import React, { useMemo, useState } from 'react'
import {
  Badge,
  Box,
  HStack,
  Heading,
  SimpleGrid,
  Table,
  TableBody,
  TableCell,
  TableColumnHeader,
  TableContainer,
  TableHeader,
  TableRow,
  Text,
  VStack,
  Select,
} from '@chakra-ui/react'

import {
  useGetAllSubmissionsQuery,
  useGetChainsQuery,
  useGetSystemStatsQuery,
} from '../../__data__/api/api'
import type { ChallengeChain } from '../../__data__/types'
import { StatCard } from '../../components/personal'
import { ABTestPanel } from '../../components/admin/ABTestPanel'
import { mapTaskMetrics, detectIssues, msToMinutes } from '../../utils/analytics'
import { keycloak } from '../../__data__/kc'

const formatNumber = (value: number | undefined) => {
  if (!value && value !== 0) return '—'
  return Intl.NumberFormat('ru-RU').format(value)
}

const hasTeacherRole = () => {
  try {
    return keycloak?.hasResourceRole?.('teacher', 'journal') ?? false
  } catch (error) {
    return false
  }
}

export const AdminDashboard = () => {
  const isTeacher = hasTeacherRole()
  const { data: systemStats, isLoading } = useGetSystemStatsQuery()
  const { data: chains = [] } = useGetChainsQuery(undefined, { skip: !isTeacher })
  const { data: submissions = [] } = useGetAllSubmissionsQuery(undefined, { skip: !isTeacher })

  const issues = useMemo(() => (systemStats ? detectIssues(systemStats) : []), [systemStats])
  const taskMetrics = useMemo(() => mapTaskMetrics(submissions), [submissions])
  const [difficultyFilter, setDifficultyFilter] = useState<'all' | 'easy' | 'medium' | 'hard'>('all')

  const filteredTaskMetrics = useMemo(() => {
    if (difficultyFilter === 'all') return taskMetrics
    return taskMetrics.filter((metric) => metric.difficulty === difficultyFilter)
  }, [difficultyFilter, taskMetrics])

  if (!isTeacher) {
    return (
      <Box bg="gray.50" minH="100vh" display="flex" alignItems="center" justifyContent="center">
        <Box borderWidth="1px" borderRadius="lg" borderColor="gray.200" bg="white" p={8} maxW="480px" textAlign="center">
          <Heading size="md" mb={4}>
            Требуется роль преподавателя
          </Heading>
          <Text color="gray.600">
            У вас нет доступа к панели администратора. Обратитесь к администратору Keycloak для назначения роли
            <Badge ml={2} colorScheme="purple">
              teacher
            </Badge>
            .
          </Text>
        </Box>
      </Box>
    )
  }

  if (isLoading || !systemStats) {
    return (
      <Box bg="gray.50" minH="100vh" display="flex" alignItems="center" justifyContent="center">
        <Text color="gray.500">Загружаем системные метрики...</Text>
      </Box>
    )
  }

  return (
    <Box bg="gray.50" minH="100vh" py={8} px={{ base: 4, md: 8 }}>
      <VStack align="stretch" spacing={8} maxW="1200px" mx="auto">
        <Heading size="lg">Панель преподавателя</Heading>

        <SimpleGrid minChildWidth="200px" spacing={4}>
          <StatCard title="Пользователей" value={formatNumber(systemStats.users)} icon="👥" />
          <StatCard title="Заданий" value={formatNumber(systemStats.tasks)} icon="🧩" />
          <StatCard title="Цепочек" value={formatNumber(systemStats.chains)} icon="🔗" />
          <StatCard title="Всего проверок" value={formatNumber(systemStats.submissions.total)} icon="✅" />
          <StatCard
            title="В ожидании"
            value={formatNumber(systemStats.queue.waiting)}
            icon="⏳"
          />
          <StatCard
            title="Среднее время проверки"
            value={`${msToMinutes(systemStats.averageCheckTimeMs)} мин`}
            icon="⏱️"
          />
        </SimpleGrid>

        <Box borderWidth="1px" borderRadius="lg" borderColor="gray.200" bg="white" p={4}>
          <Heading size="sm" mb={3}>
            Статус очереди
          </Heading>
          <SimpleGrid columns={{ base: 1, md: 3 }} spacing={4}>
            <Box>
              <Text fontSize="sm" color="gray.500">
                Всего в очереди
              </Text>
              <Text fontSize="lg" fontWeight="semibold">
                {formatNumber(systemStats.queue.queueLength)}
              </Text>
            </Box>
            <Box>
              <Text fontSize="sm" color="gray.500">
                В ожидании
              </Text>
              <Text fontSize="lg" fontWeight="semibold">
                {formatNumber(systemStats.queue.waiting)}
              </Text>
            </Box>
            <Box>
              <Text fontSize="sm" color="gray.500">
                В обработке
              </Text>
              <Text fontSize="lg" fontWeight="semibold">
                {formatNumber(systemStats.queue.currentlyProcessing)} / {formatNumber(systemStats.queue.maxConcurrency)}
              </Text>
            </Box>
          </SimpleGrid>
        </Box>

