'use client';

import { create } from 'zustand';
import type { XiaobaoVersionRisk } from '@/lib/xiaobao-risk';
import {
  markXiaobaoWarningRead,
  type XiaobaoWarningReadState,
} from '@/lib/xiaobao-warning-view';

interface XiaobaoWarningReadStoreState {
  readStates: XiaobaoWarningReadState[];
  readStateLoaded: boolean;
  error?: string;
  fetchReadStates: () => Promise<void>;
  markRiskRead: (userId: string, risk: XiaobaoVersionRisk, readAt?: string) => Promise<void>;
}

const READ_STATE_CACHE_MS = 30_000;
const READ_STATE_STORAGE_KEY = 'ftb_xiaobao_warning_views';
let lastReadStatesFetchAt = 0;

function loadReadStates(): XiaobaoWarningReadState[] {
  try {
    if (typeof window === 'undefined') return [];
    return normalizeReadStates(JSON.parse(window.localStorage.getItem(READ_STATE_STORAGE_KEY) || '[]'));
  } catch {}
  return [];
}

function saveReadStates(rows: XiaobaoWarningReadState[]) {
  try {
    if (typeof window === 'undefined') return;
    window.localStorage.setItem(READ_STATE_STORAGE_KEY, JSON.stringify(rows));
  } catch {}
}

function normalizeReadStates(rows: unknown): XiaobaoWarningReadState[] {
  if (!Array.isArray(rows)) return [];
  return rows.filter(isReadState);
}

function isReadState(row: unknown): row is XiaobaoWarningReadState {
  if (!row || typeof row !== 'object') return false;
  const item = row as Partial<XiaobaoWarningReadState>;
  return (
    typeof item.userId === 'string' &&
    typeof item.versionId === 'string' &&
    typeof item.signature === 'string' &&
    typeof item.readAt === 'string'
  );
}

function mergeReadStates(
  remoteRows: XiaobaoWarningReadState[] = [],
  localRows: XiaobaoWarningReadState[] = [],
): XiaobaoWarningReadState[] {
  const byKey = new Map<string, XiaobaoWarningReadState>();
  for (const row of [...remoteRows, ...localRows]) {
    const key = `${row.userId}::${row.versionId}`;
    const existing = byKey.get(key);
    if (!existing || row.readAt.localeCompare(existing.readAt) >= 0) {
      byKey.set(key, row);
    }
  }
  return Array.from(byKey.values()).sort((a, b) => b.readAt.localeCompare(a.readAt));
}

export const useXiaobaoWarningReadStore = create<XiaobaoWarningReadStoreState>((set, get) => ({
  readStates: [],
  readStateLoaded: false,
  error: undefined,

  fetchReadStates: async () => {
    if (get().readStateLoaded && Date.now() - lastReadStatesFetchAt < READ_STATE_CACHE_MS) return;
    const rows = loadReadStates();
    if (get().readStateLoaded && Date.now() - lastReadStatesFetchAt < READ_STATE_CACHE_MS) return;
    lastReadStatesFetchAt = Date.now();
    set({
      readStates: mergeReadStates(rows, get().readStates),
      readStateLoaded: true,
      error: undefined,
    });
  },

  markRiskRead: async (userId, risk, readAt = new Date().toISOString()) => {
    if (!userId) return;
    const optimistic = markXiaobaoWarningRead(get().readStates, userId, risk, readAt);
    set({ readStates: optimistic, error: undefined });
    saveReadStates(optimistic);
  },
}));