
 * DOM. The component layer (`<GettingStartedChecklist>`) reads inputs
 * (auth user + analytics summaries + medications count + Withings
 * status + dismissed-ids set) and renders against the result.
 */

import { VISITS_PATH } from "@/lib/encounters/visit-links";

import {
  hasEnteredOnboardingFlow,
  isOnboardingSettled,
  type OnboardingNeeds,
  type OnboardingStateDto,
} from "./needs";

export const CHECKLIST_ITEM_IDS = [
  "profile",
  "measurement",
  "medication",
  "dataSource",
  "notifications",
  "insights",
  // v1.39 — present only for an answer that named a visit within a
  // month (design spec §After the flow: "prepare the visit").
  "visit",
  // v1.39 — "someone I look after" (or "both") with no managed profile
  // yet: the answers were given for a record that does not exist, and this
  // row is where it gets created.
  "managedProfile",
] as const;

export type ChecklistItemId = (typeof CHECKLIST_ITEM_IDS)[number];

/** The rows every record has; the visit row joins only when asked for. */
export const CHECKLIST_BASE_ITEM_IDS: readonly ChecklistItemId[] =
  CHECKLIST_ITEM_IDS.filter((id) => id !== "visit" && id !== "managedProfile");

export interface ChecklistItem {
  id: ChecklistItemId;
  done: boolean;
  /**
   * Pre-built href the CTA should jump to. The settings entries point at
   * the v1.4 split routes under `/settings/[section]` (introduced by PR
   * A2-shell), so the CTA lands directly on the right section instead of
   * relying on a hash anchor on the legacy monolith.
   */
  href: string;
  /** True if the user explicitly hid this row. */
  dismissed: boolean;
}

export interface ChecklistInputs {
  /** Profile completeness — height + dateOfBirth + gender all set. */
  profile: {
    heightCm: number | null;
    dateOfBirth: string | null;
    gender: string | null;
  };
  /** Total measurements logged across all types. */
  measurementCount: number;
  /** Number of medications the user has created. */
  medicationCount: number;
  /**
   * True iff at least one data source is connected — Withings, WHOOP,
   * Oura, Polar, Nightscout, Fitbit, or Apple Health. Any one satisfies
   * the "connect a data source" step.
   */
  dataSourceConnected: boolean;
  /**
   * True iff the user has set up at least one notification channel
   * (Telegram, ntfy, or Web Push).
   */
  notificationsConfigured: boolean;
  /**
   * True iff any AI provider can serve this user — a personal key,
   * a local model, an OAuth sign-in, OR the operator's shared key.
   * `ai.provider.configured` from `GET /api/auth/me`, so the row
   * self-satisfies the moment a provider is set up (including on a
   * deployment that ships a shared operator key). Presence-only — it
   * never decrypts a credential or probes liveness.
   */
  insightsConfigured: boolean;
  /**
   * Whether AI can be set up from here at all (`ai.provider.canConfigure`)
   * and is still wanted: false while the operator has AI switched off, inside
   * a record somebody else owns, and once the person switched the Coach and
   * AI analysis off. The AI row exists only when true. HealthLog is complete
   * without AI, so the list never carries a to-do nobody on this screen can
   * finish or that was declined.
   */
  aiConfigurable: boolean;
  /** Dismissed item ids (per-item localStorage state). */
  dismissedIds: ReadonlySet<ChecklistItemId>;
  /**
   * v1.39 — visits booked from today on, for the "prepare the visit"
   * row. Read only while the row can exist, so a caller that never asked the
   * question passes zero.
   */
  upcomingVisitCount: number;
  /**
   * v1.39 — managed profiles this account looks after, for the row that
   * asks a guardian to create the one their answers were about.
   */
  managedProfileCount: number;
  /**
   * v1.39 — the needs-based setup state from `GET /api/auth/me`, or null
   * for a record that never entered the flow.
   *
   * Required rather than optional: the ordering below is the whole reason the
   * answers are published, and a caller that stops passing them should fail to
   * compile rather than quietly fall back to the fixed order.
   */
  onboarding: OnboardingStateDto | null;
}

/**
 * v1.39 — the order the answers imply.
 *
 * The rows themselves are fixed; what the questionnaire decides is which of
 * them a person sees first. Someone who said they take medication daily should
 * not have to scroll past "connect a data source" to find it, and someone who
 * named a wearable should meet that row before the manual-entry one.
 *
 * `profile` stays first whatever the answers say — it is the identity the
 * clinical surfaces derive from, not a domain choice — and any row the answers
 * do not speak to keeps its position relative to the others. The result is a
 * reordering, never a removal: nothing here drops a row.
 */
export function checklistOrderFromNeeds(
  needs: OnboardingNeeds,
): ChecklistItemId[] {
  const promoted: ChecklistItemId[] = [];
  const promote = (id: ChecklistItemId) => {
    if (!promoted.includes(id)) promoted.push(id);
  };

  // Answers given for somebody else's record say nothing about the
  // guardian's own dashboard: the one row they promote is the profile.
  if (needs.recordTarget === "someone-else") {
    promote("managedProfile");
    return [
      "profile",
      ...promoted,
      ...CHECKLIST_ITEM_IDS.filter(
        (id) => id !== "profile" && !promoted.includes(id),
      ),
    ];
  }

  if (needs.medication === "yes" || needs.medication === "sometimes") {
    promote("medication");
  }
  // "I type them in" and "a file I already have" are not connections, so they
  // say nothing about the data-source row.
  if (needs.sources.some((s) => s !== "manual" && s !== "file")) {
    promote("dataSource");
  }
  if (needs.areas.length > 0) promote("measurement");
  if (needs.visit === "within-a-month") promote("visit");

  return [
    "profile",
    ...promoted,
    ...CHECKLIST_ITEM_IDS.filter(
      (id) => id !== "profile" && !promoted.includes(id),
    ),
  ];
}

/**
 * Compute the ordered checklist for the dashboard hero. Stable order:
 * profile → measurement → medication → dataSource → notifications →
 * insights, plus the visit row for an answer that named one. Each item
 * carries the deep-link the row's CTA should navigate to.
 */
export function buildChecklist(inputs: ChecklistInputs): ChecklistItem[] {
  const profileDone = isProfileComplete(inputs.profile);
  const items: ChecklistItem[] = [
    {
      id: "profile",
      done: profileDone,
      href: "/settings/account",
      dismissed: inputs.dismissedIds.has("profile"),
    },
    {
      id: "measurement",
      done: inputs.measurementCount >= 1,
      href: "/measurements",
      dismissed: inputs.dismissedIds.has("measurement"),
    },
    {
      id: "medication",
      done: inputs.medicationCount >= 1,
      href: "/medications",
      dismissed: inputs.dismissedIds.has("medication"),
    },
    {
      id: "dataSource",
      done: inputs.dataSourceConnected,
      href: "/settings/integrations",
      dismissed: inputs.dismissedIds.has("dataSource"),
    },
    {
      id: "notifications",
      done: inputs.notificationsConfigured,
      href: "/settings/notifications",
      dismissed: inputs.dismissedIds.has("notifications"),
    },
    ...(inputs.aiConfigurable
      ? [
          {
            id: "insights" as const,
            done: inputs.insightsConfigured,
            href: "/settings/ai",
            dismissed: inputs.dismissedIds.has("insights"),
          },
        ]
      : []),
  ];
  if (!inputs.onboarding) return items;
  // The visit row exists only for the answer that asked for it; every other
  // record keeps the six rows it had. Done once a visit is on the calendar.
  const target = inputs.onboarding.needs.recordTarget;
  if (
    target !== "someone-else" &&
    inputs.onboarding.needs.visit === "within-a-month"
  ) {
    items.push({
      id: "visit",
      done: inputs.upcomingVisitCount >= 1,
      // The visits tab, where a visit is added; the bare page opens checkups.
      href: VISITS_PATH,
      dismissed: inputs.dismissedIds.has("visit"),
    });
  }
  // The profile the answers were about. Offered to "both" as well, which
  // the spec says gets the profile at the end.
  if (target === "someone-else" || target === "both") {
    items.push({
      id: "managedProfile",
      done: inputs.managedProfileCount >= 1,
      href: "/settings/access",
      dismissed: inputs.dismissedIds.has("managedProfile"),
    });
  }
  // Ordered from the answers only once the flow has been confirmed: before
  // that the answers are still being given, and re-ordering the dashboard
  // under someone mid-question would be movement they did not ask for.
  if (inputs.onboarding.completedAt === null) return items;
  const order = checklistOrderFromNeeds(inputs.onboarding.needs);
  return order
    .map((id) => items.find((item) => item.id === id))
    .filter((item): item is ChecklistItem => item !== undefined);
}

/**
 * The checklist visible to the user — drops dismissed items and items
 * already done **and** hidden by completion. We keep done items
 * visible until the user completes the whole list, so they get the
 * satisfaction of ticking the last box.
 */
export function visibleChecklist(items: ChecklistItem[]): ChecklistItem[] {
  return items.filter((item) => !item.dismissed);
}

export interface ChecklistProgress {
  total: number;
  done: number;
  /** Integer percentage 0-100. */
  percent: number;
  /** True iff every non-dismissed item is done. */
  allDone: boolean;
}

export function checklistProgress(items: ChecklistItem[]): ChecklistProgress {
  const visible = visibleChecklist(items);
  const total = visible.length;
  const done = visible.filter((item) => item.done).length;
  const percent = total === 0 ? 100 : Math.round((done / total) * 100);
  return { total, done, percent, allDone: total > 0 && done === total };
}

/**
 * Should the dashboard render the checklist at all?
 *
 * Never when the whole list is dismissed, and never when there is no
 * non-dismissed row left to show.
 *
 * For a record that ran the setup flow the design spec retires the old
 * five-reading rule: the list goes when its rows are done or the person hides
 * it. Five readings were never evidence that anything was set up. A record
 * that never entered the flow keeps the pre-v1.39 rule unchanged — first-run
 * wizard unfinished, or fewer than five readings.
 *
 * A list whose rows are all done still stays while the flow itself is
 * unfinished, because the one task the flow offered is not one of the six
 * rows: "every row done" and "the setup finished" are different statements.
 */
export interface StillInSetupInputs {
  /**
   * v1.39 — the needs-based setup state for this record, or null before
   * the account payload resolves. A record that never entered the flow reads
   * as empty answers with nine pending steps and is treated as having no
   * unfinished setup, which is what keeps every account that predates the flow
   * on the rule it already had.
   */
  onboarding?: OnboardingStateDto | null;
  onboardingCompletedAt: string | null;
  measurementCount: number;
}

/**
 * v1.39 — "is this record still being set up?", as ONE predicate.
 *
 * Two places decide this: whether the card renders at all, and whether the
 * component fetches the data its rows are about. They were two restatements of
 * the same rule and they drifted — the visibility rule gained
 * `hasEnteredOnboardingFlow`, the query gate kept the older half, and a
 * wizard-run account past five readings got a permanently visible card whose
 * every network-backed row read "not done". A record whose
 * restarted run was abandoned is in the same state: `restart` clears the
 * record's own `completedAt` and deliberately not the account stamp, so
 * `hasEnteredOnboardingFlow` is what keeps its rows live.
 *
 * Exported so the component calls it rather than restating it.
 */
export function isStillInSetup(args: StillInSetupInputs): boolean {
  return (
    hasEnteredOnboardingFlow(args.onboarding ?? null) ||
    args.onboardingCompletedAt == null ||
    args.measurementCount < 5
  );
}

export function shouldShowChecklist(
  args: StillInSetupInputs & {
    dismissedAll: boolean;
    items: ChecklistItem[];
  },
): boolean {
  if (args.dismissedAll) return false;
  const onboarding = args.onboarding ?? null;
  const visible = visibleChecklist(args.items);
  if (visible.length === 0) return false;

  if (!isStillInSetup(args)) return false;

  if (!isOnboardingSettled(onboarding)) return true;
  return visible.some((item) => !item.done);
}

/**
 * The upcoming-visit count off the visits list's own body. `GET
 * /api/encounters` answers `{ upcoming, past }` as DATA — there is no `meta`
 * on that wire, and a reader that looked for one counted zero forever (the
 * "prepare the visit" row could never flip). Pure, so the shape is pinned
 * against the DTO the route publishes.
 */
export function upcomingVisitCountFrom(
  body: { upcoming: readonly unknown[] } | null | undefined,
): number {
  return Array.isArray(body?.upcoming) ? body.upcoming.length : 0;
}

/**
 * Profile is "complete" once height, date of birth and gender are all
 * set. Display name is captured automatically at signup, so it doesn't
 * gate this item.
 */
export function isProfileComplete(
  profile: ChecklistInputs["profile"],
): boolean {
  return (
    profile.heightCm != null &&
    profile.heightCm > 0 &&
    profile.dateOfBirth != null &&
    profile.gender != null &&
    profile.gender !== ""
  );
}

/**
 * Trend hint: when the user has between 1 and 4 readings of a metric we
 * surface "First trend after 5 readings — N more to go". 0 readings is
 * handled by the existing chart empty-state. ≥5 readings hides the
 * hint entirely.
 */
export function trendHintFor(
  count: number,
): { kind: "hidden" } | { kind: "show"; remaining: number } {
  if (count < 1 || count >= 5) return { kind: "hidden" };
  return { kind: "show", remaining: 5 - count };
}