import React, { useState, useEffect, useCallback } from 'react';
import { toast } from 'sonner';
import { api } from '@/api';
import { cn } from '@/lib/utils';
import BankSyncSection from '@/components/data/BankSyncSection';
import ImportTransactionCsvSection from '@/components/data/ImportTransactionCsvSection';
import TransactionMatchingSection from '@/components/data/TransactionMatchingSection';
import ImportSpreadsheetSection from '@/components/data/ImportSpreadsheetSection';
import ImportMyDataSection from '@/components/data/ImportMyDataSection';
import SeedDemoDataSection from '@/components/data/SeedDemoDataSection';
import DownloadMyDataSection from '@/components/data/DownloadMyDataSection';
import ImportHistorySection from '@/components/data/ImportHistorySection';

const DATA_TAB_STORAGE_KEY = 'billtracker:data.activeTab';
const DATA_TABS = [
  {
    id: 'sync',
    label: 'Sync & Match',
    description: 'Bank connections, synced transactions, and CSV transaction imports.',
  },
  {
    id: 'import',
    label: 'Import Data',
    description: 'Bring in spreadsheet history, restore an app export, or seed demo data.',
  },
  {
    id: 'export',
    label: 'Export & History',
    description: 'Download your data and review previous import activity.',
  },
];

function useStoredTab() {
  const [activeTab, setActiveTabState] = useState(() => {
    if (typeof window === 'undefined') return DATA_TABS[0].id;
    const stored = window.localStorage.getItem(DATA_TAB_STORAGE_KEY);
    return DATA_TABS.some(tab => tab.id === stored) ? stored : DATA_TABS[0].id;
  });

  const setActiveTab = useCallback((tab) => {
    setActiveTabState(tab);
    if (typeof window !== 'undefined') {
      window.localStorage.setItem(DATA_TAB_STORAGE_KEY, tab);
    }
  }, []);

  return [activeTab, setActiveTab];
}

function DataStatusStrip({ history, historyLoading, simplefinConn, syncLoading }) {
  const syncStatus = simplefinConn
    ? (simplefinConn.last_error ? 'Needs attention' : 'Connected')
    : syncLoading ? 'Loading…' : 'Not connected';
  const syncTone = simplefinConn?.last_error
    ? 'text-amber-600 dark:text-amber-300'
    : simplefinConn
    ? 'text-emerald-600 dark:text-emerald-300'
    : 'text-muted-foreground';

  return (
    <div className="grid gap-2 sm:grid-cols-3">
      <div className="rounded-lg border border-border/70 bg-card/80 px-4 py-3">
        <p className="text-[10px] font-bold uppercase tracking-widest text-muted-foreground">SimpleFIN</p>
        <p className={cn('mt-1 truncate text-sm font-semibold', syncTone)}>{syncStatus}</p>
      </div>
      <div className="rounded-lg border border-border/70 bg-card/80 px-4 py-3">
        <p className="text-[10px] font-bold uppercase tracking-widest text-muted-foreground">Last Sync</p>
        <p className="mt-1 truncate text-sm font-semibold text-foreground">
          {simplefinConn?.last_sync_at ? new Date(simplefinConn.last_sync_at).toLocaleString([], { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' }) : '—'}
        </p>
      </div>
      <div className="rounded-lg border border-border/70 bg-card/80 px-4 py-3">
        <p className="text-[10px] font-bold uppercase tracking-widest text-muted-foreground">Import History</p>
        <p className="mt-1 truncate text-sm font-semibold text-foreground">
          {historyLoading ? 'Loading…' : `${history?.length || 0} record${(history?.length || 0) === 1 ? '' : 's'}`}
        </p>
      </div>
    </div>
  );
}

export default function DataPage() {
  const [history, setHistory]               = useState(null);
  const [historyLoading, setHistoryLoading] = useState(true);
  const [transactionRefreshKey, setTransactionRefreshKey] = useState(0);
  const [simplefinConn, setSimplefinConn]   = useState(null);
  const [syncLoading, setSyncLoading]       = useState(true);
  const [activeTab, setActiveTab] = useStoredTab();

  const loadHistory = async () => {
    setHistoryLoading(true);
    try {
      const { history } = await api.importHistory();
      setHistory(history);
    } catch (err) {
      setHistory([]);
      toast.error(err.message || 'Failed to load import history.');
    } finally {
      setHistoryLoading(false);
    }
  };

  const loadSimplefinSummary = useCallback(async () => {
    setSyncLoading(true);
    try {
      const [status, sources] = await Promise.all([
        api.simplefinStatus(),
        api.dataSources({ type: 'provider_sync' }),
      ]);
      if (!status.enabled) {
        setSimplefinConn(null);
        return;
      }
      const conns = Array.isArray(sources) ? sources.filter(source => source.provider === 'simplefin') : [];
      setSimplefinConn(conns[0] || null);
    } catch {
      setSimplefinConn(null);
    } finally {
      setSyncLoading(false);
    }
  }, []);

  useEffect(() => {
    loadHistory();
    loadSimplefinSummary();
  }, [loadSimplefinSummary]);

  const handleTransactionImportComplete = () => {
    loadHistory();
    setTransactionRefreshKey(key => key + 1);
  };

