import React, { useMemo, useState } from 'react'
import {
  Box,
  Button,
  Grid,
  GridItem,
  Heading,
  NumberInput,
  NumberInputInput,
  Stat,
  StatHelpText,
  StatLabel,
  StatValueText,
  Text,
  VStack,
} from '@chakra-ui/react'

import type { ABTestMetrics } from '../../__data__/types'
import { compareVariants } from '../../utils/analytics'

interface VariantFormState {
  submissionRate: number
  completionRate: number
  retryRate: number
  timeToFirstSubmission: number
  sessionDuration: number
  satisfactionScore?: number
}

const createVariantState = (): VariantFormState => ({
  submissionRate: 0,
  completionRate: 0,
  retryRate: 0,
  timeToFirstSubmission: 0,
  sessionDuration: 0,
  satisfactionScore: undefined,
})

const buildMetrics = (variant: 'A' | 'B', state: VariantFormState): ABTestMetrics => ({
  variant,
  submissionRate: state.submissionRate,
  completionRate: state.completionRate,
  retryRate: state.retryRate,
  timeToFirstSubmission: state.timeToFirstSubmission,
  sessionDuration: state.sessionDuration,
  satisfactionScore: state.satisfactionScore,
})

const MetricInput = ({
  label,
  value,
  onChange,
  suffix,
}: {
  label: string
  value: number
  onChange: (value: number) => void
  suffix?: string
}) => (
  <Box>
    <Text fontSize="sm" fontWeight="medium" mb={1}>
      {label}
    </Text>
    <NumberInput value={value} min={0} onChange={(_, val) => onChange(Number.isNaN(val) ? 0 : val)}>
      <NumberInputInput />
    </NumberInput>
    {suffix && (
      <StatHelpText fontSize="xs" color="gray.500">
        {suffix}
      </StatHelpText>
    )}
  </Box>
)

export const ABTestPanel = () => {
  const [variantA, setVariantA] = useState<VariantFormState>(createVariantState)
  const [variantB, setVariantB] = useState<VariantFormState>(createVariantState)
  const [comparison, setComparison] = useState<ReturnType<typeof compareVariants> | null>(null)

  const handleCompare = () => {
    const metricsA = buildMetrics('A', variantA)
    const metricsB = buildMetrics('B', variantB)
    setComparison(compareVariants(metricsA, metricsB))
  }

  const hasData = useMemo(
    () =>
      Object.values(variantA).some((value) => value !== 0) ||
      Object.values(variantB).some((value) => value !== 0),
    [variantA, variantB],
  )

  return (
    <Box borderWidth="1px" borderRadius="lg" borderColor="gray.200" bg="white" p={4}>
      <Heading size="sm" mb={4}>
        A/B тест: сравнение вариантов
      </Heading>

      <Grid templateColumns={{ base: '1fr', md: 'repeat(2, 1fr)' }} gap={4} mb={4}>
        <GridItem>
          <Heading size="xs" mb={2}>
            Вариант A
          </Heading>
          <VStack spacing={3} align="stretch">
            <MetricInput
              label="Submission Rate (%)"
              value={variantA.submissionRate}
              onChange={(value) => setVariantA((prev) => ({ ...prev, submissionRate: value }))}
              suffix="Процент пользователей, отправивших хотя бы одно решение"
            />
            <MetricInput
              label="Completion Rate (%)"
              value={variantA.completionRate}
              onChange={(value) => setVariantA((prev) => ({ ...prev, completionRate: value }))}
            />
            <MetricInput
              label="Retry Rate (%)"
              value={variantA.retryRate}
              onChange={(value) => setVariantA((prev) => ({ ...prev, retryRate: value }))}
            />
            <MetricInput
              label="Time to First Submission (мин)"
              value={variantA.timeToFirstSubmission}
              onChange={(value) => setVariantA((prev) => ({ ...prev, timeToFirstSubmission: value }))}
            />
            <MetricInput
              label="Session Duration (мин)"
              value={variantA.sessionDuration}
              onChange={(value) => setVariantA((prev) => ({ ...prev, sessionDuration: value }))}
            />
          </VStack>
        </GridItem>

        <GridItem>
          <Heading size="xs" mb={2}>
            Вариант B
          </Heading>
          <VStack spacing={3} align="stretch">
            <MetricInput
              label="Submission Rate (%)"
              value={variantB.submissionRate}
              onChange={(value) => setVariantB((prev) => ({ ...prev, submissionRate: value }))}
            />
            <MetricInput
              label="Completion Rate (%)"
              value={variantB.completionRate}
              onChange={(value) => setVariantB((prev) => ({ ...prev, completionRate: value }))}
            />
            <MetricInput
              label="Retry Rate (%)"
              value={variantB.retryRate}
              onChange={(value) => setVariantB((prev) => ({ ...prev, retryRate: value }))}
            />
            <MetricInput
              label="Time to First Submission (мин)"
              value={variantB.timeToFirstSubmission}
              onChange={(value) => setVariantB((prev) => ({ ...prev, timeToFirstSubmission: value }))}
            />
            <MetricInput
              label="Session Duration (мин)"
              value={variantB.sessionDuration}
              onChange={(value) => setVariantB((prev) => ({ ...prev, sessionDuration: value }))}
            />
          </VStack>
        </GridItem>
      </Grid>

      <Button onClick={handleCompare} colorScheme="teal" isDisabled={!hasData}>
        Сравнить варианты
      </Button>

      {comparison && (
        <Box mt={4} borderWidth="1px" borderRadius="md" borderColor="teal.200" bg="teal.50" p={4}>
          <Heading size="xs" mb={2}>
            Результат сравнения
          </Heading>
          <Grid templateColumns={{ base: '1fr', md: 'repeat(2, 1fr)' }} gap={4}>
            <Stat>
              <StatLabel>Δ Submission Rate</StatLabel>
              <StatValueText>{comparison.submissionRateDiff.toFixed(1)}%</StatValueText>
              <StatHelpText>Положительное значение — рост у варианта B</StatHelpText>
            </Stat>
            <Stat>
              <StatLabel>Δ Completion Rate</StatLabel>
              <StatValueText>{comparison.completionRateDiff.toFixed(1)}%</StatValueText>
              <StatHelpText>Положительное значение — рост у варианта B</StatHelpText>
            </Stat>
          </Grid>

          <Stat mt={4}>
            <StatLabel>Победитель</StatLabel>
            <StatValueText>Вариант {comparison.winner}</StatValueText>
            <StatHelpText>Основано на сравнении коэффициента завершения</StatHelpText>
          </Stat>
        </Box>
      )}
    </Box>
  )
}