        <Box borderWidth="1px" borderRadius="lg" borderColor="gray.200" bg="white" p={4}>
          <Heading size="sm" mb={3}>
            Проблемные области
          </Heading>

          {issues.length === 0 ? (
            <Text color="green.500">Критических проблем не обнаружено.</Text>
          ) : (
            <VStack align="stretch" spacing={3}>
              {issues.map((issue) => (
                <Box
                  key={`${issue.type}-${issue.message}`}
                  borderWidth="1px"
                  borderRadius="md"
                  borderColor={issue.severity === 'high' ? 'red.200' : 'yellow.200'}
                  bg={issue.severity === 'high' ? 'red.50' : 'yellow.50'}
                  p={3}
                >
                  <Text fontWeight="medium">{issue.message}</Text>
                  <Text fontSize="sm" color="gray.600">
                    Сущность: {issue.affectedEntity} · Важность: {issue.severity}
                  </Text>
                </Box>
              ))}
            </VStack>
          )}
        </Box>

        <Box borderWidth="1px" borderRadius="lg" borderColor="gray.200" bg="white" p={4}>
          <HStack justify="space-between" mb={4} align="center">
            <Heading size="sm">Метрики по заданиям</Heading>
            <Select
              size="sm"
              width="200px"
              value={difficultyFilter}
              onChange={(event) => setDifficultyFilter(event.target.value as typeof difficultyFilter)}
            >
              <option value="all">Все сложности</option>
              <option value="easy">Лёгкие</option>
              <option value="medium">Средние</option>
              <option value="hard">Сложные</option>
            </Select>
          </HStack>

          {filteredTaskMetrics.length === 0 ? (
            <Text color="gray.500">Недостаточно данных о проверках для построения аналитики.</Text>
          ) : (
            <Box overflowX="auto">
              <Table size="sm" variant="simple">
                <TableHeader>
                  <TableRow>
                    <TableColumnHeader>Задание</TableColumnHeader>
                    <TableColumnHeader textAlign="right">Попыток</TableColumnHeader>
                    <TableColumnHeader textAlign="right">Успешность</TableColumnHeader>
                    <TableColumnHeader textAlign="right">Сред. попыток</TableColumnHeader>
                    <TableColumnHeader textAlign="right">Сред. время (мин)</TableColumnHeader>
                    <TableColumnHeader>Сложность</TableColumnHeader>
                  </TableRow>
                </TableHeader>
                <TableBody>
                  {filteredTaskMetrics.map((metric) => (
                    <TableRow key={metric.taskId}>
                      <TableCell>
                        <Text fontWeight="medium">{metric.title}</Text>
                        <Text fontSize="xs" color="gray.500">
                          ID: {metric.taskId}
                        </Text>
                      </TableCell>
                      <TableCell textAlign="right">{formatNumber(metric.attemptsCount)}</TableCell>
                      <TableCell textAlign="right">{formatNumber(Math.round(metric.successRate))}%</TableCell>
                      <TableCell textAlign="right">{formatNumber(Math.round(metric.avgAttempts * 10) / 10)}</TableCell>
                      <TableCell textAlign="right">{formatNumber(Math.round(msToMinutes(metric.avgTimeToComplete * 1000)))}</TableCell>
                      <TableCell>
                        <Badge colorScheme={metric.difficulty === 'hard' ? 'red' : metric.difficulty === 'medium' ? 'yellow' : 'green'}>
                          {metric.difficulty}
                        </Badge>
                      </TableCell>
                    </TableRow>
                  ))}
                </TableBody>
              </Table>
            </Box>
          )}
        </Box>

        <Box borderWidth="1px" borderRadius="lg" borderColor="gray.200" bg="white" p={4}>
          <Heading size="sm" mb={3}>
            Цепочки заданий
          </Heading>

          {chains.length === 0 ? (
            <Text color="gray.500">Цепочки не найдены. Создайте первое задание, чтобы начать.</Text>
          ) : (
            <VStack align="stretch" spacing={3}>
              {chains.map((chain: ChallengeChain) => (
                <Box key={chain.id} borderWidth="1px" borderRadius="md" borderColor="gray.200" p={3}>
                  <Text fontWeight="medium">{chain.name}</Text>
                  <Text fontSize="sm" color="gray.600">
                    Заданий: {chain.tasks.length} · Последнее обновление:{' '}
                    {new Date(chain.updatedAt).toLocaleString()}
                  </Text>
                </Box>
              ))}
            </VStack>
          )}
        </Box>

        <ABTestPanel />
      </VStack>
    </Box>
  )
}