import React, { useState, useEffect } from 'react';
import { toast } from 'sonner';
import { api } from '@/api';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Card, CardHeader, CardTitle, CardContent } from '@/components/ui/card';
import { Toggle } from './adminShared';

function timeAgo(iso) {
  if (!iso) return null;
  const secs = Math.floor((Date.now() - new Date(iso).getTime()) / 1000);
  if (secs < 60)  return 'just now';
  if (secs < 3600) return `${Math.floor(secs / 60)}m ago`;
  if (secs < 86400) return `${Math.floor(secs / 3600)}h ago`;
  return `${Math.floor(secs / 86400)}d ago`;
}

function timeUntil(iso) {
  if (!iso) return null;
  const secs = Math.floor((new Date(iso).getTime() - Date.now()) / 1000);
  if (secs <= 0) return 'soon';
  if (secs < 60) return `${secs}s`;
  if (secs < 3600) return `${Math.floor(secs / 60)}m`;
  return `${Math.floor(secs / 3600)}h`;
}

export default function BankSyncAdminCard() {
  const [config, setConfig]             = useState(null);
  const [loading, setLoading]           = useState(true);
  const [loadError, setLoadError]       = useState('');
  const [saving, setSaving]             = useState(false);
  const [enabled, setEnabled]           = useState(false);
  const [syncInterval, setSyncInterval] = useState(4);
  const [syncDays, setSyncDays]         = useState(90);

  useEffect(() => {
    api.bankSyncConfig()
      .then(d => {
        setConfig(d);
        setEnabled(!!d.enabled);
        setSyncInterval(d.sync_interval_hours ?? 4);
        setSyncDays(d.sync_days ?? 90);
      })
      .catch(err => setLoadError(err.message || 'Failed to load bank sync config'))
      .finally(() => setLoading(false));
  }, []);

  const handleSave = async () => {
    const hours = parseFloat(syncInterval);
    const days  = parseInt(syncDays, 10);
    if (!Number.isFinite(hours) || hours < 0.5 || hours > 168) {
      toast.error('Sync interval must be between 0.5 and 168 hours.');
      return;
    }
    if (!Number.isFinite(days) || days < 1 || days > 90) {
      toast.error('Transaction history must be between 1 and 90 days — SimpleFIN Bridge does not support longer windows.');
      return;
    }
    setSaving(true);
    try {
      const result = await api.setBankSyncConfig({ enabled, sync_interval_hours: hours, sync_days: days });
      setConfig(result);
      setEnabled(!!result.enabled);
      setSyncInterval(result.sync_interval_hours ?? 4);
      setSyncDays(result.sync_days ?? 90);
      toast.success('Bank sync settings saved.');
    } catch (err) {
      toast.error(err.message || 'Failed to update bank sync setting.');
    } finally {
      setSaving(false);
    }
  };

  if (loading) {
    return (
      <Card>
        <CardContent className="py-8 text-center text-muted-foreground text-sm">
          Loading…
        </CardContent>
      </Card>
    );
  }

  if (loadError) {
    return (
      <Card>
        <CardContent className="py-8 text-center text-sm text-destructive">
          {loadError}
        </CardContent>
      </Card>
    );
  }

  const changed = enabled !== !!config?.enabled
    || parseFloat(syncInterval) !== config?.sync_interval_hours
    || parseInt(syncDays, 10) !== config?.sync_days;
  const worker = config?.worker;

  return (
    <Card>
      <CardHeader className="pb-4">
        <CardTitle>Bank Sync (SimpleFIN)</CardTitle>
        <p className="text-sm text-muted-foreground mt-1">
          Allow users to connect their own SimpleFIN Bridge account to sync
          read-only bank transactions. Each user manages their own connection
          from the Data page — no bank credentials are stored.
        </p>
      </CardHeader>
      <CardContent className="space-y-5">

        {/* Enable toggle */}
        <div className="flex items-center justify-between">
          <div>
            <p className="text-sm font-medium">Allow users to connect SimpleFIN</p>
            <p className="text-xs text-muted-foreground mt-0.5">
              When enabled, users see a Bank Sync section on their Data page.
            </p>
          </div>
          <Toggle
            checked={enabled}
            onChange={v => setEnabled(v)}
            label="Enable bank sync"
          />
        </div>

        {/* Sync interval */}
        <div className="flex items-center justify-between gap-4">
          <div>
            <p className="text-sm font-medium">Auto-sync interval</p>
            <p className="text-xs text-muted-foreground mt-0.5">
              How often the background worker checks for new transactions.
            </p>
          </div>
          <div className="flex items-center gap-2 shrink-0">
            <Input
              type="number"
              min="0.5"
              max="168"
              step="0.5"
              value={syncInterval}
              onChange={e => setSyncInterval(e.target.value)}
              className="w-20 text-sm text-right"
            />
            <span className="text-sm text-muted-foreground">hrs</span>
          </div>
        </div>

        {/* Transaction history lookback */}
        <div className="flex items-start justify-between gap-4">
          <div>
            <p className="text-sm font-medium">Transaction history</p>
            <p className="text-xs text-muted-foreground mt-0.5">
              How far back to fetch transactions. Maximum 90 days — this is a hard limit imposed by SimpleFIN Bridge and cannot be exceeded.
            </p>
          </div>
          <div className="flex items-center gap-2 shrink-0">
            <Input
              type="number"
              min="1"
              max="90"
              step="1"
              value={syncDays}
              onChange={e => setSyncDays(Math.min(90, Math.max(1, parseInt(e.target.value, 10) || 90)))}
              className="w-20 text-sm text-right"
            />
            <span className="text-sm text-muted-foreground">days</span>
          </div>
        </div>

        {/* Auto-sync worker status */}
        {config?.enabled && worker && (
          <div className="rounded-lg border border-border/60 bg-muted/20 px-4 py-3 space-y-2">
            <p className="text-xs font-semibold uppercase tracking-widest text-muted-foreground">Auto-sync worker</p>
            <div className="grid grid-cols-2 gap-x-6 gap-y-1 text-sm sm:grid-cols-3">
              <div>
                <p className="text-xs text-muted-foreground">Status</p>
                <p className="font-medium flex items-center gap-1.5">
                  <span className={`h-1.5 w-1.5 rounded-full ${worker.running ? 'bg-amber-500 animate-pulse' : 'bg-emerald-500'}`} />
                  {worker.running ? 'Running' : 'Idle'}
                </p>
              </div>
              <div>
                <p className="text-xs text-muted-foreground">Last run</p>
                <p className="font-medium">{worker.last_run_at ? timeAgo(worker.last_run_at) : '—'}</p>
              </div>
              <div>
                <p className="text-xs text-muted-foreground">Next run</p>
                <p className="font-medium">{worker.next_run_at ? `in ${timeUntil(worker.next_run_at)}` : '—'}</p>
              </div>
            </div>
          </div>
        )}

        {/* Encryption note */}
        <p className="text-xs text-muted-foreground border-t border-border/50 pt-3">
          SimpleFIN credentials are encrypted with a key stored in your database.
          Regular database backups preserve all user connections.
        </p>

        <div className="flex justify-end">
          <Button onClick={handleSave} disabled={saving || !changed}>
            {saving ? 'Saving…' : 'Save'}
          </Button>
        </div>

      </CardContent>
    </Card>
  );
}