  // Called by BankSyncSection when connection state changes (connect/sync/disconnect)
  const handleConnectionChange = useCallback((conn) => {
    setSimplefinConn(conn || null);
    setSyncLoading(false);
    setTransactionRefreshKey(key => key + 1);
  }, []);

  return (
    <div className="mx-auto w-full max-w-6xl space-y-5">
      <div className="flex flex-col gap-2 sm:flex-row sm:items-end sm:justify-between">
        <div>
          <h1 className="text-2xl font-bold tracking-tight">Data</h1>
          <p className="text-sm text-muted-foreground mt-0.5">
            Import, export, and review your user-owned bill tracker records.
          </p>
        </div>
        <div className="rounded-full border border-border/70 bg-card/80 px-3 py-1.5 text-xs font-medium text-muted-foreground">
          User data only
        </div>
      </div>

      <DataStatusStrip history={history} historyLoading={historyLoading} simplefinConn={simplefinConn} syncLoading={syncLoading} />

      <div className="rounded-lg border border-border/70 bg-card/70 p-1">
        <div className="grid gap-1 md:grid-cols-3">
          {DATA_TABS.map(tab => {
            const active = activeTab === tab.id;
            return (
              <button
                key={tab.id}
                type="button"
                onClick={() => setActiveTab(tab.id)}
                className={cn(
                  'rounded-md px-4 py-3 text-left transition-colors',
                  active ? 'bg-primary text-primary-foreground shadow-sm' : 'text-muted-foreground hover:bg-muted/50 hover:text-foreground',
                )}
              >
                <span className="block text-sm font-semibold">{tab.label}</span>
                <span className={cn('mt-0.5 block text-xs', active ? 'text-primary-foreground/75' : 'text-muted-foreground')}>
                  {tab.description}
                </span>
              </button>
            );
          })}
        </div>
      </div>

      {activeTab === 'sync' && (
        <div className="space-y-5">
          <BankSyncSection
            onConnectionChange={handleConnectionChange}
            cardProps={{
              collapsible: true,
              defaultOpen: true,
              storageKey: 'billtracker:data.card.bankSync',
              summary: simplefinConn ? `Connected as ${simplefinConn.name || 'SimpleFIN'}` : 'Connect or manage SimpleFIN bank sync.',
            }}
          />
          <TransactionMatchingSection
            refreshKey={transactionRefreshKey}
            simplefinConn={simplefinConn}
            cardProps={{
              collapsible: true,
              defaultOpen: true,
              storageKey: 'billtracker:data.card.transactions',
              summary: 'Review transaction matches and create bill payments.',
            }}
          />
          <ImportTransactionCsvSection
            onHistoryRefresh={handleTransactionImportComplete}
            cardProps={{
              collapsible: true,
              defaultOpen: false,
              storageKey: 'billtracker:data.card.transactionCsv',
              summary: 'Upload bank or credit-card CSV transaction files.',
            }}
          />
        </div>
      )}

      {activeTab === 'import' && (
        <div className="space-y-5">
          <ImportSpreadsheetSection
            onHistoryRefresh={loadHistory}
            cardProps={{
              collapsible: true,
              defaultOpen: false,
              storageKey: 'billtracker:data.card.spreadsheet',
              summary: 'Import bill/payment history from an XLSX workbook.',
            }}
          />
          <ImportMyDataSection
            onHistoryRefresh={loadHistory}
            cardProps={{
              collapsible: true,
              defaultOpen: false,
              storageKey: 'billtracker:data.card.sqliteImport',
              summary: 'Restore data from a user SQLite export.',
            }}
          />
          <SeedDemoDataSection
            onSeeded={loadHistory}
            cardProps={{
              collapsible: true,
              defaultOpen: false,
              storageKey: 'billtracker:data.card.demo',
              summary: 'Seed or clear demo data for testing.',
            }}
          />
        </div>
      )}

      {activeTab === 'export' && (
        <div className="space-y-5">
          <DownloadMyDataSection
            cardProps={{
              collapsible: true,
              defaultOpen: true,
              storageKey: 'billtracker:data.card.download',
              summary: 'Download SQLite or Excel exports of your records.',
            }}
          />
          <ImportHistorySection
            history={history}
            loading={historyLoading}
            onRefresh={loadHistory}
            cardProps={{
              collapsible: true,
              defaultOpen: false,
              storageKey: 'billtracker:data.card.history',
              summary: historyLoading ? 'Loading import activity…' : `${history?.length || 0} import record${(history?.length || 0) === 1 ? '' : 's'}.`,
            }}
          />
        </div>
      )}
    </div>
  );
}