/**
 * User-scoped localStorage utilities.
 *
 * All draft/answer data is keyed by the authenticated user's profile ID
 * so that Account A's unsynced edits can never be displayed or synced
 * for Account B.
 *
 * The raw auth token is NEVER used as a key component.
 */

import type { MarriageProfileResponse } from "@/hooks/marriage/types";

export const SCOPED_STORAGE_VERSION = 3;

// ─── Types ───────────────────────────────────────────────────────────

export interface ScopedSectionDraft {
  version: typeof SCOPED_STORAGE_VERSION;
  ownerProfileId: number;
  slug: string;
  pending: Record<string, ScopedPendingField>;
  updatedAt: string;
}

export interface ScopedPendingField {
  key: string;
  label: string;
  type: string;
  value: unknown;
  option_id?: string | string[] | null;
  private?: boolean;
}

export interface ScopedAssessmentDraft {
  version: typeof SCOPED_STORAGE_VERSION;
  ownerProfileId: number;
  slug: string;
  answers: Record<number, string | number>;
  currentIndex: number;
  totalQuestions: number;
}

// ─── Key Generators ──────────────────────────────────────────────────

export function getScopedSectionDraftKey(
  profileId: number,
  slug: string,
): string {
  return `marriage:user:${profileId}:sections:${slug}:draft:v${SCOPED_STORAGE_VERSION}`;
}

export function getScopedAssessmentDraftKey(
  profileId: number,
  slug: string,
): string {
  return `marriage:user:${profileId}:tests:${slug}:draft:v${SCOPED_STORAGE_VERSION}`;
}

// ─── Ownership Verification ──────────────────────────────────────────

export function isDraftOwnedBy(
  draft: { ownerProfileId?: number } | null | undefined,
  profileId: number,
): boolean {
  if (!draft || typeof draft !== "object") return false;
  return draft.ownerProfileId === profileId;
}

// ─── Reading ─────────────────────────────────────────────────────────

export function readScopedSectionDraft(
  profileId: number,
  slug: string,
): ScopedSectionDraft | null {
  try {
    const key = getScopedSectionDraftKey(profileId, slug);
    const raw = window.localStorage.getItem(key);
    if (!raw) return null;

    const parsed = JSON.parse(raw);
    if (
      !parsed ||
      parsed.version !== SCOPED_STORAGE_VERSION ||
      parsed.ownerProfileId !== profileId ||
      parsed.slug !== slug
    ) {
      // Corrupted or mismatched — remove it
      window.localStorage.removeItem(key);
      return null;
    }

    return parsed as ScopedSectionDraft;
  } catch {
    return null;
  }
}

export function readScopedAssessmentDraft(
  profileId: number,
  slug: string,
): ScopedAssessmentDraft | null {
  try {
    const key = getScopedAssessmentDraftKey(profileId, slug);
    const raw = window.localStorage.getItem(key);
    if (!raw) return null;

    const parsed = JSON.parse(raw);
    if (
      !parsed ||
      parsed.version !== SCOPED_STORAGE_VERSION ||
      parsed.ownerProfileId !== profileId
    ) {
      window.localStorage.removeItem(key);
      return null;
    }

    return parsed as ScopedAssessmentDraft;
  } catch {
    return null;
  }
}

// ─── Writing ─────────────────────────────────────────────────────────

export function writeScopedSectionDraft(
  profileId: number,
  slug: string,
  pending: Record<string, ScopedPendingField>,
): void {
  try {
    const key = getScopedSectionDraftKey(profileId, slug);

    if (Object.keys(pending).length === 0) {
      window.localStorage.removeItem(key);
      return;
    }

    const draft: ScopedSectionDraft = {
      version: SCOPED_STORAGE_VERSION,
      ownerProfileId: profileId,
      slug,
      pending,
      updatedAt: new Date().toISOString(),
    };

    window.localStorage.setItem(key, JSON.stringify(draft));
  } catch {
    // localStorage can fail in private mode or when storage quota is exhausted.
  }
}

export function writeScopedAssessmentDraft(
  profileId: number,
  slug: string,
  answers: Record<number, string | number>,
  currentIndex: number,
  totalQuestions: number,
): void {
  try {
    const key = getScopedAssessmentDraftKey(profileId, slug);

    if (Object.keys(answers).length === 0) {
      window.localStorage.removeItem(key);
      return;
    }

    const draft: ScopedAssessmentDraft = {
      version: SCOPED_STORAGE_VERSION,
      ownerProfileId: profileId,
      slug,
      answers,
      currentIndex,
      totalQuestions,
    };

    window.localStorage.setItem(key, JSON.stringify(draft));
  } catch {
    // localStorage can fail.
  }
}

export function removeScopedSectionDraft(
  profileId: number,
  slug: string,
): void {
  try {
    window.localStorage.removeItem(
      getScopedSectionDraftKey(profileId, slug),
    );
  } catch {}
}

export function removeScopedAssessmentDraft(
  profileId: number,
  slug: string,
): void {
  try {
    window.localStorage.removeItem(
      getScopedAssessmentDraftKey(profileId, slug),
    );
  } catch {}
}

