import { useState } from 'react'
import {
  Alert, Button, Card, Descriptions, Form, Input, Modal, Popconfirm, Space, Tag, Typography, message,
} from 'antd'
import { CrownOutlined, ReloadOutlined, SafetyCertificateOutlined } from '@ant-design/icons'
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
import { useTranslation } from 'react-i18next'

import apiClient, { isEnvelope } from '../../api/client'
import PageHeader from '../../components/PageHeader'

const { Text, Paragraph } = Typography

interface LicenseStatus {
  license_key?: string
  status: string
  type?: string
  valid?: boolean
  valid_until?: string
  expires_at?: string
  last_verified_at?: string
  last_verified_node?: string
  last_error?: string | null
  reason?: string
  payload?: {
    product?: string
    type?: string
    limits?: Record<string, number>
    features?: Record<string, boolean>
  }
}

function daysUntil(iso?: string): number | null {
  if (!iso) return null
  const ms = new Date(iso).getTime() - Date.now()
  return Math.ceil(ms / 86_400_000)
}

function statusTag(s: LicenseStatus, t: (k: string) => string) {
  if (s.status === 'active' && s.type === 'trial') return <Tag color="orange">{t('license.tagTrial')}</Tag>
  if (s.status === 'active') return <Tag color="green">{t('license.tagActive')}</Tag>
  if (s.status === 'expired') return <Tag color="red">{t('license.tagExpired')}</Tag>
  if (s.status === 'invalid') return <Tag color="red">{t('license.tagInvalid')}</Tag>
  return <Tag>{s.status}</Tag>
}

export default function LicensePage() {
  const { t } = useTranslation()
  const qc = useQueryClient()
  const [open, setOpen] = useState(false)
  const [form] = Form.useForm<{ license_key: string }>()

  const { data: status, isLoading } = useQuery({
    queryKey: ['license', 'status'],
    queryFn: async () => {
      const r = await apiClient.get('/license/status')
      return isEnvelope(r.data) ? (r.data.data as LicenseStatus) : null
    },
    refetchInterval: 60_000,
  })

  const setKey = useMutation({
    mutationFn: async (key: string) => {
      const r = await apiClient.put('/license/key', { license_key: key })
      return isEnvelope(r.data) ? r.data.data : r.data
    },
    onSuccess: (res: { verify_error?: string }) => {
      if (res?.verify_error) {
        message.warning(t('license.savedButVerifyFailed') + ': ' + res.verify_error)
      } else {
        message.success(t('license.saved'))
      }
      setOpen(false)
      form.resetFields()
      qc.invalidateQueries({ queryKey: ['license'] })
    },
    onError: (e: Error) => message.error(e.message),
  })

  const verify = useMutation({
    mutationFn: async () => { await apiClient.post('/license/verify') },
    onSuccess: () => {
      message.success(t('license.reverified'))
      qc.invalidateQueries({ queryKey: ['license'] })
    },
    onError: (e: Error) => message.error(e.message),
  })

  const clear = useMutation({
    mutationFn: async () => { await apiClient.delete('/license/key') },
    onSuccess: () => {
      message.success(t('license.cleared'))
      qc.invalidateQueries({ queryKey: ['license'] })
    },
    onError: (e: Error) => message.error(e.message),
  })

  const expiry = status?.valid_until ?? status?.expires_at
  const days = daysUntil(expiry)
  const isTrial = status?.type === 'trial' || (!status?.license_key && status?.status === 'active')

  return (
    <>
      <PageHeader
        title={t('license.title')}
        icon={<CrownOutlined />}
        extra={
          <Space>
            <Button icon={<ReloadOutlined />} onClick={() => verify.mutate()} loading={verify.isPending}
              disabled={!status?.license_key}>
              {t('license.reverify')}
            </Button>
            <Button type="primary" icon={<SafetyCertificateOutlined />} onClick={() => setOpen(true)}>
              {status?.license_key ? t('license.replaceKey') : t('license.enterKey')}
            </Button>
          </Space>
        }
      />

      {isLoading && <Alert message={t('common.loading')} type="info" />}

      {status?.last_error && (
        <Alert
          type="warning"
          showIcon
          message={t('license.lastVerifyFailed')}
          description={status.last_error}
          className="mb-16"
          closable
        />
      )}

      {isTrial && days !== null && days <= 14 && (
        <Alert
          type={days <= 3 ? 'error' : 'warning'}
          showIcon
          message={t('license.trialExpiring', { days })}
          description={t('license.trialExpiringHint')}
          className="mb-16"
        />
      )}

      <Card>
        <Descriptions column={1} bordered size="small">
          <Descriptions.Item label={t('license.status')}>
            {status ? statusTag(status, t) : '-'}
          </Descriptions.Item>
          <Descriptions.Item label={t('license.product')}>
            {status?.payload?.product || (isTrial ? 'Trial' : '-')}
          </Descriptions.Item>
          <Descriptions.Item label={t('license.key')}>
            <Text code copyable={!!status?.license_key}>
              {status?.license_key || '— ' + t('license.noKey') + ' —'}
            </Text>
          </Descriptions.Item>
          <Descriptions.Item label={t('license.validUntil')}>
            {expiry ? (
              <>
                {new Date(expiry).toLocaleString()}{' '}
                {days !== null && (
                  <Tag color={days < 0 ? 'red' : days <= 14 ? 'orange' : 'blue'}>
                    {days < 0 ? t('license.expired') : t('license.daysLeft', { days })}
                  </Tag>
                )}
              </>
            ) : '-'}
          </Descriptions.Item>
          <Descriptions.Item label={t('license.lastVerifiedAt')}>
            {status?.last_verified_at ? new Date(status.last_verified_at).toLocaleString() : '-'}
          </Descriptions.Item>
          {status?.last_verified_node && (
            <Descriptions.Item label={t('license.verifiedBy')}>
              <Text code>{status.last_verified_node}</Text>
            </Descriptions.Item>
          )}
        </Descriptions>

        {status?.payload?.limits && Object.keys(status.payload.limits).length > 0 && (
          <>
            <Paragraph strong className="mt-24">{t('license.limits')}</Paragraph>
            <Descriptions column={2} bordered size="small">
              {Object.entries(status.payload.limits).map(([k, v]) => (
                <Descriptions.Item key={k} label={k}>
                  {v === 0 ? <Tag>{t('license.unlimited')}</Tag> : v}
                </Descriptions.Item>
              ))}
            </Descriptions>
          </>
        )}

        {status?.payload?.features && Object.keys(status.payload.features).length > 0 && (
          <>
            <Paragraph strong className="mt-24">{t('license.features')}</Paragraph>
            <Space wrap>
              {Object.entries(status.payload.features).map(([k, v]) => (
                <Tag color={v ? 'green' : 'default'} key={k}>{k}</Tag>
              ))}
            </Space>
          </>
        )}

        {status?.license_key && (
          <div className="mt-24">
            <Popconfirm
              title={t('license.confirmClear')}
              description={t('license.confirmClearHint')}
              okText={t('license.clearKey')}
              okButtonProps={{ danger: true }}
              onConfirm={() => clear.mutate()}
            >
              <Button danger>{t('license.clearKey')}</Button>
            </Popconfirm>
          </div>
        )}
      </Card>

      <Modal
        title={status?.license_key ? t('license.replaceKey') : t('license.enterKey')}
        open={open}
        onCancel={() => setOpen(false)}
        onOk={() => form.submit()}
        confirmLoading={setKey.isPending}
        okText={t('license.activate')}
        destroyOnHidden
      >
        <Paragraph type="secondary">{t('license.enterKeyHint')}</Paragraph>
        <Form form={form} layout="vertical" onFinish={(v) => setKey.mutate(v.license_key.trim())}>
          <Form.Item name="license_key" label={t('license.key')} rules={[{ required: true }]}>
            <Input.TextArea rows={3} placeholder="NMG-XXXX-XXXX-XXXX-XXXX" />
          </Form.Item>
        </Form>
      </Modal>
    </>
  )
}