// ─── Legacy Migration ────────────────────────────────────────────────

/**
 * Remove old V2 unscoped answer keys. Since they have no owner metadata,
 * ownership cannot be proven, so we do NOT migrate them.
 * We also do NOT call localStorage.clear() because the application stores
 * unrelated device/UI flags.
 */
export function migrateLegacyStorageKeys(): void {
  try {
    const keysToRemove: string[] = [];

    for (let i = 0; i < window.localStorage.length; i++) {
      const key = window.localStorage.key(i);
      if (!key) continue;

      // Old V2 normal section keys: marriage:sections:{slug}:answers:v2
      if (key.match(/^marriage:sections:[^:]+:answers:v2$/)) {
        keysToRemove.push(key);
      }

      // Old unscoped assessment draft keys: marriage:tests:{slug}:draft
      if (key.match(/^marriage:tests:[^:]+:draft$/) && !key.includes(":user:")) {
        keysToRemove.push(key);
      }

      // Old unscoped completion markers: marriage:sections:{slug}:answers
      // (used by assessments to store {completed: true})
      if (key.match(/^marriage:sections:[^:]+:answers$/) && !key.includes(":user:")) {
        keysToRemove.push(key);
      }
    }

    for (const key of keysToRemove) {
      window.localStorage.removeItem(key);
    }

    // Mark migration as done so we don't re-scan every page load
    window.localStorage.setItem("marriage:storage-migration:v3", "done");
  } catch {
    // Non-critical; will retry next page load.
  }
}

/**
 * Check if the V3 migration has already been performed.
 */
export function isLegacyMigrationDone(): boolean {
  try {
    return window.localStorage.getItem("marriage:storage-migration:v3") === "done";
  } catch {
    return false;
  }
}

/**
 * Enumerate all scoped section draft keys for a given profile.
 */
export function getAllScopedSectionDraftKeys(
  profileId: number,
): string[] {
  const prefix = `marriage:user:${profileId}:sections:`;
  const suffix = `:draft:v${SCOPED_STORAGE_VERSION}`;
  const keys: string[] = [];

  try {
    for (let i = 0; i < window.localStorage.length; i++) {
      const key = window.localStorage.key(i);
      if (key && key.startsWith(prefix) && key.endsWith(suffix)) {
        keys.push(key);
      }
    }
  } catch {}

  return keys;
}

/**
 * Extract the slug from a scoped section draft key.
 */
export function extractSlugFromScopedKey(key: string): string | null {
  const match = key.match(/^marriage:user:\d+:sections:([^:]+):draft:v\d+$/);
  return match ? match[1] : null;
}

// ─── Scoped Marriage Profile Cache ─────────────────────────────────────

export interface ScopedMarriageProfileData {
  version: typeof SCOPED_STORAGE_VERSION;
  ownerProfileId: number;
  profile: MarriageProfileResponse;
  savedAt: number;
}

export function getScopedMarriageProfileKey(profileId: number): string {
  return `marriage:user:${profileId}:profile:v${SCOPED_STORAGE_VERSION}`;
}

export const LATEST_PROFILE_STORAGE_KEY = `marriage:profile:latest:v${SCOPED_STORAGE_VERSION}`;

/**
 * Persist the latest full MarriageProfileResponse from the server.
 */
export function saveScopedMarriageProfile(profile: MarriageProfileResponse): void {
  if (typeof window === "undefined" || !profile?.id) return;
  try {
    const payload: ScopedMarriageProfileData = {
      version: SCOPED_STORAGE_VERSION,
      ownerProfileId: profile.id,
      profile,
      savedAt: Date.now(),
    };
    const serialized = JSON.stringify(payload);
    window.localStorage.setItem(getScopedMarriageProfileKey(profile.id), serialized);
    window.localStorage.setItem(LATEST_PROFILE_STORAGE_KEY, serialized);
  } catch {}
}

/**
 * Retrieve the persisted MarriageProfileResponse if valid.
 */
export function getScopedMarriageProfile(
  expectedProfileId?: number,
): MarriageProfileResponse | null {
  if (typeof window === "undefined") return null;
  try {
    const key = expectedProfileId
      ? getScopedMarriageProfileKey(expectedProfileId)
      : LATEST_PROFILE_STORAGE_KEY;
    const raw = window.localStorage.getItem(key);
    if (!raw) return null;
    const parsed = JSON.parse(raw) as ScopedMarriageProfileData;
    if (!parsed || parsed.version !== SCOPED_STORAGE_VERSION || !parsed.profile) {
      return null;
    }
    if (expectedProfileId && parsed.ownerProfileId !== expectedProfileId) {
      return null;
    }
    return parsed.profile;
  } catch {
    return null;
  }
}

/**
 * Clear all persisted marriage profile caches (used on auth token/account change).
 */
export function clearScopedMarriageProfiles(): void {
  if (typeof window === "undefined") return;
  try {
    window.localStorage.removeItem(LATEST_PROFILE_STORAGE_KEY);
    const keysToRemove: string[] = [];
    for (let i = 0; i < window.localStorage.length; i++) {
      const key = window.localStorage.key(i);
      if (key && key.startsWith("marriage:user:") && key.includes(":profile:")) {
        keysToRemove.push(key);
      }
    }
    for (const key of keysToRemove) {
      window.localStorage.removeItem(key);
    }
  } catch {